MICB 3301 Exam 1

microbiology

study of organisms too small to be seen by the unaided eye

size range- nano to micrometers

• Viruses (nm)

• Bacteria (um)

Vruses

Typical size: nm

Use electron microscopy

Not in any domain of life

Bacteria

Typical size: micrometers (0.3-100)

Use light microscope

Domain: Prokaryotic

Reproduction: Asexual (Binary Fission)

Phylogenetic tree

Based on sequence and analysis of rRNA (ribosomal RNA)

• Bacteria

• Archaea

• Eukarya

16s

bacteria and archaea rRNA ~ 1500 nucleotides

18s

Eukarya rRNA ~ 1800 nucleotides

Methanogen

Prokaryotic, Archaea, produce methane

Algae and protozoa

Eukaryotic

protist

Yeasts and molds

Eukaryotic

Fungi

Prokaryotic

• No membrane-bound organelles

• No compartments

Eukaryotic

• Membrane-bound organelles

• Nucleus

Virus

Non-living

acellular

neither prokaryotic nor eukaryotic

not in a domain of life

unique categorization criteria

Robert Hooke

1600 ~ first to describe microbes (observed eukaryotic fungi)

Antony van Leeuwenhoek

1600 ~ First to see prokaryotic bacteria

built the first microscopes with grinded lenses

first to illustrate and describe microbial cells

Spontaneous generation

Living organisms could develop from nonliving matter

ex. maggots came from rotting meat

Francisco Redi

• Disproved spontaneous generation

• Used a meat-and-maggot experiment to show that maggots came from fly eggs, not from rotting meat, when flies had direct access to lay eggs on it.

• “Biological life comes from life”

Spallanzani

Boiled two jars of meat broth, sealing one jar immediately while leaving the other open to the air. The sealed jar remained free of microorganisms.

• Proposed that the air carried germs

• Wasn’t fully able to disprove spontaneous generation → heating air destroyed its ability to support life

Louis Pasteur

(1822-1895) Swan-neck flask experiments. By boiling nutrient broth in open-ended but curved flasks that trapped dust and microbes. Discovered that the air carrying the microbes must reach the broth for growth

Pasteurization

Heat to kill microbes

Came from Louis Pasteur: Studying microbes that cause wine “diseases”

Joseph Lister

Applied Louis Pasteur's germ theory to surgery, creating the principles of antiseptic medicine - Surgical procedures to prevent wound infections

Immunology

the study of host defenses

Robert Koch

First direct evidence that bacteria cause disease

• Studied a bacterial pathogen that causes anthrax

• Developed Koch’s Postulates

Koch Postulates

A series of four criteria used to establish a causal relationship between a specific microorganism and a specific disease.

1. Microbe found in all cases of disease, absent from healthy individuals

2. Microbe must be isolated and grown in pure culture

3. The same disease must result when the isolated microbe is inoculated into a healthy host

4. Same microbe must be isolated again from diseased

Pathogen

microbe that causes disease

Bacillus anthracis

pathogen causing anthrax

• Gram Negative

• Capsuled bacteria - glisten due to capsule

Edward Jenner

Produced the first vaccine (vacca, cow)

material from cowpox lesions protects against smallpox

Matchnikoff

Discovered macrophages, bacteria-engulfing

Macrophages

Human white blood cells that engulf disease-causing bacteria.

Winogradsky

Isolated chemolithotrophs (Organisms that use inorganic molecules as electron donors to power cellular respiration and ATP production)

Chemolithotrophs

bacteria that oxidize inorganic compounds (sulfur and iron) for energy

Snottites

Masses of chemolithotrophs - limy, snot-like clusters of bacteria that hang from the ceilings and walls of caves.

Beijerinck

Isolated nitrogen-fixing bacteria

Nitrogen-fixing bacteria

reduce atmospheric nitrogen (N2) to ammonia (NH3)

Made it easier to use N as N2 is too unstable to use as an N source.

Feeds NH3 to plants

______ of earth's microbes have been cultured

Thiomargarita

Thio: Sulfur

Margarita: Pearl

>100 micrometers (Largest known bacteria)

Bacterium that oxidizes sulfur - contains sulfur globules

E.Coli

Size: 4 micrometers

Domain Bacteria

Prokaryotic

Habitat: Terrestrial and aquatic environments

Asexual reproduction

0.3 micrometers- 100 micrometers

Coccus

Sphere shape

Diplococcus

pair of spheres

Streptococcus

chains of spheres

staphylococcus

grape clusters of spheres

tetrads

4 spheres in a square

bacillus

rod shaped

vibrio

curved rod

spirillum

rigid helix

spirochete

flexible helix

pleomorphic

variable shape - lacks a single characteristic form

Hyphae

Long filaments

Mycelium: A network of hyphae

A network of hyphae

Cholera

Shape: vibrio

Borrelia burgdorferi

Shape: Spirochete

• Causes Lyme disease

Mycoplasma

Shape: pleomorphic

Genus with a plasma membrane but no cell wall (peptidoglycan)

Deinococcus

Shape: tetrads

Resistant to radiation

smaller cells have a higher surface to volume ratio enabling them to…

allow for more nutrient uptake, and have faster groth

Bacterial cell envelope

Complete combination of layers surrounding the cytoplasm.

plasma membrane

cell wall

layers outside the cell wall

Plasma membrane

(Most important part of the cell envelope)

• Encompasses the cytoplasm (cytoplasmic membrane)

• Acts as a selectively permeable barrier → allows for the movement of molecules in or out of the cell

• Main site of energy generation (Electron transport chain)

• Signal Transduction system (Sense and respond to the environment)

• Made out of a phospholipid bilayer

Fluid Mosaic Model

model for the plasma membrane that is made out of a lipid bilayer with floating proteins

• Has flexible ester bonds

• Lipids are amiphipathic (Hydrophilic Head) & (Hydrophobic body)

Ester bonds

flexible lipid bonds

Amphipathic

A lipid molecule that has both a hydrophilic region and a hydrophobic region

sterols

eukaryotic plasma membranes are stabilized by

hopanoid

Sterol-like molecule believed to stabilize the plasma membrane of some bacteria

Cell wall

Rigid layer that helps maintain shape and provides protection from toxic substances

• Also protects from osmotic lysis (Water constantly moves into the cell through osmosis because the inside has a higher concentration of dissolved solutes than the outside environment, a hypotonic condition): counters high internal water pressure, preventing the delicate cell membrane from stretching and bursting.

• Lies just outside the plasma membrane

• Made out of peptidoglycan

• Also contributes endotoxins → causes septic shock

Peptidoglycan

Sugar chains crossed-linked by peptides of alternating D- and L- Amino Acids

• Polysaccharides

• N-acetylglucosamine (NAG)

• N-acetylmuramic (NAM)

Osmosis

the diffusion of water through a selectively permeable membrane

hypotonic

bacteria are often in ______ solutions

hypotonic

Solute concentration is less than that inside the cell; cell gains water

hypertonic

Solute concentration is greater than that inside the cell; cell loses water

Gram Positive

• Has a thick layer of peptidoglycan in its cell wall, allowing it to hold inital purple dye after decolorization

• No outermembrane

• Stains purple

Gram Negative

• Thin peptidoglycan cell wall sandwiched between an inner (cytoplasmic) membrane and an outer membrane.

• Stains pink

• Has Lipopolysaccharides (LPS): protection from host defenses

peptidoglycan

important component of cell wall in gram+ and gram- bacteria

polysaccharide formed from subunits (sugars)

polysaccharide of 2 alternating sugars

NAM and NAG

the alternating sugars in peptidoglycan

N-acetylglucosamine

NAG of peptidoglycan stands for

N-acetylmuramic acid

NAM of peptidoglycan stands for

B 1,4 glycosidic bond

bond holding together NAM and NAG

cross linked

sugar chains _______ by peptides of alternating D & L amino acids

Lysozyme

enzyme found in tears and breast milk that cleaves the B 1,4 glycosidic bond

important antibacterial role

Cytoplasm

NAM, NAG, and the amino acids of peptidoglycan were put together by the bacteria in the _______

decreases

having unique amino acids and amino acid forms _________ degradation

cross linked

peptides are __________ in peptidoglycan to provide most of its strength

transpeptidation

a vital chemical reaction where an amino acid or peptide residue is transferred from one compound to another

→ drives the cross-linking of peptidoglycan to build rigid bacterial cell walls

Penecilin

antibiotic that inhibits transpeptidation

peptide interbridge

short chain of amino acids that link peptides of peptidoglycan

indirect cross link

NAM

in peptidoglycan the peptide chain attaches to which sugar?

gram positive cell wall

thick, multiple layer of peptidoglycan

small periplasmic space

plasma membrane

gram negative cell wall

outer membrane

bigger periplasmic space

thin layer of peptidoglycan

plasma membrane

periplasmic space

the space between the outer and plasma membrane in gram - and between the peptidoglycan and plasma membrane in gram +

teichoic acids

polymers of glycerol or ribitol

provide stability to gram+ cells

gram positive cells

contain primarily peptidoglycan

and teichoic acids

gram negative cells

contain a thin layer of peptidoglycan surrounded by an outer membrane

no teichoic acids

porins

outer membrane

comprised of lipids, proteins, and lipopolysaccharides (LPS)

porins

form channels in the outer membrane

allow small molecules to traverse the outer membrane to eventually diffuse and be transported into cytoplasm

Lipopolysaccharide

part imbedded in the outer membrane, other part extended out into environment

made of 3 parts

lipid A

part of LPS

imbedded in outer membrane lipid bilayer

has fatty acid tails oriented inwards

core polysaccharide

part of LPS

middle section made up of a variety of sugars and phosphate groups

O side chain

Part of LPS

furthest away from outer membrane

made of variable sugars and variable numbers of sugars

aka the O antigen

protection

LPS provides ______ against host immune defenses

ex: the O antigen

O antigen

O153:H7

the O stands for

stabilizes

LPS _____ the outer membrane of a gram- cell

attachment

LPS plays a roll in gram negative cell ________

endotoxin

A toxic component of the cell itself

LPS can act as this

cause fever and septic shock