MICR 271 Final Exam Questions with
Answers Rated A+.
How do bacterial cells divide? - Answer binary fission - replication of chromosome, cellular
growth, daughter cells are pinched off
replication begins before d-cells are pinched off
How do bacterial cells age? - Answer senescence...
-inherit old cell material from "old" pole (side of cell wall inherited from parent cell)
-inherit damaged DNA
-inherit damaged proteins
-activation of damage defense systems instead of growth systems
Distinguish between the growth behaviors in microbes in response to oxygen. - Answer
obligate aerobe - aerobic respiration (O2 required)
facultative aerobe - oxygen very useful and not necessary
aerotolerant aerobe - strictly fermentative metabolism (tolerate O2)
strict anaerobe - oxygen is toxic, use fermentative metabolism or anaerobic respiration
microaerophile - require 2-10% O2 for growth... >20% is toxic
What are the types of reactive oxygen species? - Answer superoxide anion, peroxide,
hydrogen peroxide, hydroxyl radical, hydroxyl ion
How do bacteria utilize nutrients? - Answer carbon - convert carbon to organic molecules,
break down dead organic molecules (and release carbon via respiration)
nitrogen - nitrifying bacteria oxidize nitrogen to produce energy
What are the metabolic groupings of organisms? - Answer energy sources (energy)
carbon sources (cell mass growth)
electron sources (energy conservation)
What distinguishes how organisms obtain energy? - Answer chemotropic - obtain energy from
external
chemicals (energy)
phototropic - obtain energy from light (energy)
,What distinguishes how organisms obtain cell mass? - Answer autotrophic - obtain carbon
from CO2 (cell mass)
heterotrophic - obtain carbon from organic compounds (cell mass)
mixotrophs - hetero/auto
What distinguishes how organisms conserve energy in biochemical processes? - Answer
Lithotrophic - reduce from inorganics (energy conservation)
Organotrophics - reduce from organic compounds
What distinguishes the metabolic groups used to name microbes? - Answer photoautotrophs -
plants, algae and cyanobacteria
photoheterotrophs - green or purple non-sulphur bacteria, some archaea
chemoautotrophs - hydrogen/sulfur/nitrifying bacteria, some archaea
chemoheterotrophs -
aerobic: fungi, pathogenic bacteria
anaerobic: protozoa, bacteria, archaea
fermentation: bacteria, yeasts, archaea
How do bacteria utilize nutrients in anabolic processes? - Answer need an energy source, a
carbon source, an electron source
How do bacteria utilize nutrients in catabolic processes? - Answer breakdown materials to
conserve energy, to produce energy or to create cell mass
Why must peptidogylcan layers undergo continuous remodelling and restructuring? - Answer
rigidity.... cell wall will lyse otherwise
What are important factors for the survival of bacteria? - Answer ability to adapt to
environmental conditions
communication with one another to coordinate their activites
How do persister cells resist antibiotics? - Answer shift their metabolism to create enough ATP
to remain viable, antibiotics have not targets, once antibs are gone, shift back to division
focused metabolism
, How do bacteria use anabolic or catabolic processes to survive and adapt? - Answer anabolics
to grow and divide
catabolics to create enough energy to survive
How do bacteria use quorum sensing? - Answer signal using autoinducers: n-acyl homoserine
lactones, autoinducers 2, Com X
use signals to coordinate metabolic functions to adapt and survive (ie make biofilm)
How does quorum sensing work in gram-negative bacteria? - Answer autoinducer is taken into
cell, binds to intracellular receptor, receptor protein acts as a transcriptional regulator by
binding to DNA and altering gene expression
How does quorum sensing work in gram-positive bacteria? - Answer autoinducer binds to
protein on cell surface, receptor becomes activated, initiating signalling cascade, transcriptional
regulator is activated, and DNA expression is altered
How does population density affect quorum sensing and virulence - Answer low density - low
concentration of autoinducers, no gene regulation
high density - high C of autoinducer, QS complex increasing regulates genes relating to
surivability (ie shift into biofilm mode)
How do bacteria use quorum sensing to form biofilms? - Answer coordinate up-regulation of
polysaccharide synthesis and down-regulate motility
coordinate gene expression
What are the methods of enumerating microbes? - Answer plating assays, counting viral
plaques, counting bacterial colonies, counting bacterial cells using a hemocytometer or
spectrophotometer
What are the four stages of bacterial growth? - Answer lag, log/exponential, stationary,
decline
Describe the lag stage of bacterial growth - Answer bacteria adapt to conditions, maturing not
dividing, synthesis of critical molecules occurs
Describe the stationary stage of bacterial growth - Answer growth and death rate equal;
buildup of waste products and depletion of nutrients
Answers Rated A+.
How do bacterial cells divide? - Answer binary fission - replication of chromosome, cellular
growth, daughter cells are pinched off
replication begins before d-cells are pinched off
How do bacterial cells age? - Answer senescence...
-inherit old cell material from "old" pole (side of cell wall inherited from parent cell)
-inherit damaged DNA
-inherit damaged proteins
-activation of damage defense systems instead of growth systems
Distinguish between the growth behaviors in microbes in response to oxygen. - Answer
obligate aerobe - aerobic respiration (O2 required)
facultative aerobe - oxygen very useful and not necessary
aerotolerant aerobe - strictly fermentative metabolism (tolerate O2)
strict anaerobe - oxygen is toxic, use fermentative metabolism or anaerobic respiration
microaerophile - require 2-10% O2 for growth... >20% is toxic
What are the types of reactive oxygen species? - Answer superoxide anion, peroxide,
hydrogen peroxide, hydroxyl radical, hydroxyl ion
How do bacteria utilize nutrients? - Answer carbon - convert carbon to organic molecules,
break down dead organic molecules (and release carbon via respiration)
nitrogen - nitrifying bacteria oxidize nitrogen to produce energy
What are the metabolic groupings of organisms? - Answer energy sources (energy)
carbon sources (cell mass growth)
electron sources (energy conservation)
What distinguishes how organisms obtain energy? - Answer chemotropic - obtain energy from
external
chemicals (energy)
phototropic - obtain energy from light (energy)
,What distinguishes how organisms obtain cell mass? - Answer autotrophic - obtain carbon
from CO2 (cell mass)
heterotrophic - obtain carbon from organic compounds (cell mass)
mixotrophs - hetero/auto
What distinguishes how organisms conserve energy in biochemical processes? - Answer
Lithotrophic - reduce from inorganics (energy conservation)
Organotrophics - reduce from organic compounds
What distinguishes the metabolic groups used to name microbes? - Answer photoautotrophs -
plants, algae and cyanobacteria
photoheterotrophs - green or purple non-sulphur bacteria, some archaea
chemoautotrophs - hydrogen/sulfur/nitrifying bacteria, some archaea
chemoheterotrophs -
aerobic: fungi, pathogenic bacteria
anaerobic: protozoa, bacteria, archaea
fermentation: bacteria, yeasts, archaea
How do bacteria utilize nutrients in anabolic processes? - Answer need an energy source, a
carbon source, an electron source
How do bacteria utilize nutrients in catabolic processes? - Answer breakdown materials to
conserve energy, to produce energy or to create cell mass
Why must peptidogylcan layers undergo continuous remodelling and restructuring? - Answer
rigidity.... cell wall will lyse otherwise
What are important factors for the survival of bacteria? - Answer ability to adapt to
environmental conditions
communication with one another to coordinate their activites
How do persister cells resist antibiotics? - Answer shift their metabolism to create enough ATP
to remain viable, antibiotics have not targets, once antibs are gone, shift back to division
focused metabolism
, How do bacteria use anabolic or catabolic processes to survive and adapt? - Answer anabolics
to grow and divide
catabolics to create enough energy to survive
How do bacteria use quorum sensing? - Answer signal using autoinducers: n-acyl homoserine
lactones, autoinducers 2, Com X
use signals to coordinate metabolic functions to adapt and survive (ie make biofilm)
How does quorum sensing work in gram-negative bacteria? - Answer autoinducer is taken into
cell, binds to intracellular receptor, receptor protein acts as a transcriptional regulator by
binding to DNA and altering gene expression
How does quorum sensing work in gram-positive bacteria? - Answer autoinducer binds to
protein on cell surface, receptor becomes activated, initiating signalling cascade, transcriptional
regulator is activated, and DNA expression is altered
How does population density affect quorum sensing and virulence - Answer low density - low
concentration of autoinducers, no gene regulation
high density - high C of autoinducer, QS complex increasing regulates genes relating to
surivability (ie shift into biofilm mode)
How do bacteria use quorum sensing to form biofilms? - Answer coordinate up-regulation of
polysaccharide synthesis and down-regulate motility
coordinate gene expression
What are the methods of enumerating microbes? - Answer plating assays, counting viral
plaques, counting bacterial colonies, counting bacterial cells using a hemocytometer or
spectrophotometer
What are the four stages of bacterial growth? - Answer lag, log/exponential, stationary,
decline
Describe the lag stage of bacterial growth - Answer bacteria adapt to conditions, maturing not
dividing, synthesis of critical molecules occurs
Describe the stationary stage of bacterial growth - Answer growth and death rate equal;
buildup of waste products and depletion of nutrients
