DNA Replication

Question 1

Who discovered heritable material studying strains of pneumonia?

Answer 1

Frederick Griffith

Question 2

Who showed early on that heritable material is DNA?

Answer 2

Oswald Avery

Question 3

Who noted that the ratio of A:T and C:G is 1:1

Answer 3

Erwin Chargaff

Question 4

Who is given credit for the discovery of the structure of DNA?

Answer 4

Francis Crick, James Watson, Maurice Wilkins, and Rosalind Franklin

Question 5

What is the backbone of DNA composed of?

Answer 5

Deoxyribose-phosphate

Question 6

What functional group is at the 3’ end? 5’ end?

Answer 6

Free -OH at 3’; Phosphate group at 5’

Question 7

What is the relationship of the two DNA strands to each other?

Answer 7

Antiparallel

Question 8

Adenine is bound to Thymine by how many hydrogen bonds?

Answer 8

2

Question 9

Cytosine binds to Guanine via how many H-bonds?

Answer 9

3

Question 10

How are nucleotides in a strand linked?

Answer 10

Phosphodiester bonds

Question 11

In which direction does DNA synthesis occur?

Answer 11

5’—>3’

Question 12

What is the name of the pattern of DNA replication?

Answer 12

Semi-conservative

Question 13

How many origins of replication are located on bacterial chromosomes?

Answer 13

1

Question 14

What is the initiating step of DNA replication in prokaryotes?

Answer 14

DnaA ATPase recognizes and binds the origin-of-replication sequence and melts the origin open

Question 15

Following the action of DnaA, what enymes continue to unzip the DNA?

Answer 15

DNA helicases

Question 16

What prevents the single stranded DNA from reannealing following helicase seperation?

Answer 16

Single-stranded DNA Binding Protein

Question 17

Which is the only prokaryotic enzyme that can lay down a new strand “from scratch”

Answer 17

Primase

Question 18

Why are topoisomerases needed?

Answer 18

As the DNA helix is unzipped, the DNA downstream becomes supercoiled and builds up tension

Question 19

What is the action of Type I Topoisomerases?

Answer 19

Breaking of a covalent bond in the phosphodiester backbone of a single strand of DNA

Question 20

What is the action of Type II Topoisomerases?

Answer 20

Produces a clean break through a DNA duplex to pass tangled duplexes through each other

Question 21

What kind of enzyme is DNA gyrase?

Answer 21

Type II topoisomerase

Question 22

What is the mechanism of antibiotic Ciprofloxacin

Answer 22

Mixed-mode non-competative inhibitor of DNA gyrase

Question 23

What prokaryotic enzyme synthesizes DNA from the RNA primer in the 5’–>3’ direction?

Answer 23

DNA Polymerase III

Question 24

On which strand are Okazaki fragments formed?

Answer 24

Lagging strand

Question 25

What kind of enzymatic activity allows DNA pol III to proofread?

Answer 25

3’–>5’ exonuclease activity

Question 26

What prokaryotic enzyme “cleans up” by excising all RNA primers and patching resulting gaps with DNA?

Answer 26

DNA Polymerase I

Question 27

What marks the committed step of cell division in eukaryotes?

Answer 27

The onset of DNA replication

Question 28

How many origins of replication are located in the human genome?

Answer 28

Hundreds

Question 29

What eukaryotic enzyme contains primase and initiates DNA synthesis?

Answer 29

Pol alpha

Question 30

What is the major eukaryotic replication enzyme for lagging strand synthesis?

Answer 30

Pol delta

Question 31

What is the major eukaryotic replication enzyme for leading strand synthesis?

Answer 31

Pol sigma

Question 32

What eukaryotic polymerase is used for repair?

Answer 32

Pol beta

Question 33

What eukaryotic polymerase is only found in mitochondrial DNA?

Answer 33

Pol gamma

Question 34

What eukaryotic enzyme performs the same action as prokaryotic DNA Polymerase I?

Answer 34

FEN-1 nuclease

Question 35

What enzyme maintains the length of telomeres in cancer and germ cells?

Answer 35

Telomerase