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2.3 Nucleic Acids


The monomer units in nucleic acids are called nucleotides.
They consist of a pentose sugar (deoxyribose/ribose) a phosphate group and a nitrogenous
base that is either a pyrimidine or a purine.
These three components are joined in condensation reactions by covalent bonds.
Nucleotide derivatives
ATP and…

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DNA structure

DNA is made of two polynucleotide strands, antiparallel to each other.
The monomers in DNA include deoxyribose sugar, a phosphate group and the bases
cytosine, thymine, adenine and guanine.
The monomers are bonded by covalent phosphodiester bonds.
The bases are bonded with hydrogen bonds in complementary base pairing.…

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RNA Structure

The pentose sugar is ribose (has oxygen).
Uracil, cytosine, adenine and guanine are the
nitrogenous bases.
The polymer is single stranded.
RNA carries information between organelles
in a cell and is not a store of information.

DNA Replication

DNA uses semiconservative
replication as both of the
original strands…

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4) The nucleotides join together to form a new molecule of DNA

Mutations may occur in
replicating the genetic code.
These mutations occur when
DNA is not accurately copied
and when the wrong
nucleotide is inserted into
the strand. Some mutations
are harmful, such as
achondroplasia (a form of

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Exons are regions of the RNA strand that code for the amino acids of the protein being
synthesized whereas introns are segments that do not code for the protein and are not
Introns are cut out and the exon regions are spliced together to form a long chain of…

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The newly synthesized polypeptide is folded into its shape to form the protein


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