1. Cell Reproduction
Chapter 8

2. Chromosomes
Section 8.1

4. Definitions:
Chromosome: rod shaped structure made up of DNA and proteins
Sister Chromatids: identical halves of a chromosomes

5. Definitions: Centromere: protein that holds sister chromatids together
Homologous Chromosomes: chromosomes that code for the same traits that come from your mother and your father

6. Definitions: Chromatin: less tightly coiled strands of DNA
Uncoiled so that the cell can read the DNA to direct the cell’s activities
Chromosomes only occur during cell division
Chromatin coils up to make chromosomes

7. Ameba
Goldfish
Alligator
Garden Pea
Brown bat
Grasshopper
Bullfrog
Horse
Carrot
Human
Cat
Lettuce
Chicken
Onion
Chimpanzee
Redwood
Corn
Sand dollar
Earthworm
Fruit fly
All normal members of the same species have the same number of chromosomes in their body cells.

8. Sex Chromosomes
Definition: chromosomes that determine the sex of the organism
May carry other genes as well
Humans: X and Y
Males: XY
Females: XX

9. Autosomes:
Definition: All other chromosomes in the body besides the sex chromosomes
Humans = 46 total chromosomes
2 sex chromosomes
44 autosomes

10. Karyotype – map of a organism’s chromosomes

11. Diploid and Haploid Cells
Cells having 2 sets of chromosomes are diploid (2N)
The haploid number of a human egg or sperm cell is 23, and there are no homologous chromosomes in either cell (1N)

12. Mitosis
Section 8.2

13. Why Cells Divide Cell size is limited
Cells cannot keep growing indefinitely
Replacement of damaged cells
Growth - embryo
Asexual reproduction
Single celled life forms
Binary fission
Sexual reproduction - meiosis

14. Eukaryotic Cell Division
Mitosis (Growth Division): Division of cell producing two identical daughter cells
2n  2n
Meiosis (Reduction Division): Division of cell producing four haploid daughter cells
2n  1n

15. The Cell Cycle (Life Cycle of the Cell)
2 Major Parts:
1. Interphase G1 S G2
2. Cell Division
Mitosis – nucleus
Cytokinesis – cytoplasm

16. Part 1: Interphase Stage your cells are in the most amount of time
When cell does its “normal” jobs
Contains 3 stages: G1, S, and G2

17. G1 Phase
S Phase
G2 Phase

18. S Phase – DNA Replication
Process by which DNA builds an exact copy of itself
After replication has occurred, each double stranded molecule contains one old strand and one new strand of DNA

19. 1879 Walter Flemming used red dye to observe cell structures during mitosis, it killed the cells and so he had to take pictures at each stage in order to come up with a pictorial model of mitosis.

20. Part 2: The Stages of Mitosis (page 150)

21. Mitosis – Step 1: Prophase
Chromosomes (2 chromatids) form from chromatin
Nuclear membrane disassembles
Centrioles move to poles
Spindle fibers form

22. Mitosis – Step 2: Metaphase
Chromosomes line up at the middle of the cell
“Metaphase Plate”
- Stage where karyotypes are made from!

23. Mitosis – Step 3: Anaphase
Sister chromatids (from the same chromosome) separate and move to opposite poles

24. Mitosis – Step 4: Telophase
Spindle fibers disappear
Nuclear membrane forms again
Chromosomes go back into chromatin form
2 nuclei (diploid) per one cell

25. Cytokinesis Division of cytoplasm
Cell membrane pinches in to form two separate cells
Results: 2 IDENTICAL daughter cells

26. Animation
Mitosis

30. Mitosis “Flip Book” To receive full credit you must:
1. Illustrate what is going on in the life cycle
a) Title Page
b) Interphase: G1, S, G2
b) Mitosis: prophase, metaphase, anaphase, telophase
c) Cytokinesis: early & late
d) Finished product
2. Diploid # (2N) = 8
(represent homologous pairs with 4 different colors)
Need help? Consult your book or your notes!

31. Asexual Reproduction
offspring is an exact copy of parents - occurs in lower plants and animals
(bacteria, molds, algae and protozoa)
all cells form through mitosis

32. Asexual Reproduction
Regeneration
Budding
Spores
Binary Fission

33. Mitosis Slides

34. Meiosis
Section 8.3

35. 2 Stages: Meiosis I Meiosis II Results in 4 haploid cells 2n n n n n n

36. Interphase
Same as mitosis!
3 Stages: G1, S, G2

37. Meiosis I Formation of 2 haploid cells from 1 diploid cell
Production of gametes
“Reduction division”

38. Step 1: Prophase I Nuclear membrane breaks down
Centrioles move to the poles, spindle fibers form
Synapsis occurs, forming tetrads, allowing for crossing over (genetic variety)

39. Definitions:
Synapsis: When a pair of homologous chromosomes partner up inside a dividing cell
Tetrads: the name given to a partner of homologous chromosomes during synapsis
Crossing over: chromatids of homologous chromosomes twist around and trade places causing an exchange of DNA

40. Step 2: Metaphase I
Tetrads line up randomly at the metaphase plate

41. Step 3: Anaphase I
Tetrads are split and each homologue is moved toward opposite poles
Independent assortment: the random separation of maternal and paternal chromosomes
Resulting in genetic variety of offspring

42. Step 4: Telophase I Nuclear membrane reforms
Spindle fibers and centrioles disappear
2 nuclei per cell
Each nucleus now has HAPLOID number of chromosomes
2n  1n

43. Cytokinesis I
Splitting of the cytoplasm to produce 2 haploid daughter cells

44. Meiosis II NO interphase between meiosis I and II
The production of 4 haploid cells from 2 haploid cells.
EXACT same process as mitosis!

45. Step 1: Prophase II

46. Step 2: Metaphase II

47. Step 3: Anaphase II

48. Step 4: Telophase II

49. Cytokinesis II
End result = 4 haploid cells

52. Purpose: Gamete Production
Gamete: sex cells (egg & sperm)
Oogenesis – egg production
Spermatogenesis – sperm production
Sexual Reproduction: genetic diversity of offspring

53. Page 155

54. Sexual Reproduction Each parent contributes genes to the offspring.
each offspring has a different set of inherited traits from the parents
gives offspring a better chance of surviving in a changing environment

56. Mitosis vs Meiosis Meiosis Mitosis 2 divisions 4 daughter cells
Each unique
Diploid to haploid
Purpose
Make gametes/ sex cells
Leads to genetic variation
Mitosis
1 division
2 daughter cells
Exact copies of parent cells
Diploid to diploid
Purpose
Growth
Repair
Asexual reproduction

58. Cancer Cell cycle control system
Enzymes in cell control when and where cells divide
Malfunction in system means cells divide at inappropriate times and places
Benign tumor - abnormal mass of essentially normal cells
Stay at original site, don’t move
Cancer uncontrolled cell division

59. Cancer Problem not only uncontrolled division Metastisis
Cancer cells can move to other sites
New tumor at that site
Three treatments
Surgery to remove tumor
Radiation
Chemotherapy
Last two aimed at controlling division

60. Cancer treatments Radiation Chemotherapy
Disrupts cell division
Most actively dividing cells are tumor
Can damage normal cells- ovaries / testes
Chemotherapy
Some disrupt cell division
Taxol freezes spindle
Vinblastine prevents spindle formation
Cancer cells immortal in cell culture
Normal cells stop growing after 50 culture