2.7 - The Cell Cycle Flashcards
Why do multicellular organisms need to continually make new cells?
To replace damaged or dead cells.
According to The Cell Theory, every cell arisen comes from a….
Pre-existing cell.
What two distinct stages lead to mitosis in the cell cycle?
- Interphase
2. Mitosis and Cytokinesis
What is interphase during the cell cycle?
- The longest stage of the cell cycle.
- Cell content and DNA is duplicated.
There are 3 sub-stages:
- G1 (Gap 1)
- S (Synthesis)
- G2 (Gap 2)
What is mitosis and cytokinesis during the cell cycle?
- The shortest stage of the cell cycle.
- Cell divides into two identical cells.
What is the time of the total cell cycle for actively dividing cells?
Approximately 20 hours.
What happens at the G1 (Gap 1) stage and how long does it take?
Energy (ATP, sugar, lipids) accumulates, organelles are duplicated.
This takes approximately 8 hours.
What happens at the S (Synthesis) stage and how long does it take?
DNA is replicated.
This takes approximately 6 hours.
What happens at the G2 (Gap 2) stage and how long does it take?
Cell growth continues.
This takes 4 - 5 hours.
What happens at the mitosis stage and how long does it take?
Chromosomes thicken, align and separate into two new cells.
This takes 1 - 2 hours.
G1 Checkpoint:
Late in the G1 phase of the cell cycle, check for:
- Nutrients
- Growth factors
- DNA damage
G2 Checkpoint:
Late in the G2 phase of the cell cycle, check for:
- Cell size
- Correct DNA replication
Mitosis Checkpoint:
Middle of the mitosis phase of the cell cycle, check that:
The spindle has attached to chromosomes.
What can hormones do in the cell cycle?
Externally regulate the cell cycle.
What can growth-promoting hormones do?
Increase or decrease cell division.
