Biology Questions and Answers
The rule for the pairing of nitrogen-
containing bchains that form the DNA ases of the polynucleotidmolecule ise
pyrimidine base binds to purine base,
under the condition binds to adenine (A) athat thymine nd cytosine (C)(T) (^)
binds to guanine (G).
In RNA there is no binding betweennitrogen-containing bases. That is
because polynucleotide RNA is formed of only onechain; differently, DNA is (^)
formed of two chains. It is therefore not
correct to question base pairing in RNA.
- What is the numeric
relation between pyrimidine
and purine bases in the DNA
molecule? Is that relation
valid in RNA molecules?
The DNA molecule is made of two bound
polynucleotide structure (the double helix). Thchains that form a he bindingelical (^)
of the two chains is between their
nitrogen-containinobeys the following rules: adenine (A),g bases and it always
a purine base, binds with thymine (T), a
pyrimidinpurine base, binds to e base, and guanine (G), cytosine (C), aa (^)
pyrimidine base. Therefore in one
molecule of DNA number of adenine (A) and thymithere will be the samene (T) (^)
and same number of cytosine (C) and
guanine (G). The quantities ofand of pyrimidine bases then will also purine (^)
be the same in a 50% proportion for
each typG, or A/T = e. The relation A = C/G = 1, is called CT and C =hargaff’s (^)
relation anabove are known as Chargaff’s rules.d the pairing rules described
In RNA there are not two nchains. RNA is a simple chain molucleotideculee (^)
and there is no necessary
proportionalitybases to form it. of nitrogen-containing
- Which type of chemical
bond maintains the pairing of
each chain in the DNA
molecule?
To form thbind to pyrimidine e DNA molbases becule, py urine bases
intermolecular bonds called hydrogen
bonds. Hydrogen bonds occur there is hydrogen near one of thesewhen (^)
electronegative elements: fluorine,
oxygen or nitrogen.
In such conditions hydrogen looks like
having lost electrons fand a very strong polarization isor those elements
created. The highly positive hydrogen
attractsmolecules makin pairs of electrons ofg a hydrogen bond. other
- What is the completing
sequence of nitrogen-
containing bases for a
AGCCGTTAAC fragment of a
DNA chain?
TCGGCAATTG. - What is the name of the
DNA duplication process?
What is the main enzyme that
participates in it?
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