Week 7 lecture notes
Week 7 lecture notes BIO102
Popular in Biology 102
Popular in Biology
This 8 page Class Notes was uploaded by Danielle Kelly on Friday February 27, 2015. The Class Notes belongs to BIO102 at Washington State University taught by Dr. Strofer in Spring2015. Since its upload, it has received 38 views. For similar materials see Biology 102 in Biology at Washington State University.
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Date Created: 02/27/15
Biology 102 2123I 2125 and 2127 Cancer is caused by abnormal cell division 0 Cell division is part of a normal cellular process M 0 Most of the time cells are in interphase Steps of interphase are o 61 cell growth amp normal metabolism 0 S DNA replication amp chromosome duplication o 62 Growth amp preparation for mitosis S phase initiates division in chromosomes 0 S phase before mitosis DNA replicates amp into 2 sister chromatids connected by a centromere Chromosomes 0 DNA is tightly wound in chromosomes contained in cell nucleus 12 meters of DNA packed in cell size of 5 micrometers 0 Each species has different numbers amp shape of chromosomesl Karyotype 0 Most animals are diploid meaning that thy carry 2 copies of chromosomes 0 Pairs of chromosomes 1 from mom and 1 from dad are called homologous 0 Cells in human body except eggs amp sperm contain 46 chromosomes each 0 During S phase chromosomes double making 4 copies 0 Then G phase 0 Then 4 stages of mitosis 1 Prophase 2 Metaphase 3 Anaphase 4 Telophase Prophase First stage of mitosis Chromatin condenses amp becomes visible in nucleus Centrosomes move to opposite poles of cell Microtubules begin to grow out from centrosomes o Metaphase Chromosomes attach to spindle bers at centromeres Chromosomes line up in middle of cell 0 Anaphase Daughter chromosomes separate Pulled by spindle bers to opposite sides of cell 0 Telophase OOOOO Spindle bers dissolve New nuclei form Ring of actin laments forms around nuclei Cytokinesis breaks 2 quotDaughter cellsquot apart 393 Technically not part of mitosis Now that we know normal cell division process how does cancer occur 1 Single cell loses control of mitosis 2 Divides uncontrollany producing daughter cell with same problems a If contained at this stage tumor called benign 3 If these cancerous cells spread to other parts of body tumor is malignant Why don t we see cells dividing out of control all the time 0 Cell division is heavily regulated Genes that produce proteins involved in cell division called proto oncogenes Tumor suppressor genes prevent cells from dividing For cell to divide protooncogenes must be turned on and tumor suppressor genes off 0 Certain types of DNA damage cause cell to lose control of mitosis How a cell turns cancerous 1 Protooncogene become oncogenes which cause excessive cell division aWorks with single mutation 2 Damage to tumor suppressor genes a Both copies have to be damaged Cancer related to lifestyle Study 44000 pairs of twins o Most important contributor to cancer risks was environment including lifestyle and behavior oBehavioral changes can reduce risks of many types of cancer oCigarette smoking leading cause of cancer mortality in US oTobacco smoke has 40 known carcinogens 0 People who quit smoking before age 50 reduce risk of dying by 50 23515 Immunity and Vaccines Given that bacteria viruses and fungi are everywhere why aren t we always sick 0 Animals possess an immune system that protects the against most infections agents 0 3 lines of defense 0 External Defenses on the surface of the body are the rst line of defense in animals 0 Internal Defense system Innate immune system is the second line of defense Adaptive immune system third line of defense highly speci c with specialized defense cells 1ST line of defense skin and mucous Skin provides general protections Mucus traps microbes amp debris in respiratory tract Cilia lining walls sweep away mucus amp foreign matter Bypassing 1st line of defense easy for many pathogens 0 Many pathogens take advantage of breaks in the skin to gain entry to theirs hosts 0 Other pathogens are vectored by blood feeding hosts 0 Yet others are ingested by breathing 2nol line of defense innate immunity 1 Phagocytosis a Macrophages modi es white blood cells engulf amp digest microbes by phagocytosis 2 Cellular defenses a Natural killer cells iModi ed white blood cells iiDo not kill normal cells bc they recognize selfproteins in cell membrane iii Kill antigens by releasing poreforming proteins iv Dissolve cell membrane amp it leaks to death 3 In ammation aSymptoms iReddening increased blood ow iiSwelling leaky capillaries LHeat Increased metabolism and phagocytosis ivPain pressure or damage to nerve endings b Process iSkin is torn iiDamaged cells and mast cells release histamine LHistamine makes blood vessels leaky ivMacrophages squeeze through leaky vessels and engulf bacteria by phagocytosis vPateets help seal off wound clotting 4 Fever a Effective part of body s defense against infection b Most bacteria viruses adapted to 986 degrees for replication LRaising body temperature reduces replication rate of invaders d Bacteria need iron at higher temps growth reduced e Higher temperature increases white blood cell activity fFever induces production of interferon travels to uninfected cells amp increases resistance to virus attack 3rd line of defense adaptive immunity 0 The adaptive immune system has two types of response 0 1 Antibodymediated immunity uses B cells to make antibodies 0 2 Cellmeditated immunity uses T cells to destroy cells harboring pathogens Involves 3 steps 0 Immune system recognizes invader antigen 0 Immune system launches attack 0 Immune cells retain a memory of the invader 2 main players white blood cells 0 B cells Mature in bone marrow o Tcells Mature in thymus Step 1 Immune system recognizes antigen 0 Antigens are 0 Foreign molecule 0 Unique for each type of foreign invader 0 Unique shapes on cell surface 0 Different lymphocytes recognize a speci c antigen Receptors on this membrane 0 Step 2 o Nonspeci c defense attack 0 B cells and T cells become activated Bearing receptors speci c for antigen Results in clonal selection 0 Antibody production antibodymeditated immunity oz T cells that match antigen replicate cellmediated immunity 0 Step 3 Immune memory 0 B and T cells that bind to the speci c antigen have now have replicated Disproportionately represented among population of white blood cells B cells are producing antibodies Circulating in blood 0 Antibodymediated immunity Memory B cells produce antibodies speci c for antigen 393 Activate complement proteins make holes in plasma membranes oz Increase phagocytosis 393 Antibodies bind directly to antigens neutralizing toxins and proteins 0 Cell mediated immunity Memory Helper Tcells show antigens to other cells in immune system Memory Cytotoxic Tcells destroy bodies own cell that are infected damaged oz Bind to infected cells oz Release poreforming proteins and dissolve cell membrane Vaccines Vaccines work by simulating adaptive immunity by exposing people to an gens Two types of vaccine 0 quotLivequot a live virus or bacterium is used although attenuated Attenuated pathogens are usually missing key genes that make the host sick 0 Dead or antigen pathogen is not alive or perhaps just antigen is in vaccine Review types of immune cells Nonspeci c Macrophages White blood cells that engulf invading microbes amp alert other immune cells Neutrophils phagocytic white blood cells Natural killer cells WBCs that destroy infected cells Speci c B cells Lymphocytes that produce antibodies Plasma cells secrete antibodies into bloodstream Memory B cells provide future immunity T cells Lymphocytes that regulate response Cytotoxic T cells destroy speci c targeted cells Helper T cells stimulate immune responses 0 Memory T cells provide future immunity February 27 2015 quotThe Big Ideaquot 0 Several human factors are responsible for mergence and proliferation of emergent diseases Emerging infectious diseases 0 Emerging infectious diseases are new infectious disease with no previous history in humans 0 Examples HIV variant CJD SARS Ebola Infectious diseases 0 Pathogens are Things that infect you 0 Pathogens infect living things 0 Prior to 1944 in wars like the civil war world war 1 and world war 2 more people died from infections than from trauma 0 On march 11944 p zer opened the rst commercial plant for large scale production of penicillin submerged culture in Brooklyn New York Characteristics of emerging diseases 0 Relative risk of viruses highest 0 High mutation rates 0 Bacteria protozoa and fungi intermediate 0 Helminths lowest relative risk 0 Most emerging human pathogens gt75 are zoonotic passes from animals to humans 0 Twice as likely as nonzoonotic to be emerging 0 Most human pathogens 58 are zoonotic Drivers of Emergence Change in land use or agricultural practices Changes in human demographics and society Poor population health Hospitals and medical procedures Pathogen evolution Contamination of food sources of water supplies International travel Failure of public health programs International trade 10 Climate change Drivers changes in land use 0 Examples Nipah virus 0 Vectored by ying foxes o Deforestation led to bat foraging greater distances 0 Humans encroaching with pig farm 0 Virus has to mutate in pig to be infectious to human 0 Flying fox to pig to human 0 Examples SARS 0 20022003 8098 cases worldwide with 774 deaths MultiDrud Resistance Multidrug resistance has led to increasing incidence of disease with renewed virulence Drivers Tradespill over and spill back 0 Spillover 0 Domestic animals to wildlife Eg Canine distemper DPOFP P FWNE quotSpill backquot 0 Wildlife to domestic Brucellosis elk to cattle and back Drivers Climate Change 0 Climate warming can mean geographic range shifts of disease vectors 0 Eg Aedes mosquitoes carry dengue fever 0 Anopheles mosquitoes carry malaria Range increasing in subSaharan Africa Used to be in E US 0 Climate change also increases number of wet years 0 Eg increased humanrodent contact is SW 0 Increases in hantavirus outbreak Infectious Disease Conseduences 6th leading cause of specie s extinctions Other 5 Habitat loss Invasive species Pollution Overexploitation 0 Global climate change Diseaseextinction link 1 Environmental abiotic reservoir a Hosts still get infected at low species 2 Reservoir species biotic a A resistant species continually infects hosts 3 Frequencydependence a Hosts still transmit disease even at low densities b Eg STD s Extinctions due to disease 0 Stock island treesnail 0 Small population already Thylacine o Tasmanian tiger o Extinct 70 years ago 0 Small population already precipitous decline 19061910 points 0000 to disease Extinctions declines due to disease Cheetah 0 Low genetic variability o Increases disease susceptibility Eg FlPfeline infectious peritinosus FIV Elegrass limpet o Biotic reservoir 0 Elegrass declines from slime mold disease
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