MICRO STUDY GUIDE EXAM 1
MICRO STUDY GUIDE EXAM 1 Microbiology 210
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This 14 page Study Guide was uploaded by Katharyn Taylor on Wednesday February 3, 2016. The Study Guide belongs to Microbiology 210 at University of Tennessee - Knoxville taught by Elizabeth McPherson in Summer 2015. Since its upload, it has received 315 views. For similar materials see Microbiology in Biology at University of Tennessee - Knoxville.
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Date Created: 02/03/16
MICROBIOLOGY STUDY GUIDE – EXAM 1 CHAPTER 1 • WHAT ARE MICROORGANISMS? o Organisms too small to see with the naked eye that can live as clusters or as individual cells • WHAT DO MICROBES DO ON EARTH? o First living inhabitants. They are ubiquitous which means they can be found almost everywhere, and they live in places that no other organisms can o Anoxgenic and Oxygenic Photosynthesis, changed the atmosphere and produces energy as the base trophic level o Vital to nutrient recycling, breaking down dead things that can be reused by other organisms • HOW HAVE HUMANS USED AND CHANGED MICROBES? o Old examples -‐ yeast, cheese, moldy bread on wounds. People knew certain things worked but were unaware of the microbiology behind the practices o Now -‐ genetic engineering, (recombinant DNA) bioremediation (microbes introduced to restore stability to an ecosystem) • HOW MUCH HUMAN DISEASES IS CAUSED BY MICROBES? o Most microbes that we come into contact with do not make us sick. Only about 2000 pathogenic microbes o Still most common cause of death is infectious disease o Vaccines and antibiotics help control pathogens, but microbes can evolve to be drug resistant • BACTERIA & ARCHAEA o Prokaryotes (no membrane bound nucleus and some membranous organelles) and very small o Live in moist habitats (almost everywhere) and few are disease causing when colonized in humans • EUKARYOTIC MICROBES o Fungi – can be single cell or filamentous. Cell wall made of chitin. Break down organic matter for food. Two types of microbe fungi § Molds – multicellular, hyphae, sexual and asexual § Yeasts – unicellular, asexual (budding) or sexual spores o Protozoa – single celled with at least one nucleus. No cell wall. Live in water or in animal host. Locomotive through pseudopodia, cilia, or flagella o Algae – unicellular or multicellular. Photosynthetic. The unicellular ones make most of the world’s oxygen. Live in water. Simple reproductive structures, and are categorized by color and cell wall makeup. No medical importance • OTHER THINGS MICROBIOLOGISTS STUDY o Parasitic worms – eukaryotes, adults are macroscopic but microbiologists study microscopic eggs and immature ones that infect animal hosts o Viruses – no eukaryotic or prokaryotic classification, not technically alive. Must have host and are much simpler than cells • WHO STUDIED SPONTANEOUS GENERATION? o This is the idea that there are three types of ‘reproduction’ including asexual, sexual, and generation from nonliving matter, also referred to as abiogenesis (compared to biogenesis). This third one was Aristotle’s idea 2 o Redi performed an experiment where he kept meat away from flies and in exposure to flies and determined that no organisms besides microbes can arise spontaneously o Needham experimented when scientist believed that microbes were the only things that could arise spontaneously. He boiled beef gravy and plant material and sealed a container and it became cloudy, which he took to mean that microbes could, in fact, generate spontaneously o Spallanzani repeated Needham’s experiment but found that no microbes survived and concluded that Needham’s were contaminated and spontaneous generation was impossible. Critics said microbes needed air to live o Pasteur proved Spallanzani’s theory and silenced critics • IS THIS CONCEPT ACCURATE? o No. This concept is not accurate. Any microbes that developed in the liquids came from microbes in the air, and had no microbes been present in the vial, none would have developed. Microbes cannot generate spontaneously • SCIENTIFIC METHOD o Developed after the spontaneous generation debates. Four steps: 1. Ask a question, 2. Think of a potential answer, 3. Design and carry out an experiment, 4. Accept, reject, or modify answer o Control groups are important to have something to compare your tested variable to 3 • KOCH’S POSTULATES o Studied the cause of anthrax, and proved that Bacillus anthracis cause the disease. Developed isolation techniques for studying microbe colonies o His identification criteria were: 1. Microbe must be present in all cases of the disease, 2. The pathogen can be taken from the host and and grown in a culture, 3. The cultured pathogen can cause the same disease in a lab animal, 4. The pathogen can be taken from a new host and be the same as the original pathogen from the first host • BINOMIAL NAMES o Named based on description, the scientist who discovered it, the place where it was found, or the organization that funded its research with a Greek ending o Genus species CHAPTER 3 • FOUR MAJOR PROCESSES OF LIVING CELLS o Growth, Responsiveness to environment, Reproduction, Metabolism, and maintaining a structure that carries out all four of these functions • GLYCOCALYCES: COMPOSITION, FUNCTION, RELEVANCE o All bacterial cells have some form of a glycocalyx, which is essentially just a surface coating made of polysaccharides, peptides, or a combination of the two o They play a role in osmotic control: preventing the cell from drying out or taking in too much water • CAPSULES VS SLIME LAYERS o Bacteria have one of these, never both 4 o Capsule – organized, repeated chemicals. They are anchored to the cell surface, and they are useful for camouflage in the host. They can be made of chemicals like the ones found in humans, and thus the immune system may not always recognize these bacterial cells as foreign and white blood cells won’t attach o Slime layer – loosely covering, easily washed away with water. It is sticky and lets bacteria form biofilms • BACTERIAL FLAGELLA o Push bacteria toward a stimulus by spinning counterclockwise through a “run” or turn away from stimuli by spinning clockwise in a “tumble.” These movements due to stimuli are called taxis (phototaxis or chemotaxis depending on the stimulus) o Three pieces: filament (shaft made of flagellin and not covered by a membrane), hook (holds the base of the filament), and basal body (anchor to the cell wall and plasma membrane) o Four rings of integral proteins in the basal body indicates Gram-‐, while two rings of these proteins indicates Gram+ o Cells can have multiple flagella • FIMBRIAE, PILI, & FLAGELLA o Fimbriae – sticky bristles. Help bacteria stick to each other or two something in the environment. They are grappling hooks that can also help with communication through electrical signals within a biofilm o Pili – special kind of longer fimbriae. Can transfer DNA between cells (called conjugation). Like a bridge from one cell to another • GRAM+ & GRAM-‐ BACTERIA: STRUCTURE & STAINING o Cell walls provide structure and shape. Since animal cells don’t have cell walls, we can use medicines that target cell wall components to get rid of bacterial infections without harming our own cells 5 o All bacterial cell walls have a peptidoglycan layer made of alternating NAG and NAM sugars (peptidoglycan should always and only be associated with bacteria) o Gram positive – thicker layer of peptidoglycan, and therefore thicker cell wall. Teichoic acids are imbedded in the membrane. These are linked to lipid anchors on the plasma membrane. Acidic outer shell (all acid-‐fast bacteria are gram+, it helps them resist drying) o Gram negative – more complex despite having a thinner wall and less peptidoglycan. They have a more disorganized membrane that goes outside the peptidoglycan cell wall . Their outer membrane is made of two layers: the inner layer a ty pical phospholipid & protein combo, and the outer layer a lipopolysaccharide (LPS) barrier. This LPS contains endotoxin (lipid A). Channels in this outer membrane are called porins Gram-‐ also have perplasmic space between the plasma membrane and this complicated outer membrane. o Gram staining can differentiate between the two types of bacterial cell walls. Acidic gram+ holds onto the crystal violet dye and gram-‐ holds onto the red • GRAM-‐ CELL WALL: A CLINICAL LOOK o Because Gram negative cell walls have endotoxin (lipid A) in their outer layer of the outer membrane, they are more difficult to treat. If an antibacterial drug kills a gram negative bacteria inside the body, the endotoxin will be released and can be potentially lethal in certain quantities when it causes fever, vasodilation inflammation, shock, and blood clotting 6 • FLUID MOSAIC MODEL o This describes membrane structure as we understand it currently. The components of the membrane are arranged in a certain fitted together ‘mosaic’ pattern, and they are attached, but have a certain fluidity to this attachment to their neighbors. They can slide past each other without changing the makeup, but the integral proteins have certain other proteins they need to be near, so the parts of the membrane with specific proteins move as a block in order for them to still work as they should • CYTOPLASMIC MEMBRANE FUNCTIONS: PERMEABILITY o Membranes have to semi-‐permeable (allow at least some things in) because living things need to take in nutrients to use and expel waste to make room for things they use o About half of the membrane is made up of proteins. These proteins do different things. They can be receptors, recognition proteins, enzymes, carriers, or channels. Some kinds go all the way through the membrane (integral), while others are embedded in only half (peripheral) • ACROSS THE MEMBRANE: PASSIVE & ACTIVE o Passive transport processes – high to low concentration, no energy expended to move particles § Diffusion – movement directly across the membrane without a channel protein § Specific facilitated diffusion – movement through a channel that only allows a certain kind of molecule through the channel § Nonspecific facilitated diffusion – movement through a channel that allows whatever will fit to pass through § Osmosis – water movement across the membrane with or without a channel protein 7 o Active transport processes – low to high concentration, requires the use of energy to move particles § Uniport – movement of one type of molecule, one at a time against the gradient § Antiport – a trade of two molecules on opposite sides of the membrane, both against their respective gradients § Symport – coupling of a uniport with a specific facilitated diffusion. A molecule is pumped across against its gradient, and then it picks something up. It then crosses back through a specific channel protein that only lets those molecules that have ‘picked up’ what the cell wants it to through the membrane § Group translocation – the molecule passing through the channel against the gradient is altered in some way. Usually the molecule is changed into something that cannot pass back across the membrane, so it is stuck inside of the cell after passing through the membrane. It only occurs in some bacteria, and this is the first step of some bacteria’s metabolic action 8 • ISOTONIC, HYPERTONIC, & HYPOTONIC o It is important to use these terms relatively in order for them to make sense. A solution is (insert one of the three terms here) to the cell because of their relative concentrations of solute o Isotonic – equilibrium. The concentrations of solute are about the same inside and outside of the cell o Hypertonic – the environment is hypertonic to the cell when it has a higher concentration, or more solute, than the cell . In this scenario, water will flow out of the cell, and the potential danger is that the cell could dehydrate, shrivel up, and die o Hypotonic – the environment is hypotonic to the cell when it has a lower concentration, or less solute, than the cell . In this case water will flow into the cell to attempt to even out the concentrations, and the cell may burst o The bacterial cell wall is rigid and protects against these osmotic forces, however if there is any weak spot in the cell wall, osmotic forces can cause the cell to collapse • BACTERIAL CYTOPLASM o Cytosol – liquid of the cytoplasm. Many substances like ions, carbs, proteins, lipid, and wastes are dissolved into it. Nucleoid region of the cytosol has the DNA. Plasmids (small ‘optional’ sections of independent DNA that help the cell with resistance) also float around in this stuff o Inclusions – storage deposits of something the cell is saving to use. This could be gases, lipids, starch, nitrogen, phosphate, sulfur, magnetite, etc. 9 o Ribosomes – nonmembranous organelle that synthesizes proteins for the cell. o Cytoskeleton – some bacteria have this. It is an internal scaffolding made of protein fibers. Can serve both a structural and a transportational purpose o Endospores – only some bacteria produce these. They are NOT reproduction, but a survival mechanism. Basically a way for the cell’s DNA to stay dormant and protected until the environment becomes favorable for the cell to live again • RIBOSOMES: PROKARYOTES VS EUKARYOTES o Bacteria have 70S ribosomes with a 30S and a 50S subunit. Drugs that target these subunits are useful antibacterials because our ribosomes are 80S with 40S and 60S subunits o However, drugs that target bacterial ribosomes can still impact our cells because we have mitochondrial ribosomes that are analogous to bacterial ones. This means that antibacterials that target 70S ribosomes can inhibit the ribosomal activity of our mitochondria and therefor shut down our cells’ powerhouses • EUKARYOTIC GLYCOCALYCES: COMPOSITION, STRUCTURE, & FUNCTION o In eukaryotes these are only found in animals and protozoa (kingdoms without cell walls) o Comparable to a slime layer in that they are disorganized and sticky. They help cells stick to each other and they strengthen the cell surface. They serve as a recognition mechanism and they protect against dehydration • CELL WALLS & MEMBRANES: PROKARYOTES VS EUKARYO TES o Fungi, algae, plants, and some protozoa have cell walls but they do not have a glycocalyx o It helps protect the cell, gives it shape, and deals with osmotic pressure. These cell walls do NOT have peptidoglycan 10 o Similarities between the membranes include the fluid mosaic structure and the types of proteins in the membrane. Differences include the inclusion of steroid lipids and sugar signaling molecules in eukaryotes o Eukaryotes are capable of endocytosis (and therefore phagocytosis, pinocytosis, and exocytosis) • CYTOPLASM: PROKARYOTES VS EUKARYOTES o Prokaryotes have the same kinds of nonmembranous organelles, but they lack some membranous organelles in the cytoplasm o The cytoplasmic makeup is virtually the same, except eukaryotes don’t have plasmids o Eukaryotes have the smooth and rough endoplasmic reticulum • FLAGELLA: PROKARYOTES VS EUKARYOTES o Eukaryotic flagella have cytoplasm inside. They are an extension of the membrane, as opposed to the prokaryotic flagella which is embedded in the membrane. This means that the eukaryotic flagella undulates instead of rotating • EUKARYOTIC MEMBRANOUS ORGANELLES o Nucleus, endoplasmic reticulum, Golgi body, lysosomes, peroxisomes, vacuoles, vesicles, mitochondria, and chloroplasts • ENDOSYMBIOTIC THEORY o Widely accepted, but not universally o Eukaryotes came about when a large anaerobic prokaryote took in and formed a symbiotic relationship with a parasitic, aerobic prokaryote. When the cells divided, the parasites would divide as well and would be found in both daughter cells. The larger cell became dependent on the small cell for energy, and the small cell needed the big cell for resources and protection. This explains mitochondrial and chloroplastal similarity to bacteria 11 CHAPTER 5 • METABOLISM, ANABOLISM, & CATABOLISM o Metabolism – obtaining energy and nutrients necessary for survival by breaking things down and using the pieces and the energy derived to build things the cell needs o Catabolism – breaks down larger compounds into smaller ones and makes the precursor metabolites, reducing power, and ATP necessary for anabolism o Anabolism – builds small molecules into larger ones using precursor metabolites, reducing power, and ATP. This is the production of new cell structures after acquiring and organizing nutrients and energy • OXIDATION VS REDUCTION o These are the opposite reactions used to create power for oxidative phosphorylation, which generates ATP o Oxidation – losing electrons. The molecule donating the electrons is oxidized and is known as the reducing agent o Reduction – gaining electrons. The molecule receiving the electrons is reduced because its charge gets more negative, and it is known as the oxidizing agent • ATP PRODUCTION: 3 METHODS o Substrate level phosphorylation – phosphate is transferred from another organic compound (happens during glycolysis) o Oxidative phosphorylation – redox reactions power attachment of inorganic phosphate to ATP (electron transport chain within the membrane) o Photophosphorylation – we don’t talk about anything besides the name of it in this chapter 12 • CELLULAR RESPIRATION VS FERMENTATION o Cellular respiration –the complete breakdown of carbohydrates as a source of carbon, nutrition, and energy o Fermentation – does not completely break down the glucose, but its still provides some ATP and reducing power, just not as efficiently and not as much • METABOLISM STEPS o Membrane transport – the use of diffusion or integral proteins and all types of transport to obtain the substances necessary for the following processes o Catabolism – reactions that break down the substrate into precursor metabolites, reducing power, and ATP o Biosynthesis – monomers constructed and organized. Powered primarily by NADPH o Polymerization – monomers from pervious step make polymers. This requires lots of ATP o Assembly – polymers are turned into cell structures • PRECURSOR METABOLITES, REDUCING POWER, & ATP o Precursor metabolites – 11 molecules used as the bricks to build cell structures o Reducing power – reserves of protons (H+) that gives the cell the ability to perform redox reactions to generate energy molecules o ATP – molecule that stores lots of energy • PROTON GRADIENT IN OXIDATIVE PHOSPHORYLATION o This is known as chemiosmosis: using a gradient to form ATP. In this process, H+ ions are actively pumped out of the cell to create a gradient. When the ions flow back in passively, they power an ATPase that generates more ATP 13 • FINAL ELECTRON ACCEPTORS o Aerobic respiration – oxygen accepts electron and water is formed as a byproduct o Anaerobic respiration – another atom, like nitrogen for an example, accepts electron. It has to be a particular acceptor depending upon the enzyme the cell is equipped with • WHY FERMENTATION? o An organism may use fermentation as a backup when there is not an appropriate electron acceptor available o Some cells lack a transport chain 14
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