When did Microbiology begin?

Robert Hook

1665-saw eukaryotic cells & came up with the term, cell

came up with the Cell Theory

What is The Cell Theory?

Who is Antoni Van Leeuwenhoek?

1. spontaneous generation vs. biogensis

(non-living things to living) vs. (living things to living things)

2. Germ Theory of disease

(witchcraft/spirits vs. germs)

disprove spontaneous generation

wire lid= no maggots

no lid= maggots

1857-1914

showing the connection between food spoilage (beer, wine) and microorganisms was a major step towards establishing the relationship between diseases & microbes

"pasteurization"( killing germs in foods, stops spoilage) heats the food to kill bacteria by killing harmful bacteria

-Pasteur proved that disease in silkworms was caused by a protozoan

-Semmeiweis- childbirth fever and handwashing

-Lister applied theory to medical practice= started to treat surgical wounds with phenol which reduced death from surgery

1. In dead cattle blood- rod shaped bacteria= bacillus anthracis

2. He cultured the bacteria

3. Injected healthy cattle with bacteria

4. When the cow died, he isolated the same bacteria

1. The microbe must be present in every case

2. Must grow in pure culture

3. The lab culture should cause disease

4. Recover the organism from infected animals

Edward Jenner 1796; he protected people from small pox by infecting them with cowpox ( a much milder disease)

Methods to destroy microbes:

produced by one microorganism;

Alexander Fleming in 1928- mold to Pencillium

bacteria and archaea

bacteria are differientiated by:

1. chemical composition

2. nutrient requirement

3. source of enery

diameter: 0.2-2.0 micrometers

length: 2-8 micrometers

spirallum

vibrios

staphylococcus

bacteria cell envelope:

gram negative cell

outside membrane

peptioglycon

cell membrane

bacteria cell envelope:

gram positive cell

peptidoglycan

cell membrane

no outer membrane!!

-toxicity

-immunity

-drug sensitivity

- capsules: glycocalyx (acidic sugar)

use negative staining to visualize

attached to cell wall

polysaccharide & polypeptide

if the glycocalyx is loosely attached- slime layer

Capsule Functions:

1. contribute to virulance (ability to cause disease)

2. protect pathogenic bacteria from phagocytosis

3.attachment

4. protect agaisnt dehydration

capsule example:

stretococcus pneumonia

smooth?

rough?

smooth: capsule (will cause disease)

rough: no capsule (no disease)

capsule example:

stretococcus mutans

attached to teeth by capsule- requires sugar

the bacteria ferments the sugar to organic acids= erodes the tooth enamel

What are flagella?

long filamentous appendages that propel bacteria in prokaryotic cells

single polar flagellum

(looks like a sperm)

at each end

(looks like -0-)

two or more at a pole

(looks like =0)

over entire cell

(looks like a squiggly sun)

movement of flagella?

run & tumble

rotates clockwise or counterclockwise

serovars?

flagella proteins have these;

they are variations in gram negative cell

example: E. Coli has 50 different serovars

E.Coli 0157:H7 is food poisoning

found in spirochete/similar to flagella in structure

move like a corkscrew

axial filament example:

causes syphilis?

causes Lyme disease?

syphilis: trepenema pallidum

Lyme disease: borrelia burgdorferi

smaller than flagella; gram negative cells; can have hundreds

example: neisseria gonorrhoeae- whooping cough

longer than fimbriae; 1 or 2 per cell; used for transfer of DNA

(looks like 0======)

the cell wall?

-almost all prokaryotes have cell walls

-some eukaryotes have cell walls (plants, fungi, algae)

-contains peptidoglycan (peptides & sugar)

peptides= D &L form == penicillan- interfered with the peptide crossbridges

sugar= NAG & NAM=== NAG- common; found in bacteria & red blood cells

gram positive cell wall:

-25% of the weight of cell is peptidoglycan

-teichoic acides (negative surface charge=affects virulence)

example: streptococcus Group A= most dangerous pathogens

streptococcus pyogens- sore throat

gram negative cell wall:

-more prone to lyse

-no peptide cross links

-no teichoic acids

-outer membrane

-peptidoglycan

-inner membrane (all cells have inner membrane)

example: E.Coli

internal cell wall structure:

plasma membrane (cytoplasmic)

a thin structure lying inside the cell wall and enclosing the cytoplasm of the cell

in prokaryotes, consists mostly of phospholipids

in eukaryotes, also contain carbohydrates & sterols such as cholesterol

looks like two-layered structures= lipid bilayer

each phospholipid contains a polar head, composed of hydrophilic (water-loving) and soluble in water & nonpolar tails which are hydrophobic and insoluble in water

polar heads-on the surface of bilayer

nonpolar heads-interior of bilayer

certain molecules and ions pass through the membrane, but others are prevented from passing through it

folds in the plasm membrane that develop by the process used for preparing specimens for electron microscopy

passive processes- cross from an area of high concentration to an area of low concentration (move with a concentration gradient)

active processes- cell must use ATP (energy) to move substances from areas of low con. to high con. (against a con. gradient)

1.simple diffusion

2.facilitated diffusion

3.osmosis

the net (overall) movement of molecules or ions from an area of high con. to an area of low con. until the molecules or ions are evenly distributed ( equilibrium)

the net movement of solvent molecules across a selectively permeable membrane from an area with a high con. of solvent molecules to an area of low con. of solvent molecules.

in living systems, the chief solvent is water

pressure produced by a movement of water through a selectively permeable membrane

1. isotonic

2. hypotonic

3. hypertonic

a medium whose concentration of solutes is lower than that inside the cell.

most bacteria live in hypotonic solutions and swelling is contained by the cell wall

cells with weak cell walls such as gram neg. bacteria may burst or undergo osmotic lysis

a medium having a higher con. of solutes than inside the cell has

most bacterial cells shrink & collapse because water leaves the cell by osmosis

for a prokaryotic cell- the substance of the cell inside the plasma membrane

80% water & contains primarily proteins, carbohydrates, lipids, inorganic ions

thick,aqueous, semitransparent & elastic

all eu & pro cells have them

the sites of protein synthesis

within the cytoplasm of pro. cells

reserve deposits

very common in a wide variety of bacteria

large inclusions that take their name from the fact that they sometimes stain red with certain blue dyes

collectively known as volutin

inclusions typically consisting of glycogen & starch

their presence can be demonstrated when iodine is applied to the cells

glycogen appears reddish brown

starch appear blue

appear in various species of mycobacterium, bacillus, aztobacter, spirillum & other genera

revealed by staining cells with fat-soluble dyes such as Sudan dyes

derive energy by oxidizing sulfur and sulfur-containing compounds

carboxysomes:

hollow cavities found in many aquatic prok.

each vacuole consists of rows of several individual gas vesicles (hollow cylinders covered by protein)

inclusions of iron oxide formed by several gram-neg. bacteria that act like magnets

bacteria may use magnetosomes to move downward until they reach a suitable attachment site.

2 types of metabolism:

1. catabolism

2. anabolism

breakdown of organic molecules

releases energy

ATP-ADP+P

building big molecules from smaller molecules

ex: protein synthesis, DNA synthesis

maximum number of substrate molecules an enzyme molecule converts to produce each second

E+S---ES-----P +E

naming enzymes:

add -ase to the end

most enzymes require a cofactor (Fe, MG, Cal, ions

if the cofactor is an organic molecules, it is called a coenzyme (vitamins)