UTA Microbiology Exam 3 QUESTIONS WITH ACCURATE VERIFIED ANSWERS GRADED A+ 2025

4 Basic Steps of binary fission - - 1. Growth of cell size 2. Replication of DNA 3. Division of cytoplasm 4. Septum formation & cell division Z Ring Assembly - -FtsZ assembles Z ring to form divisome Generation Time - -time it takes to double the population Lag Phase - -Cells adjust to culture medium; no change in population What factors determine the duration of the lag phase? - -Genetic makeup, media composition, initial inoculum size During which phase of the growth curve is it most appropriate for the use of antibiotics? - -Log phase Following the death phase of the growth curve, ____ cells are considered the surviving cells & are considered clinically important due to their association with chronic infections, such as Tuberculosis. - -Persisters Log Phase - -Binary fission occurs; cell replication cell death Stationary Phase - -Resources become depleted; cell respiration=cell death Death Phase - -Endospores can form; cell replication cell death Close System Cultures - -Have finite resources Open System Cultures - --Nutrients and air are replenished -Dead cells and waste are removed -Beneficial for industrial microbiology Microscopic Cell Count - -Cells are counted under a microscope using a laser etched slide MICROBIOLOGY MICROBIOLOGY In using the direct microscopic cell count method, you will be able to distinguish between live vs dead cells. - -False Fluorescence Staining - -Cells are counted under a microscope or flow cytometer In fluorescent staining, the end product results in live cells staining ___________? - Green In fluorescent staining, the end product results in dead cells staining ___________? - Red Coulter counting - -Detects electrical resistance change due to cell density Viable Cell Counts - -Samples are diluted and grown on solid media What type of cells are counted when using the viable plate count method? - -Living Countable Range - -30-300 CFU/ml Optical Density - --Measured with spectrophotometer -Light is passed thru culture and measured on other side Which method of measuring growth is considered an indirect approach? - -Optical density Which method of measuring growth can be used on living or dead cells? - -Fluorescent stain How is the pour plate technique set up? - -The sample is mixed with a warm agar ranging from 45-50 C, poured onto sterile plated and swirled to mix How is the spread plate technique set up? - -The sample is poured onto a solid medium and spread using a L spreader What cell counting method is used for counting colonies from drinking water? - Membrane filtration What method of measuring growth is used in food/water testing? - -MPN (most probable number) Steps of Biofilm Formation - -1. Attachment of planktonic cells 2. Cells become sessile 3. Growth & Division on substrate 4. Production of extracellular polymeric substance 5. Attachment of secondary colonizers & dispersion MICROBIOLOGY MICROBIOLOGY Quorum Sensing - -Cell to cell communication regarding cell density What is the term that refers to the small molecules that allow microbes to detect cell density in a biofilm? - -Autoinducers What is EPS composed of? - -Hydrated polysaccharide gel, other macros & channels How is EPS used in a biofilm? - -It is secreted by the organisms When using the optical density method, when the bacteria increases, turbidity________? - -Increases Which pattern of growth is often observed in actinomycetes and anaerobic, gram positive bacteria? - -Fragmentation Where is biofilm formation typically found? - -Liquid environments; rivers, pipelines, oral cavities When is MPN used? - -When counts are lower than 30 CFU/ml What two classes make up signaling molecules? - -1. N-actuated homoserine lactones 2. Various short peptides Where can the signaling molecule, N-acylated homoserine lactones, be found? - -Gram negative bacteria Where can signaling molecules, such as a variety of short peptides, be found? - -Gram positive bacteria What is considered a "good" type of biofilm found in the human body? - -Normal biota in the lungs What is considered a "bad" type of biofilm found in the human body? - -Plaque on teeth Obligate Aerobes - -must have oxygen to survive Obligate Anaerobes - -will die in the presence of oxygen Facultative Anaerobes - -Can live without oxygen, but prefer it Aerotolerant Anaerobes - -Tolerant of oxygen, but don't use it Microaerophiles - -require 1-10% oxygen levels to function What does FTM stand for? - -Fluid Thioglycollate Medium MICROBIOLOGY MICROBIOLOGY What does FTM test for? - -The oxygen requirement of a certain bacteria, with the use of agar tube How is aero tolerance of a bacteria determined? - -Growth location in test tube What bacterial species consists of obligate anaerobes? - -Bacteroides What bacterial species consists of obligate aerobes? - -Micrococcus luteus What bacterial species consists of facultative anaerobes? - -Staphylococcus What bacterial species is considered aero tolerant? - -Lactobacillus What species consists of microaerophiles? - -Campylobacter What are the main factors that affect growth? - -Oxygen level, pH, temperature, osmotic pressure, barometric pressure What macro is most affected by pH? - -Proteins What type of microbe is most adapted to a pH that is acidic? - -Fermenters Which groups of bacteria are considered neutrophiles? - -E.coli, staphylococci, salmonella Which groups of bacteria are considered acidophiles? - -Fermenting bacteria; proteins/phospholipids What group of bacteria is considered alkaliphiles? - -Vibrio cholera Neutrophiles - -Optimal pH around 7 Acidophiles - -Optimal pH 5.5 Alkaphiles - -Optimal pH is 8-10.5 What temperature do mesophiles require to grow? - -Prefer room temp. (20-40C) What temperature do Psychotrophs require for growth? - -Prefer cooler temp. (4-20C) What temperature do psychrophiles require for growth? - -permanently cold temps. (0C) What temperature do thermophiles require for growth? - -Prefer hot temp. (50-80C)