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Chapter 12: Reproduction

Chapter 12: Reproduction. Whatever works…. 1. 12.1 Asexual Reproduction. Single Parent Genetically identical offspring (Clone) Simple process. 2. Rod Bacteria, 4000x Binary Fission. 7. Desert Whiptail Lizard - Parthenogenesis. 4. 3. 2. Bryophyllum - Fragmentation.

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Chapter 12: Reproduction

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  1. Chapter 12: Reproduction Whatever works… 1

  2. 12.1 Asexual Reproduction • Single Parent • Genetically identical offspring (Clone) • Simple process 2 Rod Bacteria, 4000x Binary Fission 7 Desert Whiptail Lizard - Parthenogenesis 4 3 2 Bryophyllum - Fragmentation Hydra, 14x - Budding Strawberry – Vegetative Propagation 3 min 5

  3. Reproductive cloning Donor cell Nucleus from donor cell Implant embryo in surrogate mother Clone of donor is born Therapeutic cloning Add somatic cell from adult donor Remove nucleus from egg cell Grow in culture to produce an early embryo Remove embryonic stem cells from embryo and grow in culture Induce stem cells to form specialized cells for therapeutic use Figure 11.6 Artificial Cloning • The procedure that produced Dolly is called reproductive cloning

  4. 12.2 Concept of Chromosome Number Each species has a “normal” or characteristic number of chromosomes Diploid (2n) 2 copies of each chromosome (homologous pairs) Haploid (n) 1 copy (homolog) of each chromosome Ordinary body cells (Somatic Cells) are diploid Gametes/Germ Cells(eggs/ova, sperm, pollen) are haploid The diploid number of chromosomes varies widely --- Humans: 2n = 46Turkeys: 2n = 82 Fruit flies: 2n = 4

  5. Homologous Pair of Chromosomes Each homolog carries genes for the same proteins. Each individual gets one homolog from Mom and one from Dad. 7

  6. Alternation of Generations6 Meiosis is a special kind of cell division that reduces chromosome number from 2n to n Multicellular Diploid Fertilization restores the chromosome number from n to 2n Multicellular Haploid (Plants)

  7. The Life Cycle of Humans Haploid gametes (n = 23) Note the Alternation of Haploid and Diploid Generations Egg cell Sperm cell Meiosis Fertilization Diploid zygote (2n = 46) Multicellular diploid adults (2n = 46) Mitosis and development Figure 8.13

  8. 12.3 Sexual Reproduction • Two Parents • Genetically varied offspring • More complex process Volvox 41 with Daughter colonies 46 Red-Eyed Tree Frogs44 45 Bald Eagle Nest43

  9. Increase variety of genes passed on to offspring. Increase number of different combinations of genes in offspring. More likely that some will survive. Why bother with sexual reproduction? 10 ~ 4 min 9

  10. Like Mitosis but not quite… PMAT occurs twice after 1 DNA replication Meiosis I separates doubled homologs Meiosis II separates sister chromatids Random distribution of homologs makes lots of combinations “Crossing Over” where homologs exchange DNA in Prophase I increases variety 3 Goals of Meiosis 1. Reduction of Chromosome number 2. Provides genetic variation 3. Ensures correct distribution of chromosomes 12.3 Meiosis and the Production of Gametes

  11. 6 3 Goals of Meiosis 1. Reduction of Chromosome number 2. Provides genetic variation 3. Ensures correct distribution of chromosomes

  12. 13SWF_MeiosisAndSexualLifeCycle\13-07a-InterphaseI.swf 13SWF_MeiosisAndSexualLifeCycle\13-07b-ProphaseI.swf Meiosis I: Homolog Separation13 See P. 322 Late Prophase I Metaphase I Anaphase I Telophase I Interphase II 13SWF_MeiosisAndSexualLifeCycle\13-10-CrossingOver.swf 13SWF_MeiosisAndSexualLifeCycle\13-07d-AnaphaseI.swf Haploid Nuclei! 13SWF_MeiosisAndSexualLifeCycle\13-07c-MetaphaseI.swf 13SWF_MeiosisAndSexualLifeCycle\13-07e-TelophaseICytokin.swf

  13. Meiosis II: Chromatid Separation13 Prophase II Metaphase II Anaphase II Telophase II Cytokinesis Haploid Daughter Cells! 13SWF_MeiosisAndSexualLifeCycle\13-07f-MeiosisIICytokin.swf

  14. Variation through Sorting6

  15. Variation through Crossing Over6 or Genetic Recombination

  16. Meiosis makes gametes (2nn) 6 Mitosis makes identical cells (2n  2n)

  17. Sperm and Egg Formation6 Polar Bodies:remnants of cells produced in oogenesis – usually disintegrate in animals -forms endosperm in flowering plants

  18. 12.4 Sexual Reproduction in Microorganisms Conjugation • Tube of cytoplasm forms between cells • DNA is exchanged • New offspring formed at next mitosis • Single celled prokaryotes and eukaryotes • Many organisms switch from sexual to asexual reproduction depending on environmental conditions 9 Spirogyra 42Conjugation

  19. Simple plants spend most of their life cycle haploid Complex plants spend most of their life cycle diploid 12.5 Sexual Reproduction in Plants • Most plants reproduce sexually • Many can also or only reproduce asexually 12 11

  20. Gametes (sperm and eggs) n Germination Mitosis Mitosis Spores n Gametophyte n Spore Formation Haploid Fertilization Meiosis Diploid Spore capsule Fertilization Zygote 2n Sporophyte 2n Mitosis Moss Life Cycle14 Figure 16.10

  21. 6 Flowering Plant Life Cycle6 Look at which parts are “n” and which are “2n!”

  22. Advantages of flowering plants Diploid dominant- allows complex structure Pollen: Fertilization without water Seed: Protects and feeds embryo Variety of pollen and seed dispersal methods Generalized Flower Parts6 Angiosperms = Flowering Plants

  23. Male Flower Parts Stamen = Anther + Filament Meiosis  Haploid Cells Mitosis  2 cells A tube cell Cell that produces 2 sperm nuclei Pollen, 200x Pollen then must land on a stigma for pollination 9 15

  24. Ovary: Contains ovules where eggs develop Oogenesis (See p. 327) 1. Meiosis  4 haploid cells 2. One  2x Mitosis  4 haploid cells 3. Mitosis produces 8 haploid nuclei Egg: one large cell with 1 nucleus Large cell w/2 polar nuclei Female Flower Parts 1 2 3 15 Egg now ready for fertilization!

  25. Pollination & Fertilization15 Pollination = pollen + stigma Fertilization = egg + sperm nucleus Brassica pollen germination, 405x Double Fertilization: Zygote (2n) = Egg + Sperm Endosperm (3n) = 2 Polar Nuclei + Sperm 15

  26. Methods of Pollination Cross Pollination: between individuals Self-Pollination: Pollen from a plant’s anther lands on its own stigma. 16 17

  27. Seed & Fruit Formation15 See P. 328 Ovule becomes the seed coat – protects embryo and endosperm Auxin stimulates ovary to become a fruit

  28. Seed Distribution By wind, water, animals, and fruit … Whatever works Dwarf mistletoe sticky seeds23 18 20 22 19 21

  29. MOST animals can reproduce sexually Gonads: organs for producing Gametes Gametes: haploid reproductive cells Ovaries  Eggs Testes  Sperm 12.6 Sexual Reproduction in Animals Salamander sperm24 Human sperm 3000x25 Did you know??Some animals like corals are hermaphrodites and produce eggs AND sperm… though they usually don’t self fertilize. Human sperm and egg26

  30. Pros Sperm and egg released directly into environment (water) Low parental involvement Cons Requires water Low % success May form food for other animals External Fertilization Acropora nasuta spawning27 Wood frog amplexus and pickerel frog eggs26

  31. Internal Fertilization Eggs and embryos protected within parent’s body – requires heavy parental investment Even mammals (Echidna) can lay eggs!30 Hippocampus breviceps mating31 Courtship rituals help ensure that sperm is added when eggs are ready29

  32. Still… sperm in the millions are needed 1. Sperm are short-lived (3 days for human sperm) 2. Sperm must still swim to the egg 3. Enzyme activity allows sperm to penetrate the egg nucleus – only one makes it in. When sperm meets egg, a zygote forms and development begins!32 Remember chapter 10…

  33. 12.7 The Human Female6

  34. The Menstrual Cycle Regulated by the nervous system, glands, organs and hormones Overall control by the hypothalamus (in brain) 1. Build-up: Day 1-14 – Start of menstrual cycle. Low estrogen & progesterone  hypothalamus secretes GnRH (gonadotrophin releasing hormone) GnRH  pituitary gland releases FSH (follicle stimulating hormone and LH (luteinizing hormone) FSH  Maturation of the egg in the ovary FSH + LH  Follicle releases estrogen Estrogen  Thickening of endometrium (uterine lining)

  35. 2. Ovulation: Around day 14 LH spike  Egg is released Follicle becomes the Corpus Luteum which produces estrogen and progesterone which continues thickening the endometrium 3. Decline – If fertilization does not occur Hypothalamus detects Progesterone and Estrogen Hypothalamus slows production of FSH and LH Corpus Luteum deteriorates, further lowering Progesterone and Estrogen Endometrium breaks down  Menstruation

  36. Ovarian hormones in blood Peak causes LH surge Control by hypothalamus Inhibited by combination of estrogen and progesterone 3 Hypothalamus Stimulated by high levels of estrogen GnRH 7 Estrogen Anterior pituitary Progesterone 6 (a) (d) Progesterone and estrogen promote thickening of endometrium 1 Low levels trigger menstruation Pituitary hormones in blood 4 Menstrual cycle Endometrium (b) (e) FSH stimulates follicle to grow 2 LH peak triggers ovulation Menstruation Ovarian cycle 5 See P. 334 Growing follicle Mature follicle Ovulation Corpus luteum Degenerating corpus luteum (c) Estrogen secreted by growing follicle Progesterone and estrogen secreted by remnant of follicle Figure 26.10a–c Figure 26.10

  37. Egg Development in the Ovary

  38. If Fertilization Occurs See P. 335 Gestation follows 1. Zygoteundergoes mitosis 2. Implantationin uterine lining Developing placenta produces HCG which maintains the corpus luteum High Progesterone/Estrogen from corpus luteum maintains endometrium until placenta produces enough of its own (~ 3 months) 3. Birth: oxytocin causes uterine contractions which expel the fetus and placenta. Oxytocin also stimulates milk secretion 4. After Birth:w/o the placenta, progesterone and estrogen drop Hypothalamus signals to increase GnRH Menstrual cycle begins again.

  39. The Onset of Pregnancy6

  40. The Male Reproductive Organs6 Scrotum: keeps sperm cool Seminiferous Tubules: sperm are produced by mitosis Epididymus: coiled tube for sperm storage Vas Deferens: sperm duct Prostate Gland and Seminal Vesicles: produce seminal fluid and fructose (food for sperm) Ejaculation: sperm and seminal fluid ejected out the urethra

  41. Sperm Production Sperm Production: GnRH  Pituitary produces FSH and LH LH  Cells between tubules secrete androgens (eg. Testosterone) FSH  Sperm production Seminiferous tubule 39

  42. 47

  43. Seminiferous tubule (cross section)38

  44. Testosterone33 Voice changes Facial Hair Height and muscle development Estrogen34 Breast development Onset of menstruation Fat deposits 12.9 Secondary Sex Characteristics

  45. Infertility Treatments Artificial insemination In vitro fertilization35 Contraception Barrier Methods Condom/Diaphragm Hormone Methods Spermicide Surgical Techniques 12.10 Infertility and Contraception 37 36

  46. Sources Cited 1. www.marksimmons.org/closeup/ microimg/pages/hydra2.htm 2. www.denniskunkel.com with permission 3. www.life.umd.edu/classroom/ bsci124/plants.html 4. http://www.goethe-net.de/botanik.htm 5. http://www.botgard.ucla.edu/html/botanytextbooks/generalbotany/typesofshoots/stolon/b0072tx.html 6. BioCD. From Biology, Fifth Edition. Campbell, Reece, Mitchell. Addison, Wesley, Longman. 1999. 7. http://www.utep.edu/museum/desertdiary/archive/reptiles/DDwhiptail.htm 8. http://www.humancloning.org/Cloning%20a%20Ewe.GIF 9. http://www.wtv-zone.com/coolmom/animals/friends/easter10.jpg 10. http://www.uca.edu/org/humane/kittens.jpg 11. www.hiddenforest.co.nz/bryophytes/ mosses/photos/intro09.htm 12. www.apopkafoliage.com/ Plants/Hibiscus.htm 13. http://www.micro.utexas.edu/courses/levin/bio304/genetics/celldiv.html 14. www.tode.demon.co.uk/ ibis/sample4.html 15. http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookflowers.html 16. www.urbanext.uiuc.edu/gpe/ case4/c4facts1b.html 17. ridge.icu.ac.jp/gen-ed/ higher-plants-etc.html 18. http://forestry.msu.edu/uptreeid/PICShardwoods/NMAP-seed.jpg 19. http://www.browncowfarm.com/Recipes_and_Poems/index.cfm?fuseaction=Detail&ID=25 20. www.aviewfromthefield.com/ fl010619.html

  47. Sources Cited, cont. 21. www.etaoin.com/mcc15.htm 22. www.foodsubs.com/ Fruittro.html 23. http://www.science.siu.edu/parasitic-plants/Viscaceae/images/Phor.tom.seed.JPEG 24. www.nd-seishin.ac.jp/ bio/yubi/imori.htm 25. dsc.discovery.com/fansites/onthecase/ humanbody/zoom_03.html 26. www.w-cpc.org/fetal1.html 27. www.state.tn.us/twra/ lifecyc.html 28. http://uri.sakura.ne.jp/~dd/cb/spawn3.htm 29. www.elkhornslough.org/ rookery/courtship.htm 30. http://abc.net.au/schoolstv/animals/ECHIDNAS.htm 31. w.pbs.org/wgbh/nova/ seahorse/roundup.html 32. http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/Medaka/stage_4a.html 33. www.america-tomorrow.com/ gmu/biochem/lipids.htm 34. eac01.hept.himeji-tech.ac.jp/ eac/ea/hormone.htm 35. home.earthlink.net/~snldittes/ wsn667A.html 36. www.pbs.org/wnet/closetohome/ policy/html/needle.html 37. http://www.co.cattaraugus.ny.us/doh/images/pills.jpg 38. http://www.udel.edu/Biology/Wags/wagart/coloredempage/coloredems.html 39. www.bio.davidson.edu/people/jeputnam/ companat/companat.html 40. http://www.uia.ac.be/u/bharding/Genetica/Hoofdstuk1/begrippen.html 41. www.microscopy-uk.org.uk/ mag/art98/volv.html 42. http://homepage.tinet.ie/~reddwarfstars/Sunspots.htm 43. www.dongettyphoto.com/ alaska/eaglenest.html 44. www.santarosa.edu/lifesciences/ crfrog9.htm 45. http://www.oznet.ksu.edu/dp_hfrr/extensn/problems/Pollination_Problems.htm 46. http://www.lovenotesfromgod.com/flower-cards/christmas-cards-cfz/squirrels-delight.htm 47. Bioshow: for Biology: Concepts and Connections, Second Edition. Campbell, Mitchell, and Reece

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