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Unit 5: Chapters 19, 20 & 21 Asexual and Sexual Reproduction Creating more organisms.

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Presentation on theme: "Unit 5: Chapters 19, 20 & 21 Asexual and Sexual Reproduction Creating more organisms."— Presentation transcript:

1 Unit 5: Chapters 19, 20 & 21 Asexual and Sexual Reproduction Creating more organisms

2 A. Asexual Reproduction 1. Mitosis and Cytokinesis 2. Forms of Asexual Reproduction a) Binary Fission - basically another name for mitosis - used by many one celled organisms

3 b) Budding - unequal division of cytoplasm - yeast and hydra c) Sporulation - making spores – like a seed but genetically identical to the parent - fungus, some bacteria

4 d) Regeneration - ability of an organism to regrow lost body parts - ability decreases as the organisms become more complex

5 e) Vegetative Propagation - asexual reproduction in plants 1) bulb 2) tuber 3) runner 4) rhizome 5) cutting 6) grafting

6 f) Cloning - exact genetic copy ADVANTAGES FOR ASEXUAL REPRODUCTION? Don’t need to find a mate Can quickly reproduce Works well if the organisms is really well adapted for the environment

7 B. Sexual Reproduction 1. Advantages for Sexual Reproduction - Variation  allows for adaptation to new environments - Evolution - Survival of the Species 2. Meiosis and Gamete Formation - Diploid  Haploid 2n  n 3. Fertilization - Restore chromosome number - n + n = 2n - formation of a zygote

8 4. Development - Development is the process by which the zygote becomes the organism - Zygote  Mitosis  Differentiation and Cell Specialization a) Embryo Development 1) Mitosis - cell division to make more cells

9 2) Cells grow between divisions - Cell layers = germ layers – become different parts of the organism Ectoderm – nervous, skin Mesoderm – bones, muscle, blood, repro Endoderm – lining of dig. & resp., liver, pancreas

10 5. Human Reproduction a) Male Reproductive System Testes – male gonads; make testosterone and sperm cells 100,000s of sperm produced Scrotum – sac that holds testes outside the body wall Sperm production and storage has to be at a lower temperature than the body

11 Epididymis – storage area for sperm Vas Deferens – tube that carries sperm from the testes to the urethra Urethra – tube through the penis in which sperm are ejaculated Semen = mixture of sperm ad fluids

12 b) Female Reproductive System Ovaries – female gonads, produce estrogen and egg cells Produces 1 egg cell per month Ovulation = release of the egg from the ovary

13 Fallopian Tubes / Oviducts – tube leading from the ovary to the uterus the Fallopian tubes are the normal site fertilization Uterus – thick muscular walled organ where implantation of the egg takes place the fertilized egg will grow and develop here Birth Canal = Vagina – site where sperm are deposited

14 c) Menstrual Cycle - hormone controlled process by which the egg develops and is released - the brain and ovary secrete 4 different hormones to control the cycle

15 1) Follicle Stage pituitary secretes follicle stimulating hormone (FSH)  causes the egg to develop in the ovary  also cause the ovary to produce estrogen  estrogen causes the uterine lining to thicken with tissue 2) Ovulation high levels of estrogen causes the pituitary to stop secreting FSH and to begin secreting luteinizing hormone LH  high levels of LH cause the ovary to release the egg (usually occurs in the middle of the cycle) 3) Corpus Luteum the release of the egg from the ovary causes the ovary to secrete progesterone (pregnancy hormone)  progesterone helps maintain the uterine lining 4) Menstruation only if the egg is not fertilized – secretions of LH and progesterone decrease and the uterine lining is shed from the body with the unfertilized egg

16 d) Human Development 1)Fertilization sperm deposited in the vagina and swim up the uterus to the Fallopian tubes One sperm fertilizes the egg in vitro fertilization Twins 2) Implantation as the fertilized egg travels down the Fallopian tubes it goes through cleavage upon reaching the uterus the egg fastens itself to the uterine lining and begins pregnancy ectopic pregnancy zygote  embryo  fetus

17 3) Differentiation – Cell Specialization - Growth A – Placenta site where mother and fetus exchange nutrients, wastes, O 2, CO 2 – blood does not cross between mother and fetus B – Umbilical Cord rope like tube that carries the nutrients and wastes to and from the fetus C – Uterus D – Amniotic Fluid surrounded by the chorion (membrane) helps protect the fetus and keep it stable

18 4) Fetal Nourishment Substances in the mother’s blood pass to the fetus Proper nutrition Avoid drugs and alcohol and Viruses 5) Birth gestation = length of pregnancy – 40 weeks (9 mon.) labor = muscular contractions of the uterus premature birth cesarian section 6) Growth  Puberty  Growth  Death


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