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KEY AMOEBA SISTERS: VIDEO RECAP MEIOSIS: THE GREAT DIVIDE

KEY: Amoeba Sisters Video Recap of Meiosis: The Great Divide

1. The purpose of meiosis is to makegametes, also known as sperm and eggcells. In humans, your body cells have 46chromosomes. How many chromosomesare in a sperm or egg cell if, when theycome together to form a fertilized zygote,there are 46 chromosomes? Write thecorrect number of chromosomes next tothe sperm and egg.

2. Interphase must occur once beforemeiosis can happen. (Same thing formitosis). What would happen ifinterphase didn’t occur first?

4. Crossing over is a very important eventin Prophase I of meiosis! What happensduring crossing over and what is thesignificance?

23

23

If interphase did not occur first,then chromosomes would not replicate. This would not allowfor chromosome copies to be correctly distributed in daughtercells.

3. A cell that begins meiosis has 23chromosomes inherited from the mother(shown in green in the cartoon below)and 23 chromosomes inherited from thefather (shown in blue in the cartoonbelow). In the process of meiosis,chromosomes begin to match up inhomologous pairs. How would you knowif two chromosomes were homologous?

Homologous chromosomes are approximately the same size withthe same types of genes (important: this does not mean identical). They can be found together in prophase I.

In crossing over, the homologouschromosomes transfer genes to each other. This is significant because it can lead to genetic variety (recombinant chromosomes).

5. Meiosis does PMAT twice! That means there is a prophase I and a prophase II. There is a metaphase I and a metaphase II. Etc… If the cartoon below has chromosomes in the middle of the cell, how would you know whether it was in metaphase I or metaphase II?Metaphase I has chromosomes lining up in the middle in homologous pairs. In metaphase II, the chromosomes are lined up in asingle file line (not in pairs). The cartoon below shows metaphase I.

6. Meiosis does not always occurwithout any difficulties. Describe whatoccurs during nondisjunction and theeffect on the resulting cells.Chromosomes are not distributedequally (example could be spindlenot separating them correctly). Thiscan result in too many or too few chromosomes per cell.

KEY AMOEBA SISTERS: VIDEO RECAP MEIOSIS: THE GREAT DIVIDE

Can you finish the meiosis chain? Write the correct stage that comes next in each circle. Don’t forget the number that comes

after the stage name! Then write any details about what this stage looks like next to it.

Now let’s play, “Which Clip Would That Be Said In?”

Keeping mitosis and meiosis separate in your mind can be a bit tricky. Read the following speech bubbles.

Determine whether they would be correctly placed in the mitosis clip, the meiosis clip, or both by drawing a

line to the correct place in the Venn diagram.

Interphase

occurs once

before the

process

begins.

Process

ends

with

identical

cells.

Produces

gametes.

Produces 4 cells

that each have 23

chromosomes.

Crossing

Over

occurs.

Process is

important

for growth

and

repair.

MetaphaseI

AnaphaseI

TelophaseI

ProphaseII

MetaphaseII

AnaphaseII

TelophaseII

Chromosomes condense and are visible, crossing over can occur here

Chromosomes line up in the middle in homologous pairs

Homologous chromosomes are pulled away from each other

Chromosomes at opposite poles, new nuclei will form in the 2 daughter cells.

Chromosomes in two cells are visible, crossing over does NOT occur Chromosomes line

up in middle in single file line (not with homologous chromosomes)

Chromatids

are pulled away.

Chromosomes at opposite poles, new nuclei will form in 4 daughter cells