Mcim 223 Midterm Exam Questions
With Verified Answers
Microbiology - ANSWER The study of microscopic organisms
Antoine van Leeuwenhoek - ANSWER Provided first known description of
bacteria & microbes
G. Fracastoro - ANSWER Contagion theory suggested that disease can be
transmitted by invisible particles through direct /indirect contact
L. Pasteur (Germ Theory) - ANSWER Suggested that microorganisms are the
actual cause of many human diseases
R Koch - ANSWER Experimentally proves the germ theory
Koch's Postulates - ANSWER a set of criteria for proving that a given
microorganism causes a given disease
Koch's Postulates - ANSWER 1) Pathogen must be present in all disease cases
absent from healthy animals
2) Isolate pathogen, cultivate in pure culture
3) Cells from pure culture should cause disease in the healthy animals
4) Re-isolate pathogen, confirm it's the same pathogen
Semmelweis - ANSWER Person who advocated hand-washing to prevention
transmission from one patient to another
J.Lister - ANSWER Found that the rates of post surgical infections could be
reduced by preventing microbes from entering surgical incisions by sterilizing
instruments &using antiseptic dressings
F.Nightingale - ANSWER Showed that hospital cleanliness was critical in
preventing infections
E. Jenner - ANSWER smallpox vaccine, and is sometimes referred to as the
"Father of Immunology". Jenner discovered that someone with cowpox infection
would never later become infected with smallpox
Beginning of vaccines
P. Erlich & A. Fleming - ANSWER Showed that certain chemicals could
preferentially kill microbes without damaging the human host
,Beginning of antibiotics
1880 - ANSWER The discovery of most of the disease causing microbes
1940 - ANSWER The introduction of antibiotics into clinical practice
modern era of microbiology - ANSWER 1. Defining the limit of microbial life in the
environment
2. Improving our understanding the human microbiome
3. Identifying tracking & combatting disease causing microbes
Procaryotes - ANSWER cells that do not have a true nucleus; lack membrane
bound organelles
Eucaryotes - ANSWER organisms whose cells have a true nucleus
Phenotype - ANSWER physical characteristics of an organism
Genotype - ANSWER genetic makeup of an organism, DNA
3 domains - ANSWER Bacteria, Archaea, Eukarya
Domain Eukarya - ANSWER includes Kingdoms Protista, Fungi, Plantae and
Animalia (eukaryotes)
Domain Bacteria - ANSWER Includes all common bacteria
Domain Archaea - ANSWER Similar in appearance to bacteria but differ
genetically & chemically
Inhabit extreme conditions
Dont cause human disease
Naming and Classifying bacteria - ANSWER All known bacteria have been
assigned a Binomial name sometimes additional designation (the strain) is
added to differentiate between 2 bacteria that have the same genus & species
Binomial name - ANSWER genus and species
microscope - ANSWER Light microscope magnifies up to 1000x
Used to observe bacterial size shape & arrangement
electron microscope (EM) - ANSWER Magnifies up to 200000x
To see special structures on bacteria & to observe the very smallest microbes &
viruses
,Staining techniques - ANSWER Staining makes the bacteria more visible easier
to determine overall shape and arrangement
Required for light microscope
Gram stain - ANSWER A staining method using 2 dyes that distinguishes
between two different kinds of bacterial cell surface structures.
gram negative - ANSWER Will be pink at the end of gram-stain
Describing the group of bacteria that have a cell wall that has a plasma
membrane, thin layer of peptidoglycan & outer-membrane.
1-2 layers of PG
gram positive - ANSWER Will be purple throughout staining process
Describing the group of bacteria that have a cell wall that has a plasma
membrane and contains thick peptidoglycan layer.
No outer membrane
Several dozen layers of PG
acid fast stain - ANSWER a differential stain used to identify bacteria that are not
decolorized by acid-alcohol
acid fast bacteria - ANSWER Retain the primary stain even when treated with
acid alcohol. Cell walls contain mycolic acid. Includes Mycobacterium and
Nocardia species which include human pathogens as M. tuberculosis and M.
Leprae.
Bacterial Anatomy - ANSWER Cell size average = 2micrometers
Cell appearance - ANSWER 1. Bacillus = rod shape
2. Coccus =round shape
3.spirochetes = spiral shape
Arranged as singles, pairs clusters or chains
Cytoplasm - ANSWER A jellylike fluid inside the cell in which the organelles are
suspended
Location of DNA
site of many biochemical rxs
cell envelope - ANSWER Multi component shell that surrounds the cytoplasm
structurally different in gram - bs gram +
plasma membrane - ANSWER phospholipid bilayer with embedded proteins
function of plasma membrane - ANSWER Permeability barrier prevents leakage
of cytoplasmic contents
Location of some metabolic proteins
, Nutrients in and waste products out
peptiodoglycan - ANSWER a protein carbohydrate compound found ONLY in
bacteria cell walls
made of 2 carbohydrates and 4 aminoacids
Continuous mesh like layer surrounding the cell
Formed in layers
Gives strength & rigidity to the cell envelope
Protects the cell against external stressors
Lysozyme - ANSWER An enzyme that breaks apart the carbohydrates bonds in
Peptidoglycan & disrupts the basic structure ; in mammals, found in sweat,
tears, and saliva.
peptidoglycan thickness - ANSWER The reason gram + & gram - bacteria stain
differently
outer membrane - ANSWER Only present in gram negative bacteria
A phospholipid bilayer that contains :
protein channels to allow entry of water & nutrients
Lipopolysaccharides (LPS)
Lipopolysaccharide (LPS) - ANSWER molecule composed of lipid A and
polysaccharide found in the outer membrane of Gram-negative cell walls
protects the cell by repelling harmful stuff
Known as endotoxin
Only found in bacteria
Important in disease causing bacteria
Toxic molecule that triggers the immune system to cause inflammation & fever
acid fast bacteria - ANSWER Envelope = inner membrane + peptidoglycan +
mycolic acid outer layer
mycolic acid - ANSWER Waxy fatty acids
Protects against germicides & environmental stressors
Stains are difficult to remove
Flagella - ANSWER A long, whip-like filament that helps in cell motility.
Allows bacteria to respond to external stimuli
Vary in location & # per cell (species dependent)
Protein ring imbedded in PG
Pili (fimbriae) - ANSWER Filamentous appendages, shorter, & thinner and
considerably smaller than flagella & cover the entire cell
they appear to make bacteria more adhesive. (Attach bacteria to other cells)
The sex pilus is essential for genetic transfer in bacterial conjugation.
With Verified Answers
Microbiology - ANSWER The study of microscopic organisms
Antoine van Leeuwenhoek - ANSWER Provided first known description of
bacteria & microbes
G. Fracastoro - ANSWER Contagion theory suggested that disease can be
transmitted by invisible particles through direct /indirect contact
L. Pasteur (Germ Theory) - ANSWER Suggested that microorganisms are the
actual cause of many human diseases
R Koch - ANSWER Experimentally proves the germ theory
Koch's Postulates - ANSWER a set of criteria for proving that a given
microorganism causes a given disease
Koch's Postulates - ANSWER 1) Pathogen must be present in all disease cases
absent from healthy animals
2) Isolate pathogen, cultivate in pure culture
3) Cells from pure culture should cause disease in the healthy animals
4) Re-isolate pathogen, confirm it's the same pathogen
Semmelweis - ANSWER Person who advocated hand-washing to prevention
transmission from one patient to another
J.Lister - ANSWER Found that the rates of post surgical infections could be
reduced by preventing microbes from entering surgical incisions by sterilizing
instruments &using antiseptic dressings
F.Nightingale - ANSWER Showed that hospital cleanliness was critical in
preventing infections
E. Jenner - ANSWER smallpox vaccine, and is sometimes referred to as the
"Father of Immunology". Jenner discovered that someone with cowpox infection
would never later become infected with smallpox
Beginning of vaccines
P. Erlich & A. Fleming - ANSWER Showed that certain chemicals could
preferentially kill microbes without damaging the human host
,Beginning of antibiotics
1880 - ANSWER The discovery of most of the disease causing microbes
1940 - ANSWER The introduction of antibiotics into clinical practice
modern era of microbiology - ANSWER 1. Defining the limit of microbial life in the
environment
2. Improving our understanding the human microbiome
3. Identifying tracking & combatting disease causing microbes
Procaryotes - ANSWER cells that do not have a true nucleus; lack membrane
bound organelles
Eucaryotes - ANSWER organisms whose cells have a true nucleus
Phenotype - ANSWER physical characteristics of an organism
Genotype - ANSWER genetic makeup of an organism, DNA
3 domains - ANSWER Bacteria, Archaea, Eukarya
Domain Eukarya - ANSWER includes Kingdoms Protista, Fungi, Plantae and
Animalia (eukaryotes)
Domain Bacteria - ANSWER Includes all common bacteria
Domain Archaea - ANSWER Similar in appearance to bacteria but differ
genetically & chemically
Inhabit extreme conditions
Dont cause human disease
Naming and Classifying bacteria - ANSWER All known bacteria have been
assigned a Binomial name sometimes additional designation (the strain) is
added to differentiate between 2 bacteria that have the same genus & species
Binomial name - ANSWER genus and species
microscope - ANSWER Light microscope magnifies up to 1000x
Used to observe bacterial size shape & arrangement
electron microscope (EM) - ANSWER Magnifies up to 200000x
To see special structures on bacteria & to observe the very smallest microbes &
viruses
,Staining techniques - ANSWER Staining makes the bacteria more visible easier
to determine overall shape and arrangement
Required for light microscope
Gram stain - ANSWER A staining method using 2 dyes that distinguishes
between two different kinds of bacterial cell surface structures.
gram negative - ANSWER Will be pink at the end of gram-stain
Describing the group of bacteria that have a cell wall that has a plasma
membrane, thin layer of peptidoglycan & outer-membrane.
1-2 layers of PG
gram positive - ANSWER Will be purple throughout staining process
Describing the group of bacteria that have a cell wall that has a plasma
membrane and contains thick peptidoglycan layer.
No outer membrane
Several dozen layers of PG
acid fast stain - ANSWER a differential stain used to identify bacteria that are not
decolorized by acid-alcohol
acid fast bacteria - ANSWER Retain the primary stain even when treated with
acid alcohol. Cell walls contain mycolic acid. Includes Mycobacterium and
Nocardia species which include human pathogens as M. tuberculosis and M.
Leprae.
Bacterial Anatomy - ANSWER Cell size average = 2micrometers
Cell appearance - ANSWER 1. Bacillus = rod shape
2. Coccus =round shape
3.spirochetes = spiral shape
Arranged as singles, pairs clusters or chains
Cytoplasm - ANSWER A jellylike fluid inside the cell in which the organelles are
suspended
Location of DNA
site of many biochemical rxs
cell envelope - ANSWER Multi component shell that surrounds the cytoplasm
structurally different in gram - bs gram +
plasma membrane - ANSWER phospholipid bilayer with embedded proteins
function of plasma membrane - ANSWER Permeability barrier prevents leakage
of cytoplasmic contents
Location of some metabolic proteins
, Nutrients in and waste products out
peptiodoglycan - ANSWER a protein carbohydrate compound found ONLY in
bacteria cell walls
made of 2 carbohydrates and 4 aminoacids
Continuous mesh like layer surrounding the cell
Formed in layers
Gives strength & rigidity to the cell envelope
Protects the cell against external stressors
Lysozyme - ANSWER An enzyme that breaks apart the carbohydrates bonds in
Peptidoglycan & disrupts the basic structure ; in mammals, found in sweat,
tears, and saliva.
peptidoglycan thickness - ANSWER The reason gram + & gram - bacteria stain
differently
outer membrane - ANSWER Only present in gram negative bacteria
A phospholipid bilayer that contains :
protein channels to allow entry of water & nutrients
Lipopolysaccharides (LPS)
Lipopolysaccharide (LPS) - ANSWER molecule composed of lipid A and
polysaccharide found in the outer membrane of Gram-negative cell walls
protects the cell by repelling harmful stuff
Known as endotoxin
Only found in bacteria
Important in disease causing bacteria
Toxic molecule that triggers the immune system to cause inflammation & fever
acid fast bacteria - ANSWER Envelope = inner membrane + peptidoglycan +
mycolic acid outer layer
mycolic acid - ANSWER Waxy fatty acids
Protects against germicides & environmental stressors
Stains are difficult to remove
Flagella - ANSWER A long, whip-like filament that helps in cell motility.
Allows bacteria to respond to external stimuli
Vary in location & # per cell (species dependent)
Protein ring imbedded in PG
Pili (fimbriae) - ANSWER Filamentous appendages, shorter, & thinner and
considerably smaller than flagella & cover the entire cell
they appear to make bacteria more adhesive. (Attach bacteria to other cells)
The sex pilus is essential for genetic transfer in bacterial conjugation.
