2 - MZH - Mitosis Flashcards
Define mitosis
Nuclear division that produces 2 genetically identical daughter nuclei, each containingg the same number of chromosomes as the parent nucleus.
List the stages of mitosis + the mnemonic?
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase?
- Cell isn’t dividing, carry out its normal cell functions
- Cell prepares for nuclear division by:
DNA replication
Increasing its ATP content as nuclear division is a very active process
- Replication of cell organelles e.g. mitochondria, occurs in the cytoplasm.
- In animals and some plant cells 2 centrioles move to opposite poles of the cell.
Prophase?
- Chromosomes condense (coil up and get shorter & thicker). Become visible because they stain more intensely.
- DNA replication occured in interphase, each chromosome now consists of 2 identical strands called sister chromatids.
- Nuclear envelope breaks down
Metaphase?
- Spindle forms across the cell, connecting to the centrioles at each side or the pole of the cell.
- Each pair of chromatids move to the equator (metaphase plate) of the cell and attaches to a spindle fibre by its centromere.
Anaphase?
- Centromere splits.
- Sister chromatids seperate (on seperation the chromatids can now be reffered to as chromosomes again).
- Each of the daughter chromosomes moves to the opposite poles of the spindle.
- Characteristic V shape as a result of their centromeres being pulled through the liquid cytosol.
- Numerous mitochondria around the spindle provide neergy for movement.
Telophase?
- Chromosomes move to opposite poles of the cell.
- Nucler envelope forms round each set of chromosomes.
- The 2 nuclei are genetically identical to each other and the original parent cell.
- The instant when the cytoplasm divides and 2 cells are formed is called cytokinesis.
Cytokinesis - What is it?
It happens at the end of telophase. ]
This is the point when the parent cell divides into 2 seperate daughter cells.
It’s different for animal and plant cells.
Cytokinesis - animals
- Cleavage furrow (sometimes called a cytoplasmic cleavage) forms around the middle of the cell.
- Cell surface membrane is pulled inwards by the cytoskeleton until it’s close enough to fuse around the middle forming 2 cells.
Cytokinesis - plants
- Can’t form a cleavage furrow due to cell wall.
- Vesicles from the golgi apparatus assemble in the same place where the metaphase plate was formed.
- Vesicles fuse with each other and the cell surface membrane, dividing the cell into 2.
- New cell wall develops along where the metaphase plate was and the cell divides into 2.
What stage of mitosis is this?
Anaphase
What stage of mitosis is this?
Prophase
What stage of mitosis is this?
Telophase
What stage of mitosis is this?
Metaphase
Compare mitosis and meiosis:
- Biological processes in which cell division is involved
- Number of chromosomes in daughter cells compared to parent cell
- Genetic identity of daughter cells compared with parent cell
