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

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.

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

Meiosis consists of two divisions

Gametes are formed by meiosis: Homologous chromosomes associate

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.

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

or paternal maternal Random assortment in meiosis II Random assortment

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

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

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.

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

Stages of mitosis interphase M prophase I T O S 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

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.

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

Cancer

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.