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AQA Biology AS Level Unit 2 Meiosis, Mitosis and the Cell Cycle.

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Presentation on theme: "AQA Biology AS Level Unit 2 Meiosis, Mitosis and the Cell Cycle."— Presentation transcript:

1 AQA Biology AS Level Unit 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 chromatids centromere chromosome Homologous chromosomes

4 Meiosis consists of two divisions Meiosis 1Meiosis 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 I Random assortment in meiosis II maternal paternal

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

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

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

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. prophase metaphase anaphase telophase cytoplasmic division (cytokinesis) interphase

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

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

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.


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