1. Sexual Reproduction
Topic 16

2. Crossing over
Ovaries
Diploid
Ovum
Fertilization
Testes
Gamete
Sperm
Haploid
Zygote
Homologous chromosomes
Meiosis

3. Advantages of Sexual Reproduction
Offspring are genetically diverse
Better chance of surviving environmental changes

4. Chromosomes
Humans: 46 chromosomes
23 from mother, 23 from father

6. Meiosis Animation

7. Homologous Chromosomes
Chromosomes are paired
Similar size and shape
Carry same genetic info

9. Diploid Number 2n Number of chromosomes in somatic (body) cells
2 sets of chromosomes

10. Haploid/Monoploid Number
Half the diploid number
Number of chromosomes in gametes
1 set of chromosomes

11. Meiosis Process of forming sex cells 2 cell divisions
Meiosis 1 and Meiosis 2
Results: 4 haploid (1n) daughter cells

12. Haploid Cells

13. Describe the similarities and differences in these individuals
Describe the similarities and differences in these individuals. Do you believe they are related? Explain why or why not.

15. Meiosis Video

16. Steps of Meiosis 1st Meiotic Division Chromosomes replicate
Each double stranded chromosome finds its homologous pair

18. Crossing Over The strands get tangled and exchange genes
Leads to variation

19. Independent Assortment
Homologous chromosomes can line up in different orders
Leads to more variation

21. 2nd Meiotic Division Both daughter cells divide again
4 haploid cells are formed

23. Results of Meiosis
4 daughter cells
Haploid (1n) number of chromosomes

24. Exit Ticket
Explain the significance of crossing over and independent assortment.
If a fish has 20 chromosomes in her diploid cells, how many chromosomes will be in each of her eggs?

25. Gametogenesis Formation of gametes (sex cells) Spermatogenesis
Oogenesis

26. Spermatogenesis Testes produce sperm Primary sex cell → meiosis→
4 haploid cells

27. Results of spermatogenesis: 4 motile sperm

28. Oogenesis Ovaries produce eggs (ova/ovum) Primary sex cell → meiosis →
1 larger ovum + 3 polar bodies
Unequal division of cytoplasm
Polar bodies disintegrate

29. Results of oogenesis: 1 non-motile ovum

31. Types of Fertilization
Internal
Occurs inside female
Usually terrestrial animals
Few eggs produced
Development internal or external

32. Types of Fertilization
External
Occurs outside of the body
Usually aquatic animals
Many eggs produced
Development external

33. Zygote Formation Zygote- fertilized egg Egg + Sperm = Zygote
Fertilization- process of combining chromosomes
Zygote is diploid

35. Fertilization Zygote Cleavage

36. Embryo Formation Zygote will divide by mitosis
Cleavage- series of mitotic divisions of the zygote
Differentiation- cells will become specialized

37. Embryo Formation Morula- solid ball Blastula- hollow ball of cells
Gastrula- 3 germ layers

39. Germ Layers Ectoderm- outer layer
Becomes nervous system, epidermis, nails, hair, & sweat glands

40. Germ Layers Mesoderm- middle layer
Becomes bones, muscles, blood vessels, dermis, reproductive & excretory systems

41. Germ Layers Endoderm- inner layer
Becomes digestive tract, trachea, bronchi & lungs

42. Embryo Formation

43. Human Reproduction

44. Male Reproductive System
2 major functions: 1. Make sperm 2. Deposit in female (internal fertilization)

45. Structures and Functions:
1. Scrotum: keeps sperm 2-4 degrees cooler than normal body temperature

46. 2. Testes: Male gonads
Seminiferous Tubules: small, coiled tubes within the testes where sperm form
Testosterone produced

47. 3. Epididymis: stores sperm while they mature 4. Vas Deferens: a
3. Epididymis: stores sperm while they mature 4. Vas Deferens: a. tube that connects testes to urethra b. sperm transported here c. along the way secretions from 3 glands are picked up to make semen.

48. Fluids which provide nutrients to sperm are produced in:
Semen: sperm + fluids
Fluids which provide nutrients to sperm are produced in:
5. Bulbourethral (Cowper’s) Gland
7. Seminal Vesicles
9. Prostate Gland .

49. Female Reproductive System
Structures and Functions 1. Ovaries: a. female gonads b. produce eggs (meiosis – oogenesis) c. eggs enclosed in follicles d. once a month egg is ovulated (released – into fallopian tube)

50. Estrogen and Progesterone:
a. regulate secondary sex characteristics
b. regulate menstrual cycle

51. 2. Fallopian Tubes (oviducts):
a. connects ovary to uterus
b. fertilization here
3. Uterus:
a. implantation here (embryo embeds itself into uterine wall)
b. development from embryo to fetus here

52. 6. Vagina: birth canal (menstruate through here too) 7
6. Vagina: birth canal (menstruate through here too) 7. Cervix: base of uterus

53. The Menstrual Cycle

54. Menstrual Cycle Series of changes in ovaries and uterus
Begins at puberty
Ends at menopause (45-55 years old)
Pregnancy stops the cycle temporarily

55. The Menstrual Cycle

56. Follicle Stage – 10 Days Uterine lining thickens
Egg matures in follicle & swells
Pituitary Gland → Follicle Stimulating Hormone (FSH)
Ovaries → Estrogen

57. Ovulation – 1 day Egg released from follicle
Remains in oviduct for 2-3 days
Pituitary Gland → Luteinizing Hormone (LH)

58. Corpus Luteum – 14 Days Follicle dies, forming a scar (corpus luteum)
Uterine lining stays thick
Corpus luteum → Progesterone

59. Menstruation
If the egg was not fertilized- uterine lining breaks down and is shed
Cycle begins again

61. Internal Development in Placental Mammals
Development inside the female uterus

62. 1. Placenta Forms inside uterus Feeds fetus- nutrition
Exchange of gases- respiration
Removal of fetus wastes- excretion
All occurs by DIFFUSION
No direct contact between mother & fetus bloodstreams

64. 2. Oviduct
Fallopian tube- transports egg from ovary to uterus
3. Uterus
Muscular organ where fetus develops

65. 4. Umbilical Cord 5. Fetus Attaches placenta to fetus
Transports nutrients, gases and wastes
5. Fetus
Developing baby

67. 6. Amniotic Sac
Filled with amniotic fluid
Protects fetus

68. Multiple Embryos Identical Twins- 1 egg, 1 sperm
Zygote splits into 2 during cleavage
1 placenta, 1 amniotic sac
Fraternal Twins- 2 eggs, 2 sperm
Separate placentas & amniotic sacs

70. Artificial Insemination
Sperm artificially inserted into female

71. In Vitro Fertilization
Fertilization takes place in a petri dish
Zygote then implanted into uterus

72. Amniocentesis
Amniotic fluid extracted
Chromosomes of fetus analyzed

73. Kangaroo Birth

75. STUDENT VERSION