Microbiology Midterm Exam Questions and Answers

Microbiology Midterm Exam Questions and Answers Define Micro- Less than 1mm and cannot see with the naked eye Need a microscope to see Microbes, microorganisms, germs, bugs What are the 5 groups of microorganisms studied? Bacteria--most famous Virus--2nd Fungus--3rd Protozoa--some but few Algae--not a human pathogen What generates 1/2 of the O2 that we breathe and would make life impossible without? Microbes What is the smallest simplest single-celled organism? Bacteria What is not a cell, can't live by itself and needs to invade a cell? Virus What are the two different classification of fungus? Molds and yeast--micro Mushrooms--Macro What is a mostly single-celled organism that is Animal like? Protozoa What are parasites? Different organisms that range from worms, insects and protozoa that need a host to survive What are the different applied microbiology fields of study Immunology Epidemiology--control spread of disease Food Micro--relationship between bacteria, food and drink Agriculture Micro--relationship between bacteria and crop Industrial Micro--microbes to produce vitamins, AA, Enzymes, etc. Eukaryotic cells are... more complete Prokaryotic cells are... all micro organisms and lack a nucleus Characteristics of microorganisms Small size Unicellular simplicity High Growth rate Adaptability microscope instrument used for enlargement of small objects simple microscope single lens and a few working parts. not strong compound microscope 2 magnifying lenses, a visible light sours, a condenser which collects light to direct toward the object magnification capacity of an optical system to enlarge small objects ocular lens one we look through. 10X objective lens 4 different, 4X, 10X, 40X, 100X What is resoltion? Capacity of optical systems to distinguish or separate 2 adjacent objects/points from each other. represents clarity of image Types of microscope? Light--visible light, bright field, dark field, phase contrast, diff interference Ultraviolet--florescence Electron--scanning, transmission what type of microscope do we use in the lab? bright field light microscope how does a microscope work? light source is on the bottom. The light travels from the lamp, hits the condenser lents which collects light and points it toward the object. the light passes through the objective lens and the real image of the object forms behind the ocular lens. the image we see is the virtual image after it asses through the ocular lens and is at the total magnification Highest magnification for all light microscopes? 2,000X and 200 nm resolution eubacteria the common bacteria of the 2 types. (-) WITH cell walls, (+) WITH cell walls, and no cell wall (mycoplasm) archebacteria less common type of bacteria. do not produce peptidoglycan and can live in extreme environments appendages attached to bacteria on one side, the other side is "free" motility appendages flagella and axial filaments flagella for motility and self propulsion. found mostly in gram negative bacteria. provide a smooth forward movement structure of flagella made of protein with 3 distinct parts: filament, hook, basal body (inside and has 4 rings and a rod that rotate) axial filament wrap around the cell and cause spiral like movements. has only two parts: a long thin microfibril inserted into a hook. attachment appendages fimbriae and pili fimbriae short appendages that allow bacteria to attach to bacteria pili long appendages are found in gram negative bacteria and are useful when mating cell envelope the bacterial surface (glycocalyx), the cell wall, cell membrane glycocalyx/bacterial surface this layer is a coating to protect the cell. two types slime layer type of glycocalyx that protects bacteria from loss of water and nutrients and loosely bound to the bacteria capsule thick, gummy consistency. It is tightly bound to the bacteria and is not easily washed off cell wall the layer beneath the glycocalyx and provides the cell with structure. It determines the shape of the bacterium from bursting or collapsing from changes in pressure. ESSENTIAL for bacterial survival peptidogylcan provides the protective quality of the cell wall. rigid. compose of long glycol chains. forms a meshwork. gram positive cell wall purple. thick sheet with peptidoglycan and tightly bound polysaccharides. has a lot of peptidoglycan which binds to the purple die gram negative cell wall pink. small amounts of peptidoglycan and there is a large space between the peptidoglycan and the outer membrane Gram Staining 1. crystal violet (both will turn purple. gram + will have more precipitin on cell wall bc more peptidoglycan) 2. grams iodine (not a stain. binding agent) 3. alcohol (washes color off gram -. too much is bound to gram + to wash off) 4. safranin (red/pink, gram negative will take up this stain) Why doesn't the outer membrane associated with gram negative bacteria prevent the alcohol from washing off the crystal violet? The outer layer is made of lipids, not glycoproteins. Alcohol can dissolve the lipids and wash the stain off of the peptidoglycan underneath cell membrane thin, flexible, has phospholipids and proteins. functions to extract energy, process nutrients. important site of metabolic activities and structural molecule synthesis protoplasm internal contents of the cell: dense, gelatinous cell pool in protoplasm, composed of water, sugar, amino acids, salts. Contains: chromatin body, plasmids, ribosomes, mesosomes, granules (membrane bound {organic compounds} and non membrane bound {store inorganic compounds}) Bacterial nucleus not surrounded by membrane, does not have mitotic apparatus, observable in stained cells Bacterial cytoplasm contains ribosomes, granules, no organelles Bacterial ribosomes bacteria has different proteins and rna that differ from eukaryotic cells, many antibiotics inhibit protein synthesis, membrane bound if engaged in protein synthesis Bacterial endospore dormant structure for withstanding hostile conditions, formed when conditions are unfavorable. When favorable conditions arise, endospore can germinate. not all bacteria can form spores spore forming bacteria in our lab? ?? coccus sphere shaped bacillus short: coccobacilli, long: spirilum, spirochetes arrangement cocci: single, paired, tetrad, cluster, chain. bacilli: single, paired, chain, palisade Differences between prokaryotes and eukaryotes both have cell walls, prokaryotic don't have cilia, both can have flagella, prokaryotes don't have organelles or cytoskeleton, they have different types of ribosomes, eukaryotes don't have peptidoglycans prokaryotic reproduction binary fission or budding binary fission when a cell divides into two. the chromosomes duplicate, cytoplasm splits into equal halves, each with one set of chromosomes. one cell becomes two. aka transverse fission budding small protuberance develops at one end of the cell. It enlarges and eventually develops into a new cell that separates from the parent cell bacterial growth in size, and in number. Bacterial growth is measured by how many there are in a population, not individual size population growth the basis of population growth is from binary fission generation time/doubling time time required for a complete fusion cycle from parent cell to 2 daughter cells generation doubling process when the population increases by a factor of two Pattern of bacterial growth 1. Lag Phase: cells increasing in size (5hrs) 2. Exponential growth phase: depends on proper growth conditions, curve increases, this phase continues as long as cells have adequate nutrients. dividing rapidly (5-16 hrs) 3. stationary phase: decline in growth rate, increase in death rate. less optimal conditions. numbers remain equal (16-33 hrs) 4. death phase: rapid death depending on resistance of species, nutrients deplete (33-45 hrs) Ways to measure bacterial growth spectrophotometer, viable colony count spectrophotometer way to measure bacterial growth. a machine that measures approximate color and cloudiness of water so we can estimate the number of bacteria in it viable colony count more detailed. involves making a serial dilution of the solution and you get the exact number of bacteria Bacterial metabolism cellular chemical changes resulting from all chemical reactions and the physical working of the cell. anabolism, catabolism anabolism synthesis of cells, molecules, or structures catabolism degrative reaction. breaking down large molecules into smaller molecules and producing energy enzyme facilitate reactions by lowering the energy of activation a) most cellular runs are catalyzed by enzymes b) enzymes are proteins that act specifically c)enzymes speed the rate of metabolic activity genetics study of the inheritance or heredity of living things genetic material long, encoded molecule of DNA with several orders of structure genome total of genetic materials in cell. varies from 4-5 genes to >100,000 genes chromosome cellular structure composed of a long neatly packaged piece of DNA gene organismic: unit of heredity responsible for a given trait cellular: site on chromosome that provides info for a certain cell function molecular: certain DNA segment that contains the necessary code to make a protein or RNA molecule DNA structure nucleic acid with 2 polynucleotide strands combined into a double helix. deoxyribose sugar phosphate attached to a nitrogenous base Nucleotide 3 parts: 1) one of 5 possible nitrogenous bases. PURINES: Adenine, Guanine PYRIMIDINES: Cytosine, Uracil, Thiamine (C-->G, A-->T) 2) one of 2 sugars: Ribose, Deoxyribose 3)phosphate group (1,2, or 3) Gene vs Code Gene: talking about the strands of DNA Code: talking about the info on the gene DNA replication (Eukaryotic) linear and the process involves: 1. Uncoil 2. DNA strands unzipped from each other 3. Biosynthesis of new strands 4. New strands are zipped and coiled semi-conservatice replication preserving the DNA code and passing it to daughter cells. Each daughter cell gets one strand of the parent DNA DNA replication (Prokaryotic) DNA in bacteria is round and begins at the bacterial replicon. double stranded. The strands separate from the origin of replication. It opens in both directions to fill in the complimentary bases from behind. Semi-conservative. How is DNA related to a specific characteristic? Genes make proteins to show a particular characteristic. If a DNA cannot make the protein, its defective and will not show the characteristic trait. DNA makes proteins by... DNA can be copied for a)make more DNA and b)to make proteins. Ribosomes make proteins from what's encoded by the DNA. this is where RNA comes in. RNA vs DNA 1. RNA's sugar (ribose) is more readily destroyed than DNA's sugar (deoxyribose) so that the body can destroy it when its purpose is served. 2. Adenine-->Uracil, Cytosine-->Guanine 3. DNA is double stranded, RNA is single stranded Types of RNA messenger RNA, ribosomal RNA, transfer RNA transcription information is transcribed from DNA to mRNA. mRNA carries the info to ribosomes. rRNA is in the ribosome. 1. DNA is unzipped by RNA polymerase 2. nitrogenous bases arrange a complimentary strand to one of the DNA strands 3. single stranded mRNA leaves the DNA and travels to the ribosome translation tRNA translates the info from nucleic acid language (AU, CG) to amino acid language. tRNA reads codes of info off the mRNA and also builds the chains of proteins out of amino acids 1. rRNA brings amino acids to the part of the ribosomes where proteins are made 2. AA's are stacked into a chain by tRNA based on mRNA 3. protein is formed, folded, released Gene regulation in bacteria controlled by the operon! OPERON: cluster of genes can control catabolism and anabolism Lactose operon (catabolism) ~controls catabolism of lactose 1. Regulator: has one gene. functions to make a protein that will repress the function of the operon 2. Control Locus (Promotor: GCTAGC, Operator:where transcription is initiated) 3. Structural Locus: 3 genes that code for enzymes needed to catabolize lactose FUNCTION: normally in the OFF mode and does not initiate the enzyme synthesis when lactose (the substrate) is not present. When lactose is present, the operon begins to function. The regulator makes repressor protein which represses the operon by blocking transcription by binding to the operator gene. Lactose binds to the repressor protein and removes it from the operator gene! SO, the operon begins functioning and transcription begins of the 3 proteins/enzymes that break down lactose. Without lactose bound to the repressor protein, it is free and can bind again so no more enzymes will be made Repressible operon Controls anabolism! The repressible operon is the bacterial system for amino acid, purine, and pyrimidine synthesis. Normally in the ON mode and will be turned off when only this nutrient is no longer needed STRUCTURE: structure is the same as the lactose operon. the repressible operon is on and the repressor protein is inactive. operator gene controls transcription for 3 genes which instruct proteins to be made--constantly being made. (i.e. proteins are needed to make arginine)