Microbiology 351 Exam 1 Flashcards - Set 11

_____ _____ (____) is a measure of how much water is available for use.

Water activity is typically measured as the ratio of the solution's _____ _____ relative to that of pure water.

Most bacteria require water activity levels > _____.

Fungi can tolerate water activity levels > ____

_____ is a measure of the number of solute molecules in a solution and is ______ related a_w

______ are membrane-channel proteins that allow water to traverse the membrane much faster than by diffusion.
- Helps protect the cell form osomtic stress

In hypertonic media, bacteria protect their internal water by synthesiszing or importing _____ _____ (e.g. proline or K+)

In hypotonic media, pressure-sensitive or _______ channels can be used to leak solutes out of the cell.

______ require really high salt concentrations.
- From __ to __ M NaCl (10-20% NaCl)
- For comparison, seawater is ~____% NaCl

To achieve a low internal concentration of Na+, halophilic microbes use special ____ ____ to excrete sodium and replace it with other cations, such as ____.

Aerobic repsiration uses oxygen as a terminal electron acceptor (TEA) in the ____ ____ ____.

Oxygen is toxic to all cells that do not have enzymes capable of efficiently destroying the _____ ____ _____ (ROS) - for example, anaerobes.

Three oxygen-removing techniques are used today:
1. Special ______ ____ (thioglycolate) or ____ systems (Oxyrase) can be added to ordinary liquid media.
2. An ______ jar
  - O2 is removed by a reaction catalyzed by _______
3. An anaerobic ______ with glove ports
  - O2 is removed by vacuum and replaced with ____ and _____

Starvation is a stress that can elicit a "______ response" in many microbes.
- ______ are produced to increase the efficiency of nutrient gathering and to protect cell macromolecules from damage.

The "starvation response" is usually triggered by the accumulation of small _____ _____ such as cAMP or guanosine tetraphosphate, which globally transform gene expression.

True/False: Small signal molecules such as cAMP and guanosine tetraphosphate are not soluble and cannot diffuse throughout the cell.
True False

Natural ecosystems are typically low in nutrients (_______). Maximum diversity is maintained in part, by the different nutrient-gathering profiles of ______ microbes.

______ is the sudden infusion of large quantities of a formerly limiting nutrient.
- it can lead to a "bloom" of microbes, which can threaten the existence of competing species.

Name the antimicrobial control measure:
- killing of all living organisms

Name the antimicrobial control measure:
- killing or removal of pathogens from inanimate objects

Name the antimicrobial control measure:
- killing or removal of pathogens from the surface of living tissues

Name the antimicrobial control measure:
- reducing the microbial population to safe levels

High temperature kills microbes.
- _____ heat is more effective than ____ heat
- _____ water (____°C) kills most cells
- Killing _____ and ____ usually requires a combination of high pressure and temperature.
- Steam autoclave: ____°C at ___ psi for ___ minutes

Pasterurization kills microbes. Many different time and temperature combinations can be used.
- LTLT (low temperature/long time): ____°C for ___ minutes
- HTST (high temperature/short time): ____°C for ___ seconds

Cold/Low temperatures slow growth and preserve microbe strains.
- Refrigeration temperature (___-___°C) are used for food preservation
- For long-term storage of cultures:
  - placing solutions in glycerol at _____°C
  - Lyophilization or ____-______

Micropore filters with pore sizes of ____ μm can remove microbial cells, but not viruses, from solutions.

Samples from ___ mL to several ____ can be drawn through a membrane filter by vacuum or can be forced through it using a syringe.

Laminar flow biological safety cabinets force air through HEPA filters, which remove > ____% of airborne particulate material ____ μm in size or larger.

Irradiation kills microbes.
- Ultraviolet light has ____ penetrating power and is used only for ______ sterilization
- Gamma rays, electron beams, and X-rays have ____ penetrating power are are used to irradiate ____ and other heat-sensitive items.

Deinococcus radiodurans has the greatest ability to survive radiation of any known organism. It has exceptional capabilities for _____ ____ damaged by radiation. It was genetically engineered for use in _______.

The ______ coefficient test compares the effectiveness of disinfectants.

Commericial disinfectants and antiseptics include ethanol, iodine, chlorine, ethylene oxide, which damage _____, _____ and/or ____.

Bacteria have developed resistance to disinfectants via several mechanisms:
- Altering the _____ ____ synthesis protein normally targeted by triclosan
- Producing membrane-spanning, multidrug ____ pumps
- Forming multispecies _____, which offer collaborative protection

______ are chemical compounds synthesized by one microbe that kill or inhibit the gorwth of other microbial species.

______ mimics part of the bacterial cell wall which prevents the cell wall formation and is bactericidal.

Antibiotics can target:
- ______ synthesis
- DNA _______
- Cell ______

______ is the use of one microbe to control the growth of another.

_______ contain certain microbes that, when ingested, aim to restore balance to intestinal flora
- Lactobacillus and Bifidobacterium

_____ therapy aims to treat infectious diseases with a virus targeted to the pathogen
- A possible alternative to antibiotics in the face of rising antibiotic resistance

_______ require high salt concentrations.

Name 5 physical agents used to control microbes.

Chemical agents used to control microbes include _____ and _____.

True/False: Antibiotics selectively control microbial growth.
True False

Biological control of microbes include ____ and _____.

Cells treated with antimicrobials die at a ______ rate.

Which of the following statements about microbes and temperature is FALSE?
A) within a specific range, the microbial growth rate roughly doubles for every 10°C rise in temperature
B) thermophiles are microbes that grow at temperatures between 40-80°C
C) changes in temperature affect membrane fluidity, and thus nutrient transport
D) microbes have mechanisms to control their temperature

Which of the following is a micronutrient?
A) calcium
B) zinc
C) sulfur
D) carbon
E) nitrogen

Human pathogens are:
A) thermophiles
B) psychrophiles
C) barophiles
D) halophiles
E) mesophiles