DNA Replication

Question 1

What is the purpose of new DNA/DNA replication?

Answer 1

growth, repair, reproduce

Question 2

What replication mechanism is used?

Answer 2

Semi-conservative

Question 3

What experiment determined the replication method dna uses? explain the experiment

Answer 3

meselon-stahl experiment

Question 4

explain triplet code

Answer 4

every 3 bases codes/combos for one of the 20 amino acids in dna, triplet code is how dna operates

Question 5

What occurs in the initiation phase?

Answer 5

1. DNA Gyrase unwinds DNA
2. DNA Helicase binds to the origin, unwinds and separates strands by breaking h-bonds holding them together to create a BUBBLE or TWO FORKS
3. SSBPs (single-strand bubble proteins) attach to newly exposed nucleotides to prevent them from binding to each other again

Question 6

what occurs on the LEADING strand during elongation phase?

Answer 6

1. RNA primase attaches parent chain puts down RNA nucleotides (primers)
2. DNA poly 3 binds to primer and adds complimentary nucleotides/bases towards the fork
3. when primase reaches end of fork, DNA Poly 1 attaches to end and dismantles it, replacing it with nucleotides

Question 7

what occurs on the LAGGING strand during elongation phase?

Answer 7

1. RNA primase attaches parent chain puts down RNA nucleotides (primers)
2. DNA poly 3 binds to primer and adds complimentary nucleotides/bases AWAY from fork
3. another rna primase/poly 3 attaches to upstream (closer to fork) of OG primer and repeats the process
4. Okazaki fragments created
5. DNA ligase binds Okazaki fragments together with phosphodiester bonds

Question 8

order of enzymes in leading

Answer 8

1. RNA PRIMASE
2. DNA POLYMERASE 3
3. DNA POLYMERASE 1

Question 9

order of enzymes in lagging

Answer 9

1. RNA PRIMASE
2. DNA POLYMERASE 3
3. DNA POLYMERASE 1
4. DNA LIGASE

Question 10

what is the purpose of dna polymerase 3?

Answer 10

binds to rna nucleotides (primers) and creates complimentary nucleotides for parent strand

Question 11

what is the purpose of dna polymerase 1?

Answer 11

dismantles rna primase when it reaches end of parent strand and replaces it with nucleotides

Question 12

what is the purpose of dna polymerase 2?

Answer 12

proof reads and fixes any mistakes by removing wrong nucleotides and replacing it with right ones
makes sure h-bonds are present between bubble pairs

Question 13

what is the purpose of DNA ligase?

Answer 13

creates phosphodiester bonds to join okazaki fragments

Question 14

what happens in termination phase?

Answer 14

• okazaki fragments dont properly match with parent stands bc primase is still in the way so theres no room for dna poly 1 to attach and dismantle it
• end of dna snipped off
• dna naturally forms its double helix structure

Question 15

what is a telomere

Answer 15

nonsense region of dna that buffer the loss of dna
- if telomere erodes, cell malfunctions and DIES

Question 16

what does telomerase do?

Answer 16

replenishes telomeres, deactivated at a certain point