Scientists discover master regulator of cellular aging
Scientists at The Scripps Research Institute (TSRI) have discovered a protein that fine-tunes the cellular clock involved in aging.
Jan 12, 2017
1
4990
Scientists at The Scripps Research Institute (TSRI) have discovered a protein that fine-tunes the cellular clock involved in aging.
Jan 12, 2017
1
4990
Male? Female? The distinction is not always clear. Exploring the scientific evidence for the biological origins of sexual orientation and gender identity must continue to both enhance patient care and fight discrimination.
Aug 21, 2015
1
299
Medical researchers at Melbourne's Murdoch Children's Research Institute have made a new discovery about how a baby's sex is determined—it's not just about the X-Y chromosomes, but involves a 'regulator' that increases ...
Dec 14, 2018
1
1284
Last December, researchers identified more than 1,000 gene mutations in individuals with autism, but how these mutations increased risk for autism was unclear. Now, UNC School of Medicine researchers are the first to show ...
Aug 6, 2015
3
6281
(Medical Xpress) -- A controversial test capable of revealing just how long you have to live is set to hit the market in Britain within the year. The test measures a person's telomeres which are the structures found on the ...
Why do animals sleep? Why do humans "waste" a third time of their lives sleeping? Throughout evolution, sleep has remained universal and essential to all organisms with a nervous system, including invertebrates such as flies, ...
Mar 5, 2019
0
7258
(Medical Xpress)—An odd and little-known feature of nerve cells may be linked to several forms of inherited intellectual disability, researchers at Washington University School of Medicine in St. Louis have learned.
Aug 30, 2013
0
0
Young Brisbane twins, a boy and a girl, have been identified as only the second set of semi-identical, or sesquizygotic, twins in the world—and the first to be identified by doctors during pregnancy.
Feb 27, 2019
1
1332
University of Minnesota Medical School and College of Biological Sciences researchers have made a key discovery showing that male sex must be maintained throughout life.
Jul 20, 2011
0
0
Past neuroscience research suggests that common differences in people's genetic profiles can explain a significant proportion of variations in people's brain anatomy. In more specific terms, they found that neuroanatomical ...
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.
This text uses material from Wikipedia, licensed under CC BY-SA