Quiz 2 Flashcards
What are bacterial endospores? How do they contribute to the survivability of sporulating
bacteria?
- Bacterial Endospores are structures that are formed inside certain types of bacteria. Structures are formed as a defense mechanism against harsh environments
-They contribute to survivability through extreme resistance such as heat resistance, chemical resistance, radiation resistance, and also longevity
How can we visualize endospores? Do normal gram staining practices work for this?
- We visualize endospores by using a wet-mount preparation and brightfield light microscope
- Normal gram staining practices don’t work because the thick layers of the endospore prevent dyes from penetrating. Some dyes penetrate such as primary stain (crystal Violet), while others don’t.
What is motility? How can you visualize it? What species are motile and how does
this impact growth?
- Motility is the movement caused by the action of the flagella.
- Tannic Acid makes the flagella appear larger to be seen under the microscope
- E.Coli, Salmonella, Proteus Mirabilis are motile
- Motility affects growth by aiding in colonization and moving towards nutrient-rich environments which also helps growth
What types of motility are there ?
- Positive Chemotaxis - a movement towards a favorable environments
- Negative Chemotaxis - Motility away from a less favorable environment or harmful
How are anaerobic conditions created and maintained?
-Anaerobic Conditions are created through specialized chambers with controlled atmospheres with low oxygen levels. An example is the class anaerobic conditions.
- Sealing techniques are one way to maintain anaerobic conditions. Also incubation in anaerobic chambers. This has a controlled environment and temperature
What type of microorganisms would thrive in an activated Anaerobe jar?
An activated anaerobe jar creates an environment without oxygen. Microorganisms that can grow in an environment without oxygen
What are the various definitions of aerobes/anaerobes?
- Aerobes - Microorganisms that grow only in the presence of oxygen
- Anaerobes - Microorganisms that are capable of growing only in the absence of oxygen
- Facultative/Facultative anaerobes - Microorganisms that can grow with or without the presence of oxygen
What is selective media? What is differential media? How do they differ?
- Selective Media - Inhibits growth of unwanted organisms and grows wanted microorganisms
- Differential Media - Designed to distinguish one type of microorganisms from another in a mixed culture.
- Selective media allows the growth of specific microorganisms while differential media is used to distinguish one organism from another.
What kinds of media fall in this category? What ingredients give them these
properties?
- High Salt Agar - Selective ; Contains all-purpose media ingredients plus salt
- Mannitol Salt Agar - Selective and Differential; Contains high salt ( Selective) and Mannitol (Differential)
What do growth patterns/ responses on the media tell you about the physiology of the
bacteria?
Yellow Petri Dish - Growth and Mannitol
Pink Petri Dish - Growth and no Mannitol
Red Petri Dish - No growth and Mannitol not applicable
How and why does temp effect growth?
Temperature affects how much bacterial growth there is. Temperature affects microbial growth by influencing the activity of enzymes within the cell, which in turn affects the cell’s metabolism and growth rate
What makes some species more or less heat/cold tolerant?
Cell wall/ Membrane and certain proteins makes species more or less heat/cold tolerant
What happens to proteins/enzymes at different ranges of growth curves?
- Increased temperature gradually enhances the activity of many enzymes in a cell
- Temperatures above the maximum will result in cell death
- Temperatures below the minimum slow or stop growth
What are halophiles? What are saccharophiles?
- Halophiles - Salt-loving bacteria ; Require higher salt concentrations to function at their optimal levels
- Saccharophiles - Sugar-loving bacteria ; organisms that like like a higher sugar content in their surrounding
How can various concentrations of solutes ultimately lead to bactericidal and
bacteriostatic outcomes?
- Bactericidal effect (Causes cell to die)
- High concentrations can lead to osmotic shock, plasmolysis and cell membrane damage; Internally there could be protein denaturation and enzyme inhibition
- Bacteriostatic Effects (Static state causing reproduction to stop)
- Osmotic stress and growth inhibition
