DNA Replication

Question 1

Aneuploidy

Answer 1

abnormal amount of chromosomes, can be more or less

Question 2

What molecule is released when a nucleotide is added to the growing DNA chain

Answer 2

PPi (nucleotides are triphosphates)

Question 3

DNA replication takes how long

Answer 3

6-12 hours on average

Question 4

Mitosis takes how long

Answer 4

Always an hour

Question 5

Prokaryotes have how many origins of replication?

Answer 5

1

Question 6

Eukaryotes (humans) have how many origins of replication?

Answer 6

30,000 to 50,000

Question 7

Eukaryotic origin examples

Answer 7

AT rich areas, CpG islands because these kinds of areas are usually open and active due to transcription

Question 8

Human cells take how long to replicate

Answer 8

8-24 hours

Question 9

Origin is recognized by what complex?

Answer 9

Origin recognition complex binds to the Origin in late M and early G1

Question 10

CDC 6 stands for

Answer 10

Cell division cycle 6

Question 11

CDT 1 stands for

Answer 11

DNA recognition 1

Question 12

MCM helicase complex stands for

Answer 12

Mini Chromosome Maintenance Helicase complex

Question 13

Licensing replication means

Answer 13

DNA can only be copied once

Question 14

The binding of the MCM creates the…

Answer 14

replication fork

Question 15

What two proteins need to be bound to the ORC to allow replication to proceed?

Answer 15

cdc6 and cdt1

Question 16

What is the function of cdc6?

Answer 16

Binds to the ORC

Question 17

What is the function of cdt1

Answer 17

binds to the MCM and brings to the ORC

Question 18

When does cdc6 peak in the cell?

Answer 18

G1 and S

Question 19

When does cdt1 peak in the cell

Answer 19

M and G1

Question 20

What is the role of gemini in DNA replication

Answer 20

Inhibits cdt1

Question 21

What three enzymes are needed for DNA replication

Answer 21

DNA primase/ Pol Alpha - lays down primer
DNA Pol Delta - copies template
Topoisomerase - prevents supercoiling

Question 22

What is the role of Replication Protein A

Answer 22

When MCM unwinds the DNA and it becomes ssDNA, to prevent degradation by the cell it is coated by RPA for protection

Question 23

What is the prokaryotic equivalent of topoisomerase I

Answer 23

DNA Gyrase

Question 24

What drugs target topoisomerase

Answer 24

Antibiotics - quinolone (cipro, naldixic acid)

Anti tumor - etoposide, doxorubicin

Question 25

DNA ligase uses what energy molecule to create a phosphodiester bond

Answer 25

ATP

Question 26

What two things happen at the replication fork?

Answer 26

Separation of the DNA strands and release of the histones

Question 27

Cohesion is found where and when

Answer 27

immediately before the replication fork and on the newly synthesized strands until separation occurs at anaphase

Question 28

Why do telomeres cause problems in replication?

Answer 28

Telomeres cause issues in replication because DNA Pol D can only add in the 5' direction if there is a strand for it to start on. At the 5' end of the chromosome there is nothing there compared to the 3' side because the RNA primers can be removed but DNA Pol D cannot add new nucleotides

Question 29

Telomerase is a

Answer 29

reverse transcriptase

Question 30

What are 4 possible mechanisms drugs could use to block DNA replication

Answer 30

Block or reduce synthesis of nucleotides Inhibit DNA Polymerase Cross link DNA strands so they do not separate Incorporate nucleoside analog into DNA chains causing weakness and chain termination

Question 31

How does Acyclovir work

Answer 31

similar to guanosine and i converted to a Acyclovir "nucleotide" and inserted into the chain causing chain termination

Question 32

How does foscarnet work (Foscavir) and what does it treat

Answer 32

reversibly blocks the pyrophosphate binding site of the viral polymerase stopping the release of PPi and stops the polymerase from continuing. Foscavir treats Herpes

Question 33

Azidothymidine treats HIV through what action

Answer 33

chain termination (Know more?)

Question 34

Sustiva treats HIV through what mechanism

Answer 34

Non nucleoside reverse transcriptase inhibitor

Question 35

Name of clamp that holds DNA Pol Delta to DNA

Answer 35

PCNA - Proliferating cell nuclear antigen

Question 36

What enzyme complex is responsible for Okazaki fragements

Answer 36

Primase/DNA Pol Alpha