Cell Cycle Flashcards
What are the main steps of the cell cycle?
- Mitosis
- Interphase made up of:
1) G1 (Gap Phase 1)
2) Synthesis
3) G2 (Gap Phase 2)
What is mitosis?
Division of a parent cell to produce 2 genetically identical diploid daughter cells
What happens in G1 - Gap Phase 1? 2
- Cell grows
- New organelles and proteins made
What happens in synthesis (s) phase?
DNA replicates
What happens in G2 - Gap Phase 2?
- Cell keeps growing
- Organelles replicated
- ATP content increased for cell division
What are the phases of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What happens in prophase? 7
- Chromosomes condense becoming shorter + thicker
- Each chromosome visible as 2 identical strands called chromatids
- These are joined at one region called centrometre, holding them in pairs
- Centrioles move to opposite ends of the cell
- Centroles form the 2 poles of spindle
- Spindle fibres form between them
- Nuclear envelope and nucleolus breaks down
What happens in metaphase? 2
- Chromatids line up along middle of the cell
- Centrometres attach to spindle fibres at equators
What happens in anaphase? 4
- Centrometres divide, seperating each pair of chromatids
- Spindles contract, pulling chromatids to opposite poles of spindle - centrometre first
- Separated chromatids reach the poles
- Spindle breaks down
What happens in telephase? 3
- Chromatids uncoil, become long and thin again (chromosomes)
- Nuclear envelope forms around each group of chromosomes forming two nuclei
- Cytokenesis occurs, a new cytoplasm forms around each new cell
What is mitotic index?
Proportion of cells undergoing mitosis
Cells with visible chromosomes/total number of cells observed
What does mitotic index show?
Rate at which cells are growing
The higher the mitotic index…
…the faster the cell is growing
What are the purposes of the cell cycle?
- Increase in cell numbers for growth
- Asexual reproduction: clone production
- Tissue repair
- Controls cell growth and division
