cellular division
- Created by: wilby99
- Created on: 28-01-16 18:01
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- cellular divisions
- Mitosis
- cell cycle
- INTERPHASE: the section of the cell cycle where the cell prepares for mitosis
- GAP PHASE ONE: the cell grows and new organelles and proteins are made
- G TWO CHECKPOINT: cell checks whether all the DNA has been replicated without any faults if it has the cell can enter Mitosis
- SYNTHESIS: cell replicates its DNA ready to divide
- GAP PHASE TWO: cell keeps growing and the proteins needed for division are made
- G ONE CHECKPOINT: cell checks that all the chemicals needed for replication are present and also checks for any damage to the DNA before entering s-phase
- The process
- PROPHASE: chromosomes condense /centrioles move to the opposite poles of the cell forming the spindle/ nuclear envelope breaks down
- METAPHASE: Chromatids line up along the equator/ spindle attaches to their centromere
- ANAPHASE: centromeres divide/ the spindles contract pulling the chromatids to opposite ends of the cell
- TELOPHASE: Chromatids reach the opposite ends of the cell and are called chromosomes again/ there are now two nuclei
- cell cycle
- Meiosis
- Meiosis 1
- PROPHASE ONE: same as in mitosis except homologous chromosomes paired up and chiasmata are formed in recombination
- ANAPHASE ONE: same as mitosis except the spindle pulls a full chromosome to each pole
- METAPHASE ONES: homologous pairs line up along the equator
- TELOPHASE ONE: a nuclear envelope forms around each homologous pair and cytokinesis occurs forming two new haploid cells.
- Meiosis 2
- The cell undergoes meiosis 1 again except with half the number of chromosomes
- In ANAPHASE TWO the sister chromatids are separated and each daughter cell inherits a chromatid from each chromosome making four haploid daughter cells
- Genetic variation
- crossing over of chromatids
- In prophase one the chromatids get tangled up a bit and some of the chromosomes swap parts.
- They have the same genes but a different combination of alleles
- Independant assortment of chromosomes
- Each homologous pair contains a maternal and paternal chromosome
- when they line up and are separated, it's completely random which chromosomes from each pair end up in which daughter cell
- This is called independent assortment and leads to genetic variation in any potential offspring.
- Each homologous pair contains a maternal and paternal chromosome
- crossing over of chromatids
- Meiosis 1
- Cytokinesis
- This is the splitting of the cytplasm
- The way this happens is by a thin ring of actin filaments that form the contractile ring contract causing the two new ces to 'pinch off'
- Mitosis
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