Cell Cycle (Q1) Flashcards
What are the two major phases of the cell cycle?
Interphase and Mitotic Phase
What is the longest event in the cell cycle?
Interphase
Three events that happen during the interphase?
- Cell grows and makes new copy of DNA
- Packs nutrients for new daughter cells
- Duplication of organelles
What is the interphase composed of?
G1, S, and G2 phases
What does the G in G1 and G2 phases stand for?
Gap or Growth
Why were the phases in the interphase called gaps?
They were initially thought to be inactive phases of the cell cycle. Instead, they turned out to be a period for intense metabolic activity.
Three events that happen in First Gap/First Growth?
- Cell growth
- Duplication of organelles
- Synthesis of nucleotides
How long does the G1 phase take?
5 to 6 hours
Two events that happen in Synthesis Phase?
- DNA replication
- Duplication of centrosomes (based on Powerpoint)
How long does the S Phase take?
10 to 12 hours
Three events that happen in Second Gap/Second Growth?
- Continuation of G1 (growth and organelle duplication)
- Fills loss energy during S Phase
- Preparation for next phase
This phase makes more proteins for the cell.
G2
What is the mitotic phase composed of?
- Mitosis/Duplication division
- Cytokinesis
Define cytokinesis.
Division of cytoplasm, producing two daughter cells
How long does the M Phase take?
Approximately an 1 hour
What happens to the two daughter cells produced in one round of the cell cycle?
They may undergo another round of cell division (G1 Phase) or enter a resting state (G0 Phase).
Give a list of reasons why cells enter G0 Phase.
- Unfavorable environmental conditions
- To restore energy
- Waiting for signals to enter G1
What cells enter a permanent state of G0 Phase?
Mature cardiac muscle cells and nerve cells
Why do nerve cells do not divide?
Lack of centrosomes
This regulator is constantly synthesized and degraded during cell division.
Cyclin
Cyclin is an activating ______ that binds to ______ to form ______.
Cyclin is an activating [protein] that binds to [kinase] to form [CDK-complex].
CDK-complex is a type of ______ that ______ or ______ another protein through ______. Gives signals at G1 and G2 checkpoints
CDK-complex is a type of [kinase] that [activates] or [deactivates] another protein through [phosphorylating]. Gives signals at G1 and G2 checkpoints
What is phosphorylation?
Process wherein a phosphate group is added to a molecule
A regulatory protein responsible for suppressing tumors and repairs damaged DNA
p53
What does the p53 do if the damaged DNA is beyond repair?
Triggers apoptosis (cell death)
What are the four basic types of cyclin?
G1 cyclin, G1/S cyclin, S cyclin, M cyclin
A typical cyclin is present at low levels for most of the cycle but increases strongly at the stage where it’s needed. With this, when does G1/S cyclin peak dramatically?
At the transition from G1 to S phase
What does the p53 signal to release when DNA damage is detected?
CDK inhibitor
Cyclin-dependent kinases bound with M cyclin produces ______.
MPF complexes (maturation-promoting factor)
What role does MPF complex play in the cell cycle?
Initiates mitosis
When the cyclin in the MPF complex is degraded, what happens to mitosis?
It ends
The MPF complex also plays a role in activating another protein complex that is responsible for degrading the M cyclin. What is this protein complex?
APC/C (Anaphase-proposing complex/cyclosome)
What are the two specific conditions checked in the G1 Phase checkpoint?
- Sufficient cell size
- Intact genetic material
What happens if the environment in G1 is not favorable?
- Delayed progress through G1
- Enters G0
What is the difference between quiescent and senescent cells?
Cells become quiescent because of the lack of nutrition while they become senescent because of aging or deterioration.
What happens if the cell’s environment is favorable but does not proceed S phase?
The cells differentiate wherein it turns into a more specialized cell.
Does the S Phase have a checkpoint?
No.
What are the three specific conditions checked in the G2 Phase checkpoint?
- Sufficient cell size
- All genetic material is duplicated
- Intact genetic material
What happens if the environment in G2 is not favorable?
Mitosis is delayed
What condition is checked in the M Phase checkpoint?
All chromosomes are attached to the spindle fibers.
What happens to the M Phase if the chromosomes are not attached to the spindle fibers?
Mitosis halts
What could be the result of not having chromosomes attached to the spindles?
Chromosomal syndromes
What happens if the control system does not the stop the damaged cell?
Could result in cancer and mutation
