Microbiology Exam 1

Microorganisms

• to small to be seen with the unaided eye

• important in maintaining earth ecological balance

• live in humans and other animals; needed to maintain good health

• produce food and chemicals

Nomenclature

Linnaeus; two names: genus and specific epithet

Bacteria

Unicellular organisms; no nucleus; prokaryotic

peptidoglycan layer, divide via binary fission

Three shapes of bacteria

bacillus, coccus, spiral

Archaea

Prokaryotic cells; lack peptidoglycan

3 types of Archaea

• methanogens

• extreme halophiles

• extreme thermophiles

Fungi

obtain nutrients by absorbing organic material from the environment

Protozoa

unicellular; eukaryotes

• obtain nourishment by absorption or injection through specialized structures

Algae

unicellular or multicellular eukaryotes

• obtain nourishment by photosynthesis

Virus

noncellular entities that are parasites of cells

• nucleic acid core, DNA or RNA, surrounded by a protein coat

Helminths

flatworms

roundworms

classifications of microorganisms

• bacteria

• archaea

• eukarya: protists, fungi, plants, animals

Robert Hooke

introduced the term cell

cell theory

all living things are composed of cells

Leeuwenhoek

first to observe microorganisms

spontaneous generation

the idea that living organisms could arise from nonliving matter

biogenesis

living cells can arise only from preexisting cells

Pasteur

demonstrated microorganisms are in the air everywhere; introduced aseptic techniques; yeast ferments sugar into alcohol and bacteria oxidizes it in to acetic acid

Pasteurization

heating process; kills bacteria in some alcoholic beverages and milk

Lister

introduced disinfectant to clean surgical wounds

Koch

proved microorganisms cause disease

Vaccination

immunity is conferred by inoculation with a vaccine

modern vaccines are prepared…

from living avirulent bacteria or killed pathogens, from isolated components of pathogens and by recombinant DNA techniques

Chemotherapy

chemical treatment of diseases

Types of chemotherapeutic agents

• synthetic drugs, chemically prepared in a late

• antibiotics, substances produced naturally by bacteria and fungi to inhibit the growth of other microorganisms

Salvarsan

Paul ehrlich introduces arsenic- containing chemical to treat syphilis

penicillin

Alex flemming observed a snugs inhibited the growth of a bacterial cultures; names the active ingredient

Bacteriology

study of bacteria

mycology

study of fungi

parasitology

study of parasitic protozoa and worms

genomics

study of all of an organisms genes, to classify bacteria, fungi, and protozoa

bioremediation

process uses bacteria to clean up toxic waste

biological control

specific for the pests and do not harm the environment

biotechnology

using microbes to make products such as foods and chemicals

gene therapy

viruses are used to carry replacements for defective or missing genes in human cells

emerging infectious disease (EID)

an emerging, infectious disease showing an increase in incidence in the recent part or a potential to increase in the near future

length

meter

simple microscope

one lens

compound microscope

two lenses; most common used in microbiology

total magnification

objective lens x ocular lens

compound light microscope

uses visible light

resolution

ability to distinguish between two points

staining bc

increases the difference between the refractive indexes of the specimen and the medium

immersion oil

used to reduce light loss between the slide and the lens

brightfield illumination

used for stained smears

• dark objects are visible against a light background

light microscopes

• compound

• darkfield

• phase-contrast

• differential interference contrast

• fluorescence

• confocal

dark field illumination

light objects are visible against a dark background

phase-contrast microscope

brings direct and reflected of diffracted light rays together to form image of specimen

differential interference contrast microscopy (DIC)

provides colored, three-dimensional image of the object being observed

• 2 beams of light= 3D image

Fluorescence microscopy

UV light source

• cells are stained with fluorescent dyes

Confocal microscopy

a specimen is stained with fluorochrome dyes (short wavelength); blue light is used to excite the dyes

• produces 3D image

two-photon microscopy

cells are stained with fluorochrome dyes

• two photons of red (long wavelength) light are used to excite the dyes

scanning acoustic microscopy

based on the interpretation of sound waves through a specimen

• used to study living cells attached to surfaces such as cancer cells, artery plaque, and biofilms

electron microscopy

a beam of elections is used

transmission electron microscopy

ultra thing sections of specimens revealed

scanning electron microscopy

electron gun produces a beam of electrons that scans the surface of a whole specimen

scanned-probe microscopy

uses a metal probe to scan a specimen

atomic force microscopy

uses a metal and diamond probe inserted into the specimen

Staining

colorizing the microbes with a dye that emphasizes certain structures

smear

a thing film of a solution of microbes on a slide

basic dye

the chromophore is a cation

acidic dye

the chromophore is an anion

negative staining

staining the background instead of the cell

simple stain

use of s single basic dye

mordant

may be used to hold the stain or coat the specimen to enlarge it

differential stain

used to distinguish between bacteria

gram stain

classifies bacteria into gram-positive or gram-negative

acid fast stain

stained waxy cell wall is not decolorized by acid-alcohol

special stains

used to distinguish parts of cell

• capsule stain

• endospore stian

• flagella stain

negative staining for capsules

cells stained; negative stain

• notice capsules are not stained; big coating around to help protect from antibodies, endocytosis, etc.

endospore staining

primary stain: malachite green, usually with heat

decolorize cells: water

counterstain: safranin

• resistant to desiccation (remove water) and heat

flagella staining

mordant on flagells

carbolfuchsin simple stain

prokaryotic cell

• one circular chromosome

• no histones

• no organelles

• bacteria: peptidoglycan cell walls

• binary fission

eukaryotes

• paired chromosomes, in nuclear membrane

• histones

• organelles

• polysaccharide cell walls

• mitotic spindle

streptococci

long chain of circles

spirillium/ spirochete

corkscrew fatter/skinny

pleomorphic bacteria

have many shapes not just one

glycocalyx

• outside cell wall

• usually sticky

• capsule: neatly organized

• slime layer: unorganized and loose

• extra cellular polysaccharide allows cells to attach

  • capsules prevent phagocytosis

capsules

prevent phagocytosis

• enables adherence to surfaces

• prevent desiccation and may provide nutrients

flagella

relatively long filamentous appendages consisting of a filament, hook, and basal body

• outside cell wall

• made of chains of flagellin

• attached to protein hook

• anchored to the wall and membrane by basal body

motile cells

exhibit taxis: positive taxis is movement toward an attractant; negative taxis is away from repellent

• rotate flagella to run or tumble

• flagella proteins are H antigens

axial filaments

endoflagella (wraps around) in spirochetes (spiral cells)

• anchored at one end of a cell

• rotation causes cell to move

fimbriae

allow for attachment

pili

facilitate transfer of DNA from one cell to another

• gliding motility

• twitching motlity

cell wall

prevents osmotic lysis

• made of peptidoglycan (bacteria)

• surrounds the plasma membrane

peptidoglycan

polymer of disaccharide

• N-acetylglucosamine (NAG)

• N-acetylmuramic acid (NAM)

Bacterial cell wall

consists of peptidoglycan

• polymer (NAG) (NAM)

• short chain of animo acids

gram-positive cell wall

thick, layered peptidoglycan

• teichoic acids

• may regulate movement of cations

• polysaccharides provides antigenic variation

• 2-ring basal body

• disrupted by lysozyme

• penicillin sensitive

gram- negative cell wall

thin peptidoglycan

• outer membrane

• periplasmic space

• protection from phagocytes, complement and antibiotics

• O polysaccharide antigen

• Lipid A is an endotoxin (part of cell wall)

• porins (proteins) form channels through membrane

• 4- ring basal body

• endotoxin

• tetracycline sensitive

gram stain mechanism

crystal violet iodine crystals form in cell

gram stain mechanism: positive

alcohol dehydrates peptidoglycan

• CV-I crystals do not leave

gram stain mechanism: negative

alcohol dissolves outer membrane and leaves holes in peptidoglycan

• CV-I washes out

mycoplasma

bacteria lacks cell walls

• sterols (protect from lysis) in plasma membrane

• can reproduce outside living host cell

Archaea cell walls

• wall-less

• walls of Pseudomurein (lack NAM and d-animo acids)

wall-less cells susceptible to osmotic pressure—lysis

gram-postive: protoplast

gram-negative: spheroplast

lysozyme

digest disaccharide in peptidoglycan

penicillin; damage to cell wall

inhibits peptide bridges in peptidoglycan

plasma membrane

• phospholipid bilayer

• peripheral proteins

• integral proteins

• transmembrane proteins

  • encloses cytoplasm

  • selectively permeable

  • contain enzymes for metabolic reactions such as nutrient breakdown, energy production, and photosynthesis

  • can be destroyed by alcohol and polymyxins

fluid mosaic model

membrane is as viscous as olive oil

• proteins move to function

• phospholipids rotate and move laterally

simple diffusion

movement of solute from area of high concentration to an area of low concentration