Download Meiosis II

Some Vocab
• Diploid (2n): two sets of chromosomes
–You are diploid ( 46 chromosomes)
• 1 set from mom
• 1 set from dad
• Haploid (n): one set of chromosomes
–Reproductive cells are haploid
(23 Chromosomes)
• Eggs
• Sperm
Some Vocab
• Homologous Chromosomes: two
chromosomes with the same gene
sequence as another, one from each
parent.
What is Meiosis?
Meiosis is a process of
reduction division in
which the number of
chromosomes per cell is
cut in half.
What is Meiosis?
Meiosis involves two divisions
◦ Meiosis I
◦ Meiosis II
Meiosis I
Interphase I – DNA replicates
Prophase I – Crossing over occurs
Metaphase I – Chromosomes line up
Anaphase I – Chromosomes are pulled
apart
Telophase I/Cytokinesis – Nuclear
membranes forms. The cell separates
into two cells.
What is Crossing Over?
Crossing over is when
two homologous chromosomes pair
up and exchange segments of their
genetic material.
• Crossing over results in genetic
recombination.
• Crossing over is what makes every egg and
sperm cell unique.
• Crossing over is why you are not exactly like
your siblings.
Crossing Over
Crossing Over
Crossing Over
Meiosis I
Meiosis I
Meiosis I
Meiosis I
Meiosis I
Meiosis II
Very similar to mitosis
FINAL PRODUCT = 4
genetically different
HAPLOID DAUGHTER
CELLS
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two
haploid (N) daughter cells,
each with half the number
of chromosomes as the
original.
The chromosomes line up
in a similar way to the
metaphase stage of
mitosis.
The sister chromatids
separate and move toward
opposite ends of the cell.
Meiosis II results in four
haploid (N) daughter cells.
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two
haploid (N) daughter cells,
each with half the number
of chromosomes as the
original.
The chromosomes line up
in a similar way to the
metaphase stage of
mitosis.
The sister chromatids
separate and move toward
opposite ends of the cell.
Meiosis II results in four
haploid (N) daughter cells.
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two
haploid (N) daughter cells,
each with half the number
of chromosomes as the
original.
The chromosomes line up
in a similar way to the
metaphase stage of
mitosis.
The sister chromatids
separate and move toward
opposite ends of the cell.
Meiosis II results in four
haploid (N) daughter cells.
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two
haploid (N) daughter cells,
each with half the number
of chromosomes as the
original.
The chromosomes line up
in a similar way to the
metaphase stage of
mitosis.
The sister chromatids
separate and move toward
opposite ends of the cell.
Meiosis II results in four
haploid (N) daughter cells.
Gamete Formation
Males
Females
• In male animals, the
haploid gametes
produced in meiosis
are called sperm.
• In female animals,
one cell receives
most of the
cytoplasm and will
become an egg cell.
The other three cells
produced are known
as polar bodies and
do not participate in
reproduction.
Gamete Formation
Males
Females
Spermatogenesis
Oogenesis
Meiosis
Mitosis
To produce gametes
(sex / gametic cells)
Production of body
cells (somatic cells)
# of cells needed to
begin
2
1
1
1
# of daughter cells
produced
4
2
Purpose
What kind of cells are
produced?
# of divisions required
# of chromosomes in
daughter cells (n/2n)
# of chromosomes in
daughter cells in
humans
Half the number of the The same number as
parent cell (n)
the parent cell (2n)
23
46
Are the daughter cells
identical to the parent
cell?
No
Yes
Does crossing over
Yes
No