Brainscape's Knowledge GenomeTM

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


See full index

CB > 6 > Flashcards

6 Flashcards

1
Q

Why is DNA replication important?

A

DNA replication is crucial for cell division, allowing one cell to divide into many, and for maintaining genetic information across generations

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

How many nucleotides are copied during each cell division?

A

Approximately 3 billion nucleotides are copied during each cell division

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

What is the error rate in DNA replication?

A

About 1-2 errors per cell division

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

What is semiconservative replication?

A

Semiconservative replication means each new DNA molecule consists of one original strand and one newly synthesized strand

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

How does base-pairing enable DNA replication?

A

Each strand of the DNA double helix serves as a template, where complementary nucleotides pair (A-T and G-C) to form new strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where does DNA synthesis begin?

A

DNA synthesis begins at replication origins, which are AT-rich regions where the DNA strands are separated

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

What is the replication fork?

A

The replication fork is the area where the two strands of DNA are separated and new strands are synthesized

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

Why is the replication fork asymmetrical?

A

The replication fork is asymmetrical because DNA polymerase synthesizes DNA only in the 5’ to 3’ direction, creating a leading strand (continuous) and a lagging strand (discontinuous)

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

What is the role of DNA polymerase in replication?

A

DNA polymerase synthesizes new DNA strands by adding nucleotides to the 3’ end of the growing strand

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

How does DNA polymerase ensure the accuracy of replication?

A

DNA polymerase is self-correcting; it has a proofreading function that checks for correct base-pairing and removes mismatched nucleotides

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

What are the two main sites on DNA polymerase?

A

The polymerization site (P) for adding nucleotides and the error-correcting (E) site for proofreading

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

What is the role of RNA primers in DNA replication?

A

Short RNA primers are synthesized by DNA primase and provide a starting point for DNA polymerase to begin adding nucleotides

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

Why are RNA primers needed on the lagging strand?

A

The lagging strand is synthesized discontinuously in short fragments (Okazaki fragments), each of which requires an RNA primer to initiate DNA synthesis

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

How are RNA primers removed and replaced?

A

Nuclease breaks down the RNA primers, repair polymerase replaces them with DNA, and DNA ligase joins the fragments

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

What is the role of helicase in DNA replication?

A

Helicase unwinds the DNA double helix, separating the strands so they can be copied

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

What does single-strand binding protein (SSB) do?

A

SSB binds to the unwound single strands of DNA to prevent them from re-annealing or forming secondary structures

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

What is the function of the sliding clamp?

A

The sliding clamp holds DNA polymerase in place as it moves along the DNA template during replication

18
Q

What is the role of DNA ligase in DNA replication?

A

DNA ligase seals the nicks in the sugar-phosphate backbone of the lagging strand, joining the Okazaki fragments into a continuous strand

19
Q

What is the difference between leading and lagging strand synthesis?

A

The leading strand is synthesized continuously in the 5’ to 3’ direction, while the lagging strand is synthesized discontinuously in short Okazaki fragments

20
Q

Why can DNA polymerase only synthesize DNA in the 5’ to 3’ direction?

A

DNA polymerase requires a free 3’-OH group to add nucleotides, so it can only synthesize DNA in the 5’ to 3’ direction

21
Q

How does DNA polymerase correct errors during replication?

A

DNA polymerase proofreads the newly synthesized DNA, and if it detects a mismatch, it removes the incorrect nucleotide and replaces it with the correct one

22
Q

What happens if DNA polymerase fails to correct an error?

A

If an error is not corrected, it can result in a mutation, which may have consequences for cell function or cause diseases like cancer

23
Q

What are the key proteins involved in the DNA replication “machine”? (8)

A
  1. Helicase
  2. Single-strand binding proteins
  3. DNA primase
  4. DNA polymerase
  5. Sliding clamp
  6. Nuclease
  7. Repair polymerase
  8. DNA ligase
24
Q

Role of Helicase

A

Unwinds the DNA

25
Q

Role of SSBs

A

Stabilize the unwound strands

26
Q

Role of DNA Primase

A

Synthesizes RNA primers

27
Q

DNA Polymerase

A

Synthesizes new DNA strands and proofreads

28
Q

Role of Sliding Clamp

A

Hold DNA polymerase in place

29
Q

Role of Nuclease

A

Removes RNA primers

30
Q

Role of Repair Polymerase

A

Replaces RNA primers with DNA

31
Q

Role of DNA Ligase

A

Seals the gap between Okazaki Fragments on the lagging strand

32
Q

What feature of DNA origins makes them easier to open for replication?

A

Replication origins are rich in adenine (A) and thymine (T) base pairs because A-T pairs have only two hydrogen bonds, making them easier to separate

33
Q

What is the role of topoisomerase in DNA replication?

A

Topoisomerase helps relieve the tension that builds up ahead of the replication fork as the DNA double helix is unwound

34
Q

Why does the replication fork move in opposite directions?

A

Replication forks move in opposite directions from each replication origin, allowing for the simultaneous replication of the leading and lagging strands

35
Q

How does DNA replication differ between prokaryotes and eukaryotes?

A

In eukaryotes, replication begins at multiple origins of replication along the DNA, while in prokaryotes, there is typically a single origin of replication

36
Q

What is the difference between Okazaki fragments in prokaryotes and eukaryotes?

A

Okazaki fragments are shorter in eukaryotes than in prokaryotes due to higher complexity of DNA packaging and organization in eukaryotic cells

37
Q

What happens if DNA polymerase encounters a damaged template?

A

replication may stall
and repair enzymes must correct the damage before replication can continue

38
Q

How do all the proteins involved in DNA replication work together?

A

The proteins at the replication fork form a coordinated “replication machine” that ensures continuous and efficient DNA synthesis, proofreading, and correction

39
Q

What is the role of chromatin remodeling during DNA replication?

A

Chromatin remodeling complexes may be required to temporarily open chromatin structure so that the DNA is accessible for replication, particularly in eukaryotic cells

40
Q

Why is the 5’ to 3’ direction critical for DNA polymerase activity?

A

DNA polymerase can only add nucleotides to the 3’ end of the growing DNA strand
- which requires the presence of a free hydroxyl group (-OH) at the 3’ position for the polymerization reaction to proceed

41
Q

How is energy supplied for the polymerization of new nucleotides during DNA replication?

A

The energy for adding new nucleotides comes from breaking off two phosphate groups from the incoming nucleoside triphosphate, driving the polymerization reaction

42
Q

What are the three steps that occur after the removal of the RNA primer on the lagging strand?

A
  • Nuclease removes the RNA primer
  • Repair polymerase replaces it with DNA
  • DNA ligase seals the nicks in the DNA backbone

CB (13 decks)

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