1. Cellular Reproduction
Ch. 8

2. (8-1) Chromosomes
DNA & protein in a coiled, rod-shaped form that occurs during cell division
Uncoiled form is chromatin
Histone: protein DNA wraps around
Maintains shape & tight packing

4. Chromosomes (cont.) 2 sister chromatids Connected by centromere
Exact copies of each other
Connected by centromere
Cell division separates chromatids
Each new cell gets 1 copy of each chromosome

6. Chromosome #
Each species has characteristic # of chromosomes in each cell
Ameba
Goldfish
Alligator
Garden Pea
Brown bat
Grasshopper
Bullfrog
Horse
Carrot
Human
Cat
Lettuce
Chicken
Onion
Chimpanzee
Redwood
Corn
Sand dollar
Earthworm
Fruit fly

7. Sex Chromosomes
Determine sex of organism & may carry genes for other characteristics
Humans (X or Y)
Autosomes: all other chromosomes besides sex
Humans = 44 (other 2 are sex)

8. Homologous Chromosomes
Homologues: pairs of chromosomes
Same size, shape, & genes
Different from other homologues
In sexual reproduction, organism receives 1 copy of each autosome from each parent

10. Karyotype Photomicrograph of chromosome in a living cell
Humans: 22 homologues & 2 sex chromo.’s

13. Diploid (2n): cells that contain 2 sets of chromosomes
Humans 2n is 46
Haploid (1n): cells that contain 1 chromosome of each hom. pair
Sex chromo.’s

14. Reproduction
When sperm (1n) & egg (1n) combine to make 1st cell of new organism, the new cell is diploid (2n)

15. (8-2) Cell Division Process in which cells produce offspring cells
Why do cells divide?
Size is limited
Replace damaged cells
Growth

16. Prokaryotic Cell Division
Binary fission: division of prokaryotes into 2 offspring cells
3 stages:
Chromosome copied
Cell grows
Cell wall forms & cell splits into 2 new identical cells

17. Eukaryotic Cell Division
Mitosis (Growth Div.): division of cell producing 2 identical daughter cells
2n  2n
Meiosis (Reduction Div.): division of cell producing 4 haploid daughter cells
2n  1n

19. The Cell Cycle Interphase Cell Division G1 S G2
Mitosis (M phase): nucleus divides
Cytokinesis: cytoplasm divides

20. Interphase Cells in this stage most 3 stages Time b/w cell divisions
G1: offspring grow to mature size
G0: leave cycle, usually when mature
S: DNA replication
G2: cell preps for cell division

22. DNA Replication
After replication, each double stranded molecule contains 1 old strand & 1 new strand of DNA

25. Step 1: Prophase Chromo.’s form from chromatin
Nuclear membrane disassembles
Centrioles move to pole
Spindle fibers form

26. Step 2: Metaphase Fibers line chromo.’s up in the middle of the cell
Metaphase plate

27. Step 3: Anaphase
Sister chromatids separate (become individual chromo.’s) & move to opposite poles

28. Step 4: Telophase Spindle fibers disappear Nuclear membrane reforms
Chromo.’s go back to chromatin
2 nuclei per 1 cell

29. Cytokinesis Division of cytoplasm Results: 2 identical daughter cells
Animals - cell membrane pinches
Plants - cell plate forms
Results: 2 identical daughter cells

33. Cancer Uncontrolled growth of cells
Don’t respond normally to body’s control mechanisms
Mutations can interfere w/ ability to slow or stop cell cycle
Brain Cancer

34. (8-3) Meiosis
Nuclear division that reduces the # of chromo.’s in new cells to ½ the # of the original cell

36. 2 Stages: Meiosis I Meiosis II Results in 4 haploid cells 2n n n n n n

37. Interphase
Same as mitosis
3 stages: G1, S, G2
Prep for meiosis I

38. Meiosis I 2 haploid cells form from 1 diploid cell
“Reduction Division”

39. Step 1: Prophase I Chromo.’s form from chromatin
Nuclear membrane breaks
down
Centrioles move to poles
Spindle fibers form
Synapsis occurs

40. Definitions Synapsis: pairing of homologues to form tetrad
Crossing over: chromatids of hom. chromo.’s twist & trade places to exchange DNA (genetic recombination)

41. Step 2: Metaphase I Tetrads line up randomly at the metaphase plate
Spindle fibers attach

42. Step 3: Anaphase I
Tetrads split & each homologue is moved toward opposite pole
Independent assortment: random separation of maternal & paternal chromo.’s
Genetic variety

43. Step 4: Telophase I Nuclear membrane reforms
Spindle fibers & centrioles disappear
Each nucleus now has haploid # of chromo.’s

44. Cytokinesis I
Cytoplasm splits to produce 2 haploid daughter cells

45. Meiosis II No interphase b/w meiosis I & II
4 haploid cells produced from 2 haploid cells
Exact same process as mitosis

46. Step 1: Prophase II
Spindle fibers form & begin to move towards middle of the cell

47. Step 2: Metaphase II
Chromo.’s move to midline

48. Step 3: Anaphase II
Chromatids separate & move to opposite poles

49. Step 4: Telophase II
Nuclear membrane forms around chromo.’s in each of 4 new cells

50. Cytokinesis II
End result =
4 haploid cells

53. Gamete Production Gamete: haploid sex cells Oogenesis: egg production
egg & sperm
Oogenesis: egg production
1 large egg & 3 polar bodies
Spermatogenesis: sperm production
4 sperm

54. Sexual Reproduction
Each parent contributes genes & offspring is different from any other member of their species (except id. twin)
Gives offspring better chance of surviving in a changing environment

56. Asexual Reproduction Offspring is an exact copy of parent
All cells form through mitosis
Mainly occurs in prokaryotes
Bacteria, molds, algae, & protozoa

57. Asexual Reproduction
Regeneration
Budding
Spores
Binary Fission

58. Mitosis vs. Meiosis Meiosis Mitosis 2 divisions 1 division
4 daughter cells
Each unique
Diploid to haploid
Purpose:
Make gametes
Genetic variation
Mitosis
1 division
2 daughter cells
Exact copies of parent cells
Diploid to diploid
Purpose:
Growth
Repair
Asexual reproduction