Chapter 6 Flashcards
microbial growth and nutrition (42 cards)
What are the essential nutrients of a bacterial cell?
Carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur (CHNOPS)
These nutrients are crucial for various cellular functions and structures.
Differentiate between macronutrients and micronutrients.
Macronutrients are required in large quantities and are crucial for cell structure and metabolism, while micronutrients are present in smaller amounts and are involved in enzyme function and protein structure
Examples of macronutrients include CHNOPS, while micronutrients include trace elements like manganese, zinc, and nickel.
List and define the four terms that describe an organism’s sources of carbon and energy.
- Heterotroph: obtains carbon in organic form
- Autotroph: uses inorganic CO2 as carbon source
- Phototroph: gets energy from sunlight
- Chemotroph: gets energy from chemical compounds
These terms categorize organisms based on their nutritional requirements.
What is a saprobe?
An organism that derives nutrients from decaying organic matter
Saprobes are essential for recycling nutrients in ecosystems.
What is a parasite?
An organism that derives nutrients from the cells or tissues of a living host
This can lead to damage or death of the host.
True or False: The terms saprobe and parasite can oversimplify the nutritional strategies of some organisms.
True
These terms may not encompass the complexity of certain organisms’ lifestyles.
Compare diffusion and osmosis.
Diffusion is the movement of molecules from high to low concentration; osmosis specifically refers to the movement of water across a selectively permeable membrane.
Both processes are passive transport mechanisms.
Identify the effects of isotonic, hypotonic, and hypertonic conditions on a cell.
- Isotonic: no net movement of water
- Hypotonic: water enters the cell, causing it to swell
- Hypertonic: water leaves the cell, leading to plasmolysis
Understanding these effects is crucial for cell biology and microbiology.
Name two types of passive transport.
- Simple diffusion
- Facilitated diffusion
Both transport mechanisms do not require energy.
What is one type of active transport?
Carrier-mediated active transport
This process requires energy to move substances against their concentration gradient.
What is the optimum temperature range for mesophiles?
Between 20°C and 40°C
Most medically significant microorganisms fall into this category.
Define psychrophiles.
Microbes that have an optimum temperature below 15°C and can grow at 0°C
They are typically found in cold environments like polar ice and deep oceans.
What organisms are classified as thermophiles?
Microbes that grow optimally at temperatures greater than 45°C
They are often found in environments associated with volcanic activity.
What is the definition of obligate aerobes?
Organisms that cannot grow without oxygen
Examples include many fungi and certain bacteria like Bacillus species.
Fill in the blank: An organism that does not utilize oxygen but can survive in its presence is called an _______.
Aerotolerant anaerobe
These organisms do not use oxygen in metabolism but can tolerate it.
What are the three types of associations microbes can have with their hosts?
- Mutualism
- Commensalism
- Parasitism
Each association has different implications for the host and the microbe.
What are anaerobes?
Microbes that lack the metabolic enzyme systems for using oxygen in respiration.
Define aerotolerant anaerobes.
Organisms that do not utilize oxygen but can survive and grow to a limited extent in its presence.
What are facultative anaerobes?
Microbes that do not require oxygen for metabolism but can use it when it is present.
Give examples of facultative anaerobes.
- Many gram-negative intestinal bacteria
- Staphylococci
What are the three categories of microbes based on oxygen usage?
- Those that use oxygen and detoxify it
- Those that can neither use oxygen nor detoxify it
- Those that do not use oxygen but can detoxify it
Which atmospheric gas has the greatest impact on microbial growth?
O2
What is the pH scale?
A series of numbers ranging from 0 to 14 that expresses the degree of acidity or alkalinity of a solution.
What is the pH of pure water?
7.0
