Chapter 4 Lecture 4 - DNA Replication and cell cycle

Question 1

Steps to DNA Replication

Answer 1

1. Double helix unwinds from histones
2. Helix is opened by DNA Helicase, creating the replication fork
3. DNA polymerase moves along each strand, reading the bases and adding complementary nucleotides
4. In one strand, DNA polymerase moves toward the fork, in the other away from the fork in segments
5. DNA ligase joins segments together in the one strand
6. Process continues until entire DNA sequence is copied

Question 2

What is the enzyme used to open the helix

Answer 2

DNA helicase

Question 3

What enzyme reads strand and adds complementary nucleotides

Answer 3

DNA polymerase

Question 4

In what direction does DNA polymerase work

Answer 4

In one strand, toward the replication fork, in the other away from the replication fork, but in small segments

Question 5

What enzyme joins together segments completed by DNA polymerase

Answer 5

DNA ligase

Question 6

What kind of replication (in terms of what is left) is DNA replication considered

Answer 6

Semi-conservative (new DNA is a combination of old and new)

Question 7

What are the 4 phases of the cell cycle

Answer 7

G1, S, G2, M

Question 8

What is another name for G1

Answer 8

First Gap Phase

Question 9

What happens during G1

Answer 9

• Cell makes organelles
• Gains materials needed for DNA replication
• Protein synthesis
• NORMAL FUNCTION

Question 10

What is another name for the S phase

Answer 10

Synthesis Phase

Question 11

What happens during the S phase

Answer 11

Cell duplicates centrioles and DNA

Question 12

What is another name for G2

Answer 12

Second Gap Phase

Question 13

What happens during G2

Answer 13

• Cell grows
• Makes organelles
• Produces enzymes needed for cell division

Question 14

What is another name for the M phase

Answer 14

Mitotic Phase

Question 15

What happens during M phase

Answer 15

Cell replicates its nucleus, pinches off to form two identical daughter cells

Question 16

Interphase

Answer 16

Every part of the cell cycle other than the mitotic phase

Question 17

What are the three checkpoints in the cell cycle

Answer 17

1. Cell growth checkpoint
2. DNA synthesis checkpoint
3. Mitosis checkpoint

Question 18

When and what happens during the Cell Growth checkpoint

Answer 18

End of G1, checks if cell is big enough and has the proper proteins

Question 19

What happens if the cell growth checkpoint is not passed

Answer 19

Cell goes into G0 resting phase

Question 20

When and what happens at the DNA synthesis checkpoint

Answer 20

During S phase, checks if DNA is replicated correctly, if yes, then it continues to mitosis

Question 21

When and what happens at the mitosis checkpoint

Answer 21

During M phase, checks whether or not mitosis is complete, if so the cell divides and the cycle repeats