News tagged with chromosomes

Related topics: genes · genome · cells · dna · cell division

Scientists find new genetic roots of schizophrenia

UCLA scientists have made a major advance in understanding the biology of schizophrenia. Using a recently developed technology for analyzing DNA, the scientists found dozens of genes and two major biological pathways that ...

Oct 19, 2016
popularity150 comments 0

Intersex—seeking the beauty in difference

At 13 years old, Sean Saifa Wall was admitted to hospital with pain in his groin. He says that he was given very little information about what might be causing it, and doctors didn't discuss different options for treatment ...

Oct 04, 2016
popularity1 comments 0

Two key proteins preserve vital genetic information

Cancer is often driven by various genetic mutations that are acquired through changes to a person's DNA over time. These alterations can occur at the chromosome level if the proteins are not properly organized and segregated ...

Aug 22, 2016
popularity5 comments 0

TERRA, the RNAs that protect telomeres

Despite their especially compact and inaccessible structure, telomeres transcribe information like the rest of the DNA. The RNAs resulting from this process are called TERRA, and their function is essential in preserving ...

Aug 17, 2016
popularity138 comments 0

Putting a brake on leukemia cells

Cancer cells need a lot of energy in order to divide without limits. Researchers from the German Cancer Consortium (DKTK) at Munich University Hospital (LMU) have discovered how leukemia cells cover these extra energy needs. ...

Jun 09, 2016
popularity3 comments 0


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

Subscribe to rss feed