Cell Cycle Flashcards
Sequence of phases in the life cycle of the cell
CELL CYCLE
Longest event in the cycle
(G1, S, and G2 phases)
Interphase
Cell GROWS and makes a new copy of DNA
Interphase
packs enough nutrients for the new daughter cells
Interphase
(Eukaryotic cell spends most of its life in the stage called)
The cell grows larger
Duplicates the organelles
Makes the molecular building blocks needed
for the succeeding steps
Creates nucleiotides
Intense metabolic activities
First Gap (G1)
DNA replication and duplication of centrosomes occur
Synthesis Phase
Cell grows continuously
Fills up the loss of energy during the S phase
Making more proteins
Continuously duplicating the organelles
Completing the preparations for the mitotic phase.
Second Gap (G2)
Duplication division
Distribution of chromosomes into 2 daughter nuclei
M Phase
Division of the cytoplasm producing 2 identically daughter cells
Cytokinesis
Nuclear division in eukaryotes occurs by
Mitosis
When cells are not dividing, their DNA exists as
Chromatin
They are reproductive cells
Gametes
When homologous chromosomes/sister chromatids don’t separate during meiosis
Nondisjunction
Resting place/Non-diving state
G0 Phase
Why do cells enter G0 phase?
Unfavorable environmental conditions (not enough nutrients & energy)
Waiting for signals to enter G1
Permanent state for some cells like nerve & cardiac muscle cells
How long does a whole cell cycle take?
24 hours
How long G1 Phase take?
5 to 6 hours
How long S Phase take?
10 to 12 hours
How long G2 Phase take?
4 to 6 hours
How long does mitosis phase take?
greater than 1 hour
Control System
Cyclin
CDK Complexes
p53
Two types of regulatory proteins are involved in cell cycle control
cyclins and cyclin-dependent kinases(Cdks)
is a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase
MPF (maturation-promoting factor)
Undergo a constant cycle of synthesis
Cyclin
An activating protein that binds to a
kinase to form CDK complex
Cyclin
degradation during cell division.
Cycline
Activates or deactivates another protein by phosphorylating them
CDK complexes
It gives the ‘ stop’ and ‘ go’ signal at the Gap 1 and Gap 2 checkpoints.
CDK Complexes
What does CDK stands for?
Cyclin-dependent kinases
Responsible for suppressing tumors, repairs the damaged DNA, and trigger apoptosis if the damaged is beyond repair
p53
MPF meaning
Maturation-promoting factor
APC/C
Anaphase-promoting complex/cyclosome
PROCESS OF CONTROL SYSTEM
CDK - binds with CYCLIN - MPF Complexes - Initiates MITOSIS - activates APC/C - M CYCLIN is degraded - CDK
Checkpoints
G1
G2
M Phase
Among the 3 checkpoints, which seems to be the most important?
G1 Checkpoint
REASON:
If a cell receives a go-ahead signal at the G1 checkpoint, it will usually complete the S, G2, and M phases and divide.If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a nondividing state called the G0 phase
FIRST GAP (G1) - Is the environment favorable? IF NOT:
- Delayed progress through G1
- Enter G0 (specialized resting phase)
> Quiescent
> Senescent
Favorable but does not proceed to S phase
- Cell differentiate
A period of inactivity/dormancy
Quiescent
Growing old; aging but still alive
Senescent
SECOND GAP (G2) - Is the environment favorable? Is all DNA replicated? IF NOT?
- Delayed Mitosis
M PHASE - Are all chromosomes attached to the spindle? IF NOT?
Halts Mitosis
The division of the nucleus of the cell into 2 new nuclei
Karyokinesis
TRUE OR FALSE?
Sometimes cells go through mitosis without going through cytokinesis
TRUE
