cell cycle Flashcards
- longest event in the cycle
- has three (3) substages: G1, S, and G2 phases
- length of the cycle is approximately 24 hours
interphase
- sequence of events where duplication of organelles and preparation for cell division occur
- cell grows and makes a new copy of DNA
- packs enough nutrients for the new daughter cells
interphase
- first checkpoint and called as the restriction point
- cell grows larger and duplicates the organelles
- makes the molecular building blocks needed for the succeeding steps
- cells will take between 5-6 hours to complete S phase
First Gap (G1)
- DNA replication and duplication of centrosomes occurs
- requires 10–12 hours
- occupies about half of the cell cycle
Synthesis Phase (S)
- continuation of G1 and the second checkpoint
- cell grows continuously
- fills up the loss of energy during the S phase
Second Gap (G2)
- making more proteins
- continuously duplicating the organelles
- completing the preparations for the mitotic phase
- lasting only 4-6 hours
Second Gap (G2)
- last checkpoint
- involves two distinct division-related processes: mitosis and cytokinesis
- lasting only >1 hour
Mitotic Phase (M)
Mitotic Phase (M)
- distribution of chromosomes into two daughter nuclei
- takes place in four stages: PMAT
mitosis or karyokinesis
Mitotic Phase (M)
division of the cytoplasm producing two daughter cells
cytokinesis
Duration of the Cell Cycle
24 hours
whole cell cycle
Duration of the Cell Cycle
5 to 6 hours
G1 Phase
Duration of the Cell Cycle
10 to 12 hours
S Phase
Duration of the Cell Cycle
4 to 6 hours
G2 Phase
Duration of the Cell Cycle
> 1 hour
M Phase
What would happen if the size is too small or if it has reserve enough only for
itself?
Gap 0 Phase (G0)
What happens to the two daughter cells produced in one round of the cell cycle?
Gap 1 Phase (G1)
Why do cells enter G0 phase?
- unfavorable environmental conditions
- permanent state for some cells like nerve and cardiac muscle cells
- waiting for signals to enter G1 (don’t divide but performs function)
- also known as the resting phase
- non-dividing and maintains itself
Gap 0 Phase (G0)
Substages of the Interphase
metabolic activity and growth
G1 Phase
Substages of the Interphase
metabolic activity, growth, and DNA synthesis
S Phase
Substages of the Interphase
metabolic activity, growth, and preparation for cell division
G2 Phase
Control System
Who are responsible in these checkpoints?
control system of the cell cycle (includes the cyclins, the cyclin-dependent kinases and p53)
Control System
undergo a constant cycle of synthesis and degradation during cell division
cyclin
Control System
an activating protein that binds to a kinase to form CDK complex
cyclin
Control System
activates or deactivates another protein by phosphorylating them
CDK complexes
Control System
gives the ‘stop’ and ‘go’ signal at the Gap 1 and Gap 2 checkpoints
CDK complexes
Control System
a cyclin-CDK complex that triggers a cell’s passage past the G2 checkpoint into the M phase
MPF (maturation-promoting factor)
Control System
- “guardian of the genome”
- prevents gene mutation
p53
Control System
two types of regulatory proteins involved in cell cycle control:
Cyclins & Cyclin-dependent Kinases (CDK)
Control System
responsible for suppressing tumors, repairs the damaged DNA, and trigger apoptosis if the damaged is beyond repair
p53
is the process of programmed cell death and is used during early development to eliminate unwanted cells
apoptosis
