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RELEVANT LEARNING OUTCOME:
(f) Describe the events that occur during the meiotic cell cycle and the main stages of meiosis (including the behaviour of chromosomes, nuclear envelope, cell membrane and centrioles) (names of the main stages are expected, but not the sub-divisions of prophase).
Meiosis
Meiosis
👁️🗨️ Watch the video to learn about different stages of meiosis in detail:
Which process at beginning stage of meiosis allows tetrad to be formed?
Will DNA be replicated after meiosis 1 (during 'Interphase 2')?
What is independent assortment?
🖊️Check Your Understanding: Conceptual Check 3
🖊️Check Your Understanding: Conceptual Check 3
With reference to the above figure, fill in the blanks in the following table.
2. With reference to the above figure, account for the changes in DNA and chromosome during meiosis.
*note that this axis for the graph is per nucleus, different from the question in conceptual check 2 of per cell*
During S-phase of interphase I, DNA replication occurs, amount of DNA per nucleus doubles from 2 a.u. to 4 a.u., there is no change in number of chromosomes, as the number of centromeres remains the same, the cell remains diploid;
Amount of DNA per nucleus and number of chromosomes remains the same from G2 to anaphase I;
During Telophase I, separated homologous chromosomes at opposite poles are enclosed in nuclear envelope forming 2 separate nuclei, as such, the the amount of DNA per nucleus is halved and the number of chromosome has also halved, the nucleus is now haploid;
Amount of DNA per nucleus and number of chromosomes remains the same from cytokinesis to anaphase II;
During Telophase II, non-identical sister chromatids at opposite poles are enclosed in nuclear envelope forming 2 separate nuclei, as such, the amount of DNA per nucleus is halved, but each nuclei remains haploid;
🕹️Labster Activity
🕹️Labster Activity
Check-in with your teacher for the following simulation.
Labster: Meiosis: Understand how traits are inherited
Join an IVF lab to help Martin and Charlotte have a baby. In this simulation, you will learn how traits are inherited and how meiosis contributes to genetic diversity in the population. You will use microscopy to study the process of cell division. You will discover the key differences between meiosis and mitosis and find out how these processes contribute to forming, growing and repairing the human body.
User: mi.biologyh1h2@gmail.com
password: @MIsci1234
🖊️Check Your Understanding: Learning Goals Checkpoint
🖊️Check Your Understanding: Learning Goals Checkpoint
How does the amount of DNA change from prophase I to prophase II?
Let x be the amount of DNA.
Per cell: Prophase I to telophase I: 4x
Telophase I to prophase II: 4x to 2x
2. How does the amount of chromosome change prophase I to prophase II?
Let n be the ploidy of cell (on pg 30 of lect notes, n=2) Per cell:
Prophase I to telophase I: 2n
Telophase I to prophase II: 2n to n
3. How does genetic variation arise during meiosis?
3. How does genetic variation arise during meiosis?
Crossing over in Prophase I
Independent assortment of chromosome in metaphase I
Random fertilisation
No. of possible gamete combinations = 2n
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