Related topics: genes · protein · cells · genome · chromosomes

'Semi-synthetic' bacteria churn out unnatural proteins

Synthetic biologists seek to create new life with forms and functions not seen in nature. Although scientists are a long way from making a completely artificial life form, they have made semi-synthetic organisms that have ...

DNA replication machinery captured at atom-level detail

July 15, 2019) Life depends on double-stranded DNA unwinding and separating into single strands that can be copied for cell division. St. Jude Children's Research Hospital scientists have determined at atomic resolution the ...

Study gives insight into sun-induced DNA damage and cell repair

A team led by a Baylor University researcher has published a breakthrough article that provides a better understanding of the dynamic process by which sunlight-induced DNA damage is recognized by the molecular repair machinery ...

Island cores unravel mysteries of ancient Maltese civilisation

The mysteries of an ancient civilisation that survived for more than a millennium on the island of Malta—and then collapsed within two generations—have been unravelled by archaeologists who analysed pollen buried deep ...

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Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.

Chemically, DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds. These two strands run in opposite directions to each other and are therefore anti-parallel. Attached to each sugar is one of four types of molecules called bases. It is the sequence of these four bases along the backbone that encodes information. This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA, in a process called transcription.

Within cells, DNA is organized into X-shaped structures called chromosomes. These chromosomes are duplicated before cells divide, in a process called DNA replication. Eukaryotic organisms (animals, plants, fungi, and protists) store most of their DNA inside the cell nucleus and some of their DNA in the mitochondria (animals and plants) and chloroplasts (plants only). Prokaryotes (bacteria and archaea) however, store their DNA in the cell's cytoplasm. Within the chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.

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