MEIOSIS
11-4
http://waynesword.palomar.edu/lmexer2a.htm
Making gametes…
Remember from Chapter 1:
CHARACTERISTICS OF LIVING THINGS
ALL LIVING THINGS __________
Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htm
Family http://babyhearing.org/Parenet2Parent/index.asp
ASEXUAL REPRODUCTION
Bacteria reproduce using
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html
__________________________________
http://fig.cox.miami.edu/~cmallery/150/mitosis/c7.13.2.hydra.jpg
Budding & regeneration are used by plants
and animals to reproduce asexually
(mitosis)
Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htm
MITOSIS
Produces cells that are __________
copies of parent cell
ADVANTAGES OF
ASEXUAL REPRODUCTION
Can make offspring
faster
Don’t need a partner
http://www.mrgrow.com/images/cutting.jpg
DISVANTAGES OF
ASEXUAL REPRODUCTION
ALL ALIKE
Species CAN’T
change and adapt
One disease can wipe
out whole population
http://www.mrgrow.com/images/cutting.jpg
SEXUAL REPRODUCTION
Family image from: http://babyhearing.org/Parenet2Parent/index.asp
Combines genetic material
from 2 parents (sperm & egg)
so offspring are
genetically __________
from parents
ADVANTAGES OF
SEXUAL REPRODUCTION
Allows for variation in population
Individuals can be different
Provides foundation for EVOLUTION
Allow species adapt to
changes in
their environment
http://naturalsciences.sdsu.edu/classes/lab8/spindex.html
Image by Riedell
EGG
Image by Riedell
+
http://www.angelbabygifts.com/
SPERM 
If egg and sperm had same number of
chromosomes as other body cells . . .
baby would have too many chromosomes!
http://www.acmecompany.com/stock_thumbnails/13217.forty-six_chromosomes.jpg
MEIOSIS is the way…
http://waynesword.palomar.edu/lmexer2a.htm
to make cells
with ½ the
number of
chromosomes
for sexual
reproduction
Video 1
Meiosis Overview
Click the image to play the video segment 11A.
DIPLOID & HAPLOID
Most cells have 2 copies of each chromosome
= ______________
(one from mom; one from dad)
HOMOLOGOUS
CHROMOSOMES
All BODY (___________) cells are diploid
DIPLOID & HAPLOID
Some cells have only one copy of each
chromosome = _____________
All sperm and egg cells
are haploid
MITOSIS
• Makes ___ cells genetically
_________ to parent cell &
to each other
• Makes ___ cells
• Makes __________
• Used by organisms to:
increase size of organism,
repair injuries,
replace worn out cells
http://waynesword.palomar.edu/lmexer2a.htm
MEIOSIS
• Makes ____ cells
genetically different from
parent cell & from each
other
• Makes _____ cells
• Makes ______________
• Used for ____________
http://waynesword.palomar.edu/lmexer2a.htm
WHAT MAKES MEIOSIS
DIFFERENT ?
1. SYNAPSIS & CROSSING OVER
(PROPHASE I)
2. SEGREGATION &
INDEPENDENT ASSORTMENT
(ANAPHASE I)
3. Skip INTERPHASE II (NO S)
CELL DIVIDES TWICE, BUT…
ONLY COPIES DNA ONCE
WHAT MAKES MEIOSIS
DIFFERENT ?
1. Homologous chromosomes pair up
during ____________=
______________
This group of FOUR (4)
chromatids is called a
_________________
Images modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
WHAT MAKES MEIOSIS
DIFFERENT?
1. Exchange of DNA between
homologous pairs = _____________
during PROPHASE I
Allows shuffling
of genetic material
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
Video 5
Crossing Over
SEE CROSSING OVER
ANIMATION
• Click the image to play the video segment.
11E
HOMOLOGOUS CHROMOSOMES
Image modified by Riedell
• SAME SIZE
• SAME SHAPE
• CARRY GENES for the
SAME TRAITS
• BUT ______________!
(Don’t have to have the
SAME CHOICES)
http://sps.k12.ar.us/massengale/genetics%20tutorial.htm
Image modified by Riedell
CROSSING
OVER
• Allows for_________________
in different combinations
• After crossing over, chromatid arms
are________________ anymore
http://sps.k12.ar.us/massengale/genetics%20tutorial.htm
WHAT MAKES MEIOSIS
DIFFERENT ?
2.Separation
during ANAPHASE I
__________________ &
_______________________
Separates gene choices and allows
shuffling of genetic material
Video 4
Segregation of Chromosomes
Click the image to play the video segment 11D.
SEGREGATION
(Anaphase I)
SEGREGATION & CROSSING OVER
together make even more combinations
See an
animation
http://waynesword.palomar.edu/lmexer2a.htm
INDEPENDENT ASSORTMENT
http://fig.cox.miami.edu/~cmallery/150/mitosis/c13x9independent-assortment.jpg
INDEPENDENT ASSORTMENT
at ANAPHASE I
Lots of different
combinations are
possible!
This is why you
don’t look exactly
like your brothers
and sisters even
though you share
the same parents!
http://www.tokyo-med.ac.jp/genet/anm/mimov.gi
WHAT MAKES MEIOSIS
DIFFERENT ?
Crossing over
Segregation
Independent
assortment
are ALL ways MEIOSIS results in
=______________________________
So daughter cells are ______________
from parents and from each other
WHAT MAKES MEIOSIS
DIFFERENT ?
3. Skip INTERPHASE II (No S)
CELL DIVIDES TWICE, BUT …
ONLY COPIES ITS DNA ONCE
MITOSIS:


1
G
S
G2  P
MEIOSIS:
G1  S


M
G2  P  M
PM

A

T C
A T C (I)
 A  T  C ( II )

Video 2
Animal Cell Meiosis, Part 1 & Part 2
Click the image to play the video
segment 11B. & C
Video 2
Figure 11-15 Meiosis
Section 11-4
Meiosis I
Go to
Section:
Figure 11-17 Meiosis II
Section 11-4
Meiosis II
Prophase II
Metaphase II
Anaphase II
Meiosis I results in two
The chromosomes line up in a The sister chromatids
haploid (N) daughter cells,
similar way to the metaphase separate and move toward
each with half the number of stage of mitosis.
opposite ends of the cell.
chromosomes as the original.
Go to
Section:
Telophase II
Meiosis II results in four
haploid (N) daughter cells.
MITOSIS vs MEIOSIS
INTERPHASE INTERPHASE I
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
• DNA is spread out as chromatin
• Nuclear membrane/
nucleolus visible
• DNA is copied during S phase
• Makes stuff new cell needs in G2
_______________
MITOSIS vs MEIOSIS
PROPHASE PROPHASE I
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
DNA scrunches into
chromosomes
Nuclear membrane/
nucleolus disappear
Centrioles/
spindle fibers appear
DNA scrunches into
chromosomes
Nuclear membrane/
nucleolus disappear
Centrioles/spindle fibers
appear
_________________________
MITOSIS vs MEIOSIS
METAPHASE
METAPHASE I
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
• Chromosomes line up
in middle
Chromosomes line up
in middle
______________________________
MITOSIS vs MEIOSIS
ANAPHASE ANAPHASE I
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
APART:
Chromatids split
APART:
Chromatids stay together
________________________
MITOSIS vs MEIOSIS
TELOPHASE TELOPHASE I
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
See TWO nuclei
Nuclear membrane/
____________________
nucleolus return
DNA spreads out as chromatin
Spindle/centrioles disappear
MITOSIS vs MEIOSIS
CYTOKINESIS CYTOKINESIS I
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
Cytoplasm splits
into 2 cells
______________________
MITOSIS vs MEIOSIS
INTERPHASE II
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
• DNA is spread out as chromatin
__________________
• Nuclear membrane/
__________________
nucleolus visible
• DNA is copied during S phase __________________
MITOSIS vs MEIOSIS
PROPHASE PROPHASE II
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
• DNA scrunches into
chromosomes
• Nuclear membrane/
nucleolus disappear
• Centrioles/
spindle fibers appear
____________________
MITOSIS vs MEIOSIS
METAPHASE
METAPHASE II
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
• Chromosomes line up
in middle
______________________
MITOSIS vs MEIOSIS
ANAPHASE ANAPHASE II
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
Chromatids split and
move apart
__________________________
MITOSIS vs MEIOSIS
TELOPHASE TELOPHASE II
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
Two nuclei
Nuclear membrane/
nucleolus returns
Centrioles/spindle fibers
disappear
DNA spreads out as
chromatin
_______________________
MITOSIS vs MEIOSIS
CYTOKINESIS CYTOKINESIS II
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
Cytoplasm splits
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
_____________________
Ways Meiosis is different?
• Homologous pairs match up & trade DNA
(SYNAPSIS & CROSSING OVER) in
PROPHASE I
•SEGREGATION
& INDEPENDENT ASSORTMENT
in Anaphase I
create genetic recombination
• Skipping INTERPHASE II(Dividing TWICE but copying DNA once)
produces 1n cells
MAKING
SPERM & EGGS
___________________=
MAKING MATURE SPERM
Mature & grow flagella
Sperm provides DNA
All the starting nutrients,
organelles, molecule building blocks,
etc. have to come from the egg.
__________________ =
MAKING a MATURE EGG
Produces:
1 “good” egg
3 __________
CYTOPLASM DIVIDES UNEVENLY
WHY MAKE ONLY ONE “GOOD” EGG?
Sperm
donates
mostly DNA
Most of the cell parts and nutrients
needed for baby come from EGG!
http://bestweekever.blogs.com/photos/uncategorized/imagemain_sperm_egg1_1.gif
POLAR BODIES DEGENERATE (DIE)
“Self digest”
Using
________________
= __________________
“cell suicide” for good of organism