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