Name:
Date
Ms. Pitt, Period
DO YOU KNOW MEIOSIS? (if not use your text!)
You only need to draw the chromosomes!!!
Prophase I – draw 3 pairs of homologous
chromosomes crossing over.
Metaphase I – draw the homologous chromosomes
lining up along the dotted line. Remember they form
a double line.
Anaphase I – draw the homologous chromosomes
separating, one in each pair moving to the left and the
other moving to the right.
Telophase I – draw 3 chromosomes in the center of
each new cell.
Prophase 2 – draw 3 chromosomes in each cell.
Metaphase 2 – draw the chromosomes lining up in the
middle of the cell. Remember they form a single line.
Anaphase II – draw the draw the sister chromatids
breaking apart and the chromosomes moving to the
left and right (3 should be moving left and 3 should be
moving right).
Telophase II / Cytokinesis – draw 3 chromosomes in
each of the new cells.
Name:
Date
Ms. Pitt, Period
QUESTIONS
1. Why is meiosis necessary for sexually reproducing organisms?
It mixes up genetic information to provide variation needed for survival.
2. Are sister chromatids identical?
Yes, they are replicates of each other. However, after crossing over occurs, they
may no longer be identical.
3. Are homologous chromosomes identical?
No, they are the maternal and paternal version of chromosomes. They carry the
same genes (i.e. – hair color, eye color) but they may have different alleles (i.e. –
blonde hair on mom’s gene and brown hair on dad’s).
4. In a human cell in prophase 1, how many homologous chromosome pairs
(clusters of 4 chromatids) are present? Hint - how many total chromosomes are
in a human cell? If they are all paired, then how many pairs are there?
23
5. What is crossing over? When does it occur and why is it important?
The exchange of portions of DNA between homologous chromosomes. It
happens during Prophase I and is important because it is the key to genetic
variation.
6. How can you tell by looking at a cell whether it is in metaphase I or II?
In metaphase I, homologous chromosomes are lined down the metaphase plate
side by side (double file). In metaphase II, sister chromatids line up down the
metaphase plate single file.
7. What is independent assortment? When does it occur and why is it important?
Independent assortment is the random orientation of homologous chromosomes
down the metaphase plate. It occurs during Meiosis I and is so important
because it further mixes up genetic information in the resulting gametes.
8. How can you tell by looking at the cell whether it is in anaphase I or II?
In anaphase I, homologous chromosomes separate. In anaphase II, sister
chromatids separate.