Category Archives: Transhuman News

The structure of DNA and RNA. DNA is a double helix, while RNA is a single helix. Both have sets of nucleotides that contain genetic information.

Deoxyribonucleic acid or DNA is a molecule that contains the instructions an organism needs to develop, live and reproduce. These instructions are found inside every cell, and are passed down from parents to their children.

DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code. Similar to the way the order of letters in the alphabet can be used to form a word, the order of nitrogen bases in a DNA sequence forms genes, which in the language of the cell, tells cells how to make proteins. Another type of nucleic acid, ribonucleic acid, or RNA, translates genetic information from DNA into proteins.

The entire human genome contains about3 billion bases and about 20,000 genes.

Nucleotides are attached together to form two long strands that spiral to create a structure called a double helix. If you think of the double helix structure as a ladder, the phosphate and sugar molecules would be the sides, while the bases would be the rungs. The bases on one strand pair with the bases on another strand: adenine pairs with thymine, and guanine pairs with cytosine.

DNA molecules are long so long, in fact, that they can't fit into cells without the right packaging. To fit inside cells, DNA is coiled tightly to form structures we call chromosomes. Each chromosome contains a single DNA molecule. Humans have 23 pairs of chromosomes, which are found inside the cell's nucleus.

DNA was first observed by a German biochemist named Frederich Miescher in 1869. But for many years, researchers did not realize the importance of this molecule. It was not until 1953 that James Watson, Francis Crick, Maurice Wilkins and Rosalind Franklin figured out the structure of DNA a double helix which they realized could carry biological information. Watson, Crick and Wilkins were awarded the Nobel Prize in Medicine in 1962 "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material." [Related: Unraveling the Human Genome: 6 Molecular Milestones]

DNA sequencing is technology that allows researchers to determine the order of bases in a DNA sequence. The technology can be used to determine the order of bases in genes, chromosomes, or an entire genome. In 2000, researchers completed the first full sequence of the human genome.

Your DNA contains information about your heritage, and can sometimes reveal whether you're at risk for certain diseases. DNA tests, or genetic tests, are used for a variety of reasons, including to diagnose genetic disorders, to determine whether a person is a carrier of a genetic mutation that they could pass on to their children, and to examine whether a person is at risk for a genetic disease. For instance, mutations in the BRCA1 and BRCA2 genes are known to increase the risk of breast and ovarian cancer, and analysis of these genes in a genetic test can reveal whether a person has these mutations.

Genetic test results can have implications for a person's health, and the tests are often provided along with genetic counseling to help individuals understand the results and consequences of the test.

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DNA: Definition, Structure & Discovery | What Is DNA?

DNA is all the same chemical

The stringy stuff in the test tube is DNA. But you can't tell which one of these organisms it came from just by looking at it. That's because DNA looks exactly the same in every organism on Earth.

All living things have DNA. And whether it comes from you, a pea plant, or your pet rat, it's all the same molecule. It's the order of the letters in the code that makes each organism different.

The order of building blocks in a strand of DNA makes up a "sequence." We can read a DNA sequence like letters in a book. In fact, we know the sequence of the entire human genomeall 3 billion letters. That's enough information to fill roughly 1,000 200-page books!

Contained within the 3 billion letters of the human genome are about 21,000 genes. Most of our known genes code for proteins, but some code for RNA molecules.

All humans have the same genes arranged in the same order. And more than 99.9% of our DNA sequence is the same. But the few differences between us (all 1.4 million of them!) are enough to make each one of us unique. On average, a human gene will have 1-3 bases that differ from person to person. These differences can change the shape and function of a protein, or they can change how much protein is made, when it's made, or where it's made.

APA format:

Genetic Science Learning Center. (2016, March 1) What are DNA and Genes?. Retrieved June 22, 2017, from http://learn.genetics.utah.edu/content/basics/dna

CSE format:

What are DNA and Genes? [Internet]. Salt Lake City (UT): Genetic Science Learning Center; 2016 [cited 2017 Jun 22] Available from http://learn.genetics.utah.edu/content/basics/dna

Chicago format:

Genetic Science Learning Center. "What are DNA and Genes?." Learn.Genetics.March 1, 2016. Accessed June 22, 2017. http://learn.genetics.utah.edu/content/basics/dna.

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What are DNA and Genes?

June 23, 2017 The jellyfish glow helped focus laser beams on proteins. Credit: University of York

Scientists at the University of York have used florescent proteins from jellyfish to help shed new light on how DNA replicates.

Using these proteins, originally found in jellyfish to make them glow, the team where able to focus laser beams on the brightly lit proteins and track them inside a bacteria that normally lives inside the human gut.

This allowed scientists to watch the molecular machinery of DNA as it replicated inside a cell one molecule at a time. It revealed for the first time that only one component of this process, called DnaB helicase, remains stable - like a molecular anchor to the process.

In most cells, whether human or bacterial, a new cell is created after an existing cell divides in two. This means that a copy of the original sequence of genes coded in its DNA must be precisely copied and placed into the new cell.

This is thought to be a process that occurs slowly and methodically at set points in time. New research at the University of York, in collaboration with the University of Oxford and McGill University Canada, however, has now tracked this replication process in real-time and shown that it is far more dynamic than the textbooks suggest, occurring instead through a 'stuttering-like process' in short bursts.

Pioneering

Professor Mark Leake, Chair of Biological Physics at the University of York, said: "We pioneered a new method of light microscopy which allowed us to see this fascinating replication process occur molecule-by-molecule.

"We were surprised to find, however, that rather than the organised and methodical way that we expected this process to unfold, it instead happened in a 'stuttering' action, much like driving too slowly in high gear of a car. The big question, of course, was why the cell performs an essential process in such an unstable way?

"The stuttering action provide 'checkpoints' at various stages of the DNA copying process to make sure there is no errors made and, if there is, correct them before it is too late. This means that the cells can pause to fix an error in a small fragment of the DNA rather than attempt an unmanageable correction in one complete and huge strand of it.

"Although the process looks inelegant and almost random, it is actually highly efficient."

Human health

The process of DNA replication is fundamental to all life and the way errors in the process are resolved is especially important to human health. Errors can give rise to forms of cancer and become more prevalent in an ageing population.

This work will help scientists not only understand more fully the basic building blocks of life but potentially also provides new insights into a range of health conditions as well as even shedding new light on how human ageing can give rise to diseases associated with errors in copying the DNA from cell to cell.

Research was conducted using the DNA of Escherichia coli cell, bacteria, but However, the next stage of this research will investigate the same process in more complex cells, ultimately including those from humans.

The research, 'Frequent exchange of DNA polymerase during bacterial chromosome replication', was supported by the BBSRC and is published in the journal,eLife.

Explore further: Excessive DNA replication and its potential use against cancer

More information: Thomas R Beattie et al. Frequent exchange of the DNA polymerase during bacterial chromosome replication, eLife (2017). DOI: 10.7554/eLife.21763

Journal reference: eLife

Provided by: University of York

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Jellyfish fluorescence shines new light on DNA copying - Phys.Org

June 23, 2017 by Bennett Mcintosh A depiction of the double helical structure of DNA. Its four coding units (A, T, C, G) are color-coded in pink, orange, purple and yellow. Credit: NHGRI

A host of proteins and other molecules sit on the strands of our DNA, controlling which genes are read out and used by cells and which remain silent. This aggregation of genetic material and controlling molecules, called chromatin, makes up the chromosomes in our cell nuclei; its control over which genes are expressed or not is what determines the difference between a skin cell and a neuron, and often between a healthy cell and a cancerous one.

Parts of the genome are only loosely coiled in the nucleus, allowing cells to access the genes inside, but large sections are compacted very densely, preventing the genes form being read until their region of the genome is unfolded again. These compacted regions, known as heterochromatin, are formed by a protein known as HP1 and similar proteins, but exactly how HP1 segregates this off-limits DNA from the rest of the nucleus has been largely a mystery, until now.

In a new study by UC San Francisco researchers published in the journal Nature on June 22, 2017, what looked at first like a failed experiment instead revealed the intriguing possibility that HP1 binds to stretches of DNA and pulls it into droplets that shield the genetic material inside from the molecular machinery of the nucleus that reads and translates the genome.

"This provides a very simple explanation for how cells prevent access to genes," said Geeta Narlikar, PhD, professor of biochemistry and biophysics and senior author of the study.

'Bad News' Led to New Discovery

Narlikar's graduate student Adam Larson was trying to purify HP1, and noticed that the liquid in his samples was growing cloudy. For protein scientists, this is typically bad news, said Narlikar: it suggests that proteins that should dissolve in water are instead clumping together into a useless mass.

But Larson thought the clumps might actually be useful. After all, previous work had shown that the role of HP1 is to sequester long strands of DNA into very small volumes. What if this was exactly the sort of clumping he was seeing in the tube?

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Larson took his samples to the lab across the hall from Narlikar's, where Roger Cooke, PhD, professor emeritus of biochemistry and biophysics, helped him examine under the microscope what could have been just a tangled molecular mess. Instead, Larson and Cooke saw clouds of delicate droplets floating around in the water, like a freshly shaken mix of oil and vinegar.

HP1 had a reputation as a difficult protein to work with get any solution too concentrated, and the protein would clump out. But if the protein was supposed to clump, said Narlikar, "a lot of things we couldn't explain started to make sense."

Narlikar speculates that other scientists may have seen the same cloudiness before, but thinking it was simply a ruined sample, never pursued it like Larson did. "It demonstrates the power of curiosity-driven research," she said.

Rapidly Compacting DNA

To see how and why the HP1 formed droplets, the team produced different mutant versions of the protein, watching which separated out. By watching which parts of the protein were important for forming droplets, and using X-rays to monitor changes in the protein's shape, the team found that the protein nearly doubles in length when small phosphate residues are added in cetain locations. "The molecule literally opens up," said Narlikar. "I was surprised at the size of the change."

This opening-up exposes electrically charged regions of the protein, which stick together, turning dissolved pairs of proteins into long chains that clump together into droplets. Just as balsamic vinegar's dark and flavorful molecules don't seep into the oil of a salad dressing without some extra effort by the chef, the molecules for reading DNA don't seep into the HP1 droplets.

The fact that such a drastic change in shape comes from such a small modification may allow the cell to tightly regulate where and when HP1 silences genes, said Narlikar. The changes come quickly and robustly too using a technology employed by Sy Redding, PhD a Sandler Fellow, the team created a "curtain" of DNA molecules pulled straight by fluid flowing around them, then added HP1 and watched the protein compress the DNA into tiny droplets, folding it up against the flow.

"People have been seeing for over a hundred years that you get these dense regions of DNA in the nucleus," said Madeline Keenen, the Ph.D. student who ran the curtain experiment. "Now we're seeing the actual mechanism."

Explore further: Researchers find new mechanism for genome regulation

More information: Adam G. Larson et al. Liquid droplet formation by HP1 suggests a role for phase separation in heterochromatin, Nature (2017). DOI: 10.1038/nature22822

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From strands to dropletsnew insights into DNA control - Phys.Org

James Opelton Bradley is charged with first-degree murder in the presumed death of his missing coworker, Shannon Rippy Van Newkirk, who vanished April 5, 2014.

WILMINGTON -- DNA, computer searches and letters written from jail by the defendant were presented to the jury in the ninth day of testimony Friday in the murder trial of James Opelton Bradley.

Bradley, 54, of Wilmington is charged with first-degree murder in the presumed death of his missing coworker Shannon Rippy Van Newkirk, 53, of Wilmington, who vanished April 5, 2014.

Investigators testified Bradley told police three different stories in the days after Van Newkirk went missing -- initially denying he saw her on the day she was last seen and then ultimately saying he'd picked her up from her house that day. When a discussion they were having became "heated," she ran from his truck near Greenfield Lake, investigators said Bradley told them.

Three weeks later, when police searched land in Hampstead owned by Bradleys employer, they unearthed the body of Elisha Tucker, 33, another missing Wilmington woman whod last been seen in August 2013. Despite the fact that Van Newkirks body was never been found, Bradley is being tried in her presumed death.

A trial in Tuckers killing has yet to be set, but prosecutors said they will seek the death penalty in that case. Bradley has a previous murder conviction for killing his 8-year-old stepdaughter in 1988. The jury learned of that prior conviction after the prosecution successfully argued it be admissible.

On Friday, Sharon Hinton, a DNA analyst with the N.C. State Crime Laboratory, told the jury that she was unable to locate Van Newkirks DNA on any of the items she tested from Bradleys apartment or vehicle.

But, Hinton said, she was able to extract a full DNA profile for Elisha Tucker from at least one stain from the carpet padding in Bradleys Chevy Tahoe. The probability of it being anyone else's DNA other than Tucker's was 1 in 359 trillion, she said. That stain, however, did not test positive for blood.

FBI computer examiner Rich Novelli testified that on April 20, 2014 -- four days after his last interview with police -- Bradley searched online for information on cellphone pinging and visited a webpage that explained how cellphones are tracked. Novelli said Bradley also searched for the StarNews.

Additionally, Jurors each read a copy of two letters. One was addressed to a relative's daughter and the other was to a friend. The contents of the letters were not discussed before court took an early recess.

Testimony in the case resumes Monday.

Reporter F.T. Norton can be reached at 910-343-2070 or Fran.Norton@StarNewsOnline.com.

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Dead Wilmington woman's DNA found in Bradley's truck - News ... - StarNewsOnline.com