quiz 12 Flashcards
DNA is a polymer made of
nucleotides
In what order do the following processes occur during DNA synthesis?
Topoisomerase (Gyrase) relieves the stress created by the unraveling of the DNA double helix
Primase synthesizes the first primer
DNA polymerase begins synthesis of the leading strand
Primase synthesizes primers for lagging strand synthesis
DNA helicase denatures double stranded DNA
DNA polymerase I removes the primers
Once replication has begun DNA helicase continues to open the replication bubble
Ligase connects all the newly replicated strands of DNA
DNA helicase denatures double stranded DNA
Topoisomerase (Gyrase) relieves the stress created by the unraveling of the DNA double helix
DNA polymerase begins synthesis of the leading strand
Primase synthesizes the first primer
Once replication has begun DNA helicase continues to open the replication bubble
Primase synthesizes primers for lagging strand synthesis
DNA polymerase I removes the primers
Ligase connects all the newly replicated strands of DNA
2
4
3
6
1
7
5
8
Why is an RNA primer necessary to initiate DNA synthesis?
DNA polymerase requires a 3’ hydroxyl to add a new nucleotide
Denatures double stranded DNA
helicase
Removes primers
DNA polymerase I
Synthesizes a primer made of RNA
Primase
Connects fragments of DNA produced during DNA synthesis
Ligase
Relieves stress created by the denaturation double stranded DNA
Gyrase
What does DNA polymerase require?
A single stranded DNA to act as a template
A free 3’ hydroxyl
Unbound nucleotides
DNA synthesis
Each of the two existing strands act as a template to produce new double strands
What enzyme best synthesizes a new strand of DNA?
DNA polymerase
How can DNA polymerase be the source of mutation?
It may incorrectly match nucleotides
Why is ionizing radiation a mutagen?
It can break double stranded DNA
How do oxygen radicals create mutagens?
They attach to cytosine to make a nucleotide that pairs with adenine rather than guanine
Why is ultraviolet light a mutagen?
It can fuse two adjacent thymine nucleotides and change the topology of the DNA molecule