Lecture 10

Question 1

What is a chromatid?

Answer 1

The product of DNA replication, two identical DNA molecules

Question 2

What is a chromatin?

Answer 2

DNA + a protein complex

Question 3

What is a chromosome?

Answer 3

One molecule of DNA

Question 4

what is a centromere?

Answer 4

Site of attachments of chromatids and kinetochore

Question 5

What is a kinetochore?

Answer 5

Protein complex that assembles at centromere

Question 6

What are the steps of the cell cycle?

Answer 6

Gap 1, S phase, Gap 2 and M phase

Question 7

What happens in S phase?

Answer 7

DNA replication, there are 2 copies of the genome after S phase

Question 8

What is interphase?

Answer 8

G1, S phase and G2

Question 9

What happens in Mitosis?

Answer 9

The chromatids sperate

Question 10

What are the phases of Mitosis?

Answer 10

1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase and Cytokinesis

Question 11

What happens in Prophase?

Answer 11

The cell has 2 chromosomes and 4 chromatids, it also has 2 MTOC that were produced during S phase. These move to the peripheral of the cell

Question 12

What is a MTOC?

Answer 12

Microtubule Organizing Center

Question 13

What happens in Prometaphase?

Answer 13

Microtubules polymerizes in all directions, hoping to catch a kinetochore. They will also attach to the membrane and other Microtubules

Question 14

What happens in Metaphase?

Answer 14

The microtubules polymerize and depolymerize to push and pull the chromosomes to the metaphase plate. Kinesin and Dynein also help move them

Question 15

What are the types of Microtubules and What do they do?

Answer 15

Kinetochore MT attach to the Kinetochores of chromatids, Astral MT attach to the membrane for security and Polar/overlapping MT elongate around cell and help cell stretch

Question 16

What happens in Anaphase?

Answer 16

The kinetochore MT pull the chromatids apart to make chromosomes

Question 17

What happens in Telophase and Cytokinesis?

Answer 17

The Cell is split into two daughter cells each with the correct chromosomes. Microfilaments and myosin squeeze the center until they split.

Question 18

What are the 3 checkpoints during the Cell Cycle?

Answer 18

1. Restriction point, 2. G2 checkpoint, 3. Metaphase/Anaphase checkpoint

Question 19

What happens at the restriction point?

Answer 19

Cell is asked: Are there signals to divide? Is there enough space? Is there enough nutrients? If the answer is yes to all of these then S Phase happens

Question 20

What happens at the G2 checkpoint?

Answer 20

The question asked is: Is DNA replication complete?

Question 21

What happens at the Metaphase/Anaphase checkpoint?

Answer 21

The question asked is: Are all kinetochores attached by MT?

Question 22

What are the 2 main classes of cancer causing genes?

Answer 22

Tumor Suppressor (TSG) and Proto-oncogene

Question 23

What does a TSG normally due and what happens if it mutates?

Answer 23

TSG usually slows the cell cycle and acts as a break pedal. If it mutates cell division can happen uncontrollably

Question 24

What does a proto-oncogene normally do and what happens when it mutates?

Answer 24

It normally promotes the cell cycle and acts as a gas pedal to the cell cycle. When mutated it ignores any signals to stop so cells divide uncontrollably