BIOL 1140 1st Edition Lecture 16Outline of Last LectureI. Accessory structures of dermisII. Multicellular organisms and homeostasisIII. Negative FeedbackIV. Cancer in the cell cycleV. Tumor suppressor genesVI. OncogenesVII. Normal cellsVIII. TumorsIX. Cancer cells lose controlX. Cancer can affect DNA repair systemsXI. BRCA1 and BRCA2XII. Cancer is heterogeneousXIII. SummaryXIV. AccomplishmentsOutline of Current LectureI. DevelopmentII. Sex Differences in MeiosisIII. FertilizationIV. One Sperm Fertilizes the eggV. TwinsVI. Development of the embryo: four stagesVII. Pre-embryonic Development: The First Two WeeksVIII. Pre-embryonic DevelopmentIX. Embryonic Development: Weeks three to eightX. Embryonic Development: Tissues and Organs Derive from three germ layersXI. Extra-embryonic MembranesXII. Placenta and Umbilical CordXIII. Gender Development Begins at six weeksXIV. Fetal Development: Nine weeks to birthXV. BirthXVI. Transition from fetus to newborn XVII. Birth to adulthood XVIII. Aging: Change over TimeXIX. Body systems age at different RatesXX. Death: final transition Current LectureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.I. Developmenta. Regulated expression of 20,000 genesb. Multiplication of cells from 1 to 50+ trillionc. Growth from 0.00001 meters to 2 metersd. Weight from a few micrograms to 100 kge. Turning a single cell into 220 cell typesII. Sex Differences in Meiosisa. Malesi. Four spermsii. All viable and functionalb. Femalei. Unequal cytokinesis during meiosis I and IIii. One egg and three polar bodiesiii. Only the egg is viable, polar bodies die III. Fertilizationa. Sperm and egg unite 6-24 hours after intercourseb. Fertilization occurs in the upper third of the oviductc. One sperm fertilizes one egg, forming a zygoted. Typical ejaculation: several hundred million spermse. Only a few hundred to a thousand sperms make it to the upper oviductf. Many barriers and challenges on the sperm's journeyi. Distanceii. Vaginal pHiii. Cervical mucusiv. White blood cellsIV. One Sperm Fertilizes the egga. Several hundred to thousand sperms reach the upper oviduct, but only one fertilizes the eggb. Fertilizationi. Acrosome - in head of spermii. Sperm penetrates corona radiate and zona pellucidiii. Sperm proteins lock with egg membrane receptorsc. Sperm actually penetrates the secondary oocyte, which then completes meiosis, forming haploid ovumd. Fertilization occurs when sperm nucleus fuses with ovum nucleus, forming diploid zygoteV. Twinsa. Fraternal (dizygotic) twinsi. Ovulation of more than one oocyte, each of which is fertilized by a different spermii. No more similar than 2 siblingsiii. May be different genderb. Identical (monozygotic) twinsi. One oocyte fertilizedii. Split before 16-cell stageiii. Same gender, look alikeVI. Development of the embryo: four stagesa. Cleavagei. Series of cell divisions without cell growthii. Produces a ball of identical cellsiii. Up to about day four after fertilizationiv. Occurs entirely within the oviductb. Morphogenesis i. Changes in shape and formii. Physical development of organismiii. Ongoingiv. At implantation, growth in sizec. Differentiationi. Individual cell take on specialized forms and functionsd. Growthi. Begins significantly at implantationii. Single cell at fertilization to > trillion cells at birthiii. Growth in sizeVII. Pre-embryonic Development: The First Two Weeksa. Concepts travels through oviductb. Growth, differentiation, and morphogenesis begini. Modula (ball of 32 identical cells)ii. Blastocyst (hollow ball)iii. Implantation occurs as the blastocyst burrows into endometrium day 6 or 7 post fertilizationiv. Embryonic disk developsVIII. Pre-embryonic Developmenta. Ectopic pregnancy i. Occurs when blastocyst implants in an oviduct prior to reaching the uterusii. Oviduct is not large enough to support the development of a full-term babyiii. Ectopic pregnancies are often terminate to protect the health of the motheriv. VERY rarely can an extra-uterine pregnancy be carried to termIX. Embryonic Development: Weeks three to eighta. Rapid growth, differentiation, morphogenesisb. All organs, organ systems established by end of embryonic periodc. Embryonic development: beginning of week 3 until end of week 8X. Embryonic Development: Tissues and Organs Derive from three germ layersa. Ectoderm: outermost layer i. Becomes epidermis, nervous system, hair, nails, tooth enamel, parts of eyeb. Mesoderm: middle layeri. Becomes muscle, connective tissue, bone, kidneys, ureters, testes, ovariesc. Endoderm: innermost layeri. Becomes liver, pancreas, alveoli, bladder lining, lining of urethra, vaginaXI. Extra-embryonic Membranesa. Develop early in embryonic developmentb. Amnioni. Lines amniotic cavity, filled with amniotic fluidii. Cushions the fetusc. Allantoisi. Temporary, helps form blood vessels of umbilical cordd. Yolk saci. Source of assorted cells for umbilical cord developmente. Chorioni. Makes human chorionic gonadotropin, which supports pregnancy for the first three monthsii. Forms structures that will become part of placentaXII. Placenta and Umbilical Corda. Developmenti. Chorion digests intro endometrium, creating pool of bloodii. Placenta seals off the pool and project chorionic villi into maternal bloodiii. Villi contain blood capillaries connected through the umbilical vessels to the fetusb. Umbilical Cord: two-way life line, connects placenta to embryo's circulationc. Placenta Functionsi. Filters nutrients, waste, and antibodies for the fetus without mixing mother and fetal circulationsii. Site of nutrient and gas exchange between embryo and mother iii. Some toxins or viruses may pass through1. Alcohol, cocaine, HIViv. Endocrine1. Produces estrogen and progesteroneXIII. Gender Development Begins at six weeksa. Y chromosome gene for sex-determining region Y activatedb. Testes-determining factor synthesized from SRY genec. Testes secrete testosteroned. Testosterone stimulates development of male genitaliaXIV. Fetal Development: Nine weeks to birtha. Eight weeks: marks the transition from embryonic to fetal developmentb. Months three and fouri. Organ developmentii. Beginnings of organ function1. Kidneys, liver, spleeniii. Cartilaginous skeleton replaced with boneiv. Bone marrow begins producing red blood cellsv. Face developsvi. Rapid growth c. Months five and sixi. Fetal movement beginsii. Fetal heartbeat