Transcript Chapter 19
Chapter 19 Bacteria and Viruses Remember homeostasis? • Maintaining proper internal conditions • pH, temp., water/salt balance, O2, CO2, etc. Factors for Disease • 1. genetics- inheritance • 2. microorganisms – pathogen: disease-causing agent • 3. pollutants/poisons (ex: asbestos, lead) • 4. organ malfunction • 5. harmful lifestyles (tobacco, alcohol, lack of nutrition or exercise) 19-1 Bacteria • Prokaryotes • Monera • Can be beneficial or disease-causing – Good: intestinal bacteria – Bad: strep throat, pneumonia • Everywhere! Identified by: • Shape- bacilli (rod), cocci (round), spirilla (spiral) • Cell walls- Gram +/- (peptidoglycan) • Movement- flagella, slime • Metabolic diversity- heterotrophs and autotrophs (chemo- or photo-) Bacteria Energy Production • Respiration or fermentation (with or without O2) • Obligate aerobes: needs O2 to live • Obligate anaerobes: cannot live with O2 • Facultative anaerobes: can live with or without O2 Bacteria Reproduction • Binary fission: (asexual) DNA is replicated and the organism splits in half • Conjugation: (sexual) genetic info is exchanged across a “bridge” • Spore formation: haploid cell that can withstand hard conditions and form a new organisms when the time is right Importance of Bacteria • Decomposers- break things down • Nitrogen fixation- cycles N thru atmosphere • Human uses: food, oil spills, medicine, intestines Treating Bacteria • Bacteria have homeostasis too! Change the conditions to stop growth – Temp, salt, pH, etc. • Sterilization (heat), disinfection (chemicals) • Antibiotics- kill bacteria or stop reproduction 19-2 Viruses • Categorized by what they infect: – Plant, animal, bacteriophage • Capsid- protein coat- signifies which host to infect (host must have a receptor) • NOT alive- has genetic material but can’t repro on own • Ex: flu virus, HIV Virus Replication • Lytic: enters host cell, copies itself continuously and bursts (lyses) • Lysogenic: combines/replicates viral DNA with host DNA – Prophage: viral DNA embedded within host DNA Treating Viruses • Antibiotics WILL NOT work! • Prevention is key! • Vaccination: inject a weak form of a virus in order to get the antibodies (immunity) The Body’s Defense System • homeostasis= includes regulating microbes • Lines of defense: • 1. physical barriers- block entry (skin) • 2. inflammation- increased blood flow • 3. immune system Immune System • Recognizes the “bad guys” • Every bacteria/virus has antigens (proteins) • Immune system makes antibodies • Antibodies fight the antigens • Vaccines- shows antigens ahead of time- allows body to create antibodies (immunity) White Blood Cells (WBCs) • Immune system MVP • 2 types: • 1. B cells: make antibodies – Memory B cells • 2. T cells: – Killer T cells: kill infected cells – Helper T cells*: help all other WBCs When the immune system goes wrong… • Allergic reactions- increase in system- produces histamines • Autoimmune diseases- system attacks self • Immunodeficiency- decrease in system- helper T cells destroyed (ex: AIDS) • inflammation- older people Viroids and Prions • Viroids: single stranded RNA molecules enter infected cells • Prions: tiny protein particles enter the brain and affect the nervous system- no DNA/RNA – Ex: mad cow disease Chapter 20 Protists 20-1 The Kingdom Protista • What is a protist? – Anything that is not a plant, animal, fungus or prokaryote • First eukaryotes • Most unicellular • Classified by how they obtain nutrients 20-2 Animallike Protists (Protozoans) • Heterotrophs • Categorized by how they move: – Flagella – pseudopodia: temporary projection of cytoplasm • food vacuole – cilium: short hair-like projections – parasitic- don’t move on own Animallike Protists and Disease • Malaria (mosquitoes) – Treatments/vaccines only partially effective • African sleeping sickness (tsetse fly) – Unconsciousness can be fatal 20-3 Plantlike Protists (Unicellular Algae) • Chlorophyll and accessory pigments • Ex: diatoms and dinoflagellates (glowing water!) 20-4 Plantlike Protists (Red, Brown and Green Algae) • Red algae- good at harvesting light E- can live at great depths • Brown algae- brown pigment • Green algae- VERY plantlike Human uses of algae • “grasses” of the sea- base of food chain • O2 production • Medicine- vitamin C and iron • Food- sushi wraps, ice cream/pudding thickener • Industry- plastics, agar 20-5 Funguslike Protists • Recycle organic matter • Different cell walls than true fungi • Slime molds • Water molds- potato famine Ecology of Protists • Base of food chain (ex: phytoplankton) • Symbiotic relationships (ex: termites) • Blooms (ex: red tide) • Recycle organic matter (ex: slime molds) Chapter 21 Fungi 21-1 What is a fungus? • Eukaryotic heterotrophs with cell walls (chitin) • Digest food externally then absorb it • Can be parasitic Fungi Structure • Hyphae: microfilaments that combine to form mycelium • Increase surface area to absorb food • Fruiting body: reproductive structure – “mushroom” Fungi Reproduction • Asexual: cells/hyphae break off • Sexual: mating types “+” and “-” • Spores: easily spread 21-2 Classification • Based on structure and reproduction • Common molds (bread mold) • Sac fungi (yeasts) • Club fungi • Imperfect fungi (unknown repro. cycle) 21-3 Fungi Ecology • Saprobes- obtain nutrients from decaying organisms • Decomposers- recycle nutrients back into earth Ecological Relationships • Parasites- affect crops (wheat rust) and humans (athletes foot, ringworm) • Symbionts (symbiosis) - work together with other organisms – Lichens- photosynthetic organisms + fungus – Mycorrhizae- roots + fungus