REVIEW OF MITOSIS.

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REVIEW OF MITOSIS.

• Mitosis is _____________________________________
• It refers to the process of replication of
  ___________ cells.
• Two purposes of mitosis ____________ and
  __________
• It results in __________________________________
• (_______________________________________)

CELL DIVISION/REPRODUCTION
BODY
REPAIR
GROWTH
TWO IDENTICAL DAUGHTER CELLS
2 CELLS WITH THE SAME DNA AS ORIGINAL CELL
Meiosis - Chapter 3
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You have body cells and gametes.
somatic

• Body cells are also called _________________
  cells.
• Germ cells develop into ______________.
• Germ cells are located in the _________ and
  ________.
• Gametes are sex cells ______________________.
• Gametes have _______ that can be passed to
  offspring.

gametes
ovaries
testes
Egg and sperm
DNA
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KEY CONCEPT Gametes have ______________________
of ______________________ that body cells have.
½ the number
chromosomes
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2

• Your cells have __________ different type of
  chromosomes- ___________________ - Chromosomes
  that carry
• _____________ body traits-
  ________________ - chromosomes that carry
• genes specific to the ___________ of an
  organism

AUTOSOMES
ONLY
SEX CHROMOSOMES
SEX/GENDER
EXAMPLES OF AUTOSOMAL TRAITS EXAMPLES OF SEX CHROMOSOME TRAITS
Cleft in chin X linked trait Red-green color blindness
Dimples Sex Linked Genes
Shape of face


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Your cells have autosomes and sex chromosomes.

• Your body cells have _______ pairs of
  chromosomes.
• Chromosome pairs
• 1-22 are ________________.
• Sex chromosomes, ______determine gender
  in humans. They are referred to as
  _________________

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Homologous pairs
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X and Y

• Y chromosome is the smallest and carries the
  fewest genes

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Understanding Homologous Chromosomes
AUTOSOMES

• ____________________of chromosomes have the same
  structure.
• For each homologous pair, one chromosome comes
  _____________________.

from each parent
Allele for straight hair
From Mom
Gene for hair texture
From Dad
Allele for curly hair
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Understanding Sex Chromosomes

• ____________________do _________ always have the
  same structure.
• Each parent still contributes one sex cell, BUT
  depending upon the parent, they can give either
  an _____________________.

Sex Chromosomes
NOT
X or a Y
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Body cells are diploid gametes are haploid.

• Fertilization between egg and sperm occurs in
  sexual reproduction.
• Diploid (2n) cells have two copies of every
  chromosome.
• n represents the pairs of chromosomes
• Human 2n __46___________________________
• Goldfish 2 n _96___________________________
• Pea 2n __18______________________________
• Body cells are diploid.
• Half the chromosomes __haploid____________________
  ___.

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Sex cells, (______________) are haploid.
GAMETES
ONLY ONE

• Haploid (n) cells have ________________ of every
  chromosome.
• Only contain DNA from ______________________

ONLY ONE PARENT
- Gametes have ___ autosomes and __ sex
chromosome.
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1
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MAINTAINED

• Chromosome number must be _____________ in
  animals.

• Many plants have more than two copies of each
  chromosome.
• Mitosis and meiosis are types of nuclear division
  that make _________________ types of cells.
• Mitosis makes more _________________ cells.
  (____________)
• Meiosis makes more __________________
  cells.(____________)

2 DIFFERENT
SOMATIC/BODY
DIPLOID
GAMETES/SEX
HAPLOID
Result of Meiosis 4 new cells, w/ ½ the DNA
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HAPLOID

• Meiosis makes _______________ cells from diploid
  cells.

SEX

• Meiosis occurs in _______________ cells.
• Meiosis produces _______________.
  (_________________)

GAMETES
SPERM EGG
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Steps of Meiosis
PROPHASE 1 METAPHASE 1 ANAPHASE 1 TELOPHASE 1 /
PROPHASE 2 METAPHASE 2 ANAPHASE 2 TELOPHASE 2
____________________________________ _____________
_______________________ __________________________
__________ ____________________________________ __
__________________________________ _______________
_____________________ ____________________________
________
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PROPHASE I
Sister Chromatids Nuclear Membrane Centrioles Fibers

Shorten and Thicken. Double File Find their
match or pair up, (one from mom with one from
dad)
Move apart from one another
Form between centrioles
Begins to break down
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METAPHASE I
From mom
From dad
From mom
From dad
Sister Chromatids Nuclear Membrane Centrioles Fibers

Stretch between two ends of the cell
Become attached to the fibers, pulled to middle
of cell
move to opposite ends of cell
Remains dissolved
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ANAPHASE I
From dad
From mom
From mom
From dad
Sister Chromatids Nuclear Membrane Centrioles Fibers

Pairs pulled apart by fibers. Pairs are
separated Sisters/copies are still connected
Still at cells poles
Pull matching pairs apart
Remains dissolved
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From mom
TELEPHASE I
From dad
From dad
From mom
Sister Chromatids Nuclear Membrane Cell Membrane Fibers

DO NOT disappear
Each end of cell has HALF the number of
chromosomes. Chromosomes DO NOT unwind.
Begins to pinch in until the cytoplasm is divided
in half forming two new cells
DOES NOT reform
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From mom
PROPHASE II
From dad
From dad
From mom
Sister Chromatids Nuclear Membrane Centrioles Fibers

Move apart from one another
Still coiled
Has not reformed
Re-form between centrioles
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From mom
METAPHASE II
From dad
From mom
From dad
Sister Chromatids Nuclear Membrane Centrioles Fibers

Become attached to the fibers. Are pulled to
middle of cell (Single File)
stretched between ends of cell. Are attached to
center of sister chromatids
Move to opposite ends of cells
Remains dissolved
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From mom
ANAPHASE II
From dad
From mom
From dad
Chromatids Nuclear Membrane Centrioles Fibers

Pull each chromatid toward opposite ends of cell
Still at cells poles
Remains dissolved
Sisters are pulled apart by fibers. Each
chromatid is separate from its sister
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From mom
TELEPHASE II
From dad
From dad
From mom
Chromatids Nuclear Membrane Cell Membrane Fibers

Begins to pinch in until the cytoplasm is divided
in half forming two new SEX cells, (4 TOTAL)
Each end of cell has HALF and SINGLE chromosomes.

Begins to reform
Begin to disappear
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KEY CONCEPT During meiosis, diploid cells
undergo _______ cell divisions that result in
_______________ cells.
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HAPLOID
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Cells go through two rounds of division in
meiosis.

• Meiosis reduces chromosome number and creates
  _______________________________.

GENETIC DIVERSITY
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• Meiosis differs from mitosis in significant ways.

2

• Meiosis has _____ cell divisions while mitosis
  has one.
• In mitosis, _____________chromosomes never pair
  up.
• Meiosis results in ____________ cells mitosis
  results in ______________ cells.

HOMOLOGOUS
HAPLOID
DIPLOID
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• Meiosis I and meiosis II each have four phases,
  similar to those in mitosis.

• Pairs of homologous chromosomes separate in
  ___________.
• Homologous chromosomes are ___________ but not
  identical.
• One from mom One from dad
• Brown Eyes - Blue Eyes
• Attached Earlobes -Free Earlobes
• Type B blood -Type A blood
• Sister chromatids divide in _____________.

MEIOSIS 1
SIMILAR
homologous chromosomes
MEIOSIS II
sister chromatids
sister chromatids
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• Meiosis I occurs after DNA has been replicated.

• Meiosis I divides homologous chromosomes in four
  phases.

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• Meiosis II divides sister chromatids in four
  phases.

• DNA is not replicated between meiosis I
  andmeiosis II.

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So What Does The Process of Meiosis Look Like?
MORE MEIOSIS EXAMPLES
MEIOSIS ANIMATION
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The Point of Meiosis
Result in four sex cells
Each cell will have HALF the number of
chromosomes as the original cell.
Sex cells develop during puberty.
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MEIOSIS MEN VS. WOMEN
WHAT IS THE SAME?

• 4 CELLS ARE PRODUCED
• EACH CELL HAS ONLY HALF THE NUMBER OF
  
  CHROMOSOMES AS THE ORIGINAL

WHAT IS THE DIFFERENT?

• MALES ALL FOUR CELLS ARE GOOD SPERM
• FEMALES 3 CELLS ARE CONSIDERED POLAR BODIES
  ONLY 1 CELL IS A VIABLE EGG
• (THIS IS DUE TO AN UNEVEN DIVISION OF CYTOPLASM
  DURING MEIOSIS)

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Haploid cells develop into mature gametes.

• _________________ is the production of gametes.
• Gametogenesis differs between ____________ and
  __________.

Gametogenesis
MALES
FEMALES

• Sperm become ____________ and _____________.
• Sperm primarily contribute ____ to an embryo.

STREAMLINED
MOTILE
DNA

• Eggs contribute _______, _____________, and
  ____________ to an embryo.
• During meiosis, the ______ gets most of the
  contents the other cells form _________________.

DNA
CYTOPLASM
ORGANELLES
DNA
POLAR BODIES
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Understanding Meiosis
Starting with Prophase I, draw a cell undergoing
MEIOSIS. Your original cell has 4 chromosomes.
Make sure to include the cell membrane, nuclear
membrane, chromosome, centrioles, and fibers.
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MITOSIS VS. MEIOSIS
What is the same?
What is different?
1.__________________________________2.____________
______________________3.__________________________
________4.__________________________________5.____
______________________________Process
__________________________________________________
________
1
1.__________________________________2.____________
______________________3.__________________________
________4.__________________________________5.____
______________________________6.__________________
____7.____________________________________
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1
1
2
3
3
4
5
4
6
5
7
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DID YOU KNOW?
The sperm is the smallest cell in the body,
whilst the egg is the largest, it is estimated
that it will take 175,000 sperm to weigh as much
as a female egg, which is a lot of sperm!
Average males produce 150 million sperm daily!
Females are born with all the oocytes (eggs) that
they will ever have in a lifetime?
Infertility sperm counts drop as low as 20
million per ml
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