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Unit 3 Biology
Chapter 2
3. Nucleic Acid
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Nucleic acids
Made up of C,
H
, O, N and
P
Nucleic acids
Polymer made up of
nucleotides
(
monomer
)
Types of nucleotides
Deoxyribonucleic
acid (
DNA
) nucleotides
Ribonucleic
acid (
RNA
) nucleotides
Nucleic acids
Store
genetic
information
Help produce the
proteins
required for
survival
Nucleotide
Has three main components:
Nitrogenous base
,
Phosphate group
, Pentose (5 carbon) sugar
DNA nucleotides
Phosphate
,
deoxyribose sugar
, nitrogenous bases (A, T, C, G)
RNA nucleotides
Phosphate
,
ribose sugar
, nitrogenous bases (A, U, C, G)
Types of nitrogenous bases
Purines
: adenine and guanine
Pyrimidines
: cytosine, uracil (RNA) and thymine (DNA)
Complementary base pairing
Gives a constant
three
ring width
Cytosine
pairs with
guanine
by three hydrogen bonds
Adenine
fits with thymine or
uracil
, but with two hydrogen bonds
Nucleotides formation
Formed by
condensation
reactions
Phosphodiester
bonds
Bonds that join
nucleotides
to form
nucleic acids
DNA
Polymer
of DNA nucleotides organized into a
double helix
Two separate DNA polymers
make up each side of the ladder
Sugar
and phosphate molecules form the backbone,
nitrogenous bases
form the rungs
Rungs attach by
hydrogen bonding
Complementary base pairing
ensures A pairs with T, and
G
pairs with C
Coding
/
complementary strand
One of the two DNA strands
Template strand
One of the two DNA strands
DNA functions
To
reproduce
itself (replication)
To manufacture all of the
proteins
in the living organisms
Gene
Section of
DNA
that codes for a particular
protein
DNA in cells
Visible as
chromosomes
Double helix
coils up and
unwinds
to allow for cell cycle processes
Protects
the molecule and allows for control of
transcription
DNA in eukaryotic cells
DNA
polynucleotide
wraps around
histones
to form a nucleosome
Nucleosomes
coil up more forming a
chromatin fibre
Supercoiling leads to the highly
condensed
chromosome being visible under a
microscope
Understanding how this coiling regulates
gene expression
is
epigenetics
RNA
Single
stranded polymer of RNA
nucleotides
Sugar (
ribose
) and phosphate molecules form the vertical supports, nitrogenous bases (A, U, C, G) form the
rungs
Types of RNA and their functions
mRNA
rRNA
tRNA
DNA vs RNA
RNA has a ribose
five-carbon
sugar, which has one more
oxygen
than a deoxyribose molecule
The
nitrogenous
base thymine in DNA is replaced by
uracil
in RNA
RNA is
single
stranded whereas DNA is
double
stranded