Biology 106 11/11 and 11/13
Biology 106 11/11 and 11/13 Biology 106- Organismal Biology
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This 6 page Class Notes was uploaded by JustAnotherStudent on Friday November 13, 2015. The Class Notes belongs to Biology 106- Organismal Biology at Washington State University taught by Dr. Cousins & Dr. Carloye in Fall 2015. Since its upload, it has received 12 views. For similar materials see Biology 106 in Biology at Washington State University.
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Date Created: 11/13/15
Biology 106 November 9, 2015 Animal Reproduction Another Example of Negative Feedback via antagonistic hormones: Regulation of Calcium Thyroid gland releases calcitonin Calcitonin Reduces Ca+2 uptake in kidneys (so more ends up in urine) OR Stimulates Ca+2 deposition in bones Blood Ca+2 level declines to set point Homeostasis Blood Ca+2 (about 10mg/100ml) Either Rising blood Ca+3 level And Falling blood Ca+2 level Parathyroid gland PTH stimulates Ca2+ release from bones And Stimulates Ca2+ uptake in kidneys- keeps it in blood Active intake vitamin D increase Ca+2 uptake in intestines bringing more into blood Blood Ca2+ level rises to set point Asexual Reproduction Budding: Branching off of parent Regeneration: generating missing parts from body fragmentation (starfish) Parthenogenesis: production of offspring from unfertilized egg - Some results in haploid individuals (male honeybees) - Some duplicate the chromosomes to make the egg diploid Advantageous in a stable environment - Genetic combination is successful Sexual Reproduction Gametes from two individuals fuse - Male cell = sperm - Female cell = egg or ovum Gametes = special cells with just 1 full set (n) of chromosomes Fusion of gametes restores full set of paired chromosomes (2n) External Fertilization - Requires moist environment for sperm to swim to egg - Typically produces LOTS of gametes to ensure that SOME will succeed - Don’t put much energy into each gamete (low investment) - Need wat to synchronize gamete release (timing) Creates a “soup” of cells Mechanisms’ to ensure that sperm and eggs of same species get together - Chemical cues - Physical “lock and key” between proteins on surface of each Internal Fertilization Moist internal environment Sperm swim to egg in special reproductive organs - Increases fertilization success Typically produce FEWER gametes Give more energy per gamete – increases chances of survival Making Sperm - Seminiferous tubule - Leydig cells - Sertoli cell - Spermatogonium - Spermatocyte Anatomy of a Sperm - Acrosome - Nucleus - Centrioles - Mitochondria - Head - Sidepiece - Flagellum Hormonal Control of Reproduction: Sperm Formation Making Eggs (ova) - Ova develop in ovary - Surrounded by smaller cells o Together = follicle November 13, 2015 Remember there is an exam on Friday after break. Hypothalamus secrets GnRH Pituitary gland releases FSH (Follicle Stimulating Hormone) follicle in one of the ovaries starts to mature and release Estrogen (estradiol) pituitary gland, reduces output of FSH estrogen peak stimulates LH burst pituitary gland releases LH burst (luteinizing hormone) target tissue in the ovary, the follicle release the ovum, ovulation empty follicle w/out egg (Corpus luteum), progesterone & some estrogen target tissue is in the brain stop hormones, buys time to see if fertilization happens Structure of an ovum (egg) External fertilization Inner: cell membrane surrounds ovum Mid: Vitelline envelope Outer: Jelly coat Internal fertilization Inner: cell membrane Mid: zona pellucida Outer: cumulus (follicle cells around egg) Animal development Basic steps 1. Fertilization (only step with two separate players) 2. Cleavage 3. Gastrulation 4. Neurulation & Organogenesis Step 1: Fertilization Both sperm and ovum have a response to the encounter Sperm: Acrosomal reaction Ovum: cortical reaction Acrosomal Reaction 1. Contact triggers release of enzymes- digests jelly coat 2. Proteins on sperm head bind ovum membrane proteins 3. Sperm cell & ovum cell fuse causing changes inside the ovum 4. Sperm head breaks from tail and enters ovum cytoplasm At this point the ovum must block other sperm from initializing fertiliation