1. MEIOSIS 11-4 Making gametes…
Making gametes…

2. Interest Grabber
1. How many chromosomes would a sperm or an egg contain if either one resulted from the process of mitosis?
2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo?
3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have?
46 chromosomes
= 92; a developing embryo would not survive if it contained 92 chromosomes.
Sperm and egg should each have 23 chromosomes.

3. Remember from Chapter 1: CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________
REPRODUCE
Planaria animation: Family

4. ASEXUAL REPRODUCTION Bacteria reproduce using BINARY FISSION
Bacteria reproduce using
__________________________________
Budding & regeneration are used by plants and animals to reproduce asexually (mitosis)
BINARY FISSION
Planaria animation:

5. BINARY FISSION & MITOSIS
Produces cells that are __________ copies of parent cell
identical

6. ADVANTAGES OF ASEXUAL REPRODUCTION
Can make offspring faster
Don’t need a partner

7. DISVANTAGES OF ASEXUAL REPRODUCTION
ALL ALIKE
Species CAN’T change and adapt
One disease can wipe out whole population

8. SEXUAL REPRODUCTION DIFFERENT Combines genetic material
Family image from:
Combines genetic material
from 2 parents (sperm & egg)
so offspring are
genetically __________
from parents
DIFFERENT

9. 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

10. + EGG SPERM  If egg and sperm had same number of
Image by Riedell
Image by Riedell
EGG +
SPERM 
If egg and sperm had same number of
chromosomes as other body cells . . .
baby would have too many chromosomes!

11. MEIOSIS is the way… to make cells with ½ the number of chromosomes
for sexual
reproduction

12. Click the image to play the video segment 11A.
Meiosis Overview
Click the image to play the video segment 11A.
Video 1

13. DIPLOID & HAPLOID HOMOLOGOUS CHROMOSOMES
Most cells have 2 copies of each chromosome = ______________
(one from mom; one from dad)
All BODY (___________) cells are diploid
DIPLOID 2n
HOMOLOGOUS CHROMOSOMES
= SOMATIC

14. DIPLOID & HAPLOID
Some cells have only one copy of each chromosome = _____________
All sperm and egg cells
are haploid
HAPLOID 1n

15. 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 2
identical 2n
SOMATIC (body)

16. MEIOSIS 4 1n Germ cells OR Gametes (sperm & eggs) sexual reproduction
Makes ____ cells genetically different from parent cell & from each other
Makes _____ cells
Makes ______________
Used for ____________ 1n
Germ cells
OR Gametes (sperm & eggs)
sexual reproduction

17. WHAT MAKES MEIOSIS DIFFERENT ?
SYNAPSIS & CROSSING OVER (PROPHASE I)
SEGREGATION &
INDEPENDENT ASSORTMENT (ANAPHASE I)
3. Skip INTERPHASE II (NO S)
CELL DIVIDES TWICE, BUT…
ONLY COPIES DNA ONCE

18. WHAT MAKES MEIOSIS DIFFERENT ?
Homologous chromosomes pair up during ________________
= ______________
PROPHASE I
SYNAPSIS
This group of FOUR (4)
chromatids is called a
_________________
TETRAD
Images modified from:

19. WHAT MAKES MEIOSIS DIFFERENT?
1. Exchange of DNA between homologous pairs = _____________ during PROPHASE I
CROSSING OVER
Allows shuffling of genetic material

20. Click the image to play the video segment. 11E
Crossing Over
SEE CROSSING OVER ANIMATION
Click the image to play the video segment. 11E
Video 5

21. HOMOLOGOUS CHROMOSOMES
SAME SIZE
SAME SHAPE
CARRY GENES for the SAME TRAITS
BUT ______________!
(Don’t have to have the SAME CHOICES)
Image modified by Riedell
NOT IDENTICAL

22. Allows for_________________ in different combinations
Image modified by Riedell
CROSSING OVER
rearranging of DNA
Allows for_________________
in different combinations
After crossing over, chromatid arms are________________ anymore
NOT IDENTICAL

23. WHAT MAKES MEIOSIS DIFFERENT ?
2.Separation during ANAPHASE I
SEGREGATION &
INDEPENDENT ASSORTMENT
Separates gene choices and allows shuffling of genetic material

24. Click the image to play the video segment 11D.
Segregation of Chromosomes
Click the image to play the video segment 11D.
Video 4

25. SEGREGATION (Anaphase I)

26. SEGREGATION & CROSSING OVER together make even more combinations
See an animation

27. INDEPENDENT ASSORTMENT

28. 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!

30. 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
GENETIC RECOMBINATION
different

31. WHAT MAKES MEIOSIS DIFFERENT ?
3. Skip INTERPHASE II (No S)
CELL DIVIDES TWICE, BUT …
ONLY COPIES ITS DNA ONCE
MITOSIS: G1 S G2 P M A T C       
MEIOSIS:
( I ) G1 A T C S G2 P M        P M A T C
( II )    

32. Click the image to play the video segment 11B. & C
Animal Cell Meiosis, Part 1 & Part 2
Click the image to play the video segment 11B. & C

33. Figure Meiosis
Section 11-4
Meiosis I

34. Figure Meiosis
Section 11-4
Meiosis I
Meiosis I

35. Figure Meiosis
Section 11-4
Meiosis I
Meiosis I

36. Figure Meiosis
Section 11-4
Meiosis I

37. Figure Meiosis
Section 11-4
Meiosis I

38. Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

39. Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

40. Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

41. Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

42. Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

43. 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