Summary
Summary Topic 4 - Genetic Information, Variation & Relationships between Organisms
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- AQA
An in depth summary of the entirety of topic 4 AQA A level biology.
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Topic 4A-DNA RNA Protein ,+
Synthesis
DNA :
=I
↳ shorter than
eukaryotic DNA
↳ circular
shaped
↳ no histones involved
they DNA ↳ chromosomes condense to
support .
fit inside the cell
by
a
forming supercoil .
GENES CHROMOSOMES :
+
GENE of DNA bases that
is a
sequence codes for polypeptide
·
a or
functional RNA
.
↳ different polypeptides have a different number and order of amino
acids
.
↳ the the order
order of bases in a
gene determines of amino acids
in a
polypeptide .
each coded sequence of triplets/codons
↳ amino acid is
by a .
↳ Genes also code for functional RNA /ERNA ,
mRNA sRNA) . ,
↳ GENOME complete set of
: in cell
genes a .
↳ PROTEOME : full that
range of proteins a cell can produce
.
NON CODING DNA :
genes that don't code for polypetides at all.
·
↳ INTRONS : Sections
of a gene that DONT code for amino acids
.
↳ EXONS : Sections
of a a gene that DOES code for amino acids
.
↳ Non
coding multiple repeats : DNA sequences that repeat and don't
code for amino acids
.
ALLES
they
:
that exist in than one code for
·
genes more form ,
different versions of the same
polypeptide.
HOMOLOGOUS CHROMOSOMES :
pair matching chromosomes :
·
of
same
same size ,
same ,
genes
but different alleles
position of locus
, RNA + PROTEIN SYNTHESIS :
·
PROTEIN SYNTHESIS is the production of proteins , also known as
2
polypeptide Synthesis. =
phosphate
RNA there are 3 :
of RNA
:
types ↳ base
·
mRNA A
messenger RNA
↳ :
&
.
Codon
made
during transcription carries
>
,
yribose sugar
genetic code from DNA to ribosomes
where it's
during
used to make
translation ↳
a
protein
JenTeotide
y
↳ ERNA : transfer RNA :
hydrogen binding
involved in translation. Carries amino amino acid site
acids used to make proteins to
ribosomes. folded in clover shape
, bonds
bonds
bases held
by hydrogen -
ranticodon
↳ rRNA : Ribosomal RNA :
Site
of translation of mRNA code
protein
trnt
into acid code
an amino
by
Made up of both proteins + RNA
TRANSCRIPTION :
The first step of protein Synthesis.
·
During transcription an mRNA
copy of is made from DNA
·
a
,
gene .
Takes place nucleus
eukaryotes and
cytoplasm prokaryotes.
·
in
for in for
I . RNA Polymerase attaches to DNA
·
↳ RNA attaches to DNA at
↳
polymerase beginning of gene .
hydrogen bonds between DNA strands in
gene
broken DNA helicase in RNA
by polymerase .
↳ strands
separates DNA uncoils exposing bases
,
.
↳ a strand is used as a
template to make mRNA copy
2
Complementary mRNA is formed
:
.
↳ RNA
Polymerase lines up free RNA nucleotides to
S
exposed bases on template strand .
↳ free bases attracted to exposed bases
.
Complimentary
↳ base
pairing means mRNA are a
complimentary copy of DNA template strand (T U)
=
.
↳ RNA
joins with DNA by RNA polymerase forming
-
,
epobam
a strand of mRNA .
3 RNA down DNA :
.
polymerase moves
·
↳
hydrogen
polymerase
bonds
has
reform at DNA after RNA
passed by
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