DNA, RNA and proteins: The three essential macromolecules of life

 

From Wikipedia, the free encyclopedia

All living organisms are dependent on three types of very large molecules for essentially all of their biological functions. These molecules are DNA, RNA and proteins, and are classified as biological macromolecules.^[1] Without DNA, RNA and proteins, no known forms of life could exist. This is because each molecule plays an indispensable role in biology.^[2] The simple summary is that DNA makes RNA, and then RNA makes proteins.

DNA is an informational macromolecule that encodes the complete set of instructions (the genome) that are required to assemble, maintain, and reproduce every living organism.^[3]

Proteins are responsible for catalyzing the myriad biochemical reactions that are required to provide food and energy for every organism, and for all forms of movement. In addition proteins carry out all of the other functions of any given organism, for example photosynthesis, or, for example in animals, neural function, vision, and structure (skin, tendons, exoskeleton, etc.).^[4]

RNA is multifunctional, its primary responsibility is to make proteins, according to the instructions encoded within a cell’s DNA. They control and regulate many aspects of protein synthesis in eukaryotes.

 

Contents

• 1 Comparison of DNA, RNA and proteins
• 2 Common structural features of DNA, RNA and proteins
• 3 Divergent structural features
• 4 Why DNA is best for encoding genetic information
• 5 Why proteins are best for catalyzing biological reactions
• 6 Why RNA is multifunctional
• 7 DNA, RNA and proteins in molecular evolution
• 8 See also
• 9 References

Comparison of DNA, RNA and proteins

Common structural features of DNA, RNA and proteins

While many typical cellular molecules (for example sugars and fats) contain tens, or rarely hundreds, DNA, RNA and proteins are typically composed of thousands of atoms (millions for most DNA molecules).

DNA, RNA and proteins are all polymers, long molecules that consist of a repeating structure of related building blocks (also termed monomers; nucleotides in the case of DNA and RNA, amino acids in the case of proteins). In general, DNA, RNA and proteins are all unbranched polymers, and so can be represented in the form of a string. Indeed, they can be viewed as a string of beads, with each bead representing a single nucleotide or amino acid monomer linked together through covalent chemical bonds into a very long chain.

In most cases, the monomers within the chain have a strong propensity to interact with other amino acids or nucleotides. In DNA and RNA, this can take the form of Watson-Crick base pairs (G-C and A-T or A-U), although many more complicated interactions can and do occur.

Divergent structural features

Because of the double-stranded nature of DNA, essentially all of the nucleotides take the form of Watson-Crick pairs between nucleotides on the two complementary strands of the double helix.

In contrast, both RNA and proteins are normally single-stranded. Therefore, they are not constrained by the regular geometry of the DNA double helix, and can and do fold into a vast number of complex three-dimensional shapes. These different shapes are responsible for many of the common properties of RNA and proteins, including the formation of specific binding pockets, and the ability to catalyze biochemical reactions.

 

Why DNA is best for encoding genetic information

DNA and RNA are both capable of encoding genetic information, because there are biochemical mechanisms which read the information coded within a DNA or RNA sequence and use it to generate a specified protein. On the other hand, the sequence information of a protein molecule is not used by cells to functionally encode genetic information.

DNA has three primary attributes that allow it to be far better than RNA at encoding genetic information. First, it is normally double-stranded, so that there are a minimum of two copies of the information encoding each gene in every cell. Second, DNA has a much greater stability against breakdown than does RNA, an attribute primarily associated with the absence of the 2'-hydroxyl group within every nucleotide of DNA. Third, highly sophisticated DNA surveillance and repair systems are present which monitor damage to the DNA and repair the sequence when necessary. Analogous systems have not evolved for repairing damaged RNA molecules.

 

Why proteins are best for catalyzing biological reactions

The single-stranded nature of protein molecules, together with their composition of 20 or more different amino acid building blocks, allows them to fold in to a vast number of different three-dimensional shapes, while providing binding pockets through which they can specifically interact with all manner of molecules. In addition, the chemical diversity of the different amino acids, together with different chemical environments afforded by local 3D structure, enables many proteins to act as enzymes, catalyzing a wide range of specific biochemical transformations within cells. In addition, proteins have evolved the ability to bind a wide range of cofactors and coenzymes, smaller molecules that can endow the protein with specific activities beyond those associated with the polypeptide chain alone.

 

Why RNA is multifunctional

RNA encodes genetic information that can be translated into the amino acid sequence of proteins, as evidenced by the messenger RNA molecules present within every cell, and the RNA genomes of a large number of viruses. The single-stranded nature of RNA, together with tendency for rapid breakdown and a lack of repair systems means that RNA is not so well suited for the long-term storage of genetic information as is DNA.

In addition, RNA is a single-stranded polymer that can, like proteins, fold into a very large number of three-dimensional structures. Some of these structures provide binding sites for other molecules and chemically-active centers that can catalyze specific chemical reactions on those bound molecules. The limited number of different building blocks of RNA (4 nucleotides vs >20 amino acids in proteins), together with their lack of chemical diversity, results in catalytic RNA (ribozymes) being generally less-effective catalysts than proteins for most biological reactions.

 

References

Berg, Jeremy Mark; Tymoczko, John L.; Stryer, Lubert (2010). Biochemistry, 7th ed. (Biochemistry (Berg)). W.H. Freeman & Company. ISBN 1-4292-2936-5. Fifth edition available online through the NCBI Bookshelf: link

Walter, Peter; Alberts, Bruce; Johnson, Alexander S.; Lewis, Julian; Raff, Martin C.; Roberts, Keith (2008). Molecular Biology of the Cell (5th edition, Extended version). New York: Garland Science. ISBN 0-8153-4111-3.. Fourth edition is available online through the NCBI Bookshelf: link

Golnick, Larry; Wheelis, Mark. The Cartoon Guide to Genetics. Collins Reference. ISBN 978-0-06-273099-2.

Takemura, Masaharu (2009). The Manga Guide to Molecular Biology. No Starch Press. ISBN 978-1-59327-202-9.

http://en.wikipedia.org/wiki/DNA,_RNA_and_proteins:_The_three_essential_macromolecules_of_life

Why thymine instead of uracil?

 

by Piter Kehoma Boll | September 29, 2012 · 12:05 pm

About a year ago, while I was in my class of Techniques of Molecular Diagnosis, an interesting doubt sprouted: why does DNA use thymine instead of uracil as RNA does?

I hope everybody reading this knows about nucleic acids and the difference between DNA and RNA. As a very quick review:

RNA (ribonucleic acid) is a polymer made of ribonucleotides, compound molecules made of three parts, or smaller molecules: a nitrogenous base (adenine, uracil, cytosine or guanine), a ribose sugar and a phosphate group.

DNA (deoxyribonucleic acid) is similar, but instead of uracil it has thymine, and instead of a ribose sugar is has a deoxyribose, so that it is made of deoxyribonucleotides. Another difference is that DNA is a double chain twisted helicoidally, where two nitrogenous bases (each from one of the chains) are connected. Adenine is always connected to thymine and cytosine always to guanine, so that one chain is always dependent on the other.

Currently it’s highly accepted that RNA was the first nucleic acid to exist and that DNA evolved from it, so the changes in the sugar and one of the nitrogenous bases must have some advantage.

To understand that, let’s take a look at the structure of the uracil:

Uracil

The only difference between it and thymine is the presence of a methyl group at the last one:

Thymine

In fact, thymine is also called 5-methyluracil. But let’s go to the explanation:

While nucleotides are synthesized, the nucleotide-monophosphates (NMPs), i.e., the set nitrogenous base + sugar + phosphate is dehydroxylated, creating 2’-deoxy-nucleotide-monophosphate (dNMPs), i.e., GMP, AMP, CMP and UMP (for guanine, adenine, cytosine and uracil) are changed to dGMP, dAMP, dCMP and dUMP.

This modification by dehydroxylation has been shown to make the phosphodiester bonds (the bonds of phosphates on the sugar) less susceptible to hydrolysis and damage by UV radiation. It assures that a DNA molecule will not be as easy to be broken as an RNA molecule, which is very useful since DNA carries all the information to build up the organism.

After the dehydroxilation of the nucleotide-monophosphates, the next step, catalyzed by folic acid, add a methyl group to the uracil to form a thymine, so turning dUMP into dTMP.

There are many explanations for that:

1. Despite uracil’s tendency to pair with adenine, it can also pair with any other base, including itself. By adding a methyl group (which is hydrophobic) and turning it into thymine, its position is reorganized in the double-helix, not allowing those wrong pairings to happen.

2. Cytosine can deaminate to produce uracil. You can see in the picture below that the only difference between them is the change from an O in uracil to an NH2 in cytosine. The problem is that, if uracil were a component of DNA, the repair systems would not be able to distinguish original uracil from uracil originated by deamination of cytosine. So using thymine instead makes it way easier and more stable, as any uracil inside DNA must come from a cytosine and so it can be replaced by a new cytosine.

Cytosine

This didn’t evolve for that purpose, of course. Evolution cannot predict what happens. Probably during the earliest times of life, eventually an error changed uracil for thymine and it was found to be more stable to carry information, since such a molecule wouldn’t be destroyed so easily and thus would succeed in passing its “layout” to the next generation.

It makes me wonder… Could some alien life form have found an alternative way to deal with RNA’s (or something equivalent) instability?

– – –

Main Reference:

Jonsson, J. (1996). The Evolutionary Transition from Uracil to Thymine Balances the Genetic Code Journal of Chemometrics, 10, 163-170 DOI: 10.1002/(SICI)1099-128X(199603)10:2

https://earthlingnature.wordpress.com/2012/09/29/why-thymine-instead-of-uracil/

DNA, genes and chromosomes

 

Your genes are part of what makes you the person you are. You are different from everyone alive now and everyone who has ever lived.

 

DNA

But your genes also mean that you probably look a bit like other members of your family. For example, have you been told that you have 'your mother's eyes' or 'your grandmother's nose'?

Genes influence what we look like on the outside and how we work on the inside. They contain the information our bodies need to make chemicals called proteins. Proteins form the structure of our bodies, as well playing an important role in the processes that keep us alive.

Genes are made of a chemical called DNA, which is short for 'deoxyribonucleic acid'. The DNA molecule is a double helix: that is, two long, thin strands twisted around each other like a spiral staircase.

The DNA double helix showing base pairs

The sides are sugar and phosphate molecules. The rungs are pairs of chemicals called 'nitrogenous bases', or 'bases' for short.

There are four types of base: adenine (A), thymine (T), guanine (G) and cytosine (C). These bases link in a very specific way: A always pairs with T, and C always pairs with G.
The DNA molecule has two important properties.

• It can make copies of itself. If you pull the two strands apart, each can be used to make the other one (and a new DNA molecule).
• It can carry information. The order of the bases along a strand is a code - a code for making proteins.

Genes

A gene is a length of DNA that codes for a specific protein. So, for example, one gene will code for the protein insulin, which is important role in helping your body to control the amount of sugar in your blood.

Genes are the basic unit of genetics. Human beings have 20,000 to 25,000 genes. These genes account for only about 3 per cent of our DNA. The function of the remaining 97 per cent is still not clear, although scientists think it may have something to do with controlling the genes.

Chromosomes

If you took the DNA from all the cells in your body and lined it up, end to end, it would form a strand 6000 million miles long (but very, very thin)! To store this important material, DNA molecules are tightly packed around proteins called histones to make structures called chromosomes.

The packaging of DNA into chromosomes

Human beings have 23 pairs of chromosomes in every cell, which makes 46 chromosomes in total. A photograph of a person's chromosomes, arranged according to size, is called a karyotype.

The sex chromosomes determine whether you are a boy (XY) or a girl (XX). The other chromosomes are called autosomes.

The karyotype of a male human being

The largest chromosome, chromosome 1, contains about 8000 genes. The smallest chromosome, chromosome 21, contains about 300 genes. (Chromosome 22 should be the smallest, but the scientists made a mistake when they first numbered them!).

The DNA that contains your genes is stored in your cells in a structure called the nucleus.

A diagram of animal cell showing the nucleus

Back to top

This work is licensed under a Creative Commons Licence.

http://www2.le.ac.uk/departments/genetics/vgec/highereducation/topics/dnageneschromosomes

NASA Rebuilds 3 Building Blocks of Life, What Next?

Left to right: Ames scientists Michel Nuevo, Christopher Materese and Scott Sandford reproduce uracil, cytosine, and thymine, three key components of our hereditary material, in the laboratory. Image Credit: NASA/ Dominic Hart

 

in SCIENCE March 4, 2015

Now that NASA scientists have reproduced uracil, cytosine, and thymine, three key components of our hereditary material, in the laboratory, the question is how would it help the mankind or replicate the mankind in outer space.

NASA said its scientists discovered that an ice sample containing pyrimidine exposed to ultraviolet radiation under space-like conditions was able to produce the three essential ingredients of life.

Pyrimidine is a ring-shaped molecule made up of carbon and nitrogen and is the central structure for uracil, cytosine, and thymine, which are found in RNA and DNA. Image Credit: NASA

The ring-shaped molecule pyrimidine is found in cytosine and thymine. Image Credit: NASA

Pyrimidine molecule is made up of carbon and nitrogen and is the central structure for uracil, cytosine, and thymine, which together form the genetic code found in ribonucleic (RNA) and deoxyribonucleic acids (DNA). RNA and DNA are key to protein synthesis, besides other uses.

“We have demonstrated for the first time that we can make uracil, cytosine, and thymine, all three components of RNA and DNA, non-biologically in a laboratory under conditions found in space,” said Michel Nuevo of NASA’s Ames Research Center in California.

“We are showing that these laboratory processes, which simulate conditions in outer space, can make several fundamental building blocks used by living organisms on Earth,” said Dr. Nuevo.

Nobody really understands how life began on Earth but now these scientists say their experiments suggest that once the Earth formed, many of the building blocks of life were likely present from the beginning. “Since we are simulating universal astrophysical conditions, the same is likely wherever planets are formed,” says Scott Sandford, a space scientist at Ames, which means replication of life in outer space is the next step that NASA may undertake.

The research was funded by the NASA Astrobiology Institute (NAI) and the NASA Origins of Solar Systems Program.

http://www.microfinancemonitor.com/2015/03/04/nasa-rebuilds-3-building-blocks-of-life-what-next/

NASA to send submarine to Saturn’s moon Titan

 

By: PTI | Washington | February 17, 2015 7:08 pm

US Space agency NASA's single-tonne concept robot submarine is equipped with a seafloor camera and sampling system. (Reuters)

 

NASA is planning to send a nuclear-powered submarine to explore one of the methane seas located on Saturn’s moon Titan.

The single-tonne concept robot submarine is equipped with a seafloor camera and sampling system.

The submarine could fit into a space plane such as Boeing’s X-37, which was recently used for a classified Air Force mission.

The plane could land on Kraken Mare, the largest known body of liquid on Titan that consists mostly of liquid methane, or possibly drop the submarine using a parachute, ‘ibtimes.com’ reported.

“The vehicle would use conventional propulsors to yaw around, using a sun sensor to determine the initial azimuth to Earth and begin communication using a terrestrial radio as a more precise reference,” NASA said.

NASA hopes to use the submarine to explore the chemistry of Titan’s seafloor and sea composition, as well as study its tides, weather, shoreline, islands and search for any type of life.

The submarine concept was showcased by NASA Glenn’s COMPASS Team and researchers from Applied Research Lab at the NASA Innovative Advanced Concepts (NIAC) Symposium in Florida.

The concept of the submarine is still in its very early stages, but the team expects that it may be up and running by 2047.

“Measurement of the trace organic components of the sea, which perhaps may exhibit prebiotic chemical evolution, will be an important objective, and a benthic sampler (a robotic grabber to sample sediment) would acquire and analyse sediment from the seabed,” the US space agency explained.

These measurements, and seafloor morphology via sidescan sonar, may shed light on the historical cycles of filling and drying of Titan’s seas.

Models suggest Titan’s active hydrological cycle may cause the north part of Kraken to be ‘fresher’ (more methane-rich) than the south, and the submarine’s long traverse will explore these composition variations.

http://www.financialexpress.com/article/lifestyle/science/nasa-to-send-submarine-to-saturns-moon-titan/44138/

Mysterious giant clouds spotted on Mars

 

Feb 17, 2015, 04.59 PM IST

On two separate occasions in March and April 2012, amateur astronomers reported definite plume-like features developing on the planet.

LONDON: Mysterious cloud-like plumes seen reaching high above the surface of Mars have puzzled scientists studying the atmosphere of the Red Planet.

On two separate occasions in March and April 2012, amateur astronomers reported definite plume-like features developing on the planet.

The plumes were seen rising to altitudes of over 250km above the same region of Mars on both occasions. By comparison, similar features seen in the past have not exceeded 100km.

"At about 250km, the division between the atmosphere and outer space is very thin, so the reported plumes are extremely unexpected," said Agustin Sanchez-Lavega of the Universidad del Pais Vasco in Spain, lead author of the paper published in the journal Nature.

The features developed in less than 10 hours, covering an area of up to 1000 x 500 km, and remained visible for around 10 days, changing their structure from day to day.
None of the spacecraft orbiting Mars saw the features because of their viewing geometries and illumination conditions at the time, researchers said.

However, checking archived Hubble Space Telescope images taken between 1995 and 1999 and of databases of amateur images spanning 2001 to 2014 revealed occasional clouds at the limb of Mars, albeit usually only up to 100km in altitude.

But one set of Hubble images from May 17, 1997 revealed an abnormally high plume, similar to that spotted by the amateur astronomers in 2012.

Scientists are now working on determining the nature and cause of the plumes by using the Hubble data in combination with the images taken by amateurs.

"One idea we've discussed is that the features are caused by a reflective cloud of water-ice, carbon dioxide-ice or dust particles, but this would require exceptional deviations from standard atmospheric circulation models to explain cloud formations at such high altitudes," said Agustin.

"Another idea is that they are related to an auroral emission, and indeed auroras have been previously observed at these locations, linked to a known region on the surface where there is a large anomaly in the crustal magnetic field," added Antonio Garcia Munoz, a research fellow at ESA's ESTEC and co-author of the study.

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READ ALSO: Kerala girl a step away from ticket to Mars
3 Indians in 100 shortlisted for one way trip to Mars

http://timesofindia.indiatimes.com/Home/Science/Mysterious-giant-clouds-spotted-on-Mars/articleshow/46274950.cms

Life on Earth May Have Begun 1 Billion Years Earlier Than Thought, Scientists Say

 

Feb 17, 2015, 10:02 AM ET

By ALYSSA NEWCOMB

The earliest life forms may have blossomed on Earth 1 billion years earlier than previously thought.

Working together, scientists at the University of Washington and the University of Johannesburg in South Africa found evidence that life may have thrived on Earth 3.2 billion years ago, upending the belief that Earth's atmosphere at the time was uninhabitable.

The study is based on an analysis of 52 rock samples collected in South Africa and northwestern Australia and range in age from 2.75 to 3.2 billion years old.

Roger Buick, a University of Washington professor and co-author of the article that was published Monday in the journal Nature, said the rock samples his team analyzed showed that there was plentiful nitrogen 3.2 billion years ago to sustain the most basic life forms, including bacteria, viruses and other organisms.

While life can exist without oxygen, nitrogen is an essential building block for genes.

"People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn't until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse," Buick told UW Today.

Rosetta Space Probe Takes Sharp, Close-up Images of Comet

Titan: How NASA Got the Clearest Photo Ever of Saturn's Moon

Astronomers Discover Ancient Solar System With 5 Earth-Like Planets

 

http://abcnews.go.com/Technology/life-earth-begun-billion-years-earlier-thought-scientists/story?id=29017106

Einstein's Theory of General Relativity

by Nola Taylor Redd, SPACE.com Contributor   |   September 18, 2012 06:52pm ET

Einstein's theory of general relativity predicted that the space-time around Earth would be not only warped but also twisted by the planet's rotation. Gravity Probe B showed this to be correct.

In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers. This was the theory of special relativity. It introduced a new framework for all of physics and proposed new concepts of space and time.

Einstein then spent ten years trying to include acceleration in the theory and published his theory of general relativity in 1915. In it, he determined that massive objects cause a distortion in space-time, which is felt as gravity.

The tug of gravity

Two objects exert a force of attraction on one another known as "gravity." Even as the center of the Earth is pulling you toward it (keeping you firmly lodged on the ground), your center of mass is pulling back at the Earth, albeit with much less force. Sir Isaac Newton quantified the gravity between two objects when he formulated his three laws of motion. Yet Newton's laws assume that gravity is an innate force of an object that can act over a distance.

Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels. As a result, he found that space and time were interwoven into a single continuum known as space-time. Events that occur at the same time for one observer could occur at different times for another.

As he worked out the equations for his general theory of relativity, Einstein realized that massive objects caused a distortion in space-time. Imagine setting a large body in the center of a trampoline. The body would press down into the fabric, causing it to dimple. A marble rolled around the edge would spiral inward toward the body, pulled in much the same way that the gravity of a planet pulls at rocks in space.

Experimental evidence

Although instruments can neither see nor measure space-time, several of the phenomena predicted by its warping have been confirmed.

 Einstein's Cross is an example of gravitational lensing.
Credit: NASA and European Space Agency (ESA)

Gravitational lensing: Light around a massive object, such as a black hole, is bent, causing it to act as a lens for the things that lay behind it. Astronomers routinely use this method to study stars and galaxies behind massive objects.

Einstein's Cross, a quasar in the Pegasus constellation, is an excellent example of gravitational lensing. The quasar is about 8 billion light-years from Earth, and sits behind a galaxy that is 400 million light-years away. Four images of the quasar appear around the galaxy because the intense gravity of the galaxy bends the light coming from the quasar.

Changes in the orbit of Mercury: The orbit of Mercury is shifting very gradually over time, due to the curvature of space-time around the massive sun. In a few billion years, it could even collide with the Earth.

Frame-dragging of space-time around rotating bodies: The spin of a heavy object, such as Earth, should twist and distort the space-time around it. In 2004, NASA launched the Gravity Probe B. The precisely calibrated satellite caused the axes of gyroscopes inside to drift very slightly over time, a result that coincided with Einstein's theory.

Gravitational redshift: The electromagnetic radiation of an object is stretched out slightly inside a gravitational field. Think of the sound waves that emanate from a siren on an emergency vehicle; as the vehicle moves toward an observer, sound waves are compressed, but as it moves away, they are stretched out, or redshifted. Known as the Doppler Effect, the same phenomena occurs with waves of light at all frequencies. In 1959, two physicists, Robert Pound and Glen Rebka, shot gamma rays of radioactive iron up the side of a tower at Harvard University and found them to be minutely less than their natural frequency due to distortions caused by gravity.

Gravitational waves: Violent events, such as the collision of two black holes, are thought to be able to create ripples in space-time known as gravitational waves. The Laser Interferometer Gravitational Wave Observatory is presently searching for the first signs of these tell-tale indicators.

— Nola Taylor Redd, SPACE.com Contributor

Related:

• Video: Flying Space-time's Warps and Twists
• Top 10 Strangest Things in Space
• Twisted Physics: 7 Mind-Blowing Findings

http://www.space.com/17661-theory-general-relativity.html?cmpid=514630_20150207_40021356&adbid=10152625773696466&adbpl=fb&adbpr=17610706465

Seven new galaxies discovered

20 Nov, 2014 at 12:41:PM IST

In a surprising development which could provide a deeper insight into the universe, seven new galaxies have been galaxies have been discovered by the astronomers.

The Subaru Telescope in Japan was used by a team of astronomers, led by graduate student Akira Konno and Dr Masami Ouchi, to identify to search a particular type called Lyman-alpha Emitters (LAEs) which are low mass galaxies.

According to astronomers, the most massive objects in the universe are galaxy clusters as they contain hundreds to thousands of galaxies. The gravitational force keeps the galaxies together.

It is notable that Big Bang led to the creation of the universe about 13.8 billion years ago. It was the time when stars and galaxies were formed initially and later their ultraviolet light ionised which is a process called 'cosmic reionisation'.

The astronomers have searched for early LAE galaxies at a distance of 13.1 billion light years, in a bid to investigate the phenomenon of cosmic reionisation.

"At first we were very disappointed at this small number. But we realised that this indicates LAEs appeared suddenly about 13 billion years ago. This is an exciting discovery. We can see that the luminosities suddenly brightened during the 700 to 800 million years after the Big Bang. What would cause this?" Konno said.

The findings of the study are published in the Astrophysical Journal.

http://www.delhidailynews.com/news/Seven-new-galaxies-discovered-1416467462/

Two New Subatomic Particles Found Using Large Hadron Collider, Scientists Say

Discovery Helps Understanding of How Things Operate on Very Small Scale

Technicians worked on part of the Large Hadron Collider at CERN in July.

Gautam Naik

Updated Nov. 19, 2014 10:14 a.m. ET

Scientists using the atom-smashing machine known as the Large Hadron Collider said Wednesday they had observed two new particles never seen before, a discovery that refines physicists’ understanding of how elementary particles interact and the forces between them.

Theoretical models had predicted the existence of the particles. Scientists used the collider to smash particles together and then sifted through the result to pinpoint the existence of the new particles and identify their mass.

“Now we know exactly what the mass is,” said Patrick Koppenburg from the Netherlands’ Nikhef Institute. Dr. Koppenburg is currently based at the European Organization for Nuclear Research, or CERN, which operates the world’s largest and most powerful particle accelerator, the Large Hadron Collider.

The new particles are six times as large as the proton, the positively-charged subatomic particle that is found in the nucleus of every atom.

The new particles are members of the baryon family, which also includes protons and neutrons. Baryons are made from three quarks, which are the building blocks of matter.

The observation of the baryons isn't of the same consequence as the CERN‘s 2012 discovery of the Higgs boson, which is a fundamental particle that helps explain how particles get their mass. But because it is extremely hard to model how baryons behave, the new discovery is a significant contribution to our understanding of how things operate on the scale of the very small.

“There are maybe three-to-five such particles discovered each year,” said Dr. Koppenburg. “Here we have two in one go, which is quite extraordinary.”

The measurements that pinpointed the baryons were based on data collected at the Large Hadron Collider during 2001 and 2012. It is currently shut down and is scheduled to restart by the spring and to operate at higher energies and using more intense beams than before.

http://online.wsj.com/articles/two-new-subatomic-particles-found-using-large-hadron-collider-scientists-say-1416409980

Facts about Titan

• Titan's atmosphere
• Titan's surface
• Life on Titan?

Titan, Saturn's largest moon

Titan is the largest moon of Saturn, the second largest in the Solar System (after Ganymede of Jupiter). It was discovered by Christiaan Huygens in 1655.

Titan's rotation period of about 16 days is synchronous to Saturn (meaning the same side always faces Saturn). It is the only moon in the Solar System known to have clouds and a thick, planet-like atmosphere.

Distance from Saturn
1 221 870 km

Distance from Sun
1 427 000 000 km (9.54 AU)

Diameter (atmosphere)
5550 km

Diameter (surface)
5150 km

Mass
1/45 that of Earth

Average density
1.881 times liquid water

Surface temperature
94K (-180 degrees C)

Atmospheric pressure at surface
1500 mbar (1.5 times Earth's)

Atmospheric composition
Nitrogen, methane, traces of ammonia, argon, ethane

Orbital period (Titanic day)
15.95 Earth days

Titan’s atmosphere

NASA's Voyager 1 provided the first detailed images of Titan in 1980. They showed only an opaque, orange atmosphere, apparently homogeneous.

It was so thick that you could not see the surface. However, other data revealed exciting things. Similarly to Earth, Titan's atmosphere is mostly nitrogen but there is also methane and many other organic compounds.

Before the arrival of the ESA Huygens probe, planned for January 2005, astronomers will observe Titan using the most powerful ground-based telescopes.

 

Titan's murky atmosphere with the Huygens probe descending on the left

Images from the WM Keck Observatory reveal methane-containing clouds near Titan's south pole. This could mean that Titan has the equivalent of a weather cycle similar to ours on Earth.

This is a major discovery which means that the atmosphere is much more dynamic than previously thought.

The NASA Cassini orbiter will clearly see these clouds, carrying out precise observations before, during and after releasing the Huygens probe.

First view of Titan from Cassini-Huygens

Titan’s surface

Over the years, scientists have dramatically changed their minds about Titan's surface. In the 1990s, the NASA/ESA Hubble Space Telescope spied an area on Titan that was brighter than the rest.

More recent observations show the same feature better. What are these bright and dark patches? Some scientists believe the bright area could be a continent and the rest oceans, but no one knows for sure, yet.

The recently discovered large continent-sized feature (red) is called Xanadu. It is unclear whether Xanadu is a mountain range, a giant basin, a smooth plain or a combination of all three. It may be dotted with hydrocarbon lakes but that is also unknown.

All that is presently known is that in Earth-based images, it is the brightest region on Titan. There is no doubt, though, that the surface appears very diverse, not uniform. There are a lot of surprises waiting for us there.

Where will Huygens land? ESA scientists predict the probe will land close to the bright patch, but not on it. This could be a landing in an ocean - which would be the first splashdown landing in an ocean off the Earth!

To land on an ocean would probably mean better data from Huygens. Even if the probe lasted only a few minutes before sinking, it would at least stay in an upright position. Being the right way up is essential for sending the data back to the Cassini orbiter and to the scientists on Earth.

Moreover, some of Huygens's instruments are better prepared to analyse liquids. If Huygens lands on a solid surface instead, there is a higher risk of falling in the wrong direction and not being able to easily communicate with Cassini.

Life on Titan

Will Huygens land or splashdown on Titan?

Titan, Saturn's largest moon, is a mysterious place. Its thick atmosphere is rich in organic compounds. Some of them would be signs of life if they were on our planet.

How do they form on Titan? Will they help us to discover how life began on Earth?

Titan's atmosphere is mostly nitrogen but there are also methane and many other organic compounds. Organic compounds form when sunlight destroys methane. If sunlight is continuously destroying methane, how is methane getting into the atmosphere?

On Earth today, it is life itself that refreshes the methane supply. Methane is a by-product of the metabolism of many organisms. On Earth, the simplest biological sources, such as those associated with peat bogs, rice fields and ruminant animals, continuously supply fresh gas to replace that destroyed by oxidation. Could this mean there is life on Titan?

Titan is not a pleasant place for life. It is far too cold for liquid water to exist, and all known forms of life need liquid water. Titan's surface is -180°C. According to one exotic theory, long ago, the impact of a meteorite, for example, might have provided enough heat to liquify water for perhaps a few hundred or thousand years.

However, it is unlikely that Titan is a site for life today. But scientists are still currently puzzled by the amount of methane that persists in Titan's atmosphere. Could there be oceans of methane on or under the surface?

http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Facts_about_Titan

Titan: Overview

 

Saturn's moon Tethys with its prominent Odysseus Crater silently slips behind Saturn's largest moon Titan.

Titan is Saturn's largest moon. It is surrounded by a thick, golden haze, and only certain kinds of telescopes and cameras can see through the haze to the surface. Titan is of great interest to scientists because it has flowing liquids on its surface and a dense, complex atmosphere.

10 Need-To-Know Things About Titan

1. If the sun were as tall as a typical front door, Earth would be the size of a nickel and Titan would be the size of a pea.
2. Titan is a moon that orbits the planet Saturn. Saturn is the sixth planet from the sun at a distance of about 1.4 billion km (886 million miles) or 9.5 AU.
3. One day on Titan (the time it takes for Titan to rotate or spin once) takes about 16 Earth days. The length of Titan's day is the same as the amount of time it takes Titan to orbit Saturn. Saturn makes a complete orbit around the sun (one Saturn year) in about 29 Earth years (10,759 Earth days).
4. Like many other moons (including Earth's moon), Titan is locked by gravity to its planet so that the same side always faces toward Saturn.
5. Titan has been called the most earthlike world in the solar system because it has lakes, seas and flowing rivers on its surface, although the liquid is methane (CH₄) and ethane (C₂H₆) instead of water.
6. Like Earth, Titan's atmosphere is mostly nitrogen (N₂). It also contains small amounts of methane and other complex hydrocarbons. Titan's atmosphere is slightly denser than Earth's.
7. Titan does not have rings. Its gravity helps to shape ringlets, gaps and other structures in Saturn's rings.
8. Titan has been visited by two spacecraft and one surface lander. Voyager 2 made the first flyby of Titan in 1980. The Cassini spacecraft has made scores of flybys of Titan since 2004. The Huygens probe, carried to Saturn by Cassini, parachuted to the surface in 2005.
9. Scientists who study living things do not think life as we know it is likely on Titan's surface. Some scientists think Titan's subsurface ocean might contain a habitable environment.
10. Seas on Titan are named for mythical sea monsters, while its mountains are named for mountains found in the works of author J.R.R. Tolkien.

Saturn's moon Tethys with its prominent Odysseus Crater silently slips behind Saturn's largest moon Titan.

Titan is the biggest of 53 confirmed moons orbiting Saturn (another 9 moons are being confirmed). Titan is a frigid world enveloped by a thick, hazy atmosphere that obscures its surface. Titan has been studied in great detail only in the past few years, with the arrival of the Cassini-Huygens mission at Saturn in 2004.

Titan is the second largest moon in our solar system, with an equatorial radius of 2,575 km (1,600 miles). It is bigger than Earth's moon, and even larger than the planet Mercury.

Only Jupiter's moon Ganymede is larger than Titan, with a diameter barely 112 km (62 miles) greater.

The temperature at Titan's surface is about -178 degrees Celsius (-289 degrees Fahrenheit). At this frigid temperature, water ice is as hard as rock - in fact, most of the rock on Titan's surface is water ice.

Titan orbits Saturn at a distance of about 1.2 million km (745,000 miles), taking almost 16 days to complete a full orbit.

Titan is of great interest to scientists because it is the only other place in the solar system known to have an earthlike cycle of liquids flowing across its surface. That Titan has seas of liquid methane was suspected before the first spacecraft flyby, but its opaque atmosphere prevented close inspection even then. In 1980, NASA's Voyager 1 spacecraft tried to take close up images of the natural features of Titan's landscape, but was unable to penetrate the thick clouds. Instead, the images showed only slight color and brightness variations in the atmosphere. Titan's atmospheric pressure is about 60 percent greater than Earth's -- roughly the same pressure found at the bottom of a swimming pool.

In 1994, NASA's Hubble Space Telescope recorded pictures of Titan, which suggested that a huge bright continent exists on the hemisphere that faces forward in orbit. These Hubble results didn't prove that liquid seas existed, however; only that Titan has large bright and dark regions on its surface.

NASA's Cassini spacecraft (currently orbiting Saturn) has finally revealed the mysterious moon's true nature. Cassini was specially designed to peer through Titan's haze with radar and in certain colors of light, called spectral windows, that allow a glimpse of what lies below. During dozens of flybys, the Cassini orbiter has mapped a large fraction of Titan's surface and made detailed studies of its atmosphere. Cassini also carried the European-built Huygens probe, which parachuted through Titan's atmosphere in 2005 to make the first landing on a body in the outer solar system.

From Cassini-Huygens, we now know that Titan has lakes and seas of liquid methane (natural gas) and ethane near its poles. These bodies of standing liquids appear to grow and shrink in a seasonal cycle as storms bring rain to one hemisphere, then the other. The mission has revealed drainage channels on the surface that were carved by flowing liquid.

Cassini's radar instrument revealed that large swaths of the surface near the equator are blanketed by dune fields, similar to the Namibian desert on Earth. The mission has also found that Titan has an internal ocean of liquid water.

Because of the extremely cold temperatures at Titan's distance from the sun, chemical processes take longer to unfold, leaving the chemistry of the moon's atmosphere in a state of deep freeze. This carbon-rich chemistry is of great interest to scientists because it could be similar to the atmosphere of early Earth, before life emerged on our planet.

Discovery:
Titan was discovered on 25 March 1655 by the Dutch astronomer Christiaan Huygens.

How Titan Got its Name:
The name Titan comes from a generic term for the children of Ouranos (Uranus) and Gaia in ancient Greek mythology. In the stories, the Titans were the ancestors of the human race. The Titans were known to have devoured the limbs of Dionysus, the son of Zeus. Enraged, Zeus struck the Titans with lightning. (Zeus had intended this child to have dominion over the world.) The lightning burned the Titans to ashes, and from the ashes, mankind was formed.

http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sat_Titan

Europa: Could Have the Ingredients Needed for Life

Europa might be the best place to look for environments where life could exist in the present day. Image credit: NASA/JPL/Ted Stryk

Four hundred years ago, the astronomer Galileo's discovery of Jupiter's four large moons forever changed humanity's view of the universe, helping to bring about the understanding that Earth was not the center of all motion. Today one of these Galilean moons could again revolutionize science and our sense of place, for hidden beneath Europa's icy surface is perhaps the most promising place to look for present-day environments that are suitable for life.

This new appreciation began to unfold in 1995, when a spacecraft named in Galileo's honor arrived in the Jupiter system to follow up on earlier discoveries by the Voyager mission. The Galileo spacecraft sent tantalizing samplings of data that provided strong evidence for a deep global ocean beneath Europa's icy crust, leading to speculation on the potential for life within icy moons.

• More about how the evidence for an ocean was assembled >

Meanwhile, over the last quarter century we have learned that Jupiter-like planets are common around other stars, and that many could have icy moons like Europa. This realization means that studying Europa will help us understand the habitability of icy worlds throughout the cosmos.

What Makes Europa Special

Cutaway diagram of Europa's interior. Artwork credit: Michael Carroll

As Europa orbits Jupiter it experiences strong tidal forces - somewhat like the tides in Earth's oceans caused by our Moon. The tidal forces cause Europa to flex and stretch because its orbit is an ellipse, rather than a circle, and the tide is much higher when the moon is close to Jupiter than when it is farther away. This continuous flexing creates heat, which makes Europa's interior warmer than it would be from the Sun's heat alone. In addition, the flexing could produce volcanic activity from the rocky interior, as on the neighboring moon Io. The tidal forces also cause Europa's icy outer shell to flex, likely causing the long, linear cracks seen in images of its surface.

• Watch a movie showing how Europa is squeezed and stretched >

Thanks in large part to measurements made by visiting spacecraft, scientists think it is probable that Europa has a saltwater ocean beneath a relatively thin and geologically active icy shell. Although evidence exists for oceans within several other large icy satellites in the outer solar system, Europa is unique because its ocean is believed to be in direct contact with its rocky interior, where conditions could be similar to those on Earth's biologically rich sea floor. (In contrast, Jupiter's other large, icy moons, Ganymede and Callisto, are thought to contain "ocean sandwiches," where a liquid ocean exists between two layers of ice.) Our planet has geologically active places on its sea floor, called hydrothermal zones, where water and rock interact at high temperatures. These zones are known to be rich with life, powered by energy and nutrients that result from reactions between the seawater and the warm, rocky ocean floor.

The Stuff of Life

Life as we know it depends upon three key "ingredients":

• Liquid water, to create an environment that facilitates chemical reactions

• Essential chemical elements that are critical for biological processes

• A source of energy that could be utilized by living things

Europa appears to meet these minimum requirements for life. It is special among the bodies of our solar system in having a potentially enormous volume of liquid water, along with geological activity that could promote the exchange of useful chemicals from the surface with the watery environment beneath the ice. However, our current understanding of how material moves within Europa's icy crust is not well-developed. Even the existence of a subsurface ocean, while strongly suspected, is not yet proven.

Continue to the first essential ingredient for life: Water >

 

Artist's concept of Europa's frozen surface. Image credit: NASA/JPL-Caltech

Water

Flexing of Europa's icy crust could create partially melted pockets, or even lakes, scattered throughout the moon's outer shell. Image credit: Britney Schmidt/Dead Pixel VFX/Univ. of Texas at Austin. (Press release related to lakes on Europa.)

 

Water is essential to life, serving as a perfect liquid medium for dissolving nutrients for ingestion or wastes for excretion, and for transporting chemicals living things can use. Several lines of evidence strongly suggest that the planet-sized moon contains an ocean of liquid water many tens of miles deep. If it does exist, the ocean lies beneath an ice shell that is at least a few miles thick, and perhaps tens of miles thick. At the ocean bottom lies a rocky seafloor in direct contact with the water, possibly supplying chemical nutrients into the ocean by hydrothermal activity.

Important clues to the presence of an ocean within Europa:

• Observations by NASA's Galileo spacecraft confirmed that Europa's surface is sparsely cratered and therefore young. (Heavily cratered surfaces are older.)

• Models for the formation of the many linear ridges and fractures on Europa's surface suggest that the moon's icy shell is relatively thin and flexes in response to tidal forces as the moon orbits Jupiter.

• Flexing of the icy crust above an ocean could create pockets of salty impurities and partially melted areas leading to features seen in spacecraft images.

Favorable environments for the chemistry of life (or even life itself, in microbial form) could exist in areas within Europa's ice shell that contain salty fluids or around possible hydrothermal systems driven by tidal heating. An ocean rich with chemistry conducive to life could be maintained by a cycle that moves water through the moon's ice shell, ocean and rocky interior.

Continue to the next essential ingredient for life: Chemistry >

Chemistry

Mineral-laden hot water pours like black smoke from a hydrothermal vent on Earth's ocean floor. Image credit: A.L. Lane/NASA/JPL

Chemistry

Studying Europa's chemistry - on the surface and within the suspected ocean - is important for understanding its habitability because living things extract energy from their environments via chemical reactions. Interactions between materials from Europa's surface and those in an ocean environment beneath the ice could produce elements essential for life such as carbon, hydrogen, nitrogen, oxygen, phosphorous and sulfur.

Europa's surface is mostly water ice (H₂O), but the surface is bombarded by intense radiation from Jupiter, which can alter the chemistry of the ice. Through this process, the hydrogen and oxygen from water ice can combine with other materials on the surface to create a host of molecules like free oxygen (O₂), hydrogen peroxide (H₂O₂), carbon dioxide (CO₂) and sulfur dioxide (SO₂).

If these compounds are finding their way into an ocean as part of an ongoing cycle, they could be used to power the reactions living things depend upon. Meanwhile, cycling of ocean water through minerals in the seafloor could replenish the water with other chemicals that are crucial for life.

Continue to the last essential ingredient for life: Energy >

Energy

How material cycles between the ice, the ocean and the rocky interior is the greatest uncertainty about energy as it relates to Europa's habitability. Image credit: NASA/JPL-Caltech

Energy

Life extracts energy from its environment in order to carry out biological processes like maintaining cellular structures, growing and reproducing. Most living things on Earth's surface depend (directly or indirectly) on energy supplied by the sun, but there are many organisms that extract their energy from chemical sources like those produced by hydrothermal activity.

Europa's constant tidal flexing provides heat energy to drive chemical reactions in the rocky interior, recycling the elements and making them available for potential use by living things. If Europa's seafloor has volcanoes (as its sibling moon Io does) or hydrothermal vents, they may drive the chemistry of the ocean and play an important role in cycling nutrient-rich water between the ocean and the rocky interior. Tidal flexing of the ice shell could create slightly warmer pockets of ice that rise slowly upward to the surface, carrying material from the ocean below. Jupiter's intense radiation also provides a source of energy by ripping apart chemicals on the surface, where they can recombine to form new compounds.

The greatest uncertainty about energy as it relates to Europa's habitability is in how material cycles between the ice, the ocean and the rocky mantle on the ocean bottom. There are, potentially, sources of chemical energy for life being created on the surface and in the rocky interior, but their availability for use by living organisms depends on how well Europa's different layers are able to exchange material. In essence, the more energetic Europa is, the more energy would be available for life. Determining the balance of all these forces - Europa's energy balance - is a major hurdle toward understanding the icy moon's habitability.

What is the evidence for an ocean within Europa? >

Evidence for an Ocean

What Makes Us Think There is an Ocean Beneath Europa's Icy Crust?

Europa and her three large sibling satellites - Io, Ganymede and Callisto - were discovered by the astronomer Galileo in 1610, but nearly 400 years passed before any detailed views of their surfaces were seen and the uniqueness of these "Galilean" moons was revealed. In the 1960s, ground-based telescope observations determined that Europa's surface composition is mostly water ice, as are most other solid bodies of the outer solar system.

A view of Europa from the Voyager 2 spacecraft

The Pioneer 10 and 11 spacecraft flew by Jupiter in the early 1970s, but the first spacecraft to image the surfaces of Jupiter's moons in significant detail were the Voyager 1 and 2 spacecraft. Voyager 1's closest approach to Jupiter occurred in March 1979, with Voyager 2 following in July of the same year. The best imaging resolution of the Voyagers was limited to just over 1 mile (2 kilometers) per pixel. These images revealed a surface brighter than that of Earth's moon, crisscrossed with numerous bands and ridges, and with a surprising lack of large impact craters, tall cliffs or mountains (in other words, a very smooth surface, relative to the other icy moons).
Even though the Voyagers did not pass extremely close to Europa, their images were of high enough quality that researchers noted some of the dark bands had opposite sides that matched each other extremely well, like pieces of a jigsaw puzzle. These cracks had separated, and dark, icy material appeared to have flowed into the opened gaps, suggesting that the surface had been active at some time in the past. Voyager images showed only a handful of impact craters, which are expected to build up over time as a planetary surface is constantly bombarded by meteorites over billions of years until the surface is covered in craters. Thus, a lack of large impact craters suggested that the moon's surface was relatively young and implied that something had erased them - such as icy, volcanic flows, or settling of the icy crust under its own weight.

Scientists also found that the patterns of some of the longest linear features on the surface did not fit predicted patterns of fractures that should be created by tides as Europa orbits Jupiter. They determined that the patterns would fit very well if Europa's surface could move independently and was not locked to the rest of the interior, as would be the case if a layer of liquid or slightly warmer ice existed between the crust and deep interior.

NASA's Galileo spacecraft detected a magnetic field around Europa, in addition to fields around Ganymede and Callisto.

There also were tantalizing hints that perhaps Europa had a warm interior at some time in the past, and perhaps still does. Studies of how tidal heating should affect Europa suggested that a global subsurface ocean might exist within the icy moon today.
These intriguing findings led to a strong sense of anticipation for the Galileo mission, which launched in 1989 and entered orbit around Jupiter in 1995. Galileo's primary mission included observations of each the four Galilean satellites during repeated flybys. The information about Europa that Galileo sent was so intriguing that the mission was extended to make a total of 12 close flybys of the icy moon. Data from the mission included images of Europa at a range of scales, revealing new details about the surface and providing context for how those details related to the moon as a whole.

One of Galileo's most important measurements showed how Jupiter's magnetic field was disrupted in the space around Europa. This measurement strongly implied that a special type of magnetic field is being created (or induced) within Europa by a deep layer of some electrically conductive fluid beneath the surface. Based on Europa's icy composition, scientists think the most likely material to create this magnetic signature is a global ocean of salty water. A future mission to Europa could confirm the ocean's existence and begin to address questions about the moon's habitability for life as we know it.

NASA is studying mission designs that would tackle the most pressing questions about Europa. The Jupiter Icy Moons Explorer (JUICE) being planned by the European Space Agency (ESA) will address some of these questions, and conduct detailed investigations of Europa's sister moon, Ganymede. Visit ESA's JUICE mission website >

http://solarsystem.nasa.gov/europa/overview.cfm