Lecture 02 Flashcards
What is the foundation of the existence of multicellular organisms?
Cell division
Differentiate mitosis and meiosis (in general).
Mitosis - produces two diploid daughter cells
Meiosis - produces 4 haploid daughter cells
What are the 5 main phases involved in cell cycle?
Gap 1 (G1),
Cellular Senescence/Quiescence (G0),
Synthesis (S),
Gap 2 (G2),
Mitosis (M)
Enumerate and describe the 5 stages/phases of Mitosis,
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
Phase where cells no longer divide, but are still active
G0 phase
________ occurs after telophase and before G1.
Cytokinesis/Cytoplasmic division
Sister chromatids are connected by which protein?
Cohesin
The presence of cohesin first occurs during which phase of the cell cycle?
S phase
Phase in the cell cycle which rechecks if cell has enough resources.
G1 phase
T or F. During the start/restriction point, the removal of signals for DNA replication will cancel its transition to S phase.
False. S/R point is where “there is no turning back” to DNA replication.
Example of multinucleated cells?
Skeletal muscles
Multinucleated cells lack ________ in its cell cycle.
Cytokinesis
Phase that checks for unreplicated or damaged DNA.
G2
In ________, cells do not undergo the M phase.
Endocycle
Endocycle results to _________ which is common in ________ but rare in _________.
polyploidy; plants; animals
In the vertebrate embryo cells, the no gap phases is observed in the ________ stage.
blastula
An artificial thymidine analog used to identify S-phase cells.
5-ethynyl-2’-deoxyuridine (EdU)
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
d.
Summarize the central dogma BRIEFLY.
Good job :D
______ are switches that control the transition between cell cycle stages.
check points/checkpoints
What are the three major regulatory transitions?
- Start/Restriction Point
- G2/M Transition
- Metaphase-to-Anaphase Transition
In this checkpoint, the cell checks for chromosomal aberrations.
Metaphase-to-Anaphase Transition
Summarize what PP2A activates and inactivates, etc.
PP2A:
- inhibits Greatwall kinase by dephosphorylation
- activates Wee1 by dephosphorylation
- inactivates Cdc25 by dephosphorylation
(Notice that PP2A always dephosphorylates IN THE CONTEXT OF OUR LECTURE)
Antagonistic or Synergistic (A/S):
Wee1 to Cdk-cyclin complex
A
Antagonistic or Synergistic:
Wee1 and Cdc25
A
Antagonistic or Synergistic:
Cdc25 to Cdk-cyclin complex
S
Antagonistic or Synergistic:
M-Cdk and PP2A
A
Antagonistic or Synergistic:
Ensa and PP2A
A
Antagonistic or Synergistic:
Greatwall kinase to M-Cdk
S
Antagonistic or Synergistic:
Greatwall kinase and Ensa
S
Antagonistic or Synergistic:
Ensa and M-Cdk
S
Antagonistic or Synergistic:
p27 and Cdk-cyclin complex
A
Antagonistic or Synergistic:
PP2A and Wee1
S
Antagonistic or Synergistic:
PP2A and Cdc25
A
Antagonistic or Synergistic:
PP2A and Greatwall kinase
A
T or F. Active M-Cdk directly inactivates PP2A, creating a positive feedback during M phase.
False. It indirectly inactivates PP2A.
How does M-Cdk indirectly inactivate PP2A?
M-Cdk activates Greatwall kinase (Gk) by phosphorylation. Gk activates Ensa by phosphorylation. Ensa binds to PP2A-B55, inactivating it.
- Wee 1 inhibits M-Cdk
- PP2A inhibits Wee 1
- M-Cdk stimulates Cdc25
- 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
e. 1, 3, and 4
- Wee 1 inactivates M-Cdk by dephosphorylation
- PP2A inactivates M-Cdk by phosphorylation
- Cdc25 activates M-Cdk by dephosphorylation
- 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
b. 3 and 4
Try to recall why :D
Protein complex that triggers Metaphase-to-Anaphase transition
Anaphase-promoting complex/cyclosome (APC/C)
T or F. Cdc25 activates APC/C
F. Cdc20 activates APC/C
Protein responsible for phosphorylating an inactive M-Cdk complex on its activating site
Cdk-activating kinase (CAK)
T or F.
1. APC/C leads into the degradation of M-Cdk.
2. M-Cdk helps in activating APC/C.
- T
- T
(negative feedback of M-Cdk)
In which checkpoint does M-Cdk lead to the destruction of cyclins?
M-to-A transition
Which occurs later in the M phase?
APC/C-Cdh1 or APC/C-Cdc20
APC/C-Cdh1
APC/C : M-Cdk :: _____ : CKI
SCF.
APC/C helps in ubiquitylation of M-Cdk. SCF helps in ubiquitylation of CKI
What are the protein subunits of cohesin that form the main ring where the sister chromatids are encircled in?
Smc1 and Smc3
Function of separase?
Cleaves and dissociates cohesins; for anaphase
How is separase activated?
By degradation of securin (inhibitory protein) initiated by the APC/C
