DNA Replication Lecture 5

Question 1

The _____ ______ _____ of DNA is like a zipper in DNA replication. ____ unzips the zipper creating two single stranded DNA strands. _____ maintains DNA structure during replication.

Answer 1

• Origin of Replication

- Topoisomerase

Question 2

What are the four steps of DNA replication?

Answer 2

1. Helicase opens double stranded DNA at the origin of replication
2. Proteins bind the single strands, creating the replication fork
3. Immediately behind the helices, DNA polymerase replicates the leading strand in a 5’ to 3’ direction to create the complementary DNA
4. The lagging strand is replicated in a disscontinuous process

Question 3

How is damaged DNA rectified?

Answer 3

• DNA polymerase proofreading

- Repair mechanisms

Question 4

Most traditional chemotherapy drugs block relatively specific biochemical reactions associated with ______ _____ during the ____ phase of the cell cycle.

Answer 4

• DNA replication

- S phase

Question 5

Traditional chemotherapy drugs _____ some aspect of DNA replication or mitosis.

Answer 5

Inhibit

Question 6

True or False: Traditional chemotherapy drugs that target fundamental biological processes only target those cells that are abnormallly rapidly dividing.

Answer 6

False, they affect both cancerous and cells that normally rapidly divide

Question 7

Where are rapidly dividing, non-cancerous cells found in the body? What happens to these cells due to chemotherapy?

Answer 7

• Bone marrow, GI tract, hair follicles

- They are affected by chemotherapy as well even though they are non-cancerous

Question 8

Traditional chemotherapy drugs block _____ ____ and/or directly _____ DNA in order to induce _____.

Answer 8

• DNA Replication
• Damage
• apoptosis

Question 9

True or False: Drugs such as Palladia target mutated RTKs.

Answer 9

False, they cannot distinguish between mutated and normal RTKs so it affects all

Question 10

The ____ _____ _____ _____ pathway is a major pro-survival and proliferation activating signal transduction pathway. In this pathway, the ligand that binds to the RTK is ______. What does it do? What happens when the RTK is activated and phosphorylated?

Answer 10

• Mitogen activated protein kinase (MAPK)
• Mitogen
• Induces cell division by binding to the RTK
• MAPK pathway is activated

Question 11

_____ is a GTP binding protein that functions as a relay protein to transmit the ligand-activated signal to the MAPK signaling pathway.

Answer 11

Ras

Question 12

MAPK pathway activation is associated with the sequential phosphorylation of a series of proteins that promote ____ _____ and ____ _____.

Answer 12

• Cell Survival

- Cell Proliferation

Question 13

_____, a mutant BRAF, causes a constitutively active MAPK pathway without need for a mitogen or RTK activation. ______ is highly specific for this constitutively active form, and has _____ effects on normal, non-mutated BRAF.

Answer 13

• BFAF V600E
• Vemurafenib
• Minimal

Question 14

Vemurafenib is highly specific for the _____ mutant BRAF in humans and ______ mutant BRAF in canines.

Answer 14

• V600E

- V450E