1. Mitosis is _____________________________________
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

2. 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
body cells
sex cells (sperm)
sex cells (egg)

3. KEY CONCEPT Gametes have ______________________ of ______________________ that body cells have.
½ the number
chromosomes

4. 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

5. 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 _________________ 23
Homologous pairs 23
X and Y

6. 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

7. 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

8. 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_______________________.

9. 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. 22 1

10. 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

11. Meiosis makes _______________ cells from diploid cells.
HAPLOID
Meiosis occurs in _______________ cells.
Meiosis produces _______________. (_________________)
SEX
GAMETES
SPERM & EGG

12. Steps of Meiosis PROPHASE 1 METAPHASE 1 ANAPHASE 1
TELOPHASE 1 / PROPHASE 2
METAPHASE 2
ANAPHASE 2
TELOPHASE 2
____________________________________

13. 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

14. METAPHASE I Sister Chromatids Nuclear Membrane Centrioles Fibers
Stretch between two ends of the cell
Become attached to the fibers, pulled to middle of cell
Remains dissolved
move to opposite ends of cell

15. ANAPHASE I Sister Chromatids Nuclear Membrane Centrioles Fibers
Pairs pulled apart by fibers.
Pairs are separated…
Sisters/copies are still connected
Still at cell’s poles
Pull matching pairs apart
Remains dissolved

16. TELEPHASE I 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

17. PROPHASE II Sister Chromatids Nuclear Membrane Centrioles Fibers
Still coiled
Has not reformed
Move apart from one another
Re-form between centrioles

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

19. ANAPHASE II Chromatids Nuclear Membrane Centrioles Fibers
Still at cell’s poles
Pull each chromatid toward opposite ends of cell
Remains dissolved
Sisters are pulled apart by fibers.
Each chromatid is separate from its “sister”

20. Each end of cell has HALF and SINGLE chromosomes.
TELEPHASE II
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

21. KEY CONCEPT During meiosis, diploid cells undergo _______ cell divisions that result in _______________ cells. 2
HAPLOID

22. Cells go through two rounds of division in meiosis.
Meiosis reduces chromosome number and creates _______________________________.
GENETIC DIVERSITY

23. Meiosis differs from mitosis in significant ways.
Meiosis has _____ cell divisions while mitosis has one.
In mitosis, _____________chromosomes never pair up.
Meiosis results in ____________ cells; mitosis results in ______________ cells. 2
HOMOLOGOUS
HAPLOID
DIPLOID

24. Pairs of homologous chromosomes separate in ___________.
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

25. Meiosis I occurs after DNA has been replicated.
Meiosis I divides homologous chromosomes in four phases.

26. Meiosis II divides sister chromatids in four phases.
DNA is not replicated between meiosis I and meiosis II.

27. So What Does The Process of Meiosis Look Like? MORE MEIOSIS MEIOSIS
EXAMPLES
MEIOSIS
ANIMATION

28. Result in four sex cells
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.

29. MEIOSIS MEN VS. WOMEN WHAT IS THE SAME? WHAT IS THE DIFFERENT?
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)

30. 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

32. 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.

33. MITOSIS VS. MEIOSIS What is the same? What is different?
1.__________________________________2.__________________________________3.__________________________________4.__________________________________5.__________________________________Process: __________________________________________________________ 1
1.__________________________________2.__________________________________3.__________________________________4.__________________________________5.__________________________________6.______________________7.____________________________________ 1 2 2 1 3 3 4 5 4 6 5 7

35. 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