lab exam 4 Flashcards
Why is it important to complete morphological and cultural characterizations before pursuing physiological testing
To help with preliminary classification and help one decide which tests are appropriate for further identification, rather than run every test available
In regard to taxonomic classification of bacteria, what is the relationship between physiological and genetic differentiation of bacteria
Genes are recipes for making cellular proteins, including enzymes. Species with similar enzymatic capabilities will likely have similar genetic makeup
What is the function of bacterial exoenzymes?
Extracellular degradation of substances so that the simpler compounds can be taken into the cell as nutrient or energy sources
Anabolism vs catabolism
Anabolism- energy driven synthesis of complex molecules from smaller ones
Catabolism- energy releasing degradation of complex molecules into smaller ones
Fermentation vs respiration
F- metabolism of sugars in the absence of oxygen
R- metabolism process that does utilize oxygen
Why is the catalase test useful for the differentiation of staph from strep
Staph = catalase postitive strep = catalse negative
How are acids or alkalines typically detected in culture medium?
pH indicators - colored dyes that change color in response to pH changes
Name two tests for reactions that produce acid end products
sugar fermentation and fat hydrolysis
Name two tests for reactions that produce alkaline end products
urea hydrolysis, citrate utilization and proteolysis
What types of gases can be produced as a results of sugar fermentation
carbon dioxide gas and hydrogen gas
How are the gases detected in fermentation rxns
in durham tube as trapped air bubble
name a non fermentative test in which gas production indicates a positive test result
catalase test yields oxygen gas as positive
which test is used to differentiate between fermentative and oxidative metabolism
o/f glucose test
The etiologic agent of acne – which hydrolysis test
+ triglyceride bc it feeds on oil clogged glands
the etiologic agent of gastric ulcers
+ urea, ammonia wil neutralize harmful stomach acid and allow bacterium to survive hostile enviornment
