Meiosis
 Meiosis and Cell
Cycle Review
Engage
 The Meiosis Dance
Explore
 Sockosomes - You will use a hands-on
manipulative that will allow you to take a
cell from the beginning of meiosis to the
end.
 Mitosis/Meiosis Manipulative
Explain: Think Back to Mitosis!!!
 What is mitosis?
 What were the different phases of the cell
cycle?
 What happened in G1?
 S?
 G2?
 What were the phases of mitosis?
Asexual vs. Sexual Reproduction
 Mitosis
 Meiosis
 Asexual: CLONES
– Single parent
– Passes all genes from
one parent
– Offspring genetically
identical
 Sexual: VARIATION
– Two parents
– Each parent passes half
of their genes
– Offspring have unique
genetic combination
Meiosis, Slide 1
 Preceded by
chromosome replication,
but is followed by TWO
cell divisions
(Meiosis I & Meiosis II)
 4 daughter cells; 1/2
chromosome number
(1N); variation
Meiosis, Slide 2
 Meiosis I
 Meiosis II
 Prophase I
 Prophase II
 Metaphase I
 Metaphase II
 Anaphase I
 Anaphase II
 Telophase I and
 Telophase II and
Cytokinesis
Cytokinesis
Prophase I
 Chromosomes condense
 Synapsis occurs:
Homologous pairs
(Tetrads) come together
 Centriole pairs move apart
 Nuclear envelope and
nucleoli disperse
 Chromosomes begin to
move to equator
Crossing Over
 Only Crossing Over
 Meiosis Crossing Over
Metaphase I
 Tetrads are aligned
Anaphase I
 Tetrads separate and
are moved towards the
poles
 Sister chromatids
remain attached
Telophase I and Cytokinesis
 Cytoplasm Division
 Does NOT replicate
chromosomes again at
this point
 Getting ready for
second division
Prophase II
 Spindle apparatus forms
and chromosomes move
towards the Metaphase II
plate
Metaphase II
 Chromosomes align
singly
 Sister chromatids
point towards opposite
poles
Anaphase II
 Sister chromatids
separate
Telophase II and Cytokinesis
 Nuclei form at
opposite poles of the
cell.
 Cytoplasm divides
four haploid (N)
daughter cells are
produced.
Sperm
 Spermatogenesis
Eggs
 Oogenesis
Meiosis
vs.
mitosis
 Synapsis/tetrad/
 Sister Chromatids join not
(prophase I)
 Homologous
(metaphase I)
 Tetrads Separate
(anaphase I)
 Meiosis I separates
homologous pairs of
chromosomes, NOT sister
chromatids of individual
chromosomes.
homologous chromosomes
or tetrads (Prophase)
 Individual chromosomes
(Metaphase)
 Sister chromatids separate
not tetrads (Anaphase)
Elaborate
 You will now complete a Flow Chart
comparing Mitosis and Meiosis.
 You will also complete a chromosome
number worksheet to help solidify the
haploid/diploid concept.