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Lesson 5 – Mitosis

Lesson 5 – Mitosis. 1.2 Cell Growth and the cell cycle (continued). What do you know?. On your desk (or in your jotter) draw out the stages of mitosis. Include as much detail as you can remember. Prophase. Key features:

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Lesson 5 – Mitosis

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  1. Lesson 5 – Mitosis 1.2 Cell Growth and the cell cycle (continued)

  2. What do you know? On your desk (or in your jotter) draw out the stages of mitosis. Include as much detail as you can remember.

  3. Prophase • Key features: • Nucleolus disappears (the nucleolus is a darker staining part of the nucleus where RNA is transcribed and assembled) • Chromatin starts to condense into discrete chromosomes, by the end of prophase the chromosomes are visible • The duplicated chromosomes appear as sister chromatids joined at the centromere • Spindle fibres begin to form between the 2 centrosomes (sometimes called centrioles) in the cytoplasm pushing them apart • The nuclear membrane begins to break up

  4. Prophase Animation

  5. Metaphase • Key features: • Nuclear membrane (envelope) breaks down • Centrosomes are at opposite ends of the cell • Microtubules extend from the centrosomes and attach to the centromeres of the chromosomes • Chromosomes line up at the equator , this is know as the metaphase plate

  6. Metaphase animation

  7. Anaphase • Key features: • Microtubules shorten leading to the separation of the chromatids • Chromatids are pulled towards the poles • Each chromatid is now called a chromosome

  8. Anaphase Animation

  9. Telophase • Key features: • Chromosomes begin to de-condense (uncoil) • Nuclear envelope begins to reform • The cell lengthens • Cytokinesis occurs. In animal cells this involves a cleavage furrow, in plant cells a cell plate forms

  10. Telophase Animation

  11. Your Tasks Add highlighted terms to your glossary. Use the Student Activity Guide to prepare for the practical “Staining a root tip and calculating its Mitotic Index”. You should have your Title, Aim, Hypothesis, Method and Results tables ready.

  12. Staining a root tip and Calculating its mitotic Index You will need to prepare for this practical over the weekend. Today we will start by marking the roots of a hyacinth bulb and those of a garlic clove 2mm before the tip. On Monday we will re-measure to see the growth over 3 days.

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