BIOL110s05-42 - BIOL 110 Principles of Biology Spring 2005...

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Unformatted text preview: BIOL 110: Principles of Biology Spring 2005 Lecture 42, F 5/13/05 • Quiz #7 (Last Quiz!): is up Today – (microbes, plants, animal Tissues & homeostasis). – • Midterm 3 (if <70%), Rewrite/Extra Credit due by Fri., 5/13. • WED. & MON. Field Trip: Edgewood Park (@ 280 & Edgewood Road) Edgewood – Grade for participation & Worksheet!!! (Replace 1 quiz!!!) – Bring: Good shoes/boots, light-colored clothing/pants, notepad & worksheet, lightbinoculars?, hat, sunblock, water, snack? – Next Mon.: Meet at Old Stage Camp entrance, 1:10pm. We leave up the Sylvan Sylvan Trail at 1:20pm. DON’T BE LATE!!! DON’ • Maps, info: • Next: 29 & 30, (31, 32). Meet Here!! 1 REVIEW: • Ch. 23: Immunity – Immunity – specificity & Memory! – B cells – humoral, antibody-antigen humoral, antibody• Extra-cellular pathogens Extra- – T cells – cell-mediated immunity cell• Intra-cellular pathogens Intra- TODAY: • Ch. 23: Immunity – T cells – cell-mediated immunity cell• Intra-cellular pathogens Intra- – Organ transplant rejection, AIDS • Ch. 29: Community Structure & Biodiversity – Community, Niche – Species interactions – symbiosis, competition…. competition… antigen on surface of bacterial cell variable region of heavy chain antigen-binding site hinge region (flexible) antigen-binding site binding site on one kind of antibody molecule for this specific antigen variable region of light chain constant region of light chain constant region of heavy chain antigen on surface of a virus particle binding site on a different antibody molecule for this specific antigen 2 Antibody- Mediated Response • “Naïve”/virgin B cell becomes antigen-presenting B cell • Helper T cell binds to antigen-MHC complex on the B cell • Interleukins stimulate B cell division and differentiation • Effector cells secrete Antibodies, which: 1. 2. 3. 4. Neutralize antigens, Agglutinate antigens, Enhance phagocytosis, phagocytosis, Activate complement Naive B cell Antigenpresenting B cell Helper T cell Interleukins Effector B cell secretes antibodies Memory B cell Click to view animation. animation 3 VII. Cell-Mediated Response • Carried out by T cells cells • Stimulated by antigenpresenting macrophages • Main target is antigenpresenting body cells (cells (cells with intracellular pathogens) or tumor cells Infected One macrophage Ingested Another macrophage interleukins Cytotoxic interleukins T cell Helper T cell Infected body cell Intracellular pathogens Intracellular pathogens Click to view animation. animation 4 Organ Rejection • Cytotoxic T cells can contribute to rejection of transplanted tissue • They recognize a portion of the donor cell’s MHC complex as self, view a portion as foreign • Treat the combination as an antigen-MHC complex and attack donor cells D. AIDS • Combination of disorders that follows infection with HIV HIV – Human Immunodeficiency Virus mmunod • Includes – Yeast (Candida) infections – Pneumocystis pneumonia – Karposi’s sarcoma 5 HIV Replication • = RNA retrovirus 1. A protein (gp120) at virus surface binds to host 1. cells with CD4 and chemokine receptors CD4 – These receptors occur on helper T cells helper 2. Once bound, RNA and viral enzymes enter the host cell 3. Viral RNA is reverse-transcribed to DNA reverse 4. HIV DNA is called provirus; it inserts into host DNA (integrates) 5. The host cell makes copies of viral DNA and viral proteins that assemble to form new virus particles lipid envelope (proteins span it, line its inner surface, spike out above it) strands of viral RNA (two) viral coat (proteins) viral genes are integrated into the host DNA viral RNA enters cell DNA is transcribed reverse a strand of viral RNA undergoes reverse transcription viral DNA viral RNA viral proteins budding integrase transcriptase STRUCTURE OF HIV host cell Fig. 35.21, p. 593 6 T Cell Decline 1. Release of new viral particles kills the host T cell new helper T cells! infect infect 2. The body is constantly making new T cells, but cannot outpace the rate of destruction 3. As infection proceeds, T cell numbers inevitably decline 4. EFFECTS of T cell Decline: 1. CD4 helper T cells play a vital role in immune function 2. They are required for both cell-mediated celland antibody-mediated immunity antibody3. Infected individual becomes vulnerable to other infections, which eventually result in death HIV-infected T-cell HIVT- Community Structure & Biodiversity Chapter 29 7 Forest of New Guinea • Community includes nine species of pigeons that partition the food supply – Each has its own niche: fruit it eats, branches it niche perches and nests in, etc….. etc… • Pigeons disperse seeds of the trees that provide their food (fruit) • These are just a few of the many interactions that shape this community A. Community • All the populations that live together in a habitat • Habitat is the type of place where individuals of a species typically live • Type of habitat shapes a community’s structure 8 Factors Shaping Community Structure 1. Climate and topography 2. Available foods and resources 3. Adaptations of species in community 4. Species interactions 5. Arrival and disappearance of species 6. Physical disturbances B. Niche Sum of activities and relationships in which a species engages • to secure and use resources necessary for survival and reproduction 9 I. Species Interactions 1. Most interactions are neutral; have no effect on neutral either species (0/0) (0/0) 2. Commensalism helps one species and has no effect on the other (+/0) (+/0) 3. Mutualism helps both species (+/+) (+/+) 4. Interspecific competition has a negative effect on both species (-/-) 5. Predation and parasitism both benefit one parasitism species at a cost to another (+/-) (+/ A. Symbiosis • Living together for at least some part of the life cycle • Commensalism, mutualism, and parasitism are forms of symbiosis 10 ** Mutualism • Both species benefit • Many examples in nature….. – Lichens – Mycorrhizae – Legume-rhizobium interaction – Yucca/Yucca Moth • Some mutualisms are obligatory; partners depend upon each other Yucca and Yucca Moth • Example of an obligatory obligatory mutualism mutualism • Each species of yucca is pollinated only by one species of moth – specialized mouth parts • Moth larvae can grow only in that one species of yucca 11 ...
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