Chapter 4: 4.3 In vivo DNA Replication Flashcards
True or False:
DNA within eukaryotic cells is very large
True
Are strands of DNA within eukaryotic cells separated?
They are not completely separate prior to replication
Where does DNA replication begin?
On specific locations designated as origins of replication
How do the multiple new strands of DNA meet one another and come together to form a brand new strand?
The replication bubbles extend out
How many origin of replications do prokaryotic chromosomes have?
One
How many origins of replication do eukaryotic chromosomes have?
Multiple
True or False:
DNA replication is conservative
False, it is semi-conservative
DNA replication is semi-conservative. What does this mean?
The newly double stranded DNA contains one strand from the original DNA and one newly synthesized strand
What is the origin of replication in prokaryotes known as?
Ori
Synthesis of New DNA (Prokaryotes):
At the origin of replication, what unwinds the DNA?
Helicase
Synthesis of New DNA (Prokaryotes):
Unwinding leaves two anti-parallel strands, creating a…
Replication fork
Synthesis of New DNA (Prokaryotes):
How do the two anti-parallel strands stay apart?
**Single stranded binding proteins (ssb) **keep the strands apart
Synthesis of New DNA (Prokaryotes):
What is the function of topoisomerase?
Responsible for “relaxing” the supercoiling of DNA
Synthesis of New DNA (Prokaryotes):
What is responsible for grabbing new nucleotides and mathcing them to the original DNA to create a new strand?
DNA polymerase III
Synthesis of New DNA (Prokaryotes):
What is required for DNA Polymerase III to bind to parental DNA?
RNA primer
Synthesis of New DNA (Prokaryotes):
What is an RNA primer? How is it created?
A short RNA sequence
* Created by an enzyme called primase
Synthesis of New DNA (Prokaryotes):
What direction does DNA Polymerase III:
1. Read?
2. Create?
- Reads DNA in the 3’ to 5’ direction
- Creates a new strand in the 5’ to 3’ direction
True or False:
DNA Polymerase III moves towards the replication fork
False, not necessarily true as leading and lagging strands move in different directions
Synthesis of New DNA (Prokaryotes):
- The strand of polymerase that moves towards the replication fork is…
- The strand of polymerase that moves away from the replication fork is…
- Leading strand
- Lagging strand
Synthesis of New DNA (Prokaryotes):
What is the purpose of the sliding clamp protein?
Tethers DNA polymerase to the strand and replication continues until the adjacent replication bubble is met
True or False:
The leading strand has multiple primers and polymerases
False
Synthesis of New DNA (Prokaryotes):
Which strand will have multiple primers and polymerases?
The Lagging Strand
Synthesis of New DNA (Prokaryotes):
What does the multiple primases and polymerases of the lagging strand create?
Okazaki Fragments
Synthesis of New DNA (Prokaryotes):
What is the purpose of DNA Polymerase I?
Removes the primer and replaces it with deoxyribonucleotides
Synthesis of New DNA (Prokaryotes):
What is the purpose of DNA Ligase?
Moves along the lagging strand and ties the Okazaki fragments together
What is the difference between DNA replication in prokaryotes and eukaryotes?
They are very similar
* Eukaryotes have different names
Why is prokaryotic DNA replication often taught in detail?
It is well understood
Compare in prokaryotes vs. eukaryotes:
Origins of replication
- Prokaryotes: Only one
- Eukaryotes: Multiple
Compare in prokaryotes vs. eukaryotes:
Rate of Replication
- Prokaryotes: Faster (~1000 nt/s)
- Eukaryotes: Slower (50-100 nt/s)
Compare in prokaryotes vs. eukaryotes:
Types of DNA Polymerase
- Prokaryotes: 5
- Eukaryotes: 14
Compare in prokaryotes vs. eukaryotes:
Enzyme for RNA Primer Removal
- Prokaryotes: DNA Polymerase I
- Eukaryotes: RNase H
Compare in prokaryotes vs. eukaryotes:
Enzyme for Strand Elongation
- Prokaryotes: DNA Polymerase III
- Eukaryotes: Polymerase a, Polymerase δ, Polymerase ε
