DNA replication

Question 1

What is the function of DNA?

Answer 1

Storage of genetic information, replication, and gene expression.

Question 2

What are the steps of DNA replication?

Answer 2

Separation, initiation, elongation, and termination.

Question 3

What does DNA helicase do?

Answer 3

Unwinds the DNA double helix by breaking hydrogen bonds between bases.

Question 4

What is the role of single-stranded binding proteins?

Answer 4

They prevent reformation of secondary structures in single-stranded DNA.

Question 5

What does DNA primase do?

Answer 5

Synthesizes RNA primers needed to start DNA replication.

Question 6

What direction does DNA polymerase work in?

Answer 6

In the 5’ to 3’ direction.

Question 7

What are Okazaki fragments?

Answer 7

Short DNA fragments formed on the lagging strand during replication.

Question 8

What does DNA ligase do?

Answer 8

Joins DNA fragments by forming covalent bonds to make a continuous strand.

Question 9

What is the role of the sliding clamp in DNA replication?

Answer 9

Keeps DNA polymerase attached to the template strand for efficient replication.

Question 10

Why is replication semi-conservative?

Answer 10

Each new DNA molecule contains one original and one new strand.

Question 11

Where does DNA replication begin in prokaryotes?

Answer 11

At specific origins of replication, such as OriC in prokaryotes.

Question 12

Which base pairs are easier to separate and why?

Answer 12

AT base pairs, because they have only 2 hydrogen bonds compared to 3 in GC pairs.

Question 13

What enzymes initiate replication at OriC in E. coli?

Answer 13

DnaA, DnaB, and DnaC.

Question 14

What is the function of DNA gyrase?

Answer 14

Relieves torsional stress by making transient double-strand breaks.

Question 15

What causes torsional stress during replication?

Answer 15

Unwinding of the DNA double helix by helicase.

Question 16

What happens during replication termination?

Answer 16

Replication forks meet at the dif site; enzymes disassemble and DNA ligase joins final fragments.

Question 17

What is proofreading in DNA replication?

Answer 17

The ability of DNA polymerase to detect and correct mismatched bases.

Question 18

What can result from a single base pair substitution?

Answer 18

A different amino acid may be incorporated, potentially altering protein function.

Question 19

Why is replication accuracy essential?

Answer 19

Errors can change protein shape/function and impact cellular function.

Question 20

How do mutations relate to evolution?

Answer 20

They introduce variation, which can be beneficial and drive natural selection.

Question 21

What is the origin of replication (OriC)?

Answer 21

A specific sequence where DNA replication begins, rich in AT bases.

Question 22

What is DnaA’s role in replication?

Answer 22

Binds to OriC and initiates strand separation.

Question 23

What is the role of DnaB helicase?

Answer 23

Unwinds DNA strands at the replication fork.

Question 24

What is the role of DnaC?

Answer 24

Assists DnaB in loading onto DNA at OriC.

Question 25

What is the function of the clamp loader?

Answer 25

Loads the sliding clamp onto DNA polymerase.

Question 26

What type of enzyme is DNA gyrase?

Answer 26

A type II topoisomerase that relieves supercoiling.

Question 27

How do topoisomerases resolve DNA tension?

Answer 27

By breaking and rejoining DNA strands to relieve torsional stress.

Question 28

What is the difference between the leading and lagging strands?

Answer 28

Leading strand is synthesized continuously; lagging strand in fragments.

Question 29

Why are RNA primers needed in DNA replication?

Answer 29

They provide a starting point for DNA polymerase to synthesize DNA.

Question 30

What is the dif site in bacterial DNA replication?

Answer 30

A termination site where replication forks converge in bacteria.

Question 31

How is the lagging strand synthesized?

Answer 31

Through synthesis of short fragments later joined by ligase.

Question 32

What are the properties of nucleic acids that aid replication?

Answer 32

Complementary base pairing and antiparallel strand orientation.

Question 33

How does ATP power DNA helicase?

Answer 33

Hydrolysis of ATP provides energy for helicase to unwind DNA.

Question 34

What type of bonding is broken during strand separation?

Answer 34

Hydrogen bonds between complementary bases.

Question 35

How do sliding clamps increase fidelity of replication?

Answer 35

They prevent DNA polymerase from falling off prematurely.

Question 36

What does the term 'fidelity' mean in replication?

Answer 36

The accuracy of copying genetic material during replication.

Question 37

What is the central dogma of molecular biology?

Answer 37

DNA → RNA → Protein; it describes genetic information flow.

Question 38

How do replication forks behave?

Answer 38

They move outward from the origin in both directions.

Question 39

Why does DNA polymerase need a template?

Answer 39

It needs a strand to match nucleotides against.

Question 40

Why is base pairing specificity crucial for replication?

Answer 40

It ensures correct bases are added, maintaining genetic integrity.

Question 41

What is a double-strand break (DSB)?

Answer 41

Break in both strands of the DNA double helix.

Question 42

What does DNA polymerase III do in prokaryotes?

Answer 42

Synthesizes new DNA strands using RNA primers.

Question 43

What does the clamp loader complex do?

Answer 43

Helps place and secure the sliding clamp onto DNA.

Question 44

Why are AT-rich regions important at OriC?

Answer 44

Easier to separate due to fewer hydrogen bonds.

Question 45

How does replication differ between prokaryotes and eukaryotes?

Answer 45

Eukaryotic replication has multiple origins and involves more enzymes and complexity.