Microbiology Midterm Notes

types of microscopy

light microscopy, dark field microscopy, phase-contract, and nomarski

light microscopy

“bright field microscopy”, compound, lenses are parfocal

dark field microscopy

A condenser prevents light from being transmitted through the specimen, specimen looks light against a dark background

parfocal

when you change the objective, the image stays in focus as you go up in magnification

scanning

40X

low power

100X

high dry

400X

oil immersion

1000X

phase-contrast and nomarski

used to examine alive and unstained organisms

flourescence microscopy

utilizes UV light

confocal microscopy

Uses UV light. Beams of UV light are focused through a thin optical fiber. Fluorescent emissions are focused on a detector. 3D image

Electron microscopy

Beams of electrons instead of light. Electromagnets instead of glass lenses to focus the beam. Electrons must travel through a vacuum.

Transmission electron microscope (TEM)

see to a single nanometer, thin slice of the specimen, electrons pass through the specimen. Look inside

scanning electron microscope (SEM)

Can see down to 20 nanometers; specimens are coated with a thin layer of heavy metal. Better 3D images of the surface of specimens. Scanning - electrons are back scattered. Look on surface

stain

a molecule that can bind to a celular structure and give it color. common are cationic since bacterial cells have a slight negative charger

simple staining

uses a single dye

differential

uses two or more dyes

wavelength

the length of a light ray

resolution

Light must pass between two objects for them to be seen as separate things. The focus of something

reflection

light strikes ann object and bounces back

Transmission

the passage of light through an object

absorption

neither bounce off or go through absorption. Luminance/fourescence

Prokaryote

no membrane bound organelles

eukaryote

have defined membrane bound organelles

pro

before

karyon

nucleus

eu

true

what do eukaryotes and prokayotes have in common?

genetic material (double stranded DNA), cell membrane (phospholipid bilayer)

what are the differences between prokaryotes and eukaryotes

Prokaryotes have a cell wall; they are haploid and have a single circular chromosome. Eukaryotes have paired linear chromosomes

the two domains of prokaryotes

archaea and bacteria

archaea

crazy extremophiles

archea and bacteria are evolutionary distinct

true

prokaryotic structure

0.5-2 micrometers in diameter but have a large surface-to-volume ratio

why is a large surface-to-volume ratio beneficial?

exchange nutrients and waste more efficiently, metabioloze quickly and therefore replicate quickly

identify the shape

cocci

identify arrengement

coccus

identify arrangement

diplococci

identify arrangement

staphlycocci

identify arrangement

streptococci

identify arrangement

sarcina

identify arrangement

tetrad

identify shape

bacilli

identify shape

bacilli

identify arrangement

coccobacillus

identify arrangement

bacilli

identify arrangement

diplobacilli

identify arrangement

palisades

identify arrangement

streptobacilli

indentify shape

spirochete

identify shape

vibrio

identify shape

corkscrew’s form

variations that effect shape of cell

plentiful conditions, nutrient deprivation, pleomorphism

pleomorphism

the ability to alter shape or size in response to environmental cues, not uniform in a culture

basic functions in a bacterial cell

reproduction, metabolism, response to environmental changes, and change through mutation

basic components of a bacterial cell

cell envelope, nucleic acids, enzymes, some have spores, and appendages for motility and adhesion

fucntion of plasma membrane

keep good things in, keep bad things out, control moveemnt of materials, sensing the environment

what the plasma membrane composed of

phospholipid bilayer

function of proteins in the cell membrane

structural support, recognition, communication, and transport

function of cell wall

maintain cell shape and protect the cell from rupturing

the most important component fo the cell wall

peptidoglycan

peptodoglycan

forms a supportive net around the bacterium, alternating with gluNAC (NAG) and murNAC (NAM), the fence is cross-linked by tertapeptides on NAM molecules

Gram (+) Bacteria

Thick layer of peptidoglycan

Gram (-) Bacteria

complex outer membrane with thin layer of peptidoglycan

Acid-fast bacteria

thick lipid layer over thin peptidoglycan, difficult to treat infections of this bacteria

mycoplasma

smallest of bacterial cells, no cell wall, respiratory infections

internal structure of bacterial cells

cytoplasm, ribosomes, nuclear region, inclusions, endospores

external structures of bacterial cells

flagella, pilli, glycocalyx

identify shape

spirochete

identify shape

vibrio

identify shape

corkscrew’s form

flagella

Confers motility via its rotation

number and arrangement of flagella varies

important for “chemotaxis”

chemotaxis

directive movement towards or away from chemical stimulus, non-random movement, occurs along a concentration gradient

flagella attachment

gram positive

flagella attachment

gram negative

types of flagella arrangement

polar (mono or amphitrichous), peritrichous, lophotrichous

lophotrichous

monotrichous

flagella at one pole

amphitrichous

flagella at each pole

monotrichous

peritrichous

run

flagella bundle rotates counter-clockwise

tumble

flagella bundle comes apart, rotates clockwise

positive chemotaxis

bacteria move towards an attractant, temblus less frequent

negative chemotaxis

bacteria move away from a repellant, tumbles more frequent

no attractant or repellant

postive chemotaxis

negative chemotaxis

the two kinds of pili

long conjugation and short attachment

long conjugation pili

F-pili/sex-pili, genetic transfer, allow the organism to mate

short attachment pili

fimbriae, allow the organism to stick to things

glycocalyx

External to the cell wall, it provides protection, like a capsule or a slime layer

endospores

found in some Gram-positive bacteria, Bacillus sp and Clostridium sp. (soil species), life after death - produce an endospore when the environment becomes harsh, highly resistant

metabolism

the total sum of chemical reactions (harvesting energy and synthesizing new components)

anabolism

reactions involved in synthesis

require energy

catabolism

degradative reactions

produce energy

metabolic pathway

starting compound is converted to intermediate molecules and end products

components of metabolic pathways

enzymes, ATP, energy source, electron carriers, and precursor metabolites

the role of enzymes

acts as chemical catalysts

lower the activation energy of a reaction

activation energy

The energy required to activate a chemical reaction

enzyme characteristics

Most are proteins, provide a reactive site for substrates, are not used up in the reaction, can be recycled and function in very low concentrations