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Microbiology Exam 2 Review Flashcards

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Terms in this set (30)

  • What is binary fission?

    Binary fission is the process by which a bacterial cell divides into two cells.

  • Generation time in bacteria.

    the amount of time it takes for a population of cells to double.

  • What happens during the lag phase of bacterial growth?

    Cells are metabolically active, making enzymes, ATP, and components, but not dividing yet.

  • Describe the log (exponential) phase.

    Cells divide at their fastest rate, are similar, and most sensitive to antibiotics.

  • What characterizes the stationary phase in bacterial growth?

    Cell division rate equals cell death rate; population levels off due to nutrient depletion and waste buildup.

  • What occurs during the death (decline) phase?

    More cells die than are produced, causing a decline in the population.

  • How do phototrophs obtain energy?

    Phototrophs get energy from sunlight.

  • How do chemotrophs obtain energy?

    Chemotrophs obtain energy by oxidizing chemical compounds.

  • What is the carbon source for autotrophs?

    Autotrophs use CO₂ as their carbon source.

  • What carbon source do heterotrophs use?

    Heterotrophs get carbon from organic compounds.

  • Define lithotrophs and organotrophs in terms of electron sources.

    Lithotrophs get electrons from inorganic molecules; organotrophs get electrons from organic molecules.

  • What oxygen requirement defines an obligate aerobe?

    An obligate aerobe requires oxygen to grow and cannot grow without it.

  • What is an obligate anaerobe?

    An obligate anaerobe cannot tolerate oxygen; oxygen can kill it.

  • Describe a facultative anaerobe's oxygen use.

    A facultative anaerobe can grow with or without oxygen but grows better with oxygen.

  • What is an aerotolerant anaerobe?

    It does not use oxygen but can tolerate its presence.

  • What is a microaerophile?

    A microaerophile needs oxygen but only at low concentrations.

  • Define psychrophiles, mesophiles, and thermophiles by temperature preference.

    Psychrophiles grow at low temps (near refrigeration), mesophiles prefer moderate temps (25–40 °C), thermophiles prefer high temps (45–60 °C or higher).

  • What pH conditions do neutrophiles, acidophiles, and alkalinophiles prefer?

    Neutrophiles prefer neutral pH, acidophiles prefer acidic, and alkalinophiles prefer basic conditions.

  • What happens to a bacterial cell in a hypotonic solution?

    Water moves into the cell, causing it to swell and possibly lyse if the cell wall is compromised.

  • What occurs to a bacterial cell in a hypertonic solution?

    Water leaves the cell, causing it to shrink or undergo plasmolysis.

  • What is the difference between obligate and facultative halophiles?

    Obligate halophiles require high salt concentrations; facultative halophiles tolerate salt but do not require it.

  • What is a selective medium?

    A medium that inhibits unwanted organisms while allowing the target organisms to grow.

  • What is a differential medium?

    A medium that allows visualization of differences between organisms, such as hemolysis patterns on blood agar.

  • What is quorum sensing?

    Microbes detect population density changes and respond using signaling molecules that diffuse through the environment.

  • What are fimbriae and sex pili used for?

    Fimbriae are for attachment; sex pili transfer genes between bacterial cells during conjugation.

  • What is peptidoglycan composed of?

    Alternating NAG and NAM molecules cross-linked by short peptide chains forming the bacterial cell wall.

  • How do Gram-positive and Gram-negative cell walls differ?

    Gram-positive have thick peptidoglycan with teichoic acids; Gram-negative have thin peptidoglycan and an outer membrane with LPS.

  • What is the nucleoid in bacteria?

    The region containing the bacterial chromosome; it is not a storage site.

  • What distinguishes a coccobacillus from other bacterial shapes?

    A coccobacillus is a short rod-shaped bacterium with features between a coccus and a bacillus.

  • What organelle carries out aerobic respiration in eukaryotes?

    The mitochondrion contains cristae and enzymes for aerobic respiration.