6.1 Cell Cycle Flashcards
What are the 2 main phases of the cell cycle?
- INTERPHASE
- MITOSIS
What is interphase?
Growth period of cell cycle
between mitotic phases
What processes occur during interphase?
- DNA replicated + checked for errors
- Protein synthesis in cytoplasm
- Chloroplasts/Mitochondria grow & divide
- Normal metabolic processes carry on occurring
What are the 3 phases of interphase?
- G1
- S
- G2
What occurs during G1 of interphase?
- protein synthesis
- organelles replicate using proteins from synthesis
- cell increases in size
What occurs during S phase of interphase?
- DNA replicates in nucleus
What occurs during G2 of interphase?
- Cell continues to increase in size
- Energy stores increased
- Replicated DNA checked for errors
What is the mitotic phase of the cell cycle?
Period of cell division
What are the 2 main stages of mitosis?
- MITOSIS - division of nucleus
- CYTOKINESIS - division of cytoplasm to form 2 cells
What is G0?
Phase during which cell leaves cell cycle
either temporarily or permanently
For what reasons may a cell enter G0?
- DIFFERENTIATION
- differentiated cells no longer divide
- DAMAGED DNA
- Cells which are damaged due to damaged DNA do not divide, in order to not create more damaged cells
- SENESCENCE
- senescence = process by which cell “ages”.
- cells can only divide limited number of times before becoming senescent.
What is the purpose of checkpoints within the cell cycle?
- monitor & verify whether each stage has been completed correctly
- before the cell is allowed to progress to the next phase.
What is the purpose of the G1 checkpoint?
To check the following criteria:
- cell size
- nutrients
- growth factors
- DNA damage
What is the purpose of the G2 checkpoint?
To check the following criteria:
- cell size
- DNA replication
- DNA damage
What is the purpose of the spindle assembly checkpoint/metaphase checkpoint?
To check the following criteria:
- chromosome attachment to spindle
What are telomeres?
repeated sequences of DNA at ends of chromosomes.
protect genes at ends & prevent fusing
Why do telomeres shorten during each cell division?
DNA does not replicate all the way to the end
the telomeres present at the ends are not fully replicated
therefore become shorter with each division
What is the difference between mitosis & cytokinesis?
mitosis is the process of replicating & dividing the genome & nucleus
cytokinesis is the physical division of the cell
