Meiosis (Updated)

What type of cells are made during meiosis?

• Body cells

• Gametes (sex cells)

How many chromosomes are there in a sperm or egg cell?

• 46

• 23

Review: What are the stages of Mitosis? (What does PMAT stand for?)

How many rounds of cell division occur in meiosis?

• One round

• Two rounds

How do the chromosomes line up in Meiosis I?

• Each one alone, all in a line.

• With their homologous pair.

Notice the way the chromosomes have lined up. From top to bottom on the left, 1, 2, 3 are blue, and 4, 5, are green. The opposite trend is on the other side. This is the 'independent assortment' part of meiosis. This process ensures that each daughter cell gets 1 copy of each chromosome, but it doesn't specify whether it's 'mostly maternal' or 'mostly paternal' For instance, it could have randomly happened that all 5 of the chromosomes on the left were 'blue'. 

The reason we say 'mostly' and not '100%' maternal is because the blue chromosomes have bits of green in them caused by

• crossing over

• independent assortment

• mutation

• genetic variation

• meiosis

Sometimes, the 'separation' step can fail. We saw this during the Down syndrome study for Baby marco. If these chromosomes were not fully pulled apart during the next phase, it would be called:

• nondisjunction

• mutation

• conjunction

• natural selection

How many chromosomes do each of the daughter cells have after Meiosis I?

• 23

• 46

• 92

What separates in Anaphase II, homologous chromosomes or sister chromatids?

• Homologous chromosomes

• Sister chromatids

How many daughter cells do you end up with when meiosis is complete (after meiosis II)?

• 2

• 4