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GBBE Final Exam questions with verified answers
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GBBE Final Exam questions with verified answers
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GBBE Final Exam questions withverified answers
Gram-positive bacteria - correct answer ✔✔Bacteria that have a thick peptidoglycan cell wall, and no
outer membrane. The cell wall contains teichoic acid (regulates the movement of positive ions). They
stain very darkly (purple) in Gram stain.
Gram-negative bacteria - correct answer ✔✔Bacteria that have complex cell walls with less
peptidoglycan but with lipopolysaccharides.
They stain very bright pink in Gram stain.
Safranin stain - correct answer ✔✔Added as the counter/secondary stain in a Gram Stain which color the
gram negative bacteria pink-red and have no effect on gram positive bacteria.
Endotoxin - correct answer ✔✔A toxic component of the outer membrane of certain gram-negative
bacteria that is released only when the bacteria die.
Exotoxin - correct answer ✔✔A toxic protein that is secreted by a prokaryote or other pathogen and that
produces specific symptoms, even if the pathogen is no longer present.
What is a mordant? - correct answer ✔✔a substance, typically an inorganic oxide, that combines with a
dye or stain and thereby fixes it in a material.
(for ex. iodine)
Purpose of iodine - correct answer ✔✔binds to primary stain and allows for substance to become
trapped in the cell wall
Three primary shapes of bacteria - correct answer ✔✔cocci, bacillus, spiral
Capsule - correct answer ✔✔Protects cell, makes it more virulent
, Pilus - correct answer ✔✔short hair-like structures on cell surface (help w/ adherence to structures and
movement)
peptidoglycan - correct answer ✔✔A protein-carbohydrate compound that makes the cell walls of
bacteria rigid (contains two monosaccharides- NAG and NAM
Plasma membrane - correct answer ✔✔A selectively-permeable phospholipid bilayer forming the
boundary of the cells
Primary chromosome - correct answer ✔✔circular DNA molecules in bacteria
Plasmid - correct answer ✔✔small, extrachromosomal DNA molecule within a cell that is physically
separated from chromosomal DNA
Fimbriae - correct answer ✔✔long filamentous polymeric protein structures located at the surface of
bacterial cells; enable the bacteria to bind to specific receptor structures/colonize surfaces
Slime layer - correct answer ✔✔a glycocalyx that is unorganized and loosely attached to the cell wall
Starch hydrolysis test - correct answer ✔✔iodine is added to agar.. if starch is present, forms a dark
brown color. Hydrolysis of starch will create a clear zone around the bacterial growth.
Motility test - correct answer ✔✔Non-motile- sharp and defined line, motile- swim away from stab line,
is not concentrated to line of inoculation
MacConkey test - correct answer ✔✔gram positive cannot grow, when it ferments lactose (becomes
acidic, red), when it doesn't ferment lactose (remains colorless)
Catalase test - correct answer ✔✔all bacteria that carry out aerobic respiration (create hydrogen
peroxide) are catalase-positive (bubbles are created)
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