1. Animal Reproduction Reproduction Sexual Reproduction
Today, will tie many concepts together & build upon them in reproduction.
We will cover:
Reproduction
Sexual Reproduction
The Human Reproductive System

2. Reproduction
The purpose of reproduction -to create new life (offspring) to pass DNA from P to F1.
From the simplest bacteria to humans, is how living things create their offspring.
How the DNA from P is passed to the F1.
Does anyone have a dead parent or grand?
If so, a part is still alive. Their genes, their DNA is alive within their descendents.

3. How does this whiptail lizard reproduce (it’s found in the American SW)? Other lizards.

4. Asexual Reproduction
Some animals can reproduce asexually, producing offspring genetically identical to their parent (clones).
Disadvantage -no genetic diversity is produced.
Advantage –if the genotype is well adapted to the environment, this keeps the genotype.

5. Asexual Reproduction budding (yeast, some plants) regeneration,
Methods of asexual reproduction:
budding (yeast, some plants)
regeneration,
and parthenogenesis. (whiptail lizards)

6. Sexual Reproduction Sexual reproduction consists of:
gametogenesis (gamete formation),
mating,
and fertilization.
Gametogenesis and fertilization are similar in all animals.
Mating has a great variety of anatomical, physiological, and behavioral adaptations.

7. Sexual Reproduction Advantage -genetic diversity is created by:
recombination of genes during gametogenesis (crossing over)
independent assortment of chromosomes.
mating and fertilization in that two genomes are used.

8. Sexual Reproduction Disadvantages:
If the genotype is well adapted to the environment, it is broken by sexual reproduction.
It may be hard to find a mate.
Only half your genome is passed to the offspring (asexual passes all of it).

9. Sexual Reproduction Gametogenesis occurs in testes and ovaries.
In spermatogenesis and oogenesis, the primary germ cells proliferate mitotically, undergo meiosis, and mature into gametes.
Review next two Figures

10. figure 42-04a.jpg
Figure 42.4 – Part 1
Spermatogenesis

11. figure 42-04b.jpg
Figure 42.4 – Part 2
Oogenesis

12. Sexual Reproduction
Spermatogonia continue to proliferate by mitosis throughout the male’s lifespan.
Each primary spermatocyte can produce four haploid sperm through two divisions of meiosis.
Millions of sperm produced daily.
Review Spermatogenesis.

13. Sexual Reproduction
Primary oocytes immediately enter prophase of the first meiotic division, and in many species (humans), their development is arrested at this point.
Each oogonium produces only one egg through meiosis. Review Oogenesis.

14. Overview Testes Sperm produced 300 million released Ovaries
Male
Testes
Sperm produced
300 million released
Female
Ovaries
One egg produced
About every 28 days
Oviduct
Sperm encounter egg
Fertilization

15. Sexual Reproduction sequential or simultaneous
Hermaphroditic species have both male and female reproductive systems in the same individual.
Hermaphrodites may be:
sequential
switch between male & female, some fish
or simultaneous
male & female at the same time
earthworms.

16. Fertilization can occur externally:
common in aquatic species.
protects gametes from desiccation and heat.
mating behaviors assure sperm and egg unite.

17. Fertilization can occur: internally
Necessary in many terrestrial species.
Terrestrial species have to keep the gametes and developing egg from drying out, so they to use internal fertilization usually involving copulation.

18. Sexual Reproduction
Copulation brings the sperm and egg into close proximity.
The shelled egg -an important adaptation to the terrestrial environment (desiccation).
Yet, the egg must be fertilized before shell formation.
All mammals except monotremes do not produce shelled eggs, retain the embryo internally.

19. Mammalian and Human Reproduction
Copulation -males produce and deliver semen into the female reproductive tract.
Semen consists of sperm suspended in a fluid that nourishes them and facilitates fertilization.

20. figure jpg
Figure 42.8
Figure 42.8

21. Spermatogenesis Primary spermatocytes Mitosis produces constant supply
Tubules in testes
Primary spermatocytes
Mitosis produces constant supply
Secondary spermatocytes
After first stage of meiosis
Two haploid cells
Sperm
After second stage of meiosis
Four haploid cells
Millions produced daily

22. figure 42-09b.jpg
Figure 42.9 – Part 2
Figure 42.9 – Part 2

23. Oogenesis Ovaries Primary oocytes—by mitosis
Prior to birth
Primary oocytes—by mitosis
Begin first meiotic division
After puberty (about one/month)
Completion of first meiotic division
Secondary oocyte and polar body
Secondary meiotic division begins
Released into oviduct during ovulation
Completes meiotic division after fertilization by sperm

24. The Human Reproductive System
Eggs mature in the female’s ovaries
are released into the oviducts, which deliver the eggs to the uterus.
Sperm deposited in the vagina move through the cervix into the uterus, some continuing up through the oviducts.
Egg secondary meiotic division completed after fertilization by sperm

25. figure jpg
Figure 42.11
Figure 42.11

26. figure jpg
Figure 42.12
Figure 42.12

27. Fertilization Ovum Follicle cells and coating Much larger than sperm
Millions released
Only hundreds reach ovum
Acrosome
Front tip of sperm—contains enzymes
Digest outer covering
Fertilization
Two nuclei fuse

28. Mate Selection Important for successful reproduction
Providing parental care and sustenance

29. Mate Selection Important for successful reproduction
Ensures quality of genes
Investment of female vs. male in reproduction
Many animals—females choose more carefully, invest a lot more than male
Some animals mate for life

30. Human Sexual Behavior
Human sexual responses consist of: excitement, plateau, orgasm, and resolution.
Males have a refractory period during which renewed excitement is not possible.

31. Human Sexual Behavior Methods to prevent pregnancy include
abstention from copulation
or use of technologies that decrease the probability of fertilization. Review Table 42.1

32. table jpg
Table 42.1
Table 42.1