The Cell Cycle (mitosis) Flashcards
Mitosis
Mitosis is the part of the cell in which a eukaryotic cell divides to produce two daughter cells, each with the identical copies of DNA produced by the parent cell during DNA replication.
Interphase
Most time is spent in interphase.
- interphase is NOT a stage of mitosis(but is part of the cell cycle)
- DNA replication occurs.
- each chromosome now exists as 2 sister chromatids joined at the centromere.
1.Prophase
- Chromosomes become visible.
- Centrioles move to the poles of the cell.
2.Metaphase
- The nuclear envelope disappears.
- Fibres appear in the cytoplasm and form a a spindle.
- The chromosomes move to the ‘equator’ of the spindle.
- Centromere joins the spindle fibre.
3.Anaphase
-The centromere divides into two.
-The spindle fibres shorten and appear to pull the chromatids apart by the centromeres.
Late anaphase:
-The chromatids are now chromosomes.
4.Telophase
-Chromosomes have reached their poles.
Cytokinesis
- The nuclear envelope forms again.
- The cell constricts.
- The chromosomes become less distinct.
The importance of mitosis.
Genetically identical cells are produced (clones).
It is for growth, repair and asexual reproduction.
Haploid
Term referring to cells that contain only a single copy of each chromosome e.g. Sex cells (gametes)
Diploid
A term applied to cells in which the nucleus contains two sets of chromosomes.
What happens in mitosis
One pair of chromosomes (1from mum,1from dad)»»»DNA replicates.
Still one pair of chromosomes (1from mum,1from dad)
But each chromosome has been replicated.
The copies are held together at the centromere.
Each strand is called a sister chromatid.
The control of mitosis in the treatment of cancer:
Mitosis is a controlled process.
Uncontrolled cell division can lead to the formation of tumours and of cancers. Many cancer treatments are directed at controlling the rate of cell division.
