AQA Biology AS Level Unit 2

1. AQA Biology AS LevelUnit 2 Meiosis, Mitosis and the Cell Cycle

2. Outcomes: • Know that cell division by meiosis results in the formation of gametes. • Can describe the importance of meiosis in creating variation by independent assortment of chromosomes and crossing over. • Know that cell division by mitosis results in an increase in number of identical cells for growth and repair. • Identify and name the stages of mitosis in diagrams and photomicrographs. • Describe the cell cycle and relate it to an understanding of cancer and its treatment.

3. Replication of chromosomes occurs prior to division Homologous chromosomes centromere chromosome chromatids

4. Meiosis consists of two divisions Meiosis 1 Meiosis 2

5. Gametes are formed by meiosis: Homologous chromosomes associate

6. Outcomes: • Know that cell division by meiosis results in the formation of gametes. • Describe the importance of meiosis in creating variation by independent assortment of chromosomes and crossing over. • Know that cell division by mitosis results in an increase in number of identical cells for growth and repair. • Identify and name the stages of mitosis in diagrams and photomicrographs. • Describe the cell cycle and relate it to an understanding of cancer and its treatment.

7. Independent segregation increases variation Random assortment in meiosis II Random assortment in meiosis I paternal maternal

8. or Random assortment in meiosis II Random assortment in meiosis I paternal maternal

9. Crossing over increases variation recombinant chromosome chiasma In the first division of meiosis the homologous chromosomes associate

10. Crossing over increases variation B B b b g g G G b, G B, G b, g B, g All gametes have a different combination of alleles on the chromosomes

11. Outcomes: • Know that cell division by meiosis results in the formation of gametes. • Can describe the importance of meiosis in creating variation by independent assortment of chromosomes and crossing over. • Know that cell division by mitosis results in an increase in number of identical cells for growth and repair. • Identify and name the stages of mitosis in diagrams and photomicrographs. • Describe the cell cycle and relate it to an understanding of cancer and its treatment.

12. Mitosis produces two identical daughter cells. metaphase prophase anaphase interphase telophase cytoplasmic division (cytokinesis)

13. interphase Chromosomes appear, nucleus disappears M I T O S I S prophase Chromatids pulled to poles Chromosomes invisible; DNA replicates metaphase Cytoplasmic division anaphase Chromosomes at equator, spindle forms telophase cytokinesis Chromatids at poles, nucleus reforms Stages of mitosis

14. Outcomes: • Know that cell division by meiosis results in the formation of gametes. • Can describe the importance of meiosis in creating variation by independent assortment of chromosomes and crossing over. • Know that cell division by mitosis results in an increase in number of identical cells for growth and repair. • Identify and name the stages of mitosis in diagrams and photomicrographs. • Describe the cell cycle and relate it to an understanding of cancer and its treatment.

15. interphase G1:Growth of daughter cell Duplication of organelles other than nucleus cytoplasmic division telophase S:Replication of DNA anaphase nuclear division metaphase prophase G2: Cell checks DNA and makes any repairs. Cell prepares for division The cell cycle

16. Cancer

17. Summary • Meoisis produces haploid gametes that are genetically different. Variation is further increased by independent segregation of chromosomes and crossing over forming recombinant chromosomes. • Mitosis is the nuclear division which produces 2 genetically identical, diploid cells. It consists of prophase, metaphase, anaphase and telophase. • Cell cycle consists of interphase, nuclear division (mitosis or meiosis) and cytplasmic division (cytokinesis). • Cancer is caused by mutation of genes that regulate the cell cycle and treatment is designed to inhibit cell division.