1. MEIOSIS

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

3. 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:

4. MITOSIS Produces cells that are __________ copies of parent cell
identical

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

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

7. SEXUAL REPRODUCTION Combines genetic material
Family image from:
Combines genetic material
from 2 parents (sperm & egg)
Offspring are genetically different from parents

8. 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

9. + 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!

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

11. 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

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

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. 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
Places where crossing over
happens
= ____________________
CHIASMATA

20. 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

21. 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. SEGREGATION (Anaphase I)

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

25. INDEPENDENT ASSORTMENT-the random distribution of the pairs of genes on different chromosomes to the gametes

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

29. Figure Meiosis
Section 11-4
Meiosis I

30. 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.

31. 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

32. 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

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

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

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

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

37. 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

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

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

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

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

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

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

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