DNA Replication Flashcards Preview

Bio 2 (Let's go Chagnon) > DNA Replication > Flashcards

Flashcards in DNA Replication Deck (43):
1

________ is circular and has only one chromosome

Bacterial DNA

2

_____ occurs in both directions of a chromosome

Replication

3

Example of prokaryotic DNA replication

E-coli (circular chromosome)
has 5M base pairs an tkes less than 1 hour to replicate

4

What are the 3 phases of DNA replication?

initiation
elongation
termination

5

What happens in the initiation phase?

Replication begins at an origin of replication

6

What happens in the elongation phase?

New strands of DNA are synthesized

7

What happens in the termination step?

Replication is terminated at the termination site

8

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

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

9

The replication proceeds in ___ directions.

2

10

A Y shaped region where the new strands are elongating

replication fork

11

What is a replication fork?

Y shaped region where the new strands are elongating

12

What is primer made of?

RNA nucleotides

13

What happens after the generation of the primer?

DNA Polymerase III will elongate the chain

14

What is the fonction of DNA polymerase I?

Proof read, repairs, replaces

15

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

Origin of Replication

16

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

Enzymes

17

The double helix is unwound by the enzyme ____

Helicase

18

________ prevent DNA from winding up

Single-stranded binding proteins

19

_____ relieves torque created by the helicase

DNA Gyrase

20

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

replisome

21

The replisome consists of 2 things...

1. primase
2. helicase

22

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

Primase

23

What happens during elongation?

Primase makes RNA primer
DNA pol III adds new nucleotides in synthesis step

24

______ is responsible for the majority of DNA synthesis

DNA polymerase III

25

What are the 2 DNA pol III restrictions?

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

26

What are the 2 steps in termination?

DNA Pol I removes RNA primer and fills gaps with DNA nuculeotides

DNA ligase seals the gap by forming a phosphodiester bond

27

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

DNA Pol I

28

______ seals the gap by forming a phosphodiester bond

DNA ligase

29

________ is semi-discontinuous

DNA replication

30

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

leading strand

31

______ is synthesized discontinuously creating Okazaki fragments

Lagging strand

32

2 reasons why it is semi-discontinuous

DNA Pol III can only add nucleotides to the 3' end of the newly synthesized strand

DNA strands run anti-parallel to each other

33

________ moves in 1 direction, synthesizing both strands simultaneously

The replication fork

34

Human has ________ and it takes few hours to copy

6 billion base pairs

35

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

Lack of a primer on the 5' end

36

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

shorter

37

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

Telomeres

38

What is the enzyme producing telomeres?

Telomerase

39

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

Telomerase

40

DNA can be damaged by chemical or physical agents called

Mutagens

41

Name a specific DNA repair mechanism

thymine dimers

42

Name a non-specific DNA repair mechanism

excision repair

43

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

5' to 3'