Review for final exam NOON
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Review for final exam NOON Review for final exam NOON Presentation Transcript

  • Review for final exam NOON 19 th of December
  • Gene Expression
    • Differentiated cells
    The Genetic Potential of Cells
      • All contain a complete set of DNA
      • May act like other cells if their pattern of gene expression is altered
    • Even though cells of an organism have the same genes (genotype):
    • Patterns of gene expression in specialized human cells
    Figure 11.3 Pancreas cell Eye lens cell (in embryo) Nerve cell Glycolysis enzyme genes Crystallin gene Insulin gene Hemoglobin gene Key: Active gene Inactive gene
  • Central Dogma of Molecular Biology
    • DNA holds the code
    • DNA makes RNA
    • RNA makes Protein
    • DNA to DNA is called REPLICATION
    • DNA to RNA is called TRANSCRIPTION
    • RNA to Protein is called TRANSLATION
  • Summary of protein synthesis
    • Proteins :
    • Chains of Amino Acids
    • Three nucleotide base pairs code for one amino acid.
    • Proteins are formed from RNA
    • The nucleotide code must be translated into an amino acid code.
  • RNA
    • Formed from 4 nucleotides, 5 carbon sugar, phosphate.
    • Uracil is used in RNA.
      • It replaces Thymine
    • The 5 carbon sugar has an extra oxygen.
    • RNA is single stranded .
  • Translation
    • Translation requires:
      • Amino acids
      • Transfer RNA: (tRNA) Appropriate to its time, transfers AAs to ribosomes. The AA’s join in cytoplasm to form proteins. 20 types. Loop structure
      • Ribosomal RNA: (rRNA) Joins with proteins made in cytoplasm to form the subunits of ribosomes. Linear molecule.
      • Messenger RNA: (mRNA) Carries genetic material from DNA to ribosomes in cytoplasm. Linear molecule .
  • Translation
    • Initiation—
      • mRNA binds to smaller of ribosome subunits, then, small subunit binds to big subunit.
      • AUG start codon--complex assembles
    • Elongation —
      • add AAs one at a time to form chain.
      • Incoming tRNA receives AA’s from outgoing tRNA. Ribosome moves to allow this to continue
    • Termintion — Stop codon--complex falls apart
    • Umbilical cord and placental blood is rich in stem cells
    • Stem cells can develop into a wide variety of different body cells
    liver heart brain blood bone Stem Cell
  • Figure 11.8 Cultured embryonic stem cells Different culture conditions Liver cells Nerve cells Heart muscle cells Different types of differentiated cells
    • The genetic code is the set of rules relating nucleotide sequence to amino acid sequence
    The Genetic Code Figure 10.11
  • Reproduction
  • Male Reproductive Structures
    • Testis --paired gonads within scrotum, sperm and steroids produced here.
    • Epididymis --tightly coiled duct where sperm maturation occurs.
    • Vas Deferens- -delivers sperm through abdomen to ejaculatory duct.
    • Urethra --duct through penis where sperm and urine exit
    • Semen --seminal fluid, contains sperm, fluid and ATP producing nutrients (sugars).
    • Prostate Gland- -adds fluid to semen.
    • Seminal Vesicles- -contribute nutrients to semen.
    • Bulbourethral gland- -contributes mucoid fluid to semen.
  • Penis
    • Penis--male organ required for intercourse. Composed of layers of connective tissue and skin surrounding the ducts and erectile tissue.
    • Erection is produced by the tissue filling with blood.
    • Ejaculation causes sperm to exit the urethra. The bladder is closed off at this time.
    • Each ejaculation releases approximately 400 million sperm.
  • Hormonal control of testes
    • Hypothalamus - secretes gonadotropin-releasing hormone (GnRH).
      • Stimulates the anterior pituitary to release
        • Follicle-stimulating hormone (FSH)
        • Promotes sperm production & release of Inhibin
        • Luteinizing hormone (LH)***
        • ***Sometimes called interstitial cell-stimulating hormone (ICSH). This stimulates the production of testosterone.
    • All these hormones are involved in negative feedback that maintains the fairly constant production of sperm and testosterone.
  • Female Reproductive System
    • Ovaries- -produce eggs and steroid hormones.
    • Oviducts - -conduct the egg to the uterus-- fertilization occurs here .
    • Uterus- -Womb, where we are developed.
    • Cervix- -Opening to Uterus.
    • Clitoris- -Female analog of the penis. This is also contains erectile and sensory tissue.
    • Vagina --site of sperm deposition, birth canal, exit for menstrual flow.
    • Vulva- -External folds of skin that protect the vagina.
  • Female Reproductive Cycles
    • Hormone levels in women cycle on a monthly basis.
    • This drives cycles required for reproduction.
    • Ovarian Cycle
    • 2) Uterine Cycle
  • Ovarian Cycle
    • Hormones drive the Ovarian Cycle.
    • The Ovarian Cycle drives the Uterine Cycle.
    • Ovarian Cycle: cycle of events required for oocyte development.
    • Ovarian Cycle: Follicle Maturation, Ovulation, Corpus Luteum Growth and Degeneration.
  • Egg Maturation
    • Primary Oocyte- -immature oocytes--200 million in a newborn girl! 400,000 at Puberty, 400 will mature to ovulation.
    • Secondary Oocyte- -mature oocyte--Egg
    • Primary Follicle- -holds oocyte and makes estrogen.
    • Secondary Follicle- -maturing follicle holds secondary oocyte and makes estrogen and progesterone .
    • Vesicular Follicle- -follicle that will release the egg.
    • Ovulation- -process of egg release.
    • Corpus Luteum- -gland-like structure that makes mostly progesterone and some estrogen.
  • Hormonal Control of Ovaries
    • Hypothalamus - secretes gonadotropin-releasing hormone (GnRH).
      • Stimulates the anterior pituitary to release
        • Follicle-stimulating hormone (FSH)
        • Luteinizing hormone (LH)
    • FSH Stimulates the follicle to produce estrogen .
    • LH Stimulates the corpus leuteum to produce progesterone .
    • Estrogen and Progesterone maintain uterus and help regulate the hypothalamus . negative feedback !!!!!!!!
  • s Ss Ovarian cycle Days 1-13- FSH secretion Day 14 – OVULATION LH SPIKE Days 15-28 – LH increases corpus luteum forms Progesterone high
  • s Uterine Cycle Days 1-5- Menstruation Day 6-13 – Endometrium rebuilds Days 15-28 – Endometrium thickens mucoid glands develop and secrete
  • Development
  • Fertilization
    • Egg must develop and be released on ovulation day.
    • Egg must be correctly positioned in the oviduct and attract sperm.
    • Vaginal tract must activate sperm.
    • Hormonal levels must be exact.
    • Ensure only one sperm joins with egg.
    • Sperm must undergo capacitation--process of activation by substances in female vaginal tract fluids.
    • Sperm motor from vagina up through cervix, uterus, to the oviduct.
    • Many sperm attempt fertilization, only one succeeds (except for twins).
  • Egg and Sperm
    • Egg--
      • Corona Radiata : Cells from follicle that nourished egg in ovary.
      • Zona Pellucida : layer that covers plasma membrane--will form fertilization envelope
      • Plasma Membrane: cell membrane around egg
      • Egg Nucleus: contains DNA
    • Sperm- -
      • Head: Contains sperm nucleus and acrosome.
      • Acrosome: Contains enzymes.
      • Mid Piece: Contains Mitochondria
      • Tail: Flagella made from Microtubules
  • REMEMBER!!!!!!!!!
    • If viable sperm contact an egg at the time of ovulation fertilization will occur.
    • This “typically” occurs on day 14. Remember Day 1 is first day of menstruation.
    • The fertilized egg will implant on day 6.
    • The new embryo will begin to produce HCG--Human Chorionic Gonadotripin .
    • HCG maintains the corpus luteum and allows the production of progesterone and estrogen until the placenta takes over this task.
  • Dev before Implantation
    • Fertilization
    • Cleavage: successive rounds of cell division. A one cell zygote--2 cell--4 cell--8 cell--.
    • Cleavage occurs in the oviduct.
    • Morula: 16 cell stage--enters the uterus.
    • Key cell differentiation step:
      • Trophoblast
      • Inner Cell Mass
  • Blastocyst
    • Hollow ball of cells.
    • Each cell is called a blastomere.
    • Inner cell mass--become the embryo.
    • Trophoblast--Incredible Altruistic Cells!
      • Escape from the Zona Pellucida
      • Digest through Endometrium
      • Initiate HCG secretion
      • Form the Placenta
  • Dev before Birth
    • Cleavage --process of cell division.
    • Morphogenesis --shaping the embryo.
    • Differentiation --how do different cells get their identity?
    • Growth- -increase in size--cell divisions continue and cells themselves grow.
  • Gastrulation
    • Truly the most important day of your life!
    • Process of forming 3 germ layers--this process requires cell movement.
    • Each germ layer forms specific tissues and organs
      • Ectoderm--(blue)-- will form skin and nervous system.
      • Mesoderm--(red)-- will form muscles, kidneys, connective tissue, and reproductive organs.
      • Endoderm--(yellow)-- will form digestive tract, lungs, liver and bladder.
  • Extraembryonic Membranes
    • Establishing extraembryonic membranes is critical. These membranes protect the embryo and link embryo to mother:
      • Amnion --provides fluid environment for fetus.
      • Chorion --becomes the placenta--site of gas and nutrient exchange with mother.
      • Allantois --becomes unbilical blood vessels
  • The Placenta
    • Nutrient and Gas Exchange between fetus and mother.
    • Fetal side--from chorion.
    • Maternal side--from uterine tissue
    • Blood of fetus and mother do not mix.
    • Fetal chorionic villi project into maternal blood.
    • Exchange occurs across membranes.
    • Umbilical cord stretches between placenta and fetus.
  • Parturition--Hormonal Control
    • Fetus -- Hypothalamus — Cortisol Releasing Hormone
    • Fetus-- Anterior pituitary -- ACTH
    • Fetus -- Adrenal Gland produces Cortisol and DHEAS .
    • Cortisol from fetus converted to prostaglandins in placenta--these begin contractions.
    • DHEAS from fetus converted to estriol in placenta--these promote oxytocin in mother.
    • Oxytocin (from Posterior pituitary ) in mother begins labor.
    • Cervical stretching--positive feedback.
  • Sex Determination
  • Embryonic Indifference
    • Both male and female embryos are indifferent.
    • That means they have the ability to be both male and female.
    • Wolfian--will form male genetalia.
    • Mullarian--will form female genitalia.
  • Sex Determination
    • How does this work? All embryos start on a neutral or "indifferent" path. The 4 week old embryo is indifferent
    • By 7 weeks, the SRY gene encoded by the short arm of the Y chromosome begins to roar.
    • Indifferent embryos have two sets of ducts:
    • Müllerian ducts- -will be come the future oviducts--thus female.
    • Wolfian ducts- -will become the future vas deferens--thus male.
  • Sex Determination
    • How does SRY determine which duct will develop? SRY causes testes to develop.
    • The Wolfian duct is dependent on testosterone for its continued development. It needs testosterone produced from the testes to grow.
    • The testes also produce an anti-Müllerian hormone that promotes regression of the Müllerian ducts.
    • So without SRY, the indifferent embryo will naturally develop into a female.
  • Sex Chromosomal Disorders
    • Turner Syndrome – XO only one sex chromosome
        • Short, thick neck and stature
        • Do not undergo puberty, or menstruate,
        • no breast development
    • Kleinfelter Syndrome – XXY
        • Testis and prostate underdeveloped
        • No facial hair
        • Brest development
        • Long arms and legs: big hands and feet
        • Can be mentally retarded
  • Two copies of DAX (double X) inactivate SRY, thus this individual would be genetically male, but look female.
  • An XY Individual with Androgen Insensitivity Syndrome Androgen Insensitivity Syndrome is a sex reversal condition where XY individuals look female. These individuals have the Y chromosome and functional SRY. These individuals have testis which generate AMH and testosterone. However, the genetic mutation results in a lack of the testosterone receptor. Estrogens are made in the adrenal gland which drive phenotypic development. As adults, these individuals have testes in the abdomen and lack a uterus and oviducts.