DNA Replication

Question 1

Replication

Answer 1

Synthesis of DNA

Question 2

Transcription

Answer 2

Synthesis of RNA

Question 3

Translation

Answer 3

Synthesis of proteins

Question 4

Prokaryotic replication occurs…

Answer 4

In the cytoplasm (no nuclei)

Question 5

Eukaryotic replication occurs…

Answer 5

In the nuclei (do have nuclei)

Question 6

S phase

Answer 6

Phase during which DNA replication occurs (duplicate chromosomes so each daughter cell inherits a whole genome)

Question 7

G phases

Answer 7

Non-dividing stages (NOT INACTIVE JUST NOT DIVIDING)

Question 8

Characteristics of DNA replication

Answer 8

Requirements (DNA polymerase,Mg, template, dNTPs, primer), direction (5-3), complimentary (A-T, G-C), proofreading (3-5 endonuclease activity excises mismatched nucleotides), bidirectional (replication proceeds in both directions from ori), discontinuous (lagging strand makes short strands called Okazaki fragments in order to maintain 5-3 direction), semiconservative (one strand of a daughter chromosome is newly replicated, the other strand is inherited intact from parental chromosome)

Question 9

Requirements

Answer 9

DNA polymerase: enzyme that catalyzes polymerization of dNTPs into DNA
Mg: not incorporated into DNA, but it’s a cofactor for DNA polymerase activity
Template: to replicate new strand, DNA polymerase must read the template
dNTPs: building blocks of DNA
Primer: free OH at 3’ at terminal nucleotide of previously existing strand

Question 10

Helicase

Answer 10

enzyme that unwinds DNA; central initiation factor

Question 11

Replisome

Answer 11

cluster of factors assembles around helicase to replicate DNA; helicase, DNA polymerase e, pol d, primase, sliding clamp, clamp loader

Question 12

DNA polymerase e

Answer 12

enzyme that replicates the leading strand

Question 13

DNA polymerase delta

Answer 13

enzyme that uses the RNA primer to replicate an Okazaki fragment

Question 14

Sliding clamp

Answer 14

ring like protein that secures the strands to poly e and pol d

Question 15

primase

Answer 15

enzyme binds the unwound lagging strand template and transcribes short stretch of RNA that serves as a primer, providing the 3’ OH group required by pol d

Question 16

Topoisomerase

Answer 16

restores DNA to proper level of supercoiling

Question 17

RNAase

Answer 17

digests any RNA

Question 18

DNA pol b

Answer 18

fills in short gaps in DNA (fills in gaps left by primers) - ONLY add nucleotides

Question 19

DNA ligase

Answer 19

enzyme binds any free 3’ hydroxyls and 5’ phosphates of DNA (seals nicks)

Question 20

Telomerase

Answer 20

a reverse transcriptase enzyme that fills in the gap of telomeres and extends the length of the telomeres

Question 21

The trick with telomerase

Answer 21

Telomerase activity decreases with age and cell culture lines divide a limited number of times and then die (this is believed to be because they have no telomerase activity) so telomerase is important with immortalization; it also is activated in cancer cells (believed to contribute to their immortalization)