Lecture 02

Question 1

What is the foundation of the existence of multicellular organisms?

Answer 1

Cell division

Question 2

Differentiate mitosis and meiosis (in general).

Answer 2

Mitosis - produces two diploid daughter cells
Meiosis - produces 4 haploid daughter cells

Question 3

What are the 5 main phases involved in cell cycle?

Answer 3

Gap 1 (G1),
Cellular Senescence/Quiescence (G0),
Synthesis (S),
Gap 2 (G2),
Mitosis (M)

Question 4

Enumerate and describe the 5 stages/phases of Mitosis,

Answer 4

Prophase - condensation of genetic material
Prometaphase - nuclear membrane dissolves
Metaphase - lining up of the chromosomes
Anaphase - separation of sister chromatids
Telophase - opposite of prometaphase and prophase

Question 5

Phase where cells no longer divide, but are still active

Answer 5

G0 phase

Question 6

________ occurs after telophase and before G1.

Answer 6

Cytokinesis/Cytoplasmic division

Question 7

Sister chromatids are connected by which protein?

Answer 7

Cohesin

Question 8

The presence of cohesin first occurs during which phase of the cell cycle?

Answer 8

S phase

Question 9

Phase in the cell cycle which rechecks if cell has enough resources.

Answer 9

G1 phase

Question 10

T or F. During the start/restriction point, the removal of signals for DNA replication will cancel its transition to S phase.

Answer 10

False. S/R point is where “there is no turning back” to DNA replication.

Question 11

Example of multinucleated cells?

Answer 11

Skeletal muscles

Question 12

Multinucleated cells lack ________ in its cell cycle.

Answer 12

Cytokinesis

Question 13

Phase that checks for unreplicated or damaged DNA.

Answer 13

G2

Question 14

In ________, cells do not undergo the M phase.

Answer 14

Endocycle

Question 15

Endocycle results to _________ which is common in ________ but rare in _________.

Answer 15

polyploidy; plants; animals

Question 16

In the vertebrate embryo cells, the no gap phases is observed in the ________ stage.

Answer 16

blastula

Question 17

An artificial thymidine analog used to identify S-phase cells.

Answer 17

5-ethynyl-2’-deoxyuridine (EdU)

Question 18

Newly synthesized DNA in S-phase cells treated with EdU appear ______ while the nuclei in general appear ________.

a. blue; yellow
b. yellow; blue
c. red; yellow
d. red; blue

Answer 18

d.

Question 19

Summarize the central dogma BRIEFLY.

Answer 19

Good job :D

Question 20

______ are switches that control the transition between cell cycle stages.

Answer 20

check points/checkpoints

Question 21

What are the three major regulatory transitions?

Answer 21

1. Start/Restriction Point
2. G2/M Transition
3. Metaphase-to-Anaphase Transition

Question 22

In this checkpoint, the cell checks for chromosomal aberrations.

Answer 22

Metaphase-to-Anaphase Transition

Question 23

Summarize what PP2A activates and inactivates, etc.

Answer 23

PP2A:

1. inhibits Greatwall kinase by dephosphorylation
2. activates Wee1 by dephosphorylation
3. inactivates Cdc25 by dephosphorylation

(Notice that PP2A always dephosphorylates IN THE CONTEXT OF OUR LECTURE)

Question 24

Antagonistic or Synergistic (A/S):
Wee1 to Cdk-cyclin complex

Answer 24

A

Question 25

Antagonistic or Synergistic: Wee1 and Cdc25

Answer 25

A

Question 26

Antagonistic or Synergistic: Cdc25 to Cdk-cyclin complex

Answer 26

S

Question 27

Antagonistic or Synergistic: M-Cdk and PP2A

Answer 27

A

Question 28

Antagonistic or Synergistic: Ensa and PP2A

Answer 28

A

Question 29

Antagonistic or Synergistic: Greatwall kinase to M-Cdk

Answer 29

S

Question 30

Antagonistic or Synergistic: Greatwall kinase and Ensa

Answer 30

S

Question 31

Antagonistic or Synergistic: Ensa and M-Cdk

Answer 31

S

Question 32

Antagonistic or Synergistic: p27 and Cdk-cyclin complex

Answer 32

A

Question 33

Antagonistic or Synergistic: PP2A and Wee1

Answer 33

S

Question 34

Antagonistic or Synergistic: PP2A and Cdc25

Answer 34

A

Question 35

Antagonistic or Synergistic: PP2A and Greatwall kinase

Answer 35

A

Question 36

T or F. Active M-Cdk directly inactivates PP2A, creating a positive feedback during M phase.

Answer 36

False. It indirectly inactivates PP2A.

Question 37

How does M-Cdk indirectly inactivate PP2A?

Answer 37

M-Cdk activates Greatwall kinase (Gk) by phosphorylation. Gk activates Ensa by phosphorylation. Ensa binds to PP2A-B55, inactivating it.

Question 38

1. Wee 1 inhibits M-Cdk 2. PP2A inhibits Wee 1 3. M-Cdk stimulates Cdc25 4. M-Cdk inhibits Wee 1 > Which of the statements above are true? a. 1, 2, and 4 b. 2 and 4 c. 2, 3, and 4 d. 1 and 3 e. 1, 3, and 4

Answer 38

e. 1, 3, and 4

Question 39

1. Wee 1 inactivates M-Cdk by dephosphorylation 2. PP2A inactivates M-Cdk by phosphorylation 3. Cdc25 activates M-Cdk by dephosphorylation 4. Cdc25 and PP2A dephosphorylates M-Cdk > Which of the statements above are true? a. 1 and 4 b. 3 and 4 c. 2, 3, and 4 d. 1, 2, and 3 e. 1, 3, and 4

Answer 39

b. 3 and 4 Try to recall why :D

Question 40

Protein complex that triggers Metaphase-to-Anaphase transition

Answer 40

Anaphase-promoting complex/cyclosome (APC/C)

Question 41

T or F. Cdc25 activates APC/C

Answer 41

F. Cdc20 activates APC/C

Question 42

Protein responsible for phosphorylating an inactive M-Cdk complex on its activating site

Answer 42

Cdk-activating kinase (CAK)

Question 43

T or F. 1. APC/C leads into the degradation of M-Cdk. 2. M-Cdk helps in activating APC/C.

Answer 43

1. T 2. T (negative feedback of M-Cdk)

Question 44

In which checkpoint does M-Cdk lead to the destruction of cyclins?

Answer 44

M-to-A transition

Question 45

Which occurs later in the M phase? APC/C-Cdh1 or APC/C-Cdc20

Answer 45

APC/C-Cdh1

Question 46

APC/C : M-Cdk :: _____ : CKI

Answer 46

SCF. APC/C helps in ubiquitylation of M-Cdk. SCF helps in ubiquitylation of CKI

Question 47

What are the protein subunits of cohesin that form the main ring where the sister chromatids are encircled in?

Answer 47

Smc1 and Smc3

Question 48

Function of separase?

Answer 48

Cleaves and dissociates cohesins; for anaphase

Question 49

How is separase activated?

Answer 49

By degradation of securin (inhibitory protein) initiated by the APC/C