MBG PART TWO: Lecture 3

Question 1

What happens with Circular DNA?

Answer 1

Replication around the circle provides a 3’ OH group in front od the primer; nucleotides can be added to the 3’OH group when the primer is replaced.

Question 1

What are some unique characteristics of Eukaryotic

Answer 1

• Bidirectional replication from multiple regions of replication
• Helices binds to initiator protein on double- stranded DNA (for prokaryotes, helicase binds to single stranded)

Question 2

What happens with linear DNA?

Answer 2

With multiple origins of replication, elongation of DNA in adjacent replicons provides a 3’ OH group for replacement of primer

Question 3

What phase does DNA replication only occur in?

Answer 3

S-phase

Question 4

What phase are Eukaryotic origins prepared in?

Answer 4

G1 phase

Question 5

What does the S phase allow for?

Answer 5

Entire genome replication once and only once.

Question 6

What is unique to eukaryotes about their RNA primers and Okazki fragments?

Answer 6

Shorter

Question 7

What does pol alpha do?

Answer 7

Primase activity (generates RNA)

Question 8

What does pol epsilon do?

Answer 8

Perfoms leading strand replication.

Question 9

What does pol delta do?

Answer 9

Perform lagging strand replication.

Question 10

What needs to happen to Nucleosomes?

Answer 10

Need to be removed form parental DNA

Question 11

What are nucleosomes?

Answer 11

Histone proteins

Question 12

What are telomeres?

Answer 12

Shorten at each round of eukaryotic replication.

Question 14

What does telomerase activity do?

Answer 14

Extend eukaryotic chromosome ends in replicating cells.

Question 15

What can telomerase without the use of complementary DNA template?

Answer 15

Extend the 3’ end of the chromosome

Question 16

What does lack of telomerase cause?

Answer 16

Shortening of telomeres over time.

Question 17

What are shorter telomeres associated with?

Answer 17

Cellular senescence and death.

Question 18

What diseases are caused by short telomeres?

Answer 18

• Progeria
• Werner’s Syndrome

*Premature Aging

Question 19

Okazaki fragments are associated with the synthesis of?

Answer 19

The lagging strand

Question 20

Which of the following does NOT employ bidirectional replication to copy DNA?

Answer 20

Rolling Circle Replication

Question 21

Primers are removed by?

Answer 21

DNA Pol I

Question 22

DNA replication is an accurate process. When a rare mistake is made, most of the time a 3’ to 5’ exonuclease activity will remove the mismatched nucleotide. In E.coli, this proofreading activity is provided by?

Answer 22

Both DNA polymerase I and III

Question 23

Eukaryotic DNA replication is similar to prokaryotic DNA replication in many respects and similar proteins or protein complexes are required. Which of the following is NOT a correct functional matching of E.coli and eukaryotic replication of proteins?

Answer 23

DNA polymerase I and translesion DNA polymerase

Question 24

Replication of Eukaryotic Chromosomes present several challenges that are not found in prokaryotic cells. What is not a challenge?

Answer 24

Eukaryotic DNA polymerases are, in general, much more error-prone.