DNA replication/chromosomes

Question 1

DNA replicates…

Answer 1

semi conservatively meaning that, 1 strand is from the parent DNA and the other is from the daughter DNA

Question 2

Replication fork and its direction

Answer 2

where DNA splits because of the helicase
it moves in the 5’ to 3’ direction

Question 3

DNA polymerization and its direction

Answer 3

when the growing 3’ of the hydroxyl chain attacks triphosate of incoming nucleotide resulting in pyrosphate

moves in the 5’ to 3’ direction

Question 4

DNA polymerization and its direction

Answer 4

when the growing 3’ of the hydroxyl chain attacks triphosphate of incoming nucleotide resulting in pyrosphate. The energy is used to drive polymerization

moves in the 5’ to 3’ direction

Question 5

The template strand

Answer 5

• moves in the 3’ to 5’ direction
• leading strand
• has a 3’ end
• adds nucleotides in the same 5’ to 3’ direction of the replication fork
• has only one RNA primer

Question 6

The non template strand

Answer 6

• lagging strand
• has a 5’ end (cant add nucleotides only to 3’ end)
• has Okazaki fragments
• moves in 3’ to 5’ intially

Question 7

Topoisomerase 2

Answer 7

works upstream of the replication fork to relieve stress during DNA unwinding

Question 8

Helicase

Answer 8

Separates the parental double helix at the replication fork

Question 9

Single-stranded binding protein

Answer 9

binds to the single-stranded regions, so that the strands don’t recombine

Question 10

DNA ligase

Answer 10

helps join DNA strands by helping the formation of phosphodiester bonds.

joins nucleotides where the RNA primers were

Question 11

DNA polymerase

Answer 11

adds nucleotides to the 3’ end of strand after primer is laid down.
Extends an RNA primer

Question 12

Chromosome replication eukaryotes vs prokaryotes

Answer 12

prokaryotes:
one replication bubble
circular
DNA doesn’t get shortened after every round

Eukaryotes:
two replication bubbles
linear
DNA sequence get shortened after every roun

Question 13

Why are nucleotide bases added quickly while replicating chromosomes ?

Answer 13

There are multiple origins of replication

Question 14

Replication bubble

Answer 14

where a bubble forms as the replication forks splits. They move in different directions

Question 15

Replication vs transcription:

Answer 15

Replication=
duplication of whole chromosomes
miotic cell division
meiosis 1

Transcription=
creating a single strand RNA copy of a gene
produces a form of RNA
The step before translation

Question 16

RNA primase

Answer 16

it creates the 3’ end for DNA polymerase.

Lays down a primer

Question 17

Meselson and Stahl experiment results

Answer 17

after 1 round: the parent strand had heavy nitrogen daughter strand had light nitrogen

after 2 round: half of the duplex have heavy nitrogen and the other half have light nitrogen

Question 18

What is telomerase why is it helpful and useful?

Answer 18

N/A adds repeated nucleotides to stop mRNA from shortening

Question 19

Telomerase is active in…. but not in?

Answer 19

gametes and cancer cells but not in somatic cells