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. Meiosis is used for reproduction
Meiosis is used for reproduction ALL LIVING THINGS __________ so all living things must go through the process of meiosis.
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 and mitosis reproduce cells that are __________ copies of the parent cell.
identical

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

7. DISVANTAGES OF ASEXUAL REPRODUCTION
Organisms are 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 populations
Individuals can be different
Provides foundation for EVOLUTION
Allow species adapt to
changes in
their environment

10. + WHY MEIOSIS? EGG SPERM  Humans have 46 chromosomes
Image by Riedell
WHY MEIOSIS?
Image by Riedell
EGG +
SPERM 
Humans have 46 chromosomes
in their body cells.
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 half the number of chromosomes
for sexual
reproduction
Meiosis Overview

12. DIPLOID & HAPLOID
Most cells have 2 copies of each chromosome = _________ or _____
(one from mom; one from dad)
All BODY (___________) cells are diploid
DIPLOID 2n
2 copies of each chromosome is called: HOMOLOGOUS CHROMOSOMES
= SOMATIC

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

14. 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) cells

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

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

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

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

19. 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

20. 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

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

22. SEGREGATION (Anaphase I)

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

24. INDEPENDENT ASSORTMENT

25. 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!

27. 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

28. WHAT MAKES MEIOSIS DIFFERENT ?
3. Skip INTERPHASE II (No S phase)
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 )    

29. Figure Meiosis
Section 11-4
Meiosis I

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

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

32. Figure Meiosis
Section 11-4
Meiosis I

33. Figure Meiosis
Section 11-4
Meiosis I

34. 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.

35. 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.

36. 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.

37. 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.

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. MITOSIS vs MEIOSIS INTERPHASE INTERPHASE I
DNA is spread out as chromatin
Nuclear membrane/ nucleolus visible
DNA is copied during S phase
Makes stuff new cell needs in G2
SAME AS
MITOSIS

40. MITOSIS vs MEIOSIS PROPHASE PROPHASE I
DNA scrunches into chromosomes Nuclear membrane/ nucleolus disappear Centrioles/spindle fibers appear
DNA scrunches into chromosomes
Nuclear membrane/
nucleolus disappear
Centrioles/ spindle fibers appear
Homologous pairs match up

41. MITOSIS vs MEIOSIS METAPHASE METAPHASE I
Chromosomes line up in middle
Chromosomes line up in middle
with homologous partner

42. MITOSIS vs MEIOSIS ANAPHASE ANAPHASE I
APART:
APART:
Chromatids split
Chromatids stay together Homologous pairs split

43. MITOSIS vs MEIOSIS TELOPHASE TELOPHASE I
See TWO nuclei
Nuclear membrane/
nucleolus return
DNA spreads out as chromatin
Spindle/centrioles disappear
SAME AS MITOSIS

44. MITOSIS vs MEIOSIS CYTOKINESIS CYTOKINESIS I
Cytoplasm splits
into 2 cells
SAME AS
MITOSIS

45. MITOSIS vs MEIOSIS INTERPHASE II
DNA is spread out as chromatin
Nuclear membrane/ nucleolus visible
DNA is copied during S phase
SKIP
INTERPHASE II
DNA NOT COPIED

46. MITOSIS vs MEIOSIS PROPHASE PROPHASE II
DNA scrunches into chromosomes
Nuclear membrane/ nucleolus disappear
Centrioles/ spindle fibers appear
SAME AS MITOSIS

47. MITOSIS vs MEIOSIS METAPHASE METAPHASE II
Chromosomes line up in middle
SAME AS MITOSIS

48. MITOSIS vs MEIOSIS ANAPHASE ANAPHASE II
Chromatids split and move apart
SAME AS MITOSIS

49. MITOSIS vs MEIOSIS TELOPHASE TELOPHASE II
Two nuclei
Nuclear membrane/ nucleolus returns
Centrioles/spindle fibers disappear
DNA spreads out as
chromatin
SAME AS MITOSIS

50. MITOSIS vs MEIOSIS CYTOKINESIS CYTOKINESIS II
SAME AS MITOSIS
Cytoplasm splits

51. 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

52. SOUTH DAKOTA CORE SCIENCE STANDARDS
LIFE SCIENCE: Indicator 1: Understand the fundamental structures,
functions, classifications, and mechanisms found
in living things
9-12.L Students are able to relate cellular functions and processes to specialized structures within cells.
Cell life cycles
Examples: somatic cells (mitosis), germ cells (meiosis)
Storage and transfer of genetic information

53. SOUTH DAKOTA CORE SCIENCE STANDARDS
LIFE SCIENCE: Indicator 2: Analyze various patterns and
products of natural and induced biological
change.
9-12.L Students are able to describe how genetic recombination, mutations, and natural selection lead to adaptations, evolution, extinction, or the emergence of new species.

54. Core High School Life Science Performance Descriptors
High school students performing at the
ADVANCED level:
predict the function of a given structure;
predict the outcome of changes in the cell cycle;
INTRODUCTION TO BE ABLE TO DO LATER
predict how traits are transmitted from parents to offspring
PROFICIENT level:
describe the relationship between structure and function
compare and contrast the cell cycles in somatic and germ cells;
explain how traits are transmitted from parents to offspring;
BASIC level
recognize that different structures perform different functions
describe the life cycle of somatic cells;
identify that genetic traits can be transmitted from parents to offspring;

55. SOUTH DAKOTA ADVANCED SCIENCE STANDARDS
LIFE SCIENCE:
Indicator 2: Analyze various patterns and products of natural and induced biological change.
9-12.L.2.1A. Students are able to predict the results of complex inheritance patterns involving multiple alleles and genes. (SYNTHESIS)
Examples: human skin color, polygenic inheritance relate crossing over to genetic variation.