1. MEIOSIS Chapter 13
Slide show modified from Tracy Jackson and Kim Foglia

2. DO NOW What are three differences between mitosis and meiosis?
HOMEWORK: Watch Bozeman Sordaria Cross Video; take notes

3. Remember from Chapter 1: CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________
REPRODUCE
ASEXUAL
SEXUAL
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 Combines genetic material
Family image from:
Combines genetic material
from 2 parents (sperm & egg)
Offspring are genetically different from parents

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. 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

13. Chromosomes that determine the sex of an organism = _________________
All other chromosomes = _________________
Sex chromosomes
autosomes
Humans have two sex chromosomes
and _____ autosomes X y 44

14. A __________ is a picture of an organism’s chromosomes
KARYOTYPE 14

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

16. 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)

17. 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

18. 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

19. 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:

20. WHAT MAKES MEIOSIS DIFFERENT?
1. Exchange of DNA between homologous pairs = _____________ during PROPHASE I
CROSSING OVER
Allows shuffling of genetic material
Places where crossing over
happens
= ____________________
CHIASMATA

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

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. GENETIC RECOMBINATION comes from:
Crossing over
Segregation
Independent assortment
Random fertilization

32. Figure Meiosis
Section 11-4
Meiosis I

33. 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.

34. 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

35. 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

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

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

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

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

40. 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

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

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

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

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

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

46. 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

47. MAKING SPERM & EGGS

48. Gametogenesis =
process of forming gametes (n) from diploid (2n) cells
Spermatogenesis = process of forming sperm cells by meiosis in animals, by mitosis in plants in specialized organs
After division all 4 cells undergo differentiation to become sperm cells

49. ___________________= MAKING MATURE SPERM
SPERMATOGENESIS
___________________= MAKING MATURE SPERM
Mature & grow flagella

50. All the starting nutrients, organelles, molecule building blocks,
Sperm provides DNA
All the starting nutrients,
organelles, molecule building blocks,
etc. have to come from the egg.

51. CYTOPLASM DIVIDES UNEVENLY
OOGENESIS
__________________ =
MAKING a MATURE EGG
Produces:
1 “good” egg 3
POLAR BODIES
CYTOPLASM DIVIDES UNEVENLY

52. APOPTOSIS LYSOSOMES POLAR BODIES DEGENERATE (DIE) “Self digest” Using
________________
LYSOSOMES
APOPTOSIS
= __________________
“cell suicide” for good of organism

53. Oogenesis = process of forming an ovum (egg) by meiosis in animals by mitosis in the gametophyte in plants in specialized gonads known as ovaries.
Unlike spermatogenesis, cytoplasm divides unevenly so that all cytoplasm/organelles go to 1 large egg.
3 other cells = polar bodies; do not develop. Thus, all the cytoplasm and organelles go into the egg.
Human males produce 200,000,000 sperm per day, while the female produces one egg (usually) each menstrual cycle.

54. Life Cycles
A life cycle is the generation-to-generation sequence of stages in the reproductive history of an organism, from conception to production of its own offspring.

55. ALTERNATION OF GENERATIONS

56. IN PLANTS AND SOME ALGAE: ____________ = SPOROPHYTE
multicellular diploid stage in which meiosis
makes haploid cells called _________
Spores give rise to
a multicellular HAPLOID organism
= ________________
without fusing
with another cell
SPOROPHYTE
SPORES
GAMETOPHYTE
Image from Biology Campbell and Reece

57. IN FUNGI and SOME PROTISTS: Gametes fuse to make a diploid zygote
Meiosis occurs in zygote without
growing into a diploid organism
Meiosis makes haploid cells that
grow into haploid
organisms which use MITOSIS to make GAMETES!
Image from Biology Campbell and Reece

58. Meiosis Animations Frame-by-frame animation
Continuous animation – no words
Continuous frame-by-frame