MEIOSIS DAY 2
Bellwork
1.
2.
Why do kids look
similar to, but not
identical to their
parents?
List 2 ways mitosis is different from
meiosis.
3. What is the product of meiosis? What is
produced
*Be thinking of a compliment for your partner!
Announcements & Purpose
Review meiosis
Use book to fill in worksheet
Quiz on Meiosis Thursday
Friday: science fair walk through.
Closure
Review/improve closure from yesterday!
Period 3/5 read and added to it.
Each of the
nucleus of
your cells
contains all
this:
Special cells
in your
body only
have ½ this
amount.
Where?
Why?
Each somatic cell has:
2 copies of chromosome ONE
-1 from mom, 1 from dad
2 copies of chromosome TWO
-1 from mom, 1 from dad
How to create a gamete: Meiosis
Or ‘How to create an egg or a sperm’
Make a copy!
Long red: mother/chromosome 1
Short red:Mother/chromosome 2
Long blue: father/chromosome 1 Each gamete has:
Short blue: father/chromosome 2 1 MIXED copy of chromosome ONE
1 MIXED copy of chromosome TWO
Meiosis Video

http://www.youtube.com/watch?v=kVMb4Js99tA
Finger Meiosis
= 2 (chromatid) chromsomes in each cell
Hold up 1 pointer finger= this is chromosome 1 from your
dad.
 Hold up other pointer finger= this is chromosome 1 from
your mom =homologous chromosomes
 Have them replicate (hold up middle fingers too)
 Recombination (mingle them together)

Meiosis 1: Pull hands apart

Meiosis 2: pull fingers apart
= 1 chromatid chromosome in each cell
How to create a gamete: Meiosis
Or ‘How to create an egg or a
sperm’
Make a copy!
Each gamete has:
1 MIXED copy of chromosome
ONE
1 MIXED copy of chromosome
TWO
Asexual Reproduction…
New
Organisms
… involves
onlyare
oneCLONES
parent. It takes
several forms, but does not involve
Akameiosis.
Mitosis
-Budding
-Binary
fission
But…
if you
want something new…
-Parthenogenesis

Saccharomyces cerevisiae


Cnemidophorus neomexicanus
Cylindropuntia bigelovii
Sexual Reproduction
 Two gamete cells, a sperm and an egg,
unite to form a zygote, the single cell
from which the organism develops
 MEIOSIS is how gametes (sperm and
eggs) are made.
Gametes Are Haploid
 Gametes (sperm/egg) must have half the
DNA of a normal cell (1 copy)
 If the DNA in the gametes was not halved,
when they combined the zygote would have
more genetic material than the parents
 Meiosis is special cell division to make
gametes with half the genetic material of the
parents
 Gametes have exactly one set of
chromosomes, this state is called
haploid (1n)
 Regular cells (somatic cells) have two
sets of chromosomes, this state is called
diploid (2n)
Fertilization Results In A
Diploid Zygote
Egg
(1n)
Haploid
nucleus
Haploid
nucleus
Sperm
(1n)
From Zygote to Embryo
Zygote
Zygote
2n
2n
From Zygote to Embryo
Cleavage
From Zygote to Embryo
Cleavage = mitosis, but daughter cells don’t split apart
From Zygote to Embryo
Cleavage
From Zygote to Embryo
Cleavage
Finger Meiosis
= 2 (chromatid) chromsomes in each cell
Hold up 1 pointer finger= this is chromosome 1 from your
dad.
 Hold up other pointer finger= this is chromosome 1 from
your mom =homologous chromosomes
 Have them replicate (hold up middle fingers too)
 Recombination (mingle them together)

Meiosis 1: Pull hands apart

Meiosis 2: pull fingers apart
= 1 chromatid chromosome in each cell
Crash Course MEIOSIS
 http://www.youtube.com/watch?v=qCLm
R9-YY7o
P. 116-117 Use book to fill
in front side of worksheet
Closure
Review/improve closure from yesterday!
Period 3/5 read and added to it.