ASU BIO 340 2025

ASU BIO 340 EXAM 3
Study online at https://quizlet.com/_gfo0hh

-Main replication enzyme
DNA Polymerase III -Has 3' to 5' exonuclease activity for
proofreading
Lays down a small piece of RNA, which
Primase
acts as a primer for DNA polymerase
Unwinds DNA at the fork of DNA synthe-
Helicase
sis
These fragments (broken up) will be on
the lagging strand where the replication
Okazaki
is in the opposite direction of the heli-
case.
Joins Okazaki fragments and seals other
Ligase
nicks in sugar-phosphate backbone
Binds to a single-stranded gap.

5' to 3' exonuclease activity for removing
DNA Polymerase I
RNA primers.

Add DNA nucleotides from 5' to 3'
Telomere DNA at the ends of chromosomes
Repairs the ends of chromosomes
Telomerase
Has RNA dependent DNA polymerase
activity
Helicase breaks hydrogen bonds and
"unzips" DNA while Topoisomerase
DNA replication Step 1
ahead of the helicase preventing over-
winding
Single-stranded binding (SSB) protein
DNA replication Step 2 prevents the broken bonds from recom-
bining
DNA replication Step 3 DnaG synthesizes RNA primers
DNA polymerase III synthesizes the
DNA replication Step 4
daughter strand once primed
DNA replication Step 5
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, ASU BIO 340 EXAM 3
Study online at https://quizlet.com/_gfo0hh
DNA polymerase III elongates the lead-
ing strand continuously (same direction
as helicase) and the lagging strand dis-
continuously (Okazaki fragments)
DNA polymerase I removes the RNA and
DNA replication Step 6
replaces it with nucleotides
DNA ligase replaces polymerase I joins
Okazaki fragments by catalyzing the for-
DNA replication Step 7
mation of phosphodiester bonds, sealing
the gaps
A base-pair change that creates a stop
codon in place of a codon specifying an
amino acid

Nonsense Mutation




A base pair change that does not alter
the resulting amino acid due to the re-
dundancy of genetic code

Silent Mutation




A base-pair substitution that results in a
Missense mutation codon that codes for a different amino
acid.



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