뒤로Microbiology Test Review: Viruses & Microbial Nutrition – Step-by-Step Study Guidance
스터디 가이드 - 스마트 노트
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Q1. What is a virion?
Background
Topic: Viral Structure
This question tests your understanding of the basic structure and terminology related to viruses.
Key Terms:
Virion: The complete, infectious form of a virus outside a host cell.
Capsid: Protein shell that encloses the viral genome.
Nucleic acid: Genetic material (DNA or RNA) inside the virion.
Step-by-Step Guidance
Recall that a virion is the extracellular form of a virus, meaning it exists outside of a host cell.
Think about the components that make up a virion: the genetic material and the protective protein coat.
Consider whether a virion is metabolically active or inactive outside the host cell.
Review the difference between a virion and a virus inside a host cell (the latter is actively replicating).
Try solving on your own before revealing the answer!
Final Answer:
A virion is the complete, infectious viral particle that exists outside a host cell. It consists of the viral genome (either DNA or RNA) enclosed in a protein coat called a capsid, and sometimes surrounded by a lipid envelope. Virions are metabolically inert until they infect a host cell.
Q2. What is a thermophile?
Background
Topic: Microbial Nutrition & Growth
This question is about the classification of microorganisms based on their temperature preferences.
Key Terms:
Thermophile: An organism that thrives at relatively high temperatures.
Optimal growth temperature: The temperature at which an organism grows best.
Step-by-Step Guidance
Recall the temperature ranges for different microbial groups: psychrophiles (cold-loving), mesophiles (moderate), and thermophiles (heat-loving).
Think about environments where thermophiles are commonly found (e.g., hot springs, compost heaps).
Consider the typical temperature range that defines thermophiles.
Try solving on your own before revealing the answer!
Final Answer:
A thermophile is a microorganism that grows optimally at high temperatures, typically between 45°C and 80°C. They are often found in environments such as hot springs and geothermal soils.
Q3. What is the difference between antibiotics used for viruses and those used for bacteria?
Background
Topic: Antimicrobial Agents
This question tests your understanding of how antibiotics work and why they are effective against bacteria but not viruses.
Key Terms:
Antibiotic: A substance that inhibits the growth of or destroys bacteria.
Antiviral: A drug used to treat viral infections.
Cell wall: Structure present in bacteria but not in viruses.
Step-by-Step Guidance
Recall the basic structural differences between bacteria (living cells with cell walls) and viruses (non-living, no cell wall).
Think about how antibiotics target specific bacterial structures or processes (e.g., cell wall synthesis, protein synthesis).
Consider why these targets are absent in viruses, making antibiotics ineffective against them.
Review what types of drugs are used to treat viral infections instead.
Try solving on your own before revealing the answer!
Final Answer:
Antibiotics are effective against bacteria because they target structures or processes unique to bacteria, such as cell wall synthesis. Viruses lack these structures, so antibiotics do not work against them. Instead, antiviral drugs are used to treat viral infections.
Q4. What is binary fission?
Background
Topic: Microbial Reproduction
This question is about the process by which prokaryotic cells, such as bacteria, reproduce.
Key Terms:
Binary fission: A method of asexual reproduction in prokaryotes.
Prokaryote: An organism without a nucleus (e.g., bacteria).
Step-by-Step Guidance
Recall that binary fission is the primary method of reproduction in bacteria.
Think about the steps involved: DNA replication, cell elongation, and division.
Consider how the two resulting cells compare to the original cell.
Try solving on your own before revealing the answer!
Final Answer:
Binary fission is an asexual process in which a single prokaryotic cell divides into two genetically identical daughter cells. The cell replicates its DNA, elongates, and then splits into two.
Q5. What is osmosis?
Background
Topic: Microbial Nutrition & Transport
This question tests your understanding of how water moves across cell membranes.
Key Terms and Formula:
Osmosis: The movement of water across a selectively permeable membrane.
Concentration gradient: Difference in solute concentration across a membrane.
Step-by-Step Guidance
Recall that osmosis involves the movement of water, not solutes.
Think about the direction water moves: from areas of low solute concentration to high solute concentration.
Consider the role of the cell membrane in controlling this movement.
Try solving on your own before revealing the answer!
Final Answer:
Osmosis is the movement of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
Q6. What is the exponential phase in microbial growth?
Background
Topic: Microbial Growth Curve
This question is about the phases of bacterial population growth in a closed system.
Key Terms:
Exponential phase (log phase): Period of rapid cell division.
Growth curve: Graph showing the growth of a microbial population over time.
Step-by-Step Guidance
Recall the four phases of the bacterial growth curve: lag, exponential (log), stationary, and death.
Think about what happens to the population size during the exponential phase.
Consider why cells grow rapidly during this phase (nutrients abundant, waste low).
Try solving on your own before revealing the answer!
Final Answer:
The exponential phase is the period during which bacteria divide at a constant and rapid rate, resulting in exponential population growth. This occurs when nutrients are plentiful and environmental conditions are optimal.
Q7. What is the difference between DNA and RNA viruses?
Background
Topic: Viral Genetics
This question tests your understanding of the genetic material found in different types of viruses.
Key Terms:
DNA virus: Virus with DNA as its genetic material.
RNA virus: Virus with RNA as its genetic material.
Replication: The process by which viruses make copies of themselves.
Step-by-Step Guidance
Recall that viruses can have either DNA or RNA as their genetic material, but not both.
Think about how DNA and RNA viruses differ in their replication strategies.
Consider the implications for how these viruses interact with host cells.
Try solving on your own before revealing the answer!
Final Answer:
DNA viruses contain DNA as their genetic material and typically replicate in the host cell's nucleus, while RNA viruses contain RNA and often replicate in the cytoplasm. Their replication mechanisms and mutation rates also differ.
Q8. What is lysogeny?
Background
Topic: Bacteriophage Life Cycles
This question is about the process by which certain viruses integrate their genetic material into the host genome.
Key Terms:
Lysogeny: Integration of viral DNA into the host cell's genome.
Prophage: The viral DNA that is integrated into the host genome.
Lytic cycle: Alternative cycle where the virus replicates and lyses the host cell.
Step-by-Step Guidance
Recall the two main life cycles of bacteriophages: lytic and lysogenic.
Think about what happens to the viral DNA during lysogeny.
Consider the consequences for the host cell and the virus during this phase.
Try solving on your own before revealing the answer!
Final Answer:
Lysogeny is a process in which a bacteriophage integrates its DNA into the host bacterium's genome, becoming a prophage. The viral DNA is replicated along with the host's DNA without causing immediate lysis.
Q9. What is a mesophile?
Background
Topic: Microbial Nutrition & Growth
This question is about the classification of microorganisms based on their temperature preferences.
Key Terms:
Mesophile: An organism that grows best at moderate temperatures.
Optimal growth temperature: The temperature at which an organism grows best.
Step-by-Step Guidance
Recall the temperature ranges for psychrophiles, mesophiles, and thermophiles.
Think about the environments where mesophiles are commonly found (e.g., human body).
Consider the typical temperature range that defines mesophiles.
Try solving on your own before revealing the answer!
Final Answer:
A mesophile is a microorganism that grows best at moderate temperatures, typically between 20°C and 45°C. Most human pathogens are mesophiles.
