L14 Cell Division PT2 Meiosis and Cell Cycle Regulation_Interactive notes_Fall 2020.docx

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Cell Division – Part 2 Meiosis Meiosis/Mitosis Comparison Cell Cycle Control Cell Division and Cancer Meiosis Sex cells, or gametes, are produced by meiotic cell division which includes TWO rounds of nuclear division - meiosis I and meiosis II, and results in four daughter cells. Each daughter cell contains half the number of chromosomes as the parent and each daughter cell is genetically unique. Click on this link to watch the animated video on meiosis and answer the questions that follow. We will do some additional exercises in the online lecture to ensure you understand this material. You can also read pages 231-235 in your textbook to supplement the animation. Why do gametes need to be haploid? Textbook reference: Chapter 11 Please come to lecture prepared. We will do some in-class activities on the material in these pre-lecture notes
Distinguish between the terms centromere, chromatid and centriole.
What is synapsis and what structure results from synapsis?
True or false, crossing over occurs between sister chromatids.
At which stage does the reductional division happen in meiosis?
Name two ways in which genetic variation is introduced in meiosis and the stage(s) in which they occur.
In an organism whose gametes are n=17, how many unique gametes can be produced? N17? 1
Cytoplasmic Division in Meiosis In mitosis, you will recall that the two daughter cells that are produced are identical both genetically and also in size. In meiosis, the four daughter cells are not genetically identical. Furthermore, in females, there is unequal division of cytoplasm as shown in the diagram. In most animals, including humans, after the oocyte forms the polar bodies undergo apoptosis . For your interest…an interesting article on polar bodies . When Things Go Wrong in Cell Division - Nondisjuntion Nondisjunction is the failure of a pair of chromosomes to separate during anaphase of cell division. The end result depends on exactly when it happens. Click on this animation to help visualize what is happening.

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