1. Reproduction… passing on the genetic code Unit 8 Ch. 18

2. Two Types of Reproduction Asexual (without sex) one parent Offspring genetically identical to parent – clone – no variation Sexual Two parents Variation in offspring

3. Asexual Reproduction

4. 1. Splitting or Binary Fission DNA replicates, cell divides into 2 identical cells

5. More complex in unicellular eukaryotes – involves mitosis and cell division: –e.g., Amoeba, Euglena, Paramecium

6. 2. Budding Small piece breaks off and grows into complete organism. Hydra yeast

7. In plants – called vegetative reproduction. Tuberous roots rhizome corm True bulbs tuber

8. creeper Side stems called runners or creepers that grow roots and leaves forming new plants that grow independently.

9. Artificial vegetative reproduction (vegetative propagation) Cuttings from roots, stems, leaves can produce new plants.

10. 3. Fragmentation and Regeneration Fragmentation - Small piece or fragment will grow into whole new adult Regeneration refers to ability to regrow missing part Sea Stars Planaria

11. 4. Spores Algae, fungi, ferns, bacteria –DNA, cytoplasm, protective coat –Doesn’t fuse with another cell –Adapted for dispersal and surviving unfavorable conditions Clostridium botulinum Fern sori Spore prints

12. 5. Parthenogenesis Eggs develop without fertilization: complex organisms including aphids, honeybees, some lizards

13. Asexual Reproduction - Advantages Rapid Doesn’t require partner Less energy Well adapted individuals spread quickly

14. Sexual Reproduction involves an exchange of genetic information – two gametes undergo fertilization.

15. 1.Conjugation genetic material is exchanged through conjugation tubes Algae, bacteria, fungi Spirogyra Bacteria

16. Flower is reproductive organ pistil

17. Pistil - female Stigma – sticky to trap pollen Style – long narrow – sperm travels through Ovary – swollen base that contains the ovules where eggs are produced

18. Stamen – Male Most flowers have both male and female parts –Anther produces pollen that contains sperm - Filament – supports anther pollen

19. Some flowers are only male or female

20. 2. Plants – alternation of generation – between n and 2n Alternation of Generation

22. Angiosperm Life Cycle Alternation of Generation

23. In anthers and ovules of diploid sporophytes are cells that undergo meiosis to produce haploid spores Spores divide by mitosis to produce male and female gametophytes. Cells in gametophytes divide by mitosis to produce sperm and eggs

24. Male gametophyte = pollen grain & pollen tube Female gametophyte = embryo sac within ovule

25. In flowering plants there is an alternation of generation between a diploid sporophyte generation and a haploid gametophyte generation.

26. Double Fertilization

27. 1 sperm nucleus + egg 2n zygote » (forms embryo) 1 sperm nucleus + 2 polar nuclei 3 n endosperm (food for embryo)

28. Double Fertilization The pollen lands on the stigma. A pollen tube grows through the style to the ovule. 2 haploid sperm nuclei travel through the style to the ovule. 1 sperm nucleus fertilizes the n (haploid) egg to form a 2n (diploid) zygote that develops into the embryo. 1 sperm nucleus fertilizes 2 polar bodies (or nuclei) to form a 3n (triploid) endosperm that nourishes the embryo.

29. Seed develops after fertilization Ovule forms the seed coat Seed coat 2n embryo

31. Fruit is the ripened ovary

32. Sexual Reproduction - Animals No alternation of generation Gametes produced in ovaries and testes

33. Sexual Reproduction – Animals Hermaphrodites – both male and female - still exchange gametes with another individual

34. Sexual Reproduction External fertilization –Aquatic environments –Large numbers of gametes released –Synchronized release of gametes ensured by mating behaviors

35. 3. Animals Internal fertilization –Many male, few female gametes –Mating behaviors (courtship, estrous cycles) –Parental care –Fewer offspring

36. ( Fallopian tube)

38. Eggs are produced in the ovaries Released midway through menstrual cycle = ovulation Travel through oviducts to uterus Uterine lining builds up tissue to support pregnancy – shed through cervix and vagina as menstrual flow Fertilization takes place in oviducts

39. *Accessory glands prostate, seminal vesicle, bulbourethral

41. Sperm are produced in the testes and stored in the epididymis They travel through the vas deferens which joins the urethra in the penis where they are discharged The accessory glands supply seminal fluid which along with the sperm comprises semen. During intercourse, sperm travel through vagina, cervix, uterus, and into oviducts to fuse with egg (fertilization)

42. Human Menstrual Cycle

44. Menstrual Cycle Hormonally controlled Ovulation - Egg matures and is released 4 phases - approximately 28 days –Thickening of uterine lining –Ovulation (release of mature egg from follicle) –Passage of egg into uterus –Loss of egg and lining or “menstruation”

45. If sperm are present, fertilization takes place in the oviducts Resulting zygote travels to uterus and implants in uterine wall for development