Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIO 111 > 14.4: Prokaryotic Replication > Flashcards

14.4: Prokaryotic Replication Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

How does Prokaryotic Replication start?

A
  • It starts at a single place= Origin
  • The 2 separate replisomes are loaded onto the origin & start synthesis in the opposite directions on the chromosome & continue until they reach termination site
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the Replicon?

A

-It controls the DNA at the Origin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What consists of Single Replicon?

A

-Chromosome + Origin (theres more in eukaryotic rep)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 3 different polymerases that help in E.Coli replication?

A
  • DNA Polymerase I
  • DNA Polymerase II
  • DNA Polyermase III
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the key characteristics of all 3 of the DNA Polymerases?

A
  • They all synthesize polynucleotide strands ONLY in the 5’-3’ direction & requires chi-che from a primer
  • They also have 3’-5’ Exonuclease activity= proofreading for enzymes to back-up & remove mispaired base
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What else can some Polymerases do?

A

-They can remove nucleotide=Nuclease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 2 classifications for enzymes that can act as Nucleases?

A
  • Endonucleases

- Exonucleases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Endonucleases?

A

-They are a class of enzymes that act as nucleases that cut out DNA internally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Exonucleases?

A

-They are a class of enzymes that act as nucleases that removes nucleotides from the end of the DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the role of DNA Polymerase III?

A

-It is the main replication enzyme & responsible for the bulk of DNA synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the role of DNA Polymerase I?

A

-It acts on the lagging strand to remove primers & replace them w/ DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of DNA Polymerase II?

A

-This one is more involved in the DNA repair processes instead of replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

True or False: all polymerases are active in DNA replication

A

-False bc DNA Polymerase II is not since its more involved w/ DNA repair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the most efficient way to replicate DNA?

A

-If the helix is unwound ahead of the polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a Helicase?

A

-It is the enzyme that unwinds the double helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does unwinding of the DNA require? what does it cause?

A
  • DNA unwinding requires ATP

- It also causes torsional strain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why would single strands after the unwound DNA be unstable? How would cells solve this problem?

A
  • The hydrophobic bases are exposed to water

- Cells would solve this problem via Single-Strand-Binding protein (SSB)= coats the exposed strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is Supercoiling?

A

-The coiling in space of double-stranded DNA molecules due to torsional strain= occurs when helix is unwound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do we describe the coiling of the double helix?

A

-Topological state of DNA

20
Q

What are Topoisomerases?

A

-They are enzymes that act to relieve the torisional strain that is caused by unwinding & prevent this supercoiling from happening

21
Q

What is DNA Gyrase

A

-It is the topoisomerase involved in DNA replication

22
Q

What is a key characteristic of Replication?

A

-It is semi discontinuous

23
Q

Why is DNA replication semi-discontinuous?

A

-Bc the polymerases can only synthesize in 5’-3’ direction= the leading strand can ONLY be synthesized continuously while the lagging strand must be made in pieces each w/ its own primer

24
Q

What are the DNA fragments that are synthesized on the Lagging strand called?

A

-Okazaki fragments

25
Q

What are the purpose of the Okazaki Fragments?

A

-They introduce a need for more enzymic activity on the lagging strand

26
Q

What is it called when there is a partial opening of a DNA helix to form 2 single strands?

A

-Replication Fork

27
Q

Where do all of the enzymatic activities occur?

A

-The Replication Fork

28
Q

What is the role of DNA Ligase?

A

-It joins the ends of DNA segments & repairs DNA

29
Q

What enzyme are the primers required by DNA polymerase during replication synthesized by?

A

-DNA Primase

30
Q

What is the role of DNA Primase?

A

-It is an RNA polymerase that synthesizes short stretches of RNA 10-20 base pairs= function are primers for DNA polymerase

31
Q

How is the leading strand synthesized?

A
  • A single priming event is required

- Then the strand can be extended indefinitely by DNA Polymerase III

32
Q

What is Processivity?

A

-It is the ability of a polymerase to remain attached to the template

33
Q

What enzyme has high Processivity?

A

-Polymerase III

34
Q

Why does Polymerase III have high Processivity?

A

-Because it consists of multisubunit & the high processivity is due to the “B subunit”

35
Q

What does the B subunit of Polymerase III do?

A
  • It forms a ring that encircles DNA= forms sliding clamp that keeps the polymerase attached to the template
  • This mech can also be found in Eukaryotes
36
Q

How does replication occur in the Lagging Strands?

A
  • Primase (polymerase III) synthesizes the primers for each Okazaki fragments
  • Then the RNA primers are removed & replaced w/ DNA by DNA Polymerase I
  • Finally the fragments are stitched together by DNA Ligase
37
Q

Where does Termination occur?

A

-It occurs at a specific site that is opposite of the oriC on the circular chromosome

38
Q

What do the last 2 stages of replication produce?

A

-They produce 2 daughter molecules that are intertwined like 2 rings in a chain

39
Q

What are the intertwined daughter molecules unlinked by?

A

-DNA gyrase= same enzyme that relieves torsional strain at replication fork

40
Q

What do all the enzymes involved in DNA replication form?

A

-A macromolecular assembly= Replisome=forms “replication organelle”

41
Q

What are the 2 subcomponents of the Replisome?

A
  • Primosome (primase & helicase w/ other proteins)

- A complex of 2 DNA Polymerase III enzymes on each strand

42
Q

True or False: The DNA Polymerase III enzyme are active on both strand simultaneously

A
  • True!

- Because there is a loop formed on the lagging strand = allows the polymerases to move in the same direction

43
Q

What is the Replisome complex held together by?

A

-By a number of proteins including clamp loader

44
Q

What is the role of the Clamp Loader in the Polymerases III?

A

-It loads a B subunit onto the next fragment & transfers the Polymerase III to this new B subunit

45
Q

Does the DNA replication complex move?

A

-No bc it is stationary= DNA moving through it like thread in a showing machine

46
Q

What are the benefits of having a stationary Replication Complex?

A

-It pushes newly synthesized DNA outward= aids in chromosomes segregation

BIO 111 (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions