News tagged with chromosomes
(Medical Xpress)—Replicative aging (also known as replicative senescence) causes mammalian cells to undergo a process of growth arrest dependent on telomeres (the shortening of repeated sequences at the ends o ...
Neuroscience Mar 27, 2013 | 4.9 / 5 (8) | 0 |
A new study looking at the genomes of more than 13,000 men identified four new genetic variants associated with an increased risk of testicular cancer, the most commonly diagnosed type in young men today. The findings from ...
Genetics May 12, 2013 | 5 / 5 (1) | 0 |
(Medical Xpress)—On April 15, the Supreme Court will hear oral argument in Association for Molecular Pathology v. Myriad Genetics, a case that could answer the question, "Under what conditions, if any, ...
Genetics Apr 11, 2013 | 4.3 / 5 (6) | 16 |
The most common inherited form of mental retardation and autism, fragile X syndrome, turns some brain cells into chatterboxes, scientists at Washington University School of Medicine in St. Louis report.
Neuroscience Feb 20, 2013 | 4.8 / 5 (4) | 1 |
We take it for granted that our chromosomes won't stick together, yet this kind of cellular disaster would happen constantly were it not for a protein called TRF2. Now, scientists at The Scripps Research Institute (TSRI) ...
Medical research Feb 06, 2013 | 5 / 5 (3) | 0 |
Using only a computer, an Internet connection, and publicly accessible online resources, a team of Whitehead Institute researchers has been able to identify nearly 50 individuals who had submitted personal genetic material ...
Genetics Jan 17, 2013 | 4.3 / 5 (4) | 2 |
Researchers have shown that transplanting stem cells derived from normal mouse blood vessels into the hearts of mice that model the pathology associated with Duchenne muscular dystrophy (DMD) prevents the ...
Medical research Jan 14, 2013 | 5 / 5 (2) | 0 |
Scientists at the Johns Hopkins Kimmel Cancer Center have combined the ability to detect cancer DNA in the blood with genome sequencing technology in a test that could be used to screen for cancers, monitor cancer patients ...
Cancer Nov 28, 2012 | not rated yet | 0 |
Women live longer than men. Individuals can appear or feel years younger – or older – than their chronological age. Diseases can affect our aging process. When it comes to biology, our clocks clearly tick differently.
Medical research Nov 21, 2012 | 5 / 5 (5) | 0 |
Scientific studies have suggested that a wandering mind indicates unhappiness, whereas a mind that is present in the moment indicates well-being. Now, a preliminary UCSF study suggests a possible link between mind wandering ...
Psychology & Psychiatry Nov 16, 2012 | 3.1 / 5 (7) | 1 |
A recent finding by medical geneticists sheds new light on how Facioscapulohumeral Muscular Dystrophy develops and how it might be treated. More commonly known as FSHD, the devastating disease affects both ...
Genetics Nov 11, 2012 | 4.5 / 5 (2) | 0 |
(Medical Xpress)—University of Washington scientists have succeeded in removing the extra copy of chromosome 21 in cell cultures derived from a person with Down syndrome, a condition in which the body's ...
Medical research Nov 09, 2012 | 4.9 / 5 (11) | 0 |
In a new paper released today in Nature, BioFrontiers Institute scientists at the University of Colorado Boulder, Tom Cech and Leslie Leinwand, detailed a new target for anti-cancer drug development that is sitting at the ...
Cancer Oct 24, 2012 | 4.8 / 5 (4) | 0 |
American and European scientists have found that increasing natural marijuana-like chemicals in the brain can help correct behavioral issues related to fragile X syndrome, the most common known genetic cause of autism.
Autism spectrum disorders Sep 25, 2012 | 4.3 / 5 (4) | 1 |
A Washington State University researcher has found new evidence that the plastic additive BPA can disrupt women's reproductive systems, causing chromosome damage, miscarriages and birth defects.
Medical research Sep 24, 2012 | 4.6 / 5 (9) | 2 |
A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. The word chromosome comes from the Greek χρῶμα (chroma, color) and σῶμα (soma, body) due to their property of being very strongly stained by particular dyes. Chromosomes vary widely between different organisms. The DNA molecule may be circular or linear, and can be composed of 10,000 to 1,000,000,000 nucleotides in a long chain. Typically eukaryotic cells (cells with nuclei) have large linear chromosomes and prokaryotic cells (cells without defined nuclei) have smaller circular chromosomes, although there are many exceptions to this rule. Furthermore, cells may contain more than one type of chromosome; for example, mitochondria in most eukaryotes and chloroplasts in plants have their own small chromosomes.
In eukaryotes, nuclear chromosomes are packaged by proteins into a condensed structure called chromatin. This allows the very long DNA molecules to fit into the cell nucleus. The structure of chromosomes and chromatin varies through the cell cycle. Chromosomes are the essential unit for cellular division and must be replicated, divided, and passed successfully to their daughter cells so as to ensure the genetic diversity and survival of their progeny. Chromosomes may exist as either duplicated or unduplicated—unduplicated chromosomes are single linear strands, whereas duplicated chromosomes (copied during synthesis phase) contain two copies joined by a centromere. Compaction of the duplicated chromosomes during mitosis and meiosis results in the classic four-arm structure (pictured to the right). Chromosomal recombination plays a vital role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe and die, or it may aberrantly evade apoptosis leading to the progression of cancer.
However, in practice "chromosome" is a rather loosely defined term. In prokaryotes, a small circular DNA molecule may be called either a plasmid or a small chromosome. These small circular genomes are also found in mitochondria and chloroplasts, reflecting their bacterial origins. The simplest chromosomes are found in viruses: these DNA or RNA molecules are short linear or circular chromosomes that often lack any structural proteins.
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