Microbiology Class Notes: The Big Picture
What causes mutations?
Radiation, Chemicals, Errors as a gene is being copied
nonsense mutation
a base substitution creating a stop (premature termination of transcription) codon which prevents the synthesis of a protein
slime layer
a glycocalyx that is unorganized and loosely attached to the cell wall
acid fast stain
A staining procedure for identifying bacteria that have a waxy cell wall.
Capsule
A sticky layer that surrounds the cell walls of some bacteria, protecting the cell surface and sometimes helping to glue the cell to surfaces. (Snot)
Species
2nd name, specific epithet (lower case)
competitive inhibitor
A substance that reduces the activity of an enzyme by binding to the enzyme's active site in place of the substrate. A competitive inhibitor's structure mimics that of the enzyme's substrate.
What are eukaryotic cells?
Cells with a nucleus and membrane bound organelles
chemically defined media
exact chemical composition is known
Transformation in bacteria
genes are transferred from one bacterium to another as "naked" DNA in solution
structural genes of operon
genes that code for proteins
Slide
holds the specimen
noncompetitive inhibitor
interact with another part of the enzyme (allosteric site), causes active site too change shape (nonconform)
Types of chemical bonds
ionic, covalent, hydrogen
Moist Heat Sterilization
kills by denaturation; uses boiling method to kill vegetative forms of bacterial pathogens, almost all viruses, fungi, and their spores within 10 mins > at 100 degrees Celsius
Organism
known as the chemical processing plant, takes things and breaks them down and rearranges them into things that provide nutrients and energy
phases of growth
lag phase, log phase, stationary phase, death phase
induced mutations
occurs in the laboratory
missense mutation
occurs when point mutation results in an amino acid substitution
complex media
made up of nutrients including extracts from yeasts, meat, or plants, or digests of proteins
promoter site of operon
region of DNA where RNA polymerase initiates transcription
stationary phase
period of equilibrium; population stabilizes; growth rate slows
Mutations
permanent changes in the base sequence of DNA
Plasmids
self-replicating circular molecules of DNA carrying genes that are not essential for the cells survival
Sterilization
the destruction or removal of all living microorganisms
What is the catalase test used for?
to distinguish between the hemolytic Streptococcus (-) and hemolytic Staphylococcus (+)
Pasteurization
a technique which kills most bacteria that cause spoilage by heating to a certain temperature
Coagulase test
a test in which organisms are mixed with plasma on a slide. if the cells clump together, the culture is coagulase positive
Chemoheterotrophs
acquire energy and carbon from organic molecules
operator site of operon
acts as a go or stop signal for transcription of the structural genes
Microaerophiles
aerobic; grow in low doses of oxygen
reducing media
anaerobic growth media used to grow anaerobic bacteria
simple stain
aqueous or alcohol solution of a single basic dye; primary purpose is to highlight the entire microorganism so that cellular shapes and basic structures are visible
Polar
at one or both poles of cell
Fixed or Fixation
attaches specimen to the slide kills the microorganisms and various parts with minimal distortion can be alcohol, heat or formalin
death phase
dead cells exceed new cells
enrichment media
designed to increase numbers of desired microbes at detectable levels
Antisepsis
destruction of vegetative (non-endospore-forming) pathogens on living tissue
Disinfection
destruction of vegetative (non-endospore-forming) pathogens on nonliving tissue
Microscope
device that enlarges objects using magnification
differential media
distinguishes colonies of desired organism from other colonies growing on the same plate
Bacillus
Rod shaped bacteria
Synthesis
- 2 or more atoms, ions, molecules, bind together forming a larger molecule - Anabolic/Anabolism (A+B=AB)
Why does gram negative stain red?
- bc the outer membrane keeps the crystal violet from penetrating and the safranin stains it red -very few layers of PG -Outer membrane
Decomposition
- breaks down compounds into smaller parts -Catabolic/Catabolism -AB=A+B
Exchange/displacement
- involve both synthesis and decomposition; bonds are both made and broken - AB+C= AC+B -AB+CD= AC+BD
Nucleus
- oval or round in shape -Contains DNA which is contained within a nuclear envelope
Endospores
-A resistant, dormant structure formed inside of some bacteria that can withstand adverse conditions - formed when nutrients are removed or depleted
types of flagella
-Atrichous -Peritrichous -Polar
types of chemical reactions
-Synthesis -Decomposition -Exchange/Displacement
Genus
1st name (capitalized)
Enzyme
-proteins involved in chemical reactions -determines a cells metabolic pathway
Ribosomes
-site of protein synthesis -consists of protein and rRNA
Factors influencing enzyme activity
1. Temperature 2. pH 3. Substrate concentration 4. Inhibitors
cephalotrichous
3 or more flagella coming from one end
Covalent Bond
A chemical bond formed when two atoms share electrons (strong)
Agar
A complex polysaccharide derived from a marine alga; produces a solid medium
Flagella
A long, whip-like filament that helps in cell motility.
Gram stain
A method for the differential staining of bacteria that involves fixing the bacterial cells to a slide and staining with crystal violet and iodine, then washing with alcohol, and counterstaining with safranin. Results in gram-positive bacteria retaining the purple dye and gram-negative organisms having it decolorized so that the red counterstain shows up.
Catabolism
Metabolic pathways that break down molecules, releasing energy.
Metabolism
All of the chemical reactions that occur within a living organism
selective and differential media
Allows only certain bacteria to grow, with a component that also differentiates among the species that survive.
Fermentation
Anaerobic (without oxygen) cellular process in which organic foods are converted into simpler compounds, and chemical energy is produced
Parts of an enzyme
Apoenzyme + Cofactor/coenzyme= Holoenzyme
inorganic compounds
Compounds that do not contain carbon (ionic bond) -Water, Salt, acid, bases
Photosynthesis
Conversion of light energy from the sun into chemical energy.
Transduction in bacteria
DNA is transferred from a donor cell to a recipient cell in a virus which infects bacteria (bacteriophage)
Photoheterotrophs
Energy from sunlight, carbon from organic compounds
commercial sterilization
Heat treatment to kill endospores in canned food (Clostridium botulinum)
Anabolism
Metabolic pathways that construct molecules, requiring energy.
Sanitization
Lowers the number of microorganisms on objects to safe public levels (eating and drinking utensils)
Diaphragm
Regulates the amount of light on the specimen
Glycocalyx
Sticky, sugary, gelatinous material; made of polysaccharides, polypeptides or both made inside the cell and secreted to surface
stage
Supports the slide
Microbiology
The study of microorganisms
what is the coagulase test used for?
To determine the ability of an organism to clot plasma by the action of the enzyme coagulase. Used to ID Staph aureus (MRSA)
Photoautotrophs
Uses light (energy) and CO2 (carbon source)
facultative anaerobes
can live with or without oxygen
aerotolerant anaerobes
cannot use oxygen for growth, but tolerate it well
components of glycocalyx
capsule and slime layer
organic compounds
carbon-based molecules (covalent bond) carbohydrates, lipids, proteins
log phase (exponential growth phase)
cells are reproducing at exponential rate (sensitive phase)
Lophotrichous
cluster of flagella at one or both ends
Condenser
condenses, collects and directs light from the light source
differential stain
consists of two or more dyes used to identify different kinds of bacteria
plasma (cytoplasmic) membrane
encloses the cytoplasm; provides a barrier; selectively permeable lack sterols
regulatory gene (the I gene)
encodes a repressor protein which switches inducible and repressor operons on and off
Ocular
eyepiece
Amphitrichous
flagella at both poles of the cell
endoflagella (axial filaments)
flagella that spiral tightly around a cell instead of protruding
Most commonly used differential stains
gram stain and acid fast stain
Parts of a microscope
illuminator, diaphragm, condenser, stage, slide, specimen, objective, ocular
Illuminator
light source
lag phase
little or no cell division
Degerming
mechanical removal of a limited area (hand washing or alcohol based hand rub)
normal microbiota
microbes normally present in and on the human body (do not harm us)
spontaneous mutations
naturally occurring; occur in the absence of mutagen causing agents
Atrichous
no flagella
frameshift mutation
one or a few nucleotide pairs are deleted or inserted in the DNA
spiral
one or more twists (vibrio, spirilla, spirochetes)
Golgi complex
organelle that modifies, packages, and transports material out of the cell. FED-EX system
obligate anaerobes
organisms that cannot live where oxygen is present
Nucleolus
produces ribosomes
Parts of the operon model
promoter site, operator site, and structural genes, regulatory gene (the I gene)
What color does gram positive stain?
purple/blue
What color does gram negative stain?
red/pink
Obligate aerobes
require oxygen
Conjugation in bacteria
requires direct cell to cell contact
special stains (structural stains)
reveal certain cell parts not revealed by conventional methods: capsule and flagellar stains
Coccus
round, oval shaped bacteria
Why does gram positive stain purple?
safranin will not stick because gram positive organisms don't have an outer membrane they just have a cell wall therefor it doesn't stick -many layers of peptidoglycan (PG) -contains Techoic acid -contains lipotechoic acid
Specimen
sample
point mutation (substitution)
single base in the DNA sequence replaced with a different base
Monotrichous
single flagellum at one end
Chromosomal structure of a prokaryotic organism
single; circular; double stranded DNA
atom
smallest unit of a chemical element
selective media
suppress growth of unwanted bacteria and encourage growth of desired microbes
Peritrichous
surrounds the entire cell
polymerase chain reaction (PCR)
technique where small specific sequences of DNA can be amplified
Ionic bond
the attraction between oppositely charged ions
objective
two or more lenses, closest to specimen attached to nose piece
Catalase Test
used to identify organisms that produce the enzyme catalase
Chemoautotrophs
uses electrons from reduced inorganic compounds (energy) and CO2 (carbon source)
Naming enzymes
usually end in -ase; grouped based on the reaction they catalyze
Hydrogen bonds
weak attraction between a hydrogen atom and another atom