2.1.3 Nucleotides and nucleic acids
(a) the structure of a nucleotide as the monomer from which nucleic acids
are made
Nucleotide: a molecule consisting of a pentose sugar, a phosphate group and a nitrogenous base
Nucleic acids: Large polymers formed from nucleotides: DNA and RNA
Nucleotides are phosphate esters of pentose sugars,
where a nitrogenous base is linked to the C 1 of the
sugar residue, and a phosphate group (PO42-) is linked
to either the C3 or the C5, by covalent bonds formed
from condensation reactions.
Nucleotides are the monomers that form the nucleic acids DNA
(Deoxyribose Nucleic Acid) and RNA (Ribose Nucleic Acid). In DNA the
pentose sugar is deoxyribose and in RNA it is ribose.
There are four nitrogenous bases in DNA: adenine, thymine, guanine
and cytosine. In RNA the only difference is that instead of a thymine
base there is a uracil base. Adenine and guanine are purines (two C
rings) and thymine, cytosine and uracil are all pyrimidines
(one C ring). Pyrimidines always bond with purines, giving equal-
sized ‘rungs’ on the DNA ladder. Adenine pairs with thymine (A-T) Remembering purines vs. pyrimidines:
and guanine with cytosine (G-C), known as complementary base Pyrimidines: Thymine and Cytosine
Purines: Adenine and Guanine - giant
pairing.
(b) the synthesis and breakdown of polynucleotides by the formation and
breakage of phosphodiester bonds
Polynucleotides are the polymers of nucleotides, for
example one DNA strand consist of many nucleotides
bonded together.
Polynucleotides are formed by condensation reactions
where the phosphate group at the C5 atom of one
nucleotide covalently bonds to the hydroxyl group at the
C3 of another, known as a phosphodiester bond. This
forms a long, strong sugar-phosphate ‘backbone’ with a
base attached to each sugar.
(c) the structure of ADP and ATP as phosphorylated nucleotides
The nucleotides ADP (Adenosine Diphosphate) and ATP
(Adenosine Triphosphate) are phosphorylated nucleotides,
as they contain more than one phosphate group. Their
pentose sugar is ribose and their nitrogenous base is
adenine. ADP has 2 phosphate groups while ATP has 3. ATP
is an energy-rich product of most energy-releasing
biochemical pathways and is needed to drive most energy-
requiring metabolic processes in cells. ATP is hydrolysed
into ADP and energy is released.
(a) the structure of a nucleotide as the monomer from which nucleic acids
are made
Nucleotide: a molecule consisting of a pentose sugar, a phosphate group and a nitrogenous base
Nucleic acids: Large polymers formed from nucleotides: DNA and RNA
Nucleotides are phosphate esters of pentose sugars,
where a nitrogenous base is linked to the C 1 of the
sugar residue, and a phosphate group (PO42-) is linked
to either the C3 or the C5, by covalent bonds formed
from condensation reactions.
Nucleotides are the monomers that form the nucleic acids DNA
(Deoxyribose Nucleic Acid) and RNA (Ribose Nucleic Acid). In DNA the
pentose sugar is deoxyribose and in RNA it is ribose.
There are four nitrogenous bases in DNA: adenine, thymine, guanine
and cytosine. In RNA the only difference is that instead of a thymine
base there is a uracil base. Adenine and guanine are purines (two C
rings) and thymine, cytosine and uracil are all pyrimidines
(one C ring). Pyrimidines always bond with purines, giving equal-
sized ‘rungs’ on the DNA ladder. Adenine pairs with thymine (A-T) Remembering purines vs. pyrimidines:
and guanine with cytosine (G-C), known as complementary base Pyrimidines: Thymine and Cytosine
Purines: Adenine and Guanine - giant
pairing.
(b) the synthesis and breakdown of polynucleotides by the formation and
breakage of phosphodiester bonds
Polynucleotides are the polymers of nucleotides, for
example one DNA strand consist of many nucleotides
bonded together.
Polynucleotides are formed by condensation reactions
where the phosphate group at the C5 atom of one
nucleotide covalently bonds to the hydroxyl group at the
C3 of another, known as a phosphodiester bond. This
forms a long, strong sugar-phosphate ‘backbone’ with a
base attached to each sugar.
(c) the structure of ADP and ATP as phosphorylated nucleotides
The nucleotides ADP (Adenosine Diphosphate) and ATP
(Adenosine Triphosphate) are phosphorylated nucleotides,
as they contain more than one phosphate group. Their
pentose sugar is ribose and their nitrogenous base is
adenine. ADP has 2 phosphate groups while ATP has 3. ATP
is an energy-rich product of most energy-releasing
biochemical pathways and is needed to drive most energy-
requiring metabolic processes in cells. ATP is hydrolysed
into ADP and energy is released.
