aqa biology as level unit 2 meiosis, mitosis and the cell cycle
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AQA Biology AS LevelUnit 2
Meiosis, Mitosis and the Cell Cycle
![Page 2: AQA Biology AS Level Unit 2 Meiosis, Mitosis and the Cell Cycle](https://reader033.vdocuments.mx/reader033/viewer/2022061305/551405e7550346d8488b4b3b/html5/thumbnails/2.jpg)
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.
![Page 3: AQA Biology AS Level Unit 2 Meiosis, Mitosis and the Cell Cycle](https://reader033.vdocuments.mx/reader033/viewer/2022061305/551405e7550346d8488b4b3b/html5/thumbnails/3.jpg)
Replication of chromosomes occurs prior to division
chromatids
centromere
chromosome
Homologous chromosomes
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Meiosis consists of two divisions
Meiosis 1 Meiosis 2
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Gametes are formed by meiosis:
Homologous chromosomes associate
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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.
![Page 7: AQA Biology AS Level Unit 2 Meiosis, Mitosis and the Cell Cycle](https://reader033.vdocuments.mx/reader033/viewer/2022061305/551405e7550346d8488b4b3b/html5/thumbnails/7.jpg)
Independent segregation increases variation
Random assortment in meiosis I
Random assortment in meiosis II
maternal paternal
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or
Random assortment in meiosis I
Random assortment in meiosis II
maternal paternal
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Crossing over increases variation
In the first division of meiosis the homologous chromosomes associate
chiasma
recombinant chromosome
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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
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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.
![Page 12: AQA Biology AS Level Unit 2 Meiosis, Mitosis and the Cell Cycle](https://reader033.vdocuments.mx/reader033/viewer/2022061305/551405e7550346d8488b4b3b/html5/thumbnails/12.jpg)
Mitosis produces two identical daughter cells.
prophase
metaphase
anaphase
telophase
cytoplasmic division (cytokinesis)
interphase
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Stages of mitosis
MITOSIS
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
![Page 14: AQA Biology AS Level Unit 2 Meiosis, Mitosis and the Cell Cycle](https://reader033.vdocuments.mx/reader033/viewer/2022061305/551405e7550346d8488b4b3b/html5/thumbnails/14.jpg)
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.
![Page 15: AQA Biology AS Level Unit 2 Meiosis, Mitosis and the Cell Cycle](https://reader033.vdocuments.mx/reader033/viewer/2022061305/551405e7550346d8488b4b3b/html5/thumbnails/15.jpg)
The cell cycle
interphase
G1:Growth of daughter cellDuplication of organelles other than nucleus
S:Replication of DNA
G2: Cell checks DNA and makes any repairs. Cell prepares for division
cytoplasmic division
nuclear divisionprophasemetaphaseanaphasetelophase
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Cancer
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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.