| slovo | definícia |
deoxyribonucleic acid
(encz) | deoxyribonucleic acid, |
deoxyribonucleic acid
(gcide) | deoxyribonucleic acid \deoxyribonucleic acid\ n.
a nucleic acid, usually of very high molecular weight,
consisting of a linear sequence of monomer units of
deoxyribonucleotides, occurring in most organisms in pairs of
strands, wound together in the form of a double helix; it is
the main component of chromosomes and contains the genetic
information which is the basis of heredity, transmitted from
parent to progeny, and found in all living organisms except
for certain viruses which have RNA as their basic genetic
material; -- usually referred to by the acronym DNA.
Syn: DNA, desoxyribonucleic acid.
[PJC]
Note: The monomer units making up the DNA each contain one of
four heterocyclic bases: thymine, adenine, cytosine, or
guanine. The genetic information is contained in the
precise sequence of these monomer units, which
ultimately specify the sequence of proteins to be made
by the organism's biosynthetic processes, mediated
through the synthesis of RNA having a base sequence
corresponding to that of the DNA. The DNA sequence also
specifies the sequence of the various RNA molecules the
RNA base sequence being a copy of that on one of the
DNA strands. Most of the RNA synthesized is involved in
protein synthesis. In the double-helical form of DNA,
the thymine on one strand is paired with the adenine on
the opposite strand, and cytosine of one strand is
paired with guanine on the opposite strand. There is in
DNA also certain controlling information concerning the
timing and amount of RNA to be made, encoded within the
sequence of the DNA in ways that are still being
elucidated.
When this structure is replicated in the course of cell
multiplication, two identical double-helical molecules
are formed, each containing one strand from the
original molecule. Each resulting molecule is
distributred to either the parent or progeny organism,
and this is the basic mechanism for transmission of
hereditary information. In RNA-based viruses, or those
having single strands of DNA (as certain viruses), the
genetic information transmission occurs through a
double-stranded intermediate by a similar mechanism.
In some organisms slight modifications of the bases of
DNA are found, such as methylcytosine or, in some
viruses, uracil or hydroxymethyluracil; these unusual
bases act analogously to the normal bases in their
genetic coding function. A small percentage of
methylcytosine is found in many organisms, and it
serves in some cases as a special signal, as for
restriction enzymes.
[PJC] |
deoxyribonucleic acid
(wn) | deoxyribonucleic acid
n 1: (biochemistry) a long linear polymer found in the nucleus
of a cell and formed from nucleotides and shaped like a
double helix; associated with the transmission of genetic
information; "DNA is the king of molecules" [syn:
deoxyribonucleic acid, desoxyribonucleic acid, DNA] |
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