Microbio Exam 1

Koch's Postulates

1) every person with disease must have the microorganism.
2) the microorganisms must be isolated and grown in pure culture
3)the same disease must result when the isolated microorganism is inoculates in a healthy host
4) the same microorganism must be isolated from the diseased host

Problems with Koch's Postulates

1) asymptomatic carriers
2) unculturable or hard-to-grow pathogens
3) using humans would be unethical
4) mutation and evolution
5) may not affect animals

Robert Hooke

published the first drawings of microorganisms; microscope prototype

Antwon van Leeuwenhoek

First person to observe living cells and invented the microscope

Louis Pasteur

A French chemist, this man discovered that heat could kill bacteria that otherwise spoiled liquids including milk, wine, and beer. founded pasteurization and disproved spontaneous generation by using swan-neck flasks

Ferdinand Cohn

discovered endospores and played an instrumental role in classifying bacteria based on morphology and physiology

Martinus Beijerinck and Ivanowski

the agent of tobacco mosaic disease is not a bacterium, because it passes through a filter that retains bacteria

Emil von Behring and Shibasaburo Kitasato

Publicised the importance of antibodies. He actually used animal antibodies to cure diptheria.

Elie Metchnikoff

discovered bacteria-engulfing, phagocytic cells in blood
evidence for cellular immunity

Sergei Winogradsky

discovered iron, sulfur, and ammonia oxidizing bacteria; studied anaerobic nitrogen fixation and cellulose decomposition

Charles Chamberland

created a porcelain filter for bacteria

Edward Jenner

Smallpox vaccine

Bacteria

Do not have a membrane bound nucleus and no DNA complexed with histones

Bacteria chromosomes

usually circular with a single origin of replication and some are polyploid and have plasmids

Bacteria nucleic acids

it is rare to have introns in the genes and have no nucleolus and no membrane bound organelles

Bacteria plasma membrane lipids

Ester-linked phospholipids some have sterols

Bacterial Flagella

submicroscopic in size and filament contain one type of flagellin protein

Bacterial cell wall

Have peptidoglycan

Bacterial ribosomes

70s rRNA's; 49-59 ribosomal proteins

Bacterial and Archaeal cytoskeleton

Rudimentary

Archaeal organization of Genetic materal

no membrane bound nucleus and some DNA complexed with histones

Archaeal Chromosomes

one circular chromosome with multiple origins of replication and some are polyploid and have plasmids

Archaeal nucleic acids

it is rare to have introns in the genes and have no nucleolus and have no golgi, ER, etc

Arachaeal membrane

Glycerol diethers and diglycerol tetraethers

Archaeal Flagella

-thinner
-more than one type of -flagellin protein
flagellum not hollow
-hook and basal body difficult to distinguish

Archaeal Cell Walls

contain polysaccharides and proteins but lack peptidoglycan

Archaeal Ribosomes

same as bacterial (16S small subunit and 23S and 5S large subunit)
BUT also have additional 5.8SEu

Eukarya

linear chromosomes and diploid, rare to have plasmids, has introns in genes, membrane bound organelles, nucleolus

Eukarya cell membranes

Ester-linked phospholipids and sterols and no peptidoglycan

Eukarya Ribosomes and cytoskeleton

80S; rRNA's; 78-80 ribosomal proteins

Refractive Index

a measure of how greatly a substance slows the velocity of light

Working distance

distance between objective lens and specimen

Resolution

ability of a lens to separate or distinguish small objects that are close together and shorter wavelength of light\= greater resolution

Types of Light Microscopes

bright-field, dark-field, phase-contrast, fluorescence, and confocal

Dark-field microscope

Dark background but produces a light image and used for imagine living and unstained preparations

brightfield microscope

Produces a dark specimen on a light background

phase contrast microscope

light microscope that enhances contrast; useful in examining living, unstained cells Specimen appears dark compared to bright background, excellent way to observe living cells. Look for halo!

THE DIFFERENTIAL INTERFERENCE CONTRAST MICROSCOPE (DIC)

creates image by detecting differences in refractive indices and thickness of different parts of specimen good way to show in 3D

The Fluorescence Microscope:

Expose specimen to ultraviolet, violet, or blue light. Specimen usually stained with fluorochromes. Bright image of the object results from fluorescent light emitted by the specimen. Good for finding antibodies

Confocal Microscope

creates sharp, composite 3-D image use laser beam to eliminate stray light. good for studying biofilms

heat fixation

a technique that uses the heat from a flame to attach a smear to a slide usually used for bacteria and archaea

chemical fixation

used with larger, more delicate organisms. protects fine cellular substructure and morphology

Transmission Electron Microscope (TEM)

electrons scatter when they pass through thin sections of a specimen transmitted electrons are under vacuum reduces scatter, gives clear image denser regions in specimen, scatter more electrons and appear darker

scanning electron microscope

Image created from electrons reflected from specimen surface, realistic 3-D image of surface features,Can determine actual in situlocation of microorganisms in ecological niches

Cocci

Spherical cells

Diplococci

cocci growing in pairs

Rods/bacilli

bacteria with a rod shaped morphology and differ widely in their length to width ratio

vibrios

comma shaped

spirilla

rigid spiral shaped bacteria

spirochetes

flexible spiral shaped bacteria

pleomorphic

variable in shape

Macronutrients

required in large amounts ex. carbon, oxygen, phosphorus, nitrogen, hydrogen, sulfur

micronutrients

manganese, zinc, cobalt, nickel, copper aid in catalysis of reactions

growth factors

must be obtained from the environment ex. amino acids, purine, pyrimidines, and vitamins

Gram negative bacteria

Bacteria that have a thin peptidoglycan cell wall covered by an outer plasma membrane. They stain very lightly (pink) in Gram stain. more resistant to antibiotics

Gram positive bacteria

Bacteria that have a thick peptidoglycan cell wall, and no outer membrane. They stain very darkly (purple) in Gram stain. They also have a large amount of techoic acid which help maintain the structure of the cell envelope

Inner leaflet of gram negative

composed of phospholipids

outerleaflet

comprised of lipopolysaccharides which contain both lipids and carbs which have three parts lipid A, the core polysaccharide, and the O side chain

S-layer

regular geometric pattern and is composed of protein or glycoprotein and protects the cell from ion and pH fluctuations, osmotic stress, enzymes and helps maintain envelope shape and rigidity

Fimbriae and pilli

attachment to surfaces, bacterial conjugation and transformation, twitching and gliding motility

pili

grow by adding subunits to their bases

Monotrichous

single flagellum

amphitrichous

one flagella at both poles of the cell

lophotrichous

cluster of flagella at one or both ends

peritrichous

flagella distributed over the entire cell

Bacterial flagella movement

driven by proton motive force

sporulation cycle

Vegetative (ACTIVE!) Mother Cell -\> Adverse environment \=\>. Sporulation -\> Endospore -\> Spore -\> Germination (desirable conditions) -\> Vegetative

Streptococci

bacteria that form a chain

Staphylococci

grape-like clusters

Tetrads

4 cocci in a square

sarcinae

cubic configuration of 8 cocci

coccobacillus

short round rod

bacterial Inclusions

Storage of carbon, phosphate, and other substances; site of chemical reactions (microcompartments); movement

Periplasmic space

In typical Gram-negative bacteria, contains hydrolytic enzymes and binding proteins for nutrient processing and uptake; in typical Gram-positive bacteria, may be smaller or absent

hopanoids

Structurally similar to sterols Present in membranes of many Bacteria stabilize membrane mark microdomain boundaries

group translocation

chemical modification of the transported substance into the cell and the most common is driven by phosphoenolpyruvate

siderophores

proteins secreted by pathogens that bind iron more tightly than host cells allowing for the intake of Fe

peptidoglycan Structure

repeating NAG and NAM units and have alternating D- and L- amino acids attached to alternating sugars• D-glutamic acid, D-alanine, meso-diaminopimelic acid• D-amino acids resistant to peptidases
-strands have helical shape and peptide cross links add strength

Gram positive envelope

tick peptidoglycan, contains techoic acid, smaller periplasmic space and less periplasmic proteins

Outer membrane

Lipids• Lipoproteins •Lipopolysaccharide (LPS)• more complex than gram positive •Braun's lipoproteins connect OM to peptidoglycan.

LPS

causes a negative charge, stabilizes outer membrane structure, attachment to surfaces, biofilm production, permeability barrier, protection from host defenses, endotoxin (lipid A)• Lipid A embedded in outer membrane• Core polysaccharide & O antigen extend out from cell

Protoplasts

gram + cell with peptidoglycan wall removed

spheroplast

cell wall almost completely removed•Gram - cells on which penicillin has acted •Outer membrane still intact despite absence of peptidoglycan

Mycoplasma

no cell wall plasma membrane more resistant to osmotic pressure•Stains gram negative

Glycocalyx

layer of polysaccharide extending from cell surface

Bacterial ribosomal RNA

16S small subunit
23S and 5S in large subunit

Flagellar movement

ccw\= run CW\= tumble

How are endospores resistant?

Calcium (complexed with dipicolinic acid)—inserts in between nitrogenous bases of DNA and stabilizes genetic material• Small, acid-soluble, DNA-binding proteins (SASPs)—also stabilize DNA• Dehydrated core• Spore coat & exosporium protect from chemicals and lytic enzymes

Cannulae

hollow glycoprotein tubes that link cells together to form a complex network, on thermophilic archaea

hami

tiny grappling hooks

Archaella

move by ATP hydrolysis, forward or back, relocate and seek strategy

Glycerol diether lipids

C20 diethers make bilayers

Diglycerol tetraether lipids

formed when two glycerol residues are linked by two long hydrocarbons that are 40 carbons in length, these form monolayers

Polar phospholipids, sulfolipids, glycolipids, and unique lipids

What are found in archaeal plasma membranes

Archaeal Cell Envelopes

- S layer may be only component outside plasma membrane
- some lack cell wall
- capsules/slime layers are rare
Other layers may be complex polysaccharides, proteins, or glycoproteins
•pseudomurein (peptidoglycan-like polymer)

Archaea flagella

Flagella thinner•Some made of more than one type of flagellin protein•Flagellum are not hollow•Hook and basal body difficult to distinguish•More related to type IV bacterial pili, which are involved in twitching motility in that Domain•Growth occurs at the base, not the end

Eukaryotic cell membrane

composed of phospholipids and sphingolipids

Endocytosis

only performed by eukaryotic cells

motor proteins

myosin, kinesin, dynein

actin function

help with amoeboid movement, endocytosis, and cytokinesis