Cell division, cell diversity and cell differentiation

1. What is the purpose of check points?
• Prevent uncontrolled cell division • Detect and repair damage to DNA • Ensure cycle cannot be reversed • That DNA is duplicated only once during the cell cycle
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2. Order of phases of the cell cycle
• M phase • Gap 0 phase • Gap 1 phase/ growth phase • Synthesis phase (of interphase) • Gap 2 (of interphase)
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3. What is M phase and what checkpoints are present?
• Chemical checkpoint that triggers condensation of chromatin • Half way through the cycle the metaphase checkpoint ensures that the cell if ready to complete mitosis
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4. What occurs within the cell during m phase?
• Cell growth stops • Nuclear division (PMAT) • Cytokinesis
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5. What is Gap 0 phase and what checkpoints are present?
• A resting phase triggered during early Gap 1 at the restriction point by a chemical checkpoint
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6. Which cells do not have a Gap 0 phase?
• Some cells like epithelial cells lining the gut
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7. What occurs within the cell during Gap 0 phase?
• Cells may undergo apoptosis, differentiation or senescence
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8. What is Gap 1 phase?
• Check point control mechanism ensuring that the cell is ready to enter the S phase and begin DNA synthesis
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9. What occurs within the cell during Gap 1 phase?
• Cell growth • Transcription of genes to make RNA occurs • Organelles duplicate • Biosynthesis • The p53 (tumour suppressant) gene helps control this phase
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10. What is S phase of interphase?
• Chromosomes are unwound, DNA is diffuse, DNA if replicated, housekeeping genes (active in all cells) are replicated first. Genes that are inactive in specific types of cells are replicated last
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11. What occurs within the cell during S phase?
• Once in phase committed to finishing the cell cycle • DNA replicates • Chromosomes have been duplicated, each once consists of an identical pair of identical sister chromatids • This phase is rapid as exposed DNA base pairs are susceptible mutation
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12. What is Gap 2 phase?
• Special chemicals ensure the cell is ready for mitosis by stimulating proteins that will be involved in making chromosomes condense and formation of the spindle
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13. What occurs within the cell during Gap 2 phase?
• Cells grow
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14. Why do all living organisms need to create genetically identical daughter cells?
• Asexual reproduction • Growth • Tissue repair
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15. Order of the stages of mitosis
• Prophase • Metaphase • Anaphase • Telophase
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16. What occurs in prophase (mitosis)?
• Chromosomes condense and super coil • Centrioles divide and move to cell poles forming spindle protein network • Nuclear envelope breaks down
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17. What occurs in metaphase (mitosis)?
• Chromosomes line up along the cell equator • Spindle attaches to the centromere of each chromosome
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18. What occurs in anaphase (mitosis)?
• Centromere divide, separating the chromosome into sister chromatids • Spindles contract, pulling chromatids to the poles of the cell
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19. What occurs in telophase (mitosis)?
• Chromatids reach the opposite poles and uncoil • Nuclear envelope forms around both groups, forming nuclei • Cytokinesis occurs after telophase resulting in two diploid daughter cells
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20. What is cytokinesis (mitosis)?
• In animal cells where the plasma membrane folds inwards and nips in the cytoplasm • In plant cells an end plate forms where the equator of the spindle was and new plasma membrane and cellulose cell wall material are laid down on either side along
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21. What is a benefit of genetic variation?
• Genetic variation in a population increases its chances of survival when the environment changes as some individuals will have characteristics that enable them to be better adapted to the change
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22. How meiosis produces genetic variation?
• Crossing over during prophase 1 • Independent assortment of chromosomes in anaphase 1 AND chromatids in anaphase 2 • Haploid gametes are produced which can undergo random fusion with gametes derived from another organism of the same species
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23. How many chromosomes does each person have?
• 23 pairs/46 chromosomes • 23 from mother, 23 from father
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24. What occurs during prophase 1 (meiosis)?
• Chromosomes condense and supercoil • Centrioles divide and move to cell poles forming a spindle protein network • Nuclear envelope breaks down • Crossing over occurs, sister chromatids wrap around each other, joining at the chiasmata and exchange t
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25. What occurs during metaphase 1 (meiosis)?
• Homologous chromosomes align on the equator attached to the spindle by their centromeres • The way they line up determines how they will separate in anaphase
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26. What occurs during anaphase 1 (meiosis)?
• Homologous chromosomes are pulled apart • Centromeres do not divide
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27. What occurs during telophase 1 (meiosis)?
• Two nuclear envelopes from, cytokines occurs and there is a brief interphase • Most plants skip this stage going from anaphase 1 to prophase 2
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28. What occurs during prophase 2 (meiosis)?
• Reformed nuclear envelope breaks down • Chromosomes condense and • Spindles form from the centrioles that divide and move to the poles
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29. What occurs during metaphase 2 (meiosis)?
• Chromosomes attach to the spindle fibres by their centromere at the cell equator • The chromatids are randomly arranged their alignment determines the way they will be separated during anaphase 2
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30. What occurs during anaphase 2 (meiosis)?
• Centromeres divide and chromatids pulled apart
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31. What occurs during telophase 2 (meiosis)?
• Nuclear envelope form around each of the four new haploid nuclei • In animal cells the two cells divide to form four new haploid cells • In plants a tetrad structure of four haploid cells forms
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32. What is differentiation?
• The process by which stem cells become specialised into different types of cells
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33. What is a zygote?
• An undifferentiated, unspecialised cell, a stem cell • When a ovum is fertilised by a spermatozoon and two haploid nuclei fuse to give a cell with a diploid nucleus
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34. What happens when a cell differentiates?
• Certain genes are switched off and other genes may be supressed more, meaning that: the proportion of different organelles differs from those of other cells, the shape of the cell changes, some of the contents of the cell change
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Other cards in this set

Card 2

Front

2. Order of phases of the cell cycle

Back

• M phase • Gap 0 phase • Gap 1 phase/ growth phase • Synthesis phase (of interphase) • Gap 2 (of interphase)

Card 3

Front

3. What is M phase and what checkpoints are present?

Back

Preview of the front of card 3

Card 4

Front

4. What occurs within the cell during m phase?

Back

Preview of the front of card 4

Card 5

Front

5. What is Gap 0 phase and what checkpoints are present?

Back

Preview of the front of card 5
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