DNA replication and gene expression

Question 1

What does DNA rep require?

Answer 1

Template and primer

Question 2

What is the direction of DNA ?

Answer 2

5’ >3’

Question 3

What are Purines?

Answer 3

Adenine and Guanine

Question 4

What are Pyrimidines?

Answer 4

Thymine and Cytosine

Question 5

What is prokaryotic DNA?

Answer 5

circular

Question 6

What is phosphodiester bond?

Answer 6

between phosphate and 3’0H of next nucleotide

Question 7

How many H bonds between Guanine and Cytosine?

Answer 7

3 H bonds

Question 8

What is semi conservative rep.?

Answer 8

Template strand is original parent

Question 9

What happens in semi conservative rep?

Answer 9

original parent unwinds> 2 template strands

Question 10

What enzyme used on Replication fork?

Answer 10

DNA polymerase

Question 11

What is used to unwind DNA ?

Answer 11

DNA binding proteins
Enzymes -HELICASES
Hydrolysis of ATP

Question 12

How many origins of replication in prokaryotes ?

Answer 12

1 since circular DNA

Question 13

What primes DNA replication?

Answer 13

RNA Primer - Primase synthesises it

Question 14

What is Exonucleases?

Answer 14

For proof reading and remove wrong nucleotide

- catalyses synthesis of dNTPs

Question 15

What happens at replication fork in SCR?

Answer 15

Leading strand synthesised continuously

Lagging strand synthesised in Okazaki Fragments

Question 16

What joins okazaki fragments ?

Answer 16

DNA Ligase

Question 17

What adds new nucleotides to primers in SCR?

Answer 17

DNA POLYMERASE 3 - synthesises both lagging and leading strand

Question 18

What replaces the primer with DNA ?

Answer 18

DNA POLYMERASE 1

Question 19

What is the primosome?

Answer 19

primase and helicase

Question 20

What does Helicase do?

Answer 20

unwind the chain and break H bonds

Question 21

What stabilizes DNA?

Answer 21

Single strand binding proteins

Question 22

What does transcription make ?

Answer 22

RNA

Question 23

What are transcription steps?

Answer 23

1) Initiation
2) elongation
3) Termination

Question 24

What happens during Initiation ?

Answer 24

RNA polymerase binds to PROMOTER sequence

Question 25

where are promoter region found?

Answer 25

Upstream of start site like TATA Box

Question 26

What does RNA polymerase do?

Answer 26

unwinds base pairs of template DNA in transcription bubble

Question 27

What is TATA box called in prokaryotes?

Answer 27

Pribnow box

Question 28

What happens during Elongation?

Answer 28

RNA polymerase proceeds along DNA template srand

Question 29

What is produced in elongation??

Answer 29

RNA product that is identical to non template strand but RNA has Uracing and not Thymine in DNA

Question 30

How does transcription terminate?

Answer 30

RHO INDEPENDANT

RHO DEPENDANT

Question 31

What is Rho independent termination ?

Answer 31

when mRNA HAIRPIN formed and causes RNA polymerase to stall

Question 32

How is mRNA liberated in rho independent ?

Answer 32

weak mRNA interactions with template DNA

Question 33

What is Rho Dependant termination?

Answer 33

Termination is RHO protein based

Question 34

What happens in Rho dependant?

Answer 34

helicase rho binds to RNA and pulls away from RNA polymerase and DNA template so mRNA released

Question 35

What is RHO protein?

Answer 35

Helicase

Question 36

What strands are identical?

Answer 36

mRNA and coding strand but U not Thymine for mRNA

Question 37

What does transcription not require ?

Answer 37

PRIMERS