DNK
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Deoxyribonucleic acid (DNA) is a
type of nucleic acid. It contains
deoxyribose, nitrogen bases adenine
(A), guanine (G), cytosine (S) and
thymine (T), and phosphoric acid.
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All living organisms are found in
ischemic cells and are part of
most viruses. It is responsible for
the preservation and
transmission of hereditary traits
in living organisms.
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The nucleotide structure of DNA, that is, its primary structure, is unique to each
organism and is the encoding of biological information (see Genetic code). The genetic
significance of DNA was first identified by O. Every with his students (1944, USA).
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The interaction of nucleotides in DNA is governed by certain laws. These laws were
defined by E. Chargaff (USA) (1950). According to this creed, the sum of the purine bases
in DNA is equal to the sum of the pyrimidine bases, where the amount of A is equal to
the amount of T and the amount of G is equal to the amount of S. Based on these rules,
D. Watson and F. Crick discovered a structural model of DNA (1953).
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According to this model, the
DNA molecule consists of
two polynucleotide chains
that form a double helix, and
both chains have a common
axis.
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The distance between one coil of the chain is 34 A and consists of 10 nucleotide crystals
(Figure V). The pentose phosphate groups of the polynucleotide chains are located on the
outside of the spiral, while the nitrogen bases are located on the inside. Polynucleotide
chains are inversely related to each other. The sequence of nucleotides in one strand of
DNA provides the sequence of nucleotides in the second strand, or they are
complementary.
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Complementarity is a universal principle in the structural and functional structure of
nucleic acids. Although most natural DNA molecules are double-stranded and straight-
line, they are very large. It can take the form of a folded, ring, superspiral, or other shape
to accommodate a molecule of m.
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Some viruses have a single strand of DNA. In a prokaryotic cell, the DNA is clustered on
a single chromosome. m.si more than 10 'and en. approximately 1 mm. The DNA in
eukaryotic cells is mainly in the nucleus in the form of deoxynucleoprotein (DNP), a
major component of the chromosome or chromatin. In addition to the nucleus, DNA is
also found in mitochondrial and chloroplast structures.
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