Chapter 14- Part 3 Molecular Aspects of DNA replication

Question 1

What is the model organism for prokaryotic replication?

Answer 1

E. Coli- has single circular molecule of DNA

Question 2

Explain Prokaryote replication.

Answer 2

Replication begins at one one Origen of replication - ori

Proceeded in both directions around the chromosome- bidirectional

Replicon- DNA controlled by an Origen

Ended at termination site

Question 3

What is a replicon?

Answer 3

DNA controlled by an origin.

Question 4

What does the replication in prokaryotes?

Answer 4

Replisomes replicates linear DNA in prokaryotes and terminates at the termination site

Question 5

Do eukaryotes have one Origen or replication?

Answer 5

No it has multiple origins of replications because they have multiple large chromosomes.

Question 6

Eukaryotic Replication is complicated by:

Answer 6

Large amount of DNA in multiple chromosomes and its liner structure but basic enzymology is the same but just more complex.W

Question 7

Why do we neeed to use new enzymatic activity in eukaryotes?

Answer 7

Since they have ends and are linear we have to protect them via telomeres which are 400 to 500 repeat sequences that are attached to the ends of linear DNA in the eukaryotic cell.

Question 8

What are telomeres?

Answer 8

Repeat sequences of 400> nucleotides that is attached to the ends of linear DNA in eukaryote cells which protect the DNA encoding genes.

Question 9

What adds telemores to the ends of strands?

Answer 9

Telomerase

Question 10

What happens without telemores?

Answer 10

important parts of DNA in the ends get lost

Question 11

IS telemores present in prokaryotes?

Answer 11

No only in eukaryotes

Question 12

Replication machinery aka..

Answer 12

Replisome

Question 13

Two main components of replisome?

Answer 13

• Primosome- Primase, helicase, SSB, toposipmerase
• Complex of 2 DNA pol III- main replication enzyme- one for each strand.

Question 14

What is the main replication enzyme?

Answer 14

COmplex of DNA pol II (2 one for each strand)

Question 15

What does DNA polymerase I do?

Answer 15

Acts on lagging strand Replaces the RNA primer with deoxyribosenuclease

Question 16

What does DNA polymerase II do?

Answer 16

Repairs issues with the DNA

Question 17

What enzyme binds Okazaki fragments together?

Answer 17

DNA ligase

Question 18

What enables DNA polymerase I to be able to act on the lagging strand?

Answer 18

Exonuclease

Question 19

What is the exonuclease activity?

Answer 19

Coming in from the 3’ to 5’ end for proofreading in all three DNA polymerase

Question 20

What only has 5’ to 3’ exonuclease activity?

Answer 20

DNA pol I has 5’ to 3’ exonuclease activity

Question 21

What is a nuclease?

Answer 21

Enzyme that works on polynucleotides and breaks them down

Question 22

What is deoxyribose nuclease?

Answer 22

Works on DNA and breaks it into deoxyrbose nucleotides

Question 23

What is Ribonuclease

Answer 23

Works on RNA and breaks it into ribonucleotides

Question 24

Exonuclease can come in anywhere from the_

Answer 24

end

Question 25

Endonuclease can attack from the ___

Answer 25

Center

Question 26

Example of endonuclease:

Answer 26

Eco R1- restriction endonuclese

Question 27

What is a nick?

Answer 27

ONe phosphodiester bond is missing where DNA POL 1 came in and replaced RNA primer w/ DNA and previous synthesis ended just before primer

Question 28

What seals nicks?

Answer 28

DNA ligases connecting the two fragments

Question 29

How can DNA replication be supported when strand replication is happening in the opposite direction?

Answer 29

The lagging strand template loops around so it moves in the same direction as the leading strand.

Question 30

DNA gyrase is what

Answer 30

Topoisomerase

Question 31

In G1 how does cell prepare for S?

Answer 31

They make all the proteins aka helicase, primase, SSBS DNA gyrase, DNA polymerase III, I and II DNA ligase

Question 32

DNA TO PROTEIN