OCTC-Micro-Test 1

Which disease was the 1st proven to be bacterial in origin?
Who discovered penicillin?
negative taxis (flagella movement)
Movement away from
positive taxis (flagella movement)
Movement towards
positive phototaxis
Movement toward light
positive chemotaxis
Movement toward chemical
negative chemotaxis
Movement away from chemical
negative phototaxis
Movement away from light
What causes negative chemotaxis, or negative phototaxis?
What causes the flagellum to swim forward and thus promotes positive chemotaxis or phototaxis?
What are biofilms
Biofilms are a complex community of microbes that form a protective adhesive matrix that attaches microbes to surfaces
How are biofilms made?
Capsules allow the bacteria to attach to solid surfaces and form biofilms.and
Fimbriae are found forming biofilms
so both the glycocalyx and fimbriae form the biofilm.
Where do biofilms form?
Infected tissues
Plastic catheters
Metal pacemakers
Industrial pipelines.
located on Eukaryotic cells and protozoa.extensions of cell membrane; protozoa, sperm cells of mammals (also in bacteria)
located ONLY on eukaryotic cells
Bacteria do not have cilia!!
Bacterial flagella can move by means of rotating flagella how many degrees?
bacterial flagella are easily seen with which microscope?
electron microscope.
Bacterial Flagella are composed of which three parts?
basal body
what is bacterial flagella composed of?
What is a sex pilus? (also called conjugations pilus)
long hollow tubules composed of protein called pilin.
What do sex or conjugation pilus do?
Mediate the transfer of DNA from one cell to the other via a process termed conjugation. (a form a genetic exchange) Remember that bacteria produce asexually.
Components of a bacterial cell wall
Composed of peptidoglycan(PG), a complex polysaccharide.
What have some types of bacteria developed to deal with dehydration?
glycocalyx (slime layer and capsule)
What are the functions of glycocalyx(capsule and slime layer)?
They aid in attachment to surfaces.
2. They prevent phagocytosis by WBC which increases the bacteria’s pathogenicity. (capsule slide in lab)
3. They protect the bacteria from dehydration.
Solely eukaryotic-active transport-substances surrounded by pseudopodia and brought into the cell
Solely eukaryotic process-reverse of endocytosis-enables wastes and secretions to be exported from the cell
How are Mitochondria different from Chloroplasts?
Mitochondria function in aerobic ATP production and chloroplasts function in photosynthesis.
What are the major tenants of the endosymbionic theory?
1) Eukaryotes are formed from the union of small aerobic prokaryotes with larger anaerobic prokaryotes.
2)Parasites eventually lose the ability to exist independently, but retain a portion of their DNA, some ribosomes and their cytoplasmic membranes.
3)Aerobic prokaryotes eventually evolved into mitocondria and their cytoplasmic membranes became cristae.
What is another way to explain what the endosymbiotic Theory is?
It’s a theory where the mitochondria and chloroplasts of the cell are believed to have evolved from bacteria, because they have their own DNA and ribosomes (which is very similar to the bacteria that scientists believe the they evolved from) and reproduce like bacteria. Scientists believe this happened because the cell and the ancient bacteria that the two organelles evolved from transitioned into “endosymbiotic living” (which basically just means that two organisms that aren’t the same species live in close association).
What are the functions of the Eukaryotic cytoskeleton?
anchors organelles
gives shape to the cell
performs endocytosis
aids in contraction of the cell
Which stain originated as a specific method to detect Mycobacterium tuberculosis in specimens?
Acid Fast Stains
what do Acid Fast stains do for us?
They detect myobacterium that the gram stain cannot because the cell walls of myobacterium are composed of waxy materials that repel the water based dyes of the Gram stain.
Why do microbiologists stain thier specimens?
to create contrast.
Staining cells increases contrast but the procedure requires that the cells are what?
What are some examples of dyes used for staining? Name 3
Methylene blue, crystal violet, and saffranin
Positive stains
Dye sticks to cells (specimen)
Gives the bacterial cell color against a bright background.
Examples of dyes used in Positive staining:
Crystal violet
Methylene blue
Malachite green
Negative stains
Dye does not stick to the cell or a structure of a cell
Dye settles around its outer boundary of the cell or structure forming a silhouette or “dark cloud”.
Negative stains
The glass slide is stained with the dye
The bacteria do not take up the stain and remains white or colorless
The bacterial structure does not take up the stain and remains white or colorless
Some dyes used in negative staining:
Nigrosin = black stain
India ink = pink stain
Types of Stain include:
Simple stains
Special stains
Differential stains
Simple stains are
positive stains that use only one dye such as methylene blue or crystal violet.
What are simple stains used to do?
reveal size, morphology and arrangement of cells
What results occur during a simple stain?
Uniform purple stain
Uniform blue stain
Differential stains
Use two dyes or more dyes to see:
Differences between cells
Differences between cell structures.
Differential stains Include
Gram stain
Acid-fast stain
Endospore stain.
Gram Staining shows differences between
thicknesses of peptidoglycan in bacteria’s cell wall
That is all a Gram stain does!!
Why do We Perform Gram Stains?
Bacteria with a thick layer of PG stain purple = gram positive cells.
Certain antibiotics work only on Gram +
Why do We Perform Gram Stains?
Bacteria with a thin layer of PG stain red (pink) = gram negative cells.
Certain other antibiotics work only on Gram –
Gram negative (–) bacteria contain
Lipid A which is on their lipopolysaccharide(LPS) outer membrane
What is Lipid A
Lipid A is an endotoxin that is released when Gram – bacteria die.
Lipid A may trigger:
Blood clotting in humans
Release of toxin is what harms human

Cause for concern with Gram – pathogens.

Acid Fast Stains
Originated as a specific method to detect Mycobacterium tuberculosis in specimens
Acid fast stains detect
Mycobacterium tuberculosis causes TB or Consumption.
Mycobacterium leprae causes Hansen’s disease
Mycobacterium bovis causes Bovine TB
Endospore Stains
Stains are used to detect endospores
Dye is forced by HEAT into resistant bodies called endospores.
What is the primary stain in Endospore Stains?
Malachite green is the primary stain
What is the counter stain in Endospore stains?
Special Stains are
simple stains used to show special structures on the microbe
Special stains include
Flagellar stains
Negative stains
Fluorescent stains.
Flagellar stains are used to reveal
Flagella filaments are so thin that they can only be seen with an
electron microscope.
Flagella can only be seen with a light microscope after a
flagellar stain.
The flagellar stain enlarges the filament by depositing a
coating of the stain on the flagella.
Gram stain results that are pink are
gram negative cells
Gram stain results that are purple are
Gram positive cells
Which stains use heat to drive the stain in?
Acid fast stains and endospore stains
Carl Woese developed a system of
Three Domains. (super-kingdoms) 1980s
Carl Woese Domains were based on the sequence of
DNA nucleotides that code for rRNA.
Robert Whittaker proposed a system (1969) that recognized
Five Kingdoms:
Protist (protozoa)
Monera (bacteria).
What is the Domain System?
what process uses refraction of light to make the apparent size of an object larger?
Is there are consensus between taxonomists?
What does the term growth in microbiology mean?
an increase in the number of microbial cells.
The first true vaccine protected humans against what type of organism?
Endospores survive a variety of harsh conditions in part because of the presence of
dipicolinic acid
Hetero =
Auto =
Trophe =
Photos =
Autotrophs =
feed self, nutrition
feed themselves, self feeders, automatic.
Plants are also examples of autotrophs.
Autotrophs obtain carbon atoms from
CO2 and make their own organic compounds like plants
Heterotrophs =
eat other, nutrition
different (other) feeders.
Heterotrophs obtain carbon atoms from
organic compounds from other organisms like animals (humans)
Heterotrophs are
Animals (humans)
Heterotrophs breakdown other organism’s proteins, carbohydrates, fatty acids, and amino acid and use those Carbon atoms to
make their own organic compounds.
Microbes are categorized into which two groups based on whether they use chemicals or light as source of energy?
Chemotrophs use chemicals for energy (we use chemical glucose)
Phototrophs use light for energy
Chemotrophs are_____ that acquire energy from chemical reactions involving inorganic and organic chemicals.
Who are chemotrophs?
Examples of Chemotrophs
Phototrophs are bacteria that acquire energy from
Examples of Phototrophs
Photosynthetic archaea = cyanobacteria. Annabeana
Plants and algae are phototrophs.
Type of organism: Photoautotroph
Energy Source=? Carbon source=?
sunlight, CO2
Type of organism: Photoheterotrophs
Energy Source=? Carbon source=?
sunlight, organic compds
Type of organism: Chemoautotrophs
Energy Source=? Carbon source=?
inorganic compounds, CO2
Type of organism: Chemoheterotroph
Energy Source=? Carbon source=?
organic compounds, organic compds
Sputum is mucus that is coughed up from the lower airways
obligate aerobes
Oxygen is essential
obligate anaerobes
Oxygen is deadly for them
Obligate Aerobes use aerobic metabolism which has an absolute requirement for
grow better in presence of O2 but can grow without O2.
Facultative Anaerobes
Facultative Anaerobes use _____ metabolism and grow best in presence of O2 but can grow in its absence.
require just a small amount of O2 from 2-10%.
Obligate (strict) Anaerobes
cannot grow if O2 is present.
Ex. Clostridia
The presence of O2 often kills bacteria
They do not use aerobic metabolism
They cannot multiply if O2 is present
They are often killed in the present of O2
Obligate (strict) Anaerobes
They cannot use O2 but tolerate it fairly well.
Aerotolerant anaerobes are anaerobic bacteria
Aerotolerant anaerobes can tolerate O2 and can grow in the presence of oxygen because
They have enzymes that detoxify oxygen’s poisonous forms.
What are endospores?
A resistant asexual spore that develops inside some bacteria cells. (does not reproduce)
How are endospores formed? 8 step process
1)Vegetative cell’s DNA is replicated
2)DNA aligns along long axis
3)cytoplasmic membrane invaginates to form forespore
4)Second membrane forms around the forespore and the vegetative cell’s DNA disintegrates.
5) Calcium and dipicolinic acid is deposited between the first and second membranes.
6)Spore coat forms around endospore
7) Spore coat maturation complete. Results in an increase in resistance to heat and chemicals.
8) Endospore released from original cell
Two types of Microscopes:
Simple microscope
Compound Microscope
Simple microscope =
one lens = magnifying glass
Compound Microscope have
two lens: objective lens and an ocular lens
Categories: Microbiology