1. Gamete Production Day One
Meiosis
Gamete Production
Day One

2. Chromosomes and Meiosis
Specialized cells in the body –
2 types:
Somatic cells (body cells)
Makes up your body tissues and organs
DNA in your body cells not passed onto your children
Germ cells (Sex cells – turns into gametes)
Cells in your reproductive organs

3. Chromosomes
Threadlike structure made up of DNA and protein that carries genetic information (characteristics for an organism)
DNA (deoxyribonucleic acid)
Hereditary material carried by organisms
Visible when cells is dividing
Number of chromosomes vary per organism
Ferns

4. Human Body Cells
Each of your body cells contains a set of 46 chromosomes
Comes in 23 pairs
Cells are genetically identical to each other unless there is a mutation
Remember, cells within an organism differ from each other
Different genes are expressed, NOT because they have different genes

5. Human cells have autosomes and sex chromosomes
We have a total of 46 chromosomes (23 from mother and 23 from father)
Human cells use both sets of chromosomes to function properly
Each pair of chromosomes – homologous pair
Homologous “same structure”
2 chromosomes – one from mom and one from dad – that have the same length and general appearance

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

7. Homologous Chromosomes
Have copies of the same genes
Numbers are assigned to each pair of homologous chromosomes, ordered from largest to smallest
Largest pair is number 1
Pairs 1 through 22 are autosomes
Not related to sex of organism

8. Sex chromosomes What about the 23rd pair? Sex chromosomes
Directly control the development of sexual characteristics
Human have 2 different chromosomes: X and Y
Sex determined varies upon species
Sex in humans is determined by XY system
XX is a female
XY is male

9. Body Cells are diploid; gametes are haploid
Sexual reproduction –
Involves the fusion of 2 gametes that results in offspring that are a genetic mixture of both parents;
Not genetically identical
Fertilization –
Fusion of egg and sperm
Body cells and gametes have different numbers of chromosomes.

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

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

12. Remember from Chapter 1: CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________
REPRODUCE

13. ASEXUAL REPRODUCTION BINARY FISSION Mitosis Bacteria reproduce using
__________________________________
Budding & regeneration are used by plants and
animals to reproduce asexually _________________
BINARY FISSION
Mitosis

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

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

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

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

18. 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

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

20. Makes ___ cells genetically _________ to parent cell & to each other
REVIEW: MITOSIS 2
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
identical 2n
SOMATIC (body)

21. Mitosis Review

22. 4 1n Gametes (sperm & eggs) sexual reproduction MEIOSIS
Makes ____ cells genetically different from parent cell & from each other
Makes _____ cells
Makes ______________
Used for ____________ 1n
Gametes (sperm & eggs)
sexual reproduction

23. Meiosis

24. 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

25. 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:

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

27. rearranging of DNA CROSSING OVER NOT IDENTICAL
Allows for_________________
in different combinations
After crossing over, chromatid arms are________________ anymore
NOT IDENTICAL

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

29. SEGREGATION (Anaphase I)

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

31. INDEPENDENT ASSORTMENT

32. 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!

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

34. 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

35. Ticket out the Door What are somatic cells and germ cells?
How many chromosomes do your body cells have?
How many pairs of chromosomes do your body cells have?
What is the difference between autosomes and sex chromosomes?
What are the three points that make meiosis different from mitosis?

36. Gamete Production Day Two
Meiosis
Gamete Production
Day Two

37. 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

38. MITOSIS vs MEIOSIS PROPHASE PROPHASE I
DNA scrunches into chromosomes
Nuclear membrane/
nucleolus disappear
Centrioles/ spindle fibers appear
Same as mitosis
Difference: Homologous pairs match up

39. MITOSIS vs MEIOSIS METAPHASE METAPHASE I
Chromosomes line up in middle
Same as mitosis
Difference: With homologous
partner

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

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

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

43. 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

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

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

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

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

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

49. Meiosis Animation - Sumanas
Meiosis - McGraw Hill
Meiosis Animation

50. Ticket Out the Door