DNA Replication

Question 1

________ is circular and has only one chromosome

Answer 1

Bacterial DNA

Question 2

_____ occurs in both directions of a chromosome

Answer 2

Replication

Question 3

Example of prokaryotic DNA replication

Answer 3

E-coli (circular chromosome)

has 5M base pairs an tkes less than 1 hour to replicate

Question 4

What are the 3 phases of DNA replication?

Answer 4

initiation
elongation
termination

Question 5

What happens in the initiation phase?

Answer 5

Replication begins at an origin of replication

Question 6

What happens in the elongation phase?

Answer 6

New strands of DNA are synthesized

Question 7

What happens in the termination step?

Answer 7

Replication is terminated at the termination site

Question 8

What is the difference between bacteria and eukaryotes in the initiation step?

Answer 8

Bacteria: 1 origin of replication
Eukaryotes: hundreds or thousands of origin replications

Question 9

The replication proceeds in ___ directions.

Answer 9

2

Question 10

A Y shaped region where the new strands are elongating

Answer 10

replication fork

Question 11

What is a replication fork?

Answer 11

Y shaped region where the new strands are elongating

Question 12

What is primer made of?

Answer 12

RNA nucleotides

Question 13

What happens after the generation of the primer?

Answer 13

DNA Polymerase III will elongate the chain

Question 14

What is the fonction of DNA polymerase I?

Answer 14

Proof read, repairs, replaces

Question 15

______ is a specific sequence of nucleotides (A and T rich) on DNA

Answer 15

Origin of Replication

Question 16

________initiate replication by identifying origin of replication sequence (AT’s), then attach to DNA

Answer 16

Enzymes

Question 17

The double helix is unwound by the enzyme ____

Answer 17

Helicase

Question 18

________ prevent DNA from winding up

Answer 18

Single-stranded binding proteins

Question 19

_____ relieves torque created by the helicase

Answer 19

DNA Gyrase

Question 20

_____ is a DNA replicating structure made up of protein clamps and enzymes which binds at the replication fork.

Answer 20

replisome

Question 21

The replisome consists of 2 things…

Answer 21

1. primase

2. helicase

Question 22

_____ makes an RNA primer to which new nucleotides will be added

Answer 22

Primase

Question 23

What happens during elongation?

Answer 23

Primase makes RNA primer

DNA pol III adds new nucleotides in synthesis step

Question 24

______ is responsible for the majority of DNA synthesis

Answer 24

DNA polymerase III

Question 25

What are the 2 DNA pol III restrictions?

Answer 25

1. only add nucleotides to the 3' end of DNA | 2. only add nucleotides to an existing nucleotide

Question 26

What are the 2 steps in termination?

Answer 26

DNA Pol I removes RNA primer and fills gaps with DNA nuculeotides DNA ligase seals the gap by forming a phosphodiester bond

Question 27

______ removes the RNA primer and fills the gaps with DNA nucleotides

Answer 27

DNA Pol I

Question 28

______ seals the gap by forming a phosphodiester bond

Answer 28

DNA ligase

Question 29

________ is semi-discontinuous

Answer 29

DNA replication

Question 30

is synthesized continuously (in the same direction as the replication fork)

Answer 30

leading strand

Question 31

______ is synthesized discontinuously creating Okazaki fragments

Answer 31

Lagging strand

Question 32

2 reasons why it is semi-discontinuous

Answer 32

DNA Pol III can only add nucleotides to the 3' end of the newly synthesized strand DNA strands run anti-parallel to each other

Question 33

________ moves in 1 direction, synthesizing both strands simultaneously

Answer 33

The replication fork

Question 34

Human has ________ and it takes few hours to copy

Answer 34

6 billion base pairs

Question 35

What is the problem existing in synthesizing the ends of the chromosomes?

Answer 35

Lack of a primer on the 5' end

Question 36

With each round of DNA replication, the linear eukaryotic chromosome becomes ____.

Answer 36

shorter

Question 37

______ are repeated DNA sequence on the ends of eukaryotic chromosome.

Answer 37

Telomeres

Question 38

What is the enzyme producing telomeres?

Answer 38

Telomerase

Question 39

contains an RNA region that is used as a template so a DNA can be produced

Answer 39

Telomerase

Question 40

DNA can be damaged by chemical or physical agents called

Answer 40

Mutagens

Question 41

Name a specific DNA repair mechanism

Answer 41

thymine dimers

Question 42

Name a non-specific DNA repair mechanism

Answer 42

excision repair

Question 43

DNA polymerase can only go from the __' to the __'

Answer 43

5' to 3'