1. Chapter 8: Cell Reproduction

2. 8.1 Chromosomes

3. 8.1 Chromosomes

4. 8.1 Chromosomes

5. 8.1 Chromosomes Objectives: I will be able to:
Describe the structure of a chromosome
Identify the differences in structure between prokaryotic chromosomes and eukaryotic chromosomes
Compare the numbers of chromosomes in different species
Explain the differences between sex chromosomes and autosomes
Distinguish between diploid and haploid cells

6. How Chromosomes are Formed
DNA – genetic information of the cell
“Double helix shape”

7. How Chromosomes are Formed
DNA wrapped around histones
Histone – protein that supports shape of chromosomes

8. How Chromosomes are Formed
DNA wrapped around histones creates chromatin
Chromatin – loosely coiled DNA and histones

9. How Chromosomes are Formed
During cell reproduction, chromatin condenses to form tightly wound chromosomes
Chromosomes – tightly packed bodies of DNA

10. How Chromosomes are Formed
Why must the DNA be so tightly packed?

11. How Chromosomes are Formed
DNA → chromatin → chromosome

12. How Chromosomes are Formed

13. Chromosome Structure
Chromosome made of 2 chromatids
Chromatid – 2 identical halves of a chromosome

14. Chromosome Structure
Centromere – where the chromatids are attached

15. Prokaryote Chromosome
Review: what are the differences between prokaryotes and eukaryotes?

16. Prokaryote Chromosome
Review: what are the differences between prokaryotes and eukaryotes?
Prokaryotes do NOT have a membrane-bound nucleus nor membrane-bound organelles!!!!!!!!!!!!!!!!!!!

17. Prokaryote Chromosome
usually has only 1 chromosome
Chromosome has circular DNA

18. 8.2 Cell Division

19. Sunda Colugo

20. 8.2 Cell Division Learning Targets I will be able to:
Describe the events of cell division in prokaryotes
Summarize the events of interphase
Describe the stages of mitosis
Compare cytokinesis in animal cells with cytokinesis in plant cells

21. 8.2 Cell Division

22. Prokaryote Cell Division
Binary fission – process of cell division used by prokaryotes
Review: what shape is prokaryotic DNA?

23. Prokaryote Cell Division
Binary fission – process of cell division used by prokaryotes
Review: what shape is prokaryotic DNA?
CIRCULAR ! ! ! ! !   ! ! ! ! !

24. Prokaryote Cell Division

25. Eukaryote Cell Division
Mitosis – 1 cell divides into 2 cells with same genetic material as parent cell

26. Cell Cycle

27. Interphase 1. Interphase – time when cells are NOT dividing
2. Cell spends most of its time in interphase
3. DNA replicates (doubles) here

28. 4 Stages of Mitosis Prophase
1. DNA turns into chromosomes and become visible
2. Nucleus disappears

29. 4 Stages of Mitosis Metaphase 1. chromosomes move to middle of cell
“metaphase = middle”

30. 4 Stages of Mitosis 1. Anaphase
Chromatids get pulled apart and start moving to opposite sides of cell

31. 4 Stages of Mitosis
Telophase 1. Chromatids arrive on opposite sides of cell 2. Nucleus reforms

32. Cytokinesis
Cytoplasm separates
2 new identical cells are formed

33. Cytokinesis
Cleavage – where cell membrane pinches in to separate 2 new cells

34. Cytokinesis

35. Prophase Metaphase Anaphase Telophase Cytokinesis Please Make A Terrific Cake

36. Uncontrolled Mitosis
Results in cells that do NOT stop dividing
Eventually become tumors
cancer

37. Apoptosis
Apoptosis –cell suicide

38. 8.3 Meiosis

39. 8.3 Meiosis (okapi)

40. 8.3 Meiosis Objectives I will be able to:
Compare the end products of meiosis with the end products of mitosis
Summarize the events of meiosis I
Explain crossing-over and how it contributes to the production of unique individuals
Summarize the events of meiosis II
Compare spermatogenesis and oogenesis
Define sexual reproduction

41. Meiosis – cell division resulting in haploid cells
Produces gametes (sperm and egg cells)

42. Meiosis has 2 stages
Meiosis I
Meiosis II

43. Meiosis I
Called reduction division
Has 4 stages………guess what they are

44. Meiosis I Has 4 phases………guess what they are Prophase I Metaphase I
Anaphase I
Telophase I and Cytokinesis I

45. Prophase I Early Prophase I DNA is copied here
DNA coils tightly into chromosome
Nucleus disappears
Tetrad – pair of homologous chromosomes
Early Prophase I

46. Prophase I

47. Crossing-over occurs here
Prophase I
Crossing-over occurs here
Crossing-over – parts of chromatids break off and attach to neighbor chromatids
Allows for the exchange of genetic material between chromosomes from mother and father
Genetic recombination – new mixture of genetic material created

48. Prophase I

49. Metaphase I
Tetrads line up in the middle of the cell

50. Anaphase I
Each homologous chromosome moves to opposite poles of cell
Independent assortment – random separation of maternal and paternal chromosomes

51. Telophase I and Cytokinesis I
2 new cells produced with half the number of chromosomes (haploid) (n)

52. Cells undergo division similar to mitosis
Meiosis II
DNA is NOT copied
Cells undergo division similar to mitosis

53. Prophase II
Nucleus disappears

54. Metaphase II
Chromosomes are aligned along the middle of the cell

55. Anaphase II
Chromatids separate towards opposite ends of cell

56. Telophase II
Nuclear envelope reforms

57. Cytokinesis II
Cytoplasm splits forming 4 new cells

58. Development of Gametes
Meiosis results in 4 haploid gametes
Gamete – haploid reproductive cell
Sperm in human males
Egg in human females

59. Males 4 spermatids form through meiosis
Spermatids develop into mature sperm cells through spermatogenesis

60. Females Oogenesis – production of ova Ova – mature egg cells
1 ovum produced during meiosis

61. Females Oogenesis – production of ova Ova – mature egg cells
1 ovum produced during meiosis
3 polar bodies also produced
Ovum retains most of the cytoplasm
Why?

62. Sexual Reproduction
Production of offspring through fusion of sperm and egg
Offspring are genetically different from parents
Allows species to adapt quickly to new conditions

63. Asexual Reproduction Offspring come from a single organism
Binary fission and mitosis are examples

64. Bellwork
With your tablemate, quietly review prophase, metaphase, anaphase, and telophase (in mitosis, meiosis I, and meiosis II)
Write down a muddiest point (most confusing idea) about mitosis/meiosis, if you have one, to submit. You don’t have to include your name.

65. Chromosome Numbers
Different organisms have different numbers of chromosomes

66. Chromosome Numbers
Different organisms have different numbers of chromosomes
Organism
Chromosome Number
Fruit Fly 8
Pea 14
Human 46
Chimpanzee 48
Goldfish 94
Adder’s Tongue Fern
1,262

67. Chromosome Numbers

68. Types of Chromosome
Sex chromosomes – determine sex of an organism
X and Y in humans
XX = female XY = males
Humans have 2
Autosomes – all other chromosomes
humans have 44

69. Types of Chromosome

70. Autosomes
Homologous chromosomes - 2 identical copies of each autosomes present in all cells
One copy from each parent

71. Autosomes
Genes – small segment of DNA that code for specific trait (eye color or hair color)
Many genes located on each chromosome

72. Karyotype
What is a karyotype?

73. Karyotype What is a karyotype? Photomicrograph of chromosomes
What you made yesterday by cutting and gluing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

74. Karyotype What is a karyotype? Photomicrograph of chromosomes
What you made yesterday by cutting and gluing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
22 pairs of homologous chromosomes (44 total)
2 sex chromosomes

75. Karyotype (female or male)

76. Karyotype (what’s wrong with this picture?)

77. Diploid Cells
Diploid cells – cells with 2 sets of chromosomes
all human cells (except egg and sperm cells) are diploid

78. Diploid Cell Abbreviation
Abbreviated as 2n
In humans 2n = 46 chromosomes

79. Haploid Cell
Haploid cells – contain only 1 set of chromosomes
Only sperm and egg cells in humans

80. Haploid Cell Abbreviation
Abbreviated as n
In humans n = 23 chromosomes

81. Diploid vs. Haploid Cells

82. 3 Stages of Interphase G1 Phase – cells grow S phase – DNA copied
G2 Phase – preparation for cell division

83. Optional 4th Stage of Interphase
G0 Phase – cells rest
Resting phase