Term
| How do prokaryotes divide, and how do eukaryotes divide? |
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Definition
| prokaryotes = binary fission (replication of chromosomes, and then cytokenises). Eukaryotes = mitosis. |
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Term
| What are the 5 phases of mitosis? |
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Definition
| Interphase, prophase, metaphase, anaphase, telophase. |
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Term
| What are the three stages of interphase? |
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Definition
| G1 (all organelles except chromosomes duplicated). Synthesis (DNA replication). G2 (error repair) |
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Term
| What happens in prophase? |
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Definition
| The chromatin increasingly shortens and thickens by a process of supercoiling until the chromosomes become visible. |
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Term
| What happens in metaphase? |
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Definition
| centrioles move to opposite ends of the cell, spindle fibres form out of the centrioles. spindle fibres attach to each side of chromatids, which then align in middle of cell. |
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Term
| What happens in anaphase? |
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Definition
| The spindle fibres contract, centromeres divide and chromatids are pulled to opposite poles of cell. |
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Term
| What happens in telophase? |
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Definition
| nuclear membrane reforms around both groups of chromosomes, chromosomes uncoil, nucleolus reforms in each nucleus. |
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Term
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Definition
| a family of proteins that control the progression of cells through the cell cycle by activating cyclin-dependent kinase enzymes |
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Term
| Why is the discovery of cyclins a serependipituous discovery? |
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Definition
| Timothy Hunt, Lee Hartwell and Paul Nurse were all working on separate areas of the cell cycle, with different organisms, by chance their work coincided. |
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Term
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Definition
| an excess of cells, which clump together |
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Term
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Definition
| physical, chemical and biological agents that can modify DNA and cause mutations (nt all have to be harmful) |
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Term
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Definition
| special genes with the potential to cause cancer |
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Term
| What is the mitotic index? |
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Definition
| the ratio of the number of cells undergoing mitosis to the number of cells in view. (low MI means treatment against cancer is working, if ther is cancer) |
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