Meiosis Summary
NAME______________________
From
mother
From
father
paired
2N diploid cell;
4chromosomes
2N diploid cell containing
4 duplicated chromosomes,
each with 2 chromatids
DNA replication during the _____ phase
produces a duplicate number of chromosomes
that have _____ genetically identical
chromatids each.
In this example, 2N=4, so N=____.
The number of chromosomes in a skin cell for
this organism would be_____, but in a gamete,
it would be_____. In humans, where 2N=46,
after the S phase leading up to meiosis there
would be ____duplicated chromosomes,_____
total chromatids, and _____tetrads.
Name 2 ways that
prophase I of meiosis I
differs from prophase in
mitosis?
Diploid cell containing 2 sets of
paired homologous chromosomes
A tetrad is composed of
___duplicated chromosomes,
but____ chromatids.
tetrad
Benefit of Crossing Over =
diversity
How does metaphase I of meiosis I differ from
metaphase in mitosis?
In metaphase during mitosis, _______________
________________ line up across the middle, each
having___ chromatids.
In metaphase I of meiosis I, ________________line up.
They are composed of ___homologous chromosomes
each and a total of ___chromatids between them.
1. ____________
________occurs in
prophase I, but not
in prophase during
mitosis.
2. Formation
of___________
does not occur in
mitosis.
Meiosis Summary
NAME______________________
tetrads have split, but duplicated chromosomes are
intact; the cell remains diploid
Chromosomes move toward opposite poles in anaphase of mitosis.
Name two ways the chromosomes in anaphase I of meiosis I differ from
the chromosomes that pull apart in mitosis. What effect does this have
on daughter cells?
In mitosis, duplicated chromosomes split at their________________
and the _____________chromatids move toward the poles. Each cell is
receiving identical copies of the genetic material. In anaphase I of
meiosis, paired________________chromosomes containing varied
genetic information separate. The centromeres are still attached. When
tetrads seperate, further diversity will be seen because it is random as
to which members of the tetrad end up together.
Homologous chromosome
pairs have split, but
duplicated chromosomes
have yet to separate. There
is a random combination of
members of the
homologous pairs and the
cell is still diploid.
Two diploid cells are produced at the
end of mitosis that are genetically
identical to the original cell. What is
produced at the end of meiosis I?
Two______________cells with
variances in ______________material
due to ____________ ____________.
2 haploid cells that still have
duplicated chromosomes
How does 2N differ from 2 x N ?
2N represents a ______________cell.
2 x N means that there are ___ cells,
each which are _____________.
The two cells produced at the end of
meiosis I can enter a brief period of
interphase called interkinesis before
beginning meiosis II. This period of
interkinesis differs from normal
interphase. How is it different?
In interphase before meiosis begins,
_____is replicated. This replication
will not occur a second time when the
cells enter interkinesis.
Meiosis I has managed to separate paired homologous chromosomes called ____________________. For this example,
N=2, and there are two cells containing two duplicated chromosomes in each. However, the cells are considered haploid
now because they have half the total chromosomes as when they started. However, there are two duplicated
chromosomes in each. They have yet to separate, which explains the need for meiosis II.
Meiosis Summary
NAME______________________
2 cells that are
each 2 x N
How does prophase I of meiosis differ
from prophase II ? How is it similar to
prophase in mitosis? Different?
In prophase II, there is no
____________ ________, and the
duplicated chromosomes are not
paired to form_______________.
In prophase II, chromosomes are
duplicated as in mitosis, but the
chromatids are not identical.
How is metaphase II different from
metaphase I ?
The duplicated chromosomes that line
up across the middle of the spindle are
not tetrads.
Metaphase II is more similar to
metaphase in mitosis, except that the
chromatids that will separate are not
identical.
How is anaphase II different from anaphase I ?
____________ _________________ are pulling
apart rather than homologous chromosome pairs
that separated in meiosis I.
2 cells that are
each still 2 x N
Meiosis Summary
NAME______________________
2 cells that
are 2 x N
4 haploid
cells that
are N
How does the product of meiosis II differ from the product of meiosis I ? From mitosis?
Product of Meiosis II: ____genetically unique cells containing the____________ # of chromosomes
Product of Meiosis I: ___ genetically unique daughter cells containing the ________________# of
duplicated chromosomes.
Product of mitosis: _____genetically identical daughter cells
A diploid cell duplicates its chromosomes before the process of meiosis starts. However, the cell is
still diploid because it has really just produced two copies of the same chromosomes. At the
completion of meiosis I, the cell has managed to divide into two cells, each containing one
random homolog from the pair. These cells are now called haploid, even though the
chromosomes remain duplicated. These cells will each divide, and in that process separate the
duplicated chromosomes into two new cells. Even still, these cells remain haploid because they
contain half the chromosome number of the original cell.
In conclusion, meiosis I separates homologous chromosome pairs; meiosis II separates duplicated chromosomes
into chromatids.
Phase..........
# human chromosmes
# human chromatids
MetaphaseI
46
2N
92
Telophase I
23
N
46*
Metaphase II
23
N
46
Telophase II
23
N
23**
*The homologs have split into two cells but the chromosomes remain duplicated so the cell is
haploid but has 46 unique chromatids, or 23 duplicated chromosomes.
**The centromeres have split and duplicated chromosomes are separated, cutting the 46 total
chromatids to 23 chromatids in 2 cells.