Exam 2 Study Guide Animal Viruses More varied replication cycle than bacteriophages Adsorption Capsid or envelope attach to cell surface receptors Use spikes to attach to host cell Penetration Nucleic acid is released 3 different methods 1 Endocytosis Engulfing a particle virus o Enveloped and non enveloped viruses 2 Membrane fusion Absorbs virus into host cell o Enveloped viruses only 3 Translocation Direct penetration o Only few groups of viruses use this Synthesis and Maturation assembly Varied depending on type of nucleic acid Release o Lysis o Exocytosis budding only for enveloped virus bud off host cell membrane Budding or exocytosis is the release stage in enveloped virus Types of Animal Viruses Persistent Animal Viruses Cause long lasting infection could be last years or the life span of animal Viruses remain inactive inside host cells Little to no host cell damage No synthesis maturation or release Can become active again and begin to replicate Chronic Infection long lasting virus is always detectable o Ex Hepatitis B HIV AIDS Latent Infection long lasting virus is undetectable No symptoms and no antibody production Shows up in blood when infected with virus o Ex Herpes viruses simplex zoster Epstein Barr o Simplex oral herpes lasts for years life span o Zoster Chicken pox shingles latency in spinal cord Chicken pox then reactivated to shingles Oncogenic Viruses Viruses that cause cancer Viral nucleic acid moves into the host genome chromosomes and damages the normal growth patterns of host cells which leads to cancer neoplasia new growth o Examples Burkitt s Lymphoma Epstein Barr Virus Some leukemias retroviruses Human papillomavirus cervical cancer Prions Infection particles made from only proteins that cause disease Infectious protein particles PrP cause infection of CNS neurological Pathogens of animals Cause chronic persistent infections Examples o Scrapie sheep o BSE mad cow cattle o Creutzfelt Jacob disease humans o Kuru humans caused by contaminated nervous tissue from cannibalism Viroids Infectious RNA particles No proteins present Pathogens of plant cells Spread through ingestion of infected animal tissue Microbial Nutrition and Growth Major Bioelements The bulk elements found in highest amounts in the body CHNOPS Carbon Hydrogen Nitrogen Oxygen Phosphorus Sulfur Carbon in largest amount Minor Bioelements Calcium Sodium Potassium Chlorine Iron Both major and minor bioelements make up 98 99 of elements in body Micronutrients The trace minerals that make up 1 2 of the elements in the body Metals that helps with chemical reactions Magnesium Zinc Copper ect Organic Biomolocules contain lots of carbon Found in humans animals microbes Sources are proteins carbs lipids and nucleic acids Most are macromolecules that were made from smaller inorganic or organic growth factors vitamins Organic molecules or vitamins cannot be made in the body and must be taken into the cell from outside sources Microbes take in nutrients by transporting small inorganic and organic molecules salts simple sugars amino acids and carbon dioxide across the cell membrane Most bacteria fungi and protozoa use this transport system Although macromolecules are useful they are too large to fit through cell wall and membrane which leads to extracellular digestion Extracellular Digestion Carried out by bacteria fungi and protozoa They secrete enzymes to break down carbs or proteins into smaller pieces Carbs break down into monosaccharides Proteins break down into amino acids Phagocytosis Certain types of protozoa wrap membrane around particle and bring it into the cell Carbon Based Nutritional Types Based on how organisms get their carbon and energy Heterotroph Must obtain carbon from organic form Nutritionally dependent on other life forms Chemoheterotrophs Organic chemical compound that extracts energy from organic molecules Ex Most common o Most bacteria o All protozoa o All fungi o All animals o Humans Types of chemoheterotrophs Predators ingests living organisms some protozoa few bacteria fungi Saprobes Feeds off dead or decaying organisms most fungi bacteria some protozoa Commensals No harm to host bacteria protozoa fungi Parasites pathogens harms host bacteria fungi protozoa viruses Photoheterotrophs Light energy source from organic molecules Ex Purple and green non sulfur Autotroph Organism that uses inorganic CO2 as its carbon source Not nutritionally dependent on other organisms Photoautotrophs Energy from light carbon from inorganic CO2 Ex Plants and microbes o Cyanobacteria o Green sulfur o Purple sulfur o Algae Chemoautotroph Gets energy by extracting energy from inorganic compounds or chemicals Ex Minerals in soil iron sulfur hydrogen nitrifying bacteria o Archeaobacteria found in soil Bacterial Growth Open System Unlimited nutrients no build up of wastes Best system for fastest growth Closed System Runs out of nutrients and space accumulation of wastes Method of reproduction Binary fission Asexual reproduction splits into 2 Growth in an open system Doubling or exponential growth When the cells are in the perfect environment they go through binary fission Doubling Time Time required for the population to double in size in hours generation time Shorter generation time quicker production Most bacteria 1 hour generation time Growth in a closed system follows a normal growth curve counting number if cells over time 1 Lag Phase Slow growth adjustment 2 Exponential Doubling growth most active time 3 Stationary Nutrients start to run out of space growth rate decreases flat lines dying cells is to produced cells 4 Death Phase No more nutrients no more space more cells die than those that are being produced Methods of Enumeration Standard Plate Count viable Counting growth colonies of growth medium or petri plate Direct Count Microscopy Tedious to count all individual cells Turbidity Cloudiness in liquids estimates the number of cells The more cloudy the liquid the more cells in sample Flow Cytometry Counts individual cells with cytometer Factors Influencing Growth Nutrient limitation Waste accumulation Physical space Physical forces temperature o Enzymes effects rates of catalysis o Catalysis Enzymes critical for making reaction begin or speed up o Higher temperature leads to higher metabolism o Too high of temperatures will eventually degrade proteins o Cold temperatures tend not to be as harmful as very hot and destroy enzymes temperatures Membrane Fluidity Affects stability of cell membrane