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Title: Genetics Outlline
Description: chart of the enzymes used in DNA replication, transcription and translation and their actions. chart of the actions and processes of DNA replication, transcription, and translation.
Description: chart of the enzymes used in DNA replication, transcription and translation and their actions. chart of the actions and processes of DNA replication, transcription, and translation.
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Enzymes
Ch
11
Overall Process
DNA
Replication/Compacti
on
Enzyme
DNA Gyrase/
Topoisomerase II
Prokaryotes
Relax positive
supercoils and
Introduces negative
supercoils (x2)
• Cuts both
DNA strands
• Both
endonuclease
& ligase
Eukaryotes
DNA Gyrase
absent
Topoisomerase
II in human cells
relieves torsional
stress
11
DNA Replication
Topoisomerase I
10
DNA Compaction
Histones
Relaxes negative
supercoils(1 strand)
absent
Relaxes negative
supercoils
• Comes in an
octamer
• 2 H2A
subuni
ts
• 2 H2B
subuni
ts
• 2 H3
subuni
ts
• 2 H4
subuni
ts
11
DNA Replication
DNA Polymerases: •
Catalyze covalent
attachment between
phosphate of one
nucleotide and the
sugar in the
previous nucleotide •
•
10
DNA Compaction
Condensin
DNA Polymerase
I: removes
primers and fills
in the gaps of in
the strand with
DNA
DNA Polymerase
III: synthesizes
leading and
lagging strands
• Subunit α:
synthesize
s DNA
primer
• Subunit β:
clamp
protein
• Subunit ε:
removes
mismatche
d
nucleotide
s
• Subunit θ:
stimulates
proofreadi
ng
• γ, δ, δ',ψ,χ:
clamp
loader
complex,
helps the
clamp bind
to the
complex
DNA Polymerases
II, IV, and V:
repair damaged
DNA
• DNA
Polymerase α:
synthesizes
primer; only
polymerase that
associates with
primer
• DNA
Polymerase ε:
Replication of the
leading strand
• DNA
Polymerase δ:
Replication of the
lagging strand
• DNA
Polymerase γ:
Replication of
mitochondrial
DNA
• Other
polymerases:
Repair damaged
DNA
Condenses
interphase
chromosomes;
found outside the
nucleus until M
phase
10
DNA Compaction
Cohesin
12
DNA Transcription
RNA Polymerase:
each transcribes
different categories
of genes
•
Helps align sister
chromatids and
holds them
together until
anaphase
Holoenzyme
• RNA
consisting of the
Polymerase I:
core enzyme
Transcribes all
subunits + σ
genes that encode
factor
rRNA except 5s
• 2α
rRNA
subunits:
• RNA
assemble
Polymerase II:
holoenzym transcribes all
e
protein encoding
• β and β’
genes,
subunits:
synthesizes
important mRNA,
for binding transcribes some
the core
snRNA genes
enzyme to • RNA
DNA; also Polymerase III:
catalyzes
transcribes all
synthesis
tRNA genes, 5s
of RNA
rRNA,
• ω subunit:
microRNA
proper
assembly
of core
enzyme
• σ factor:
differentiat
es between
core
enzyme
and
holoenzym
e;
recognizes
the
promotor
12
DNA Transcription
Core enzyme
•
•
•
12
DNA Translation
tRNA
nucleotidyltransfera
se
11
DNA Transcription
Spliceosome
11
Translation
Triphosphatase
2 α subunits:
assemble
holoenzyme
β and β’ subunits:
important for
binding the core
enzyme to DNA;
also catalyzes
synthesis of RNA
ω subunit: proper
assembly of core
enzyme
•
Consists of
TATAA box;
is the binding
site for
GTFs* and
polymerase
Adds CCA
sequence to
produce proper 3’
end in mature
tRNA
• Splices
introns from
pre-mRNA
• U1:
binds to
5’ splice
site
• U2:
binds to
branch
site
• U4, U5,
U6:
form
trimer
that cuts
5’ splice
site and
adds 5’
end of
intron to
2’ -OH
of an
adenine
Removes
phosphate from
5’ end of the
transcript
11
Translation
Gyanylyltransferase
Hydrolyzes GMP
from GTP to
attach GMP to
the 5’ end of
tRNA
Attaches methyl to nitrogen
position at the
seventh carbon in a
guanine base
11
Translation
Methyltransferase
13
Translation
RNA Polymerase
III
•
• Transcribes
tRNA as pretRNAs
Aminoacyl-tRNA
Synthetase
•
• 20 of them,
one for each
amino acid, adds
correct one
Processes
C
Process
h
10 Compaction •
•
Prokaryotes
Eukaryotes
Formation of chromosomal
• Interphase compaction methods:
loops
• Histone octamer attaches to the
• In the form of:
negatively charged backbone of
• Loop domains DNA
Proteins
• Using negative supercoils
• Radial loops • DNA is arranged in 30 nm fibers
Condensins
• Solenoid or Zigzag molecule
Negative and positive supercoils • Forms radial loops bound to a
can form
nuclear matrix filament
• Negative
• MARs bind to specific
• More common
proteins in the nuclear
• Left handed twist
matrix and form
• Induces tens
Title: Genetics Outlline
Description: chart of the enzymes used in DNA replication, transcription and translation and their actions. chart of the actions and processes of DNA replication, transcription, and translation.
Description: chart of the enzymes used in DNA replication, transcription and translation and their actions. chart of the actions and processes of DNA replication, transcription, and translation.