1. Reproduction
Chapter 27

2. Reproduction Asexual Sexual Genetically identical offspring (clones)
1 parent
No gamete fusion
Mitosis only
Pro
Ease for nonmotile and isolated individuals, and quick
Con
Changing environments
Genetically unique individuals
2 parents
Haploid gametes (n) fuse (2n)
Egg: large, nonmotile, female
Sperm: small, motile, male
Mitosis and meiosis
Pro
Variability = better survival chance
Con
Finding mates

3. Asexual Reproduction Fission Budding Fragmentation Parthenogenesis
Prokaryotes
Invertebrates
Budding
Hydras
Fragmentation
Some sea stars & sponges
Parthenogenesis
Bees, ants, & Komodo dragons

4. Sexual Reproduction Simultaneous hermaphroditism
Cross-fertilization
Sequential hermaphroditism
Many fish
Blue-banded gobies
Separate sexes
External
Internal

5. Fertilization External Internal
External: timing is crucial; environmental clues, chemical signals, or courtship rituals; cost large numbers
Internal: terrestrial adaptation; requires copulation and specific organs; cost parental care

6. Human Reproductive Systems

7. Female Reproductive System
Ovaries and follicles produce estrogen
Follicles release eggs about every 28 days
Without fertilization, corpus luteum and endometrium degenerate
Occurs in oviduct
Zygote, embryo, fetus (9th week)

8. Male Reproductive System
Sperm
Develop in seminiferous tubules
Epididymis store while developing
Semen
Seminal vesicles: nutrients for energy and uterine entry
Prostate gland: nourishes and activates
Bulbourethral glands: neutralize urethra
Ejaculation
Bladder sphincter contracts
Ducts and glands contract to propel semen
Urethra sphincter relaxes
Contractions of penis releases semen

9. Oogenesis Prior to birth Birth Puberty
Cell in follicle undergo mitosis and start meiosis
Birth
Primary oocyte (2n) halted at prophase I
Puberty
LH stimulates meiosis I completion
Secondary oocyte (n) halted at metaphase II & polar body
Ovulation releases
Fertilization completes meiosis
Second polar body

10. Spermatogenesis Diploid cells undergo mitosis after puberty
1 Primary (2n) to 2 secondary spermatocytes (n)
Secondary spermatocyte to 2 spermatids
Completes meiosis to become sperm
Process about 10 weeks

11. Gametogenesis Oogenesis Spermatogenesis
Mitotic division adolescence till death
4 spermatocytes result
Mature sperm continuously produced
Mitotic division completed by birth
1 oocyte develops, polar bodies degenerate
1 ovum per cycle (28 days)

12. Fertilization
Receptor protein binding to middle layer prevents other sperm from fertilizing

13. Infertility Technology
Male
Female
Sperm count low or defective
Scrotum temperature change
Sperm bank
Impotence
Viagra
Implants (irreversible)
Intracytoplasmic sperm injection
Lack of eggs
Implant from a donor
Risk to donor
Failure to ovulate
Hormone injections
Multiple pregnancies
Can’t support embryo
Surrogate mother
In vitro fertilization

14. STD’s United States w/ highest rates (developed countries)
Bacterial and fungal
Antibiotics can cure if early; resistance
Gonorrhea, chlamydia, and syphilis
Candidiasis
Viral
Not curable, but controllable; infect others for life
Genital herpes (most difficult), HPV, HIV
Protozoan
Trichomoniasis

15. Contraception Sterilization prevents gamete transport
Condoms prevent pregnancy and STD’s
Abstinence only 100%
Rhythm method is unreliable
3-5 day sperm survival rate
Oral contraceptives prohibit hormonal signal to follicle
Morning after pill
RU486 induces abortion (7 weeks)
Blocks progesterone receptors