3.12 - Mitosis Flashcards
The importance of mitosis in living organisms The stages of mitosis The process of cytokinesis How uncontrolled cell division can lead to cancer (17 cards)
What two processes occur after interphase?
Mitosis and cytokinesis
What is mitosis?
Division of the nucleus
What is cytokinesis?
Division of the whole cell and cytoplasm
What is the importance of mitosis?
Produces two genetically identical daughter cells
What processes use mitosis in multicellular organisms?
3 uses
- Growth - Unicellular zygotes can divide by mitosis to form multicellular organisms.
- Replacement of damaged or dead tissues - Cells are constantly dying and being replaced using mitosis.
- Asexual reproduction - Some organisms reproduce using mitosis to form genetically identical offspring.
- Development of body plans - Mitosis is used to form the different parts of an organism.
- Production of stem cells - Stem cells divide by mitosis.
What are the four stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What happens during prophase?
3 Key notes
- Chromosomes condense and now visible under a microscope.
- Centrioles migrate to opposite poles of the cell (each centriole starts forming spindles fibres)
- The nucleolus disappears and the nuclear envelope starts to break down
What happens during metaphase?
2 key notes
- Chromosomes line up at the equator
- Each chromosome attaches to the spindle by their centromere
What happens during anaphase?
- Centromeres divide to separate each pair of sister chromatids
- The spindle fibres contract and shorten to pull the chromatids to opposite poles of the cell
- Each chromatid is pulled by its centromere, causing them to take on a āVā shape when viewed under a microscope
What happens during telophase?
2 key notes
- The chromatids reach the opposite poles of the cell where they uncoil to become long and thin chromosomes again
- A nuclear envelope forms around each set of chromosomes to form two nuclei and the nucleolus starts to reform
What happens during cytokinesis?
Cytoplasm divides to produce two daughter cells
What can mutations in genes controlling the cell cycle lead to?
Uncontrolled cell division and tumours
When do tumours become cancerous?
When they invade neighbouring tissues
How do some cancer treatments disrupt cell division?
By targeting specific stages of the cell cycle
What stages do cancer drugs target?
S phase and metaphase
What is the issue with cancer drugs?
They also disrupt the cell cycle of healthy cells
Why are tumour cells more likely to be damaged by cancer drugs?
They divide at a faster rate
