Chapter 3 & 4 Collaborative Flashcards
What is a bright field microscope?
Background is bright
What is a dark field microscope?
Background is dark. Done by adding a disc into the condenser
What are fluorescence microscopes?
Microscopes that use UV light and fluorescent dyes
What is electron microscopy?
Forms an image w/ a beam of electrons with waves 100,000x shorter than waves of visible light, causing an extremely high resolution
What is a transmission electron microscope (TEM)?
It shows internal structures of slides with sliced specimen
What is a scanning electron microscope (SEM)?
Provides an external view of the surface of an organism. No slicing
6 I’s of microbiology?
Inoculation, incubation, isolation, inspection, information gathering, identification
What is inoculation?
Transferring microbes from 1 area to another, or delivery
What is incubation?
Promoting growth
What is isolation?
Isolating a microbe to obtain a pure culture (where only 1 type of organism is growing in a given area)
What is inspection?
Examination
Macroscopic - with eyes
Microscopic - using microscope
What is information gathering?
About:
Biochemical traits - such as metabolic enzymes
Immunological testing - such as antigens and antibodies
Genetic typing - gives most information
What is identification?
Attaching a name or identity to a microbe. Allows you to pick the correct treatment
What is magnification?
Enlarging apparent size of an object
What is resolving power?
Smallest separation at which 2 small, separate objects can be distinguished. 0.2 μm
Some key parts of the microscope?
Ocular lens/eyepiece, revoling nosepiece, objective lenses, coarse focus knob, fine focus knob, base, arm, light source, iris diaphragm, condenser
Where is the light source?
On the base
Where is the iris diaphragm?
A little lever on top of the condenser, underneath the stage
Where is the condenser?
Underneath the stage
Total magnification is?
Objective power x ocular power
What is resolution?
Capacity to distinguish or separate 2 adjacent objects. AKA clarity of an image. Shorter wavelength = higher resolution
What mounts are for live cells and what are for dead cells?
Live - wet mounts and hanging drop mounts
Dead - fixed mounts
What is a smear?
A thin film of solution of microbes on a slide
What is staining?
Coloring microbe with a dye that emphasizes certain structures
What are basic dyes?
Cationic, positively charged dyes. They are used for positive staining
What is positive staining?
The positively-charged basic dye is attracted to the negatively charged microbe, microbe is stained
What is an acidic dye?
An anionic, negatively charged dye. Used for negative staining
What is negative staining?
The negative microbe repels the negatively-charged dye, causing it to stain the background. Opposites attract
What are simple stains?
1 dye is used
What are differential stains?
A primary stain and a counterstain, 2 dyes, are used to reveal different structures. Gram stain and acid-fast stains!
What is a structural/special stain?
Reveals structures external to the cell such as the capsule, flagella, or endospores
How do differential and structural stains work?
If the color you see at the end is the primary stain, it’s positive for whatever you’re testing for
What is a colony?
A substance that has increased in numbers to the point where it is visible with our eyes
Most commonly used isolation technique?
A streak plate. Gets organisms growing on surface
What is media?
Stuff used to grow microbes
How is media classified?
Physical state (liquid, semisolid, solid), chemical composition (synthetic or complex), and functional type (general purpose, enriched, selective, differential, etc)
What is agar?
The most commonly used solidifying agent. It’s solid at room temp and liquefies at 100°C (boiling)
Most commonly used media?
Nutrient broth and nutrient agar, which are complex (since beef extract, an ingredient in both, is not chemically defined)
What is a synthetic chemical composition?
A compound which has pure compounds in an exact chemical formula. Everything is known and every quantity is defined
What is a complex chemical composition?
At least 1 ingredient is not chemically defined
What is general purpose media?
Grows a broad range of microbes
What is enriched media?
Media with complex, organic substances to aid in growth
What is selective media?
Contains 1 or more ingredients that inhibit growth of some microbes, and encourage growth of desired microbes
What is differential media?
Allows growth of several types of microbes and produces visible differences among those microbes
What features do all bacteria have?
A cell membrane, a nucleoid/bacterial chromosome, ribosomes, and cytoplasm
What features do some bacteria have?
Atypical cell wall, glycocalyx, external structures (flagella and axial filaments), and pili and fimbriae
What is a cell membrane?
A phospholipid bilayer embedded w/ proteins which provides a site for nutrient passing/processing and nutrient synthesis. Selectively permeable
What are ribosomes?
Organelles which synthesize proteins
What is cytoplasm?
A dense gelatinous solution inside cells. Mostly water
What is an atypical cell wall?
Mycobacterium - acid-fast
Mycoplasma - wallless, no cell wall
What is a glycocalyx?
A coating of molecules external to the cell wall, made of sugars and proteins
Functions of glycocalyx?
Protects cells from dehydration and nutrient loss, inhibits killing by WBCs , contributes to pathogenicity, forms biofilms
2 types of glycocalyx?
Slime layer - loosely organized and attached
Capsule - highly organized and tightly attached
What are external structures?
Flagella and axial filaments, fimbriae, and pili
What is the difference between flagella of gram positive and gram negative flagella?
Gram pos - 2 rings
Gram neg - 4 rings
Flagellar arrangements?
Monotrichous, lophotrichous, amphitrichous, and peritrichous
What is a monotrichous flagella shape?
Single flagella at one end. Think mono for 1
What is a lophotrichous flagella shape?
Small bunches emerging on one side
What is a amphitrichous flagella shape?
Flagella at both ends. Think ambidextrous, for 2
What is a peritrichous flagella shape?
Flagella dispersed all around. Think perimeter
What are fimbriae and their functions?
Hairlike bristles emerging from a cell surface which provide adhesion to other cells and surfaces
What determines cell shape and prevents lysis?
Structure of cell wall
What is pleomorphism?
Variation in cell shape and size within a single species
What is Bergey’s manual of systematic bacteriology?
A five-volume resource covering all known prokaryotes
What is sporulation?
The formation of endospores
What are endospores?
Inert, resting cells produced by clostridium and bacillus. They have a thick coat, live indefinitely , and arise from vegetative cells
What is rickettsia?
An obligate intracellular parasite. Strange in that it’s a bacteria, not a virus (as are most other obligate intracellular parasites)
What is chlamydias?
An obligate intracellular parasite which can cause a severe eye infection or a lung infection. An STD
What are some specific unusual forms of medically significant bacteria?
Rickettsia and chlamydias
What 2 genus form endospores?
Clostridium and bacillus
What kind of stains are Gram stains and acid-fast stains?
Differential stains of the cell wall
When would you use a wet mount?
For looking at a living organism for a short period of time
When would you use a hanging drop mount?
For looking at a living organism for a long period of time
What cell’s wall has mycolic acid?
Mycobacterium, or an acid-fast cell wall. Makes it thick and waxy
What can mycobacterium cause?
Leprosy or tuberculosis
What stabilizes mycoplasma?
Sterols or cholesterol. It is pleomorphic bc of this
What kind of stain would you perform to look for capsules?
A negative stain. Presence of capsules also means the cell cannot be phagocytized
What is the best way to identify a microbe?
Looking at its’ DNA sequence
What is a name for a liquid media?
Broth
What is a name for a solid media?
Agar
Are nutrient agar and nutrient broth complex or synthetic?
Complex, they contain beef extract that is not chemically defined
What is CHROMagar?
A differential media used for determining the cause of a UTI
3 domains?
Archaea (prokaryotes), bacteria (prokaryotes), and eukarya
What do all living things have?
DNA (and RNA), ribosomes, metabolism, and a cell membrane
What are types of eukarya?
Animals (helminths), plants, fungi, protists (protozoa and algae)
What are other names for axial filaments?
Periplasmic flagella, endoflagella
What are flagella and axial filaments for?
Motility
What are fimbriae for?
Attachment
What are pili for?
Conjugation
What is conjugation?
A partial DNA transfer using pili and exchanging plasmids
What is a cell envelope?
A term referring to the cell wall and cell membrane. In humans, lacking cell walls, this is only the cell membrane
Traits of gram-positive bacteria?
Thick peptidoglycan, teichoic and lipoteichoic acid, stains purple, 2 rings on flagellum
Traits of gram-negative bacteria?
Thin peptidoglycan, outer membrane, lipopolysaccharides (LPS), endotoxin, periplasmic space, stains pink, 4 rings on flagellum
What is peptidoglycan?
It’s present in all bacteria that have cell walls. Made of NAG and NAM
Ribosome S numbers for prokaryotes?
70S, 50S large subunit and 30s small subunit. P for prime numbers
Ribosome S numbers for eukaryotes?
80S, 60S large subunit and 40S small subunit. E for even
What are vegetative cells?
Ones that will turn into endospores, in the meantime they are metabolically active and growing
What is germination?
A return to vegetative growth (in endospores)
What does the staph(ylo) prefix mean?
A cluster, or irregulary shaped
What does the strep(to) prefix mean?
A chain
What does coccus mean?
Round
What does bacillus mean?
Rod
What does coccobacillus mean?
Short and plump
What does vibrio mean?
Gently curved rod
What does spirillum mean?
Spiral, without corkscrew movement
What does spirochete mean?
Springlike, with corkscrew movement
What does diplo mean?
2
What does tetrad mean?
4
What does sarcina mean?
8
What is a strain?
The smallest unit of organization
What do archaea with cell walls have?
Pseudomurein. It’s a fake form of peptidoglycan, since only bacteria can have peptidoglycan
What are archaea?
Extremophiles. Such as hyperthermophiles and extreme halophiles
When would you use a fixed mount?
When looking at dead organisms
