1. Reproduction

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. BINARY FISSION & 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. MEIOSIS is the way… to make cells with ½ the number of chromosomes
for sexual
reproduction
If egg and sperm had same number of
chromosomes as other body cells . . .
baby would have too many chromosomes!

10. A __________ is a picture of an organism’s chromosomes
KARYOTYPE 10

11. 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

12. 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:

13. 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

14. 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

15. SEGREGATION (Anaphase I)
Orientation of the chromosome pairs is random with respect to the poles
Separation of homologous chromosomes ensures that each gamete receives a haploid set of chromosomes composed of both maternal and paternal chromosomes

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

17. INDEPENDENT ASSORTMENT

18. 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!

19. GENETIC RECOMBINATION comes from:
Crossing over
Segregation
Independent assortment
Random fertilization
fusion of two gametes, increase genetic variation in populations by providing new combinations of genetic information in the zygote, and restores diploid number of chromosomes

20. Phases of Meiosis

21. Figure Meiosis
Section 11-4
Meiosis I

22. 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.

23. 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

24. 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

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

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

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

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

29. 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

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

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

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

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

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

35. 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

36. Nondisjunction –
Failure of homologous chromosomes OR chromatids to separate at anaphase

37. Mistakes in Meiosis
Meiosis Lecture 4

38. Nondisjunction
Results in ANEUPLOIDY = one or more chromosomes have extra or missing copies
AFTER FERTILIZATION: Cell with only 1 copy of a chromosome instead of 2
= MONOSOMY
Cell with 3 copies of a
chromosome instead of 2
= TRISOMY

39. Errors in mitosis or meiosis can result in changes in phenotype
Changes in chromosome number often result in:
New phenotypes
Sterility caused by triploidy and increased vigor of other polyploids
human disorders with developmental limitations
Trisomy 21 (Down syndrome)
XO (Turner Syndrome)

40. Karyotype can show: Sex of baby Missing or extra chromosomes
Major deletions or translocations
Can’t see individual gene changes

41. Down syndrome (Trisomy 21)
Most common chromosomal abnormality (1 in 800 births)
Similar facial features Slanted eyes / Protruding tongue Mild to severe mental retardation
50% have heart defects that need surgery to repair
Both older (35+ years) and younger (under 16 years) mothers are more at risk.

42. Some individuals with Down syndrome have the normal number of chromosomes but have all or part of a third chromosome 21 attached to another chromosome by translocation.

43. Turner syndrome (X0)
1 in 5000 births
Females have only one X chromosome
Small size
Broad chest
Slightly decreased intelligence
35% have heart abnormalities
Hearing loss common
Reproductive organs don’t develop at puberty

44. http://www. akdeniz. edu
Klinefelter syndrome
1 in 2000 births live births
Males have extra X chromosomes
(Can be XXy, XXXy, or XXXXy)
Taller than average
Normal intelligence have male sex organs, but are sterile. may be feminine characteristics,
Often not discovered until puberty when don’t mature like peers
Presence of BARR BODIES