Download Overview of Mitosis and Meiosis

MEIOSIS I
NOTE:
Diploid =
Has BOTH
mom AND
dad’s
chromosome
Example:
In a cell, if it
has
chromosome
number 1 for
dad and
chromosome
number 1 for
mom
Haploid =
Has EITHER
Mom OR dad’s
chromosome
Example:
In a cell, if it
has
chromosome
number 1 for
dad or
chromosome
number 1 for
mom, but not
both
CHROMOSOME
NUMBERS
(MEIOSIS)
Interphase
- Growth to maturity (G1)
- DNA replication (S)
46 single to 92 single
- copies of both mom and
dad (diploid)
- Replication of organelles
(G2)
46 single
Prophase I
- Homologous
chromosomes pair to form
tetrad by synapsis
- Crossing over can occur
- Centrioles spread and
spindles extend
- Polar spindles extend
centriole to centriole
- Kinetochore spindles
attach to centromeres of
each double chromosome
46 double (23
double mom
and 23 double
dad)
Homologous
chromosomes
find to make
23 tetrads
Metaphase I
- tetrads are organized in
the middle of the cell
- crossing over could occur
23 tetrads
(total 46
chromosomes)
Anaphase I
- Spindles retract pulling
the homologous
chromosomes to opposite
sides of the cell
(disjunction) allowing
independent assortment by
- Cleavage furrow is obvious
23 double
chromosomes
to one side, 23
double to the
other side
(random)
Telophase I
- Cleavage furrow continues
until cytokinesis occurs
- 2 haploid cells form. They
have, for ex, double
chromosome 1 of mom or
dad, not both in the same
cell.
92 single
2 cells (23
double
chromosomes
in each, but
mom’s double
chromo. 1 in
one cell, dad’s
double
chromo. 1 in
another
cell…haploid
CHROMOSOME
NUMBERS
(MITOSIS)
46 single
(diploid)
92 single
46 double
46 double
46 single to
one side and
46 single to
other side
46 single in
each cell (23
single mom
and 23 single
dad in
each cell..
diploid)
MITOSIS
Interphase
- Growth to maturity (G1)
- DNA replication (S)
46 single to 92 single
- copies of both mom and
dad (diploid)
- Replication of organelles
(G2)
MEIOSIS II
Begin with 2 haploid
cells (example: one cell
has mom’s chromosome
1 and the other cell has
dad’s chromosome
1…..if the cell has mom
or dad’s then haploid
CHROMOSOME
NUMBERS
(MEIOSIS)
Prophase
- Chromosomes pair to
double chromosomes (made
of identical single
chromosomes)
- Centrioles spread and
spindles extend
- Polar spindles extend
centriole to centriole
- Kinetochore spindles
attach to centromere
Prophase II
- Double chromosomes
present (mixture of mom
and dad)
- Centrioles spread and
spindles extend
- Polar spindles extend
centriole to centriole
- Kinetochore spindles
attach to centromere
Metaphase
- Double chromosomes are
organized in the middle of
the cell
Metaphase II
- Double chromosomes are
organized in the middle of
each cell
2 cells with 23
double in each
(haploid)
Anaphase
- Spindles retract pulling
the chromatids (now single
chromosomes) apart to
opposite sides of the cell.
- Cleavage furrow is obvious
Anaphase II
- Spindles retract pulling
the chromatids (now single
chromosomes) apart to
opposite sides of the cell.
- Cleavage furrow is obvious
2 cells with 23
single to one
side and 23
single to other
side of each
cell
Telophase
- Cleavage furrow continues
until cytokinesis occurs
- 2 identical cells form.
They have copies of both
mom and dad’s
chromosomes (diploid)
Telophase II
- Cleavage furrow continues
until cytokinesis occurs
- 4 haploid sex cells form.
In men, 2 are same as each
other, while the other 2 are
the same as one another.
23 single in
each of the 4
cells (haploid)
2 cells with 23
double in each
(haploid)