Lab Final Review - Week #8 Flashcards
What role does food play in infectious disease transmission?
It is an inanimate vector by which a disease can be transmitted
Why is food such an optimum place for microorganisms to grow?
Because it provides lots of organic nutrients
What are 5 sources of contamination that involve food?
- soil and water
- food utensils
- enteric microorganisms of humansEHy and animals
- food handlers
- animal hides and feeds
Why are extracellular enzymes so important to microorganisms?
Because large essential nutrients like lipids, polysaccharides, and proteins are incapable of crossing the cell membrane and need to be hydrolyzed extracellularly in order to get into the cell.
What is a starch molecule composed of?
glucose molecules linked together by glycosidic bonds.
What is starch hydrolyzed into and how?
amylase breaks it down into dextrins and then into maltose molecules, than maltase breaks them down into glucose molecules.
What is starch agar made of? What is it used for?
It is made up of nutrient agar supplemented with starch, it is used to detect hydrolytic acitivity of exoenzymes
How does a starch agar test work?
A line of the test microorganism is inoculated onto the agar and following incubation, iodine is placed onto the agar. A clear zone will indicate starch hydrolysis.
What are lipids broken down into and how?
They are broken down into triglycerides via lipases, then they are further broken down into glycerol and fatty acids
How is lipid hydrolysis detected?
By inoculating the test organism onto tributyrin agar, following incubation a clear zone indicates lypolysis
How is protein hydrolysis detected?
A clear zone following incubation of the test organism inoculated onto nutrient agar supplemented with milk that contains the protein casein, indicates proteolysis
What is gelatin?
A protein produced by hydrolysis
How is gelatinase detected?
A broth tube with gelatin is inoculated, following incubation if the broth is liquid even after refrigeration than gelatinase is present
Why is identifying hydrolysis so important clinically?
Because most known pathogens have been characterized by their ability to digest proteins, lipids, and starch
Hydrolysis of lipids produces what?
glycerol and fatty acids
