MicroBio 4000 Exam #1

Microorganisms ("microbes")

organisms that are too

small to be seen with the unaided eye

Microbiology

- the study of microscopic organisms, such as bacteria, viruses, archaea, fungi and protozoa.

- includes research on the biochemistry, physiology, cell biology, ecology, evolution and clinical aspects of microorganisms, including the host response to these agents

microbes are the...

- the foundation for ALL life on Earth

- Life still depends on them today

- A few are Pathogens (disease-causing); most are beneficial

Three Domains

- proposed by Carl Woese in the 1970s

- Based on ribosome RNA sequence

1. Bacteria (prokaryotic)

2. Archaea (prokaryotic)

3. Eukarya (eukaryotic)

Eukarya subgroups

Algae

Protozoa

Fungi

Plants

Animals

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Bacteria

- Single-celled

- Peptidoglycan cell walls

- Some are motile (flagella)

- Nutrition from organic or inorganic chemicals, or photosynthesis

Archaea

- Similar to bacteria in shape and size

- Cell walls (NOT peptidoglycan)

- Some are motile (flagella)

- Nutrition from organic or inorganic chemicals

- Not pathogens

- Some can live in extreme environments - Extremophiles

Microbe Eukaryotes =

fungi, algae, protozoa, multicellular parasites

Fungi

- Cell walls - chitin

- Absorb organic chemicals for energy (decomposers)

- Yeasts are unicellular

- Molds and mushrooms are multicellular

- Some are pathogens

Algae

- Diverse grouping of photosynthetic eukaryotes that are plants

- Cell walls (cellulose or pectin, or even silica - diatoms)

- Found in freshwater, saltwater, and soil

- Multicellular and Unicellular species

- Pathogenesis is rare

- Produce oxygen and carbohydrates for others (bottom of the food chain)

Protozoa

- Absorb or ingest organic chemicals for nutrition

- NO cell walls

- May be motile via pseudopods, cilia, or flagella

- Free-living or Parasitic (derive nutrients from a living host)

Multicellular Parasites

- Not strictly microorganisms

- Parasitic flatworms and roundworms are called Helminths

- Some microscopic stages in their life cycles e.g. tapeworms, Ascaris lumbricoides (roundworm)

Acellular Infectious Agents

- needs living host for replication (nonliving)

- viruses, viroids, prions

Viruses

- Consist of DNA or RNA core (genome)

- Genome is surrounded by a protein coat

- Coat may be enclosed in a lipid envelope

- Inert outside living hosts

Viroids

- Infectious RNA

- Found in some plants

Prions

- Infectious proteins

Binomial System

Identifying organisms by their genus and species names

EX. E. coli (k12/156:H7 strain)

Genus = Escherichia

coli = coli

Staphylococcus aureus Informal Naming

"staphylococci" or "staph"

Robert Hooke

- (1665) First to observe cells

Formed Cell theory: All living things are composed of little boxes, or "cells"

Anton van Leeuwenhoek

- 1600s, Observed "Animalcules" (protozoa) and microbes

- wrote about his findings to the Royal Society of London

Spontaneous generation

- the hypothesis that life arises from

nonliving matter; a "vital force" is necessary for life

Biogenesis

- the hypothesis that living cells arise only from preexisting living cells

Francesco Redi

- 1668, filled sealed jars with decaying

meat; flies can't generate to show that Spontaneous generation was false

Louis Pasteur (1861)

- demonstrated that microorganisms

are present in the air, broth, surfaces, etc.

- used S-shape flask experiment to show Microorganisms cannot originate from mystical forces

- disproved spontaneous generation

What was Louis Pasteur's positive control for his experiment?

- after years of no growth he tipped the flask of broth To be exposed to bacteria and it grew

pasture also showed...

- yeast are responsible for fermentation

- microbial growth is responsible for spoilage of food/drinks (bacteria spoil wine by turning it to vinegar.

Pasteurization

- spoilage and harmful bacteria can be killed by brief exposure to heat, without ruining the wine.

Golden Age of Microbiology

- 1857-1914

- discoveries included the relationship between microbes and disease, immunity, and antimicrobial drugs.

- early techniques for classifying and identifying microbes

Lister

- performed surgery under aseptic conditions using phenol. Proved that microbes caused surgical wound infections

Koch

- (1867) established experimental steps for directly linking a specific microbe to a specific disease (anthrax, tuberculosis, cholera)

- developed techniques to isolate pure cultures on solid media with starch and agar.

Koch's Postulates definition

- experimental criteria to demonstrate that a specific microbe causes a specific disease (this is the solidified germ theory)

Koch's Postulates

1. The organism must be observed in every case of the disease.

2. It must be isolated and grown in pure culture.

3. can cause disease in healthy individual

4. The organism must be observed in, and recovered from, the experimental animal. (can be reisolated)

First Smallpox Vaccination

- china in 1500's physicians first vaccinated for smallpox

Edward Jenner

- (1796) experimented by inoculating a person with milder cowpox virus, protected it from getting smallpox.

- Years later Pasteur uncovered why Jenner's experiment worked

- Unknown at the time, this protection is called Immunity

Paul Ehrlich

- (1890s) came up with theory of Immunity: early, basic concept that the body produces substance to destroy

pathogens.

- speculated a "magic bullet" that could destroy a pathogen without harming the host.

- Developed the Salvarsan, to treat syphilis "chemotherapy" in 1910

Alexander Fleming

- (1928) discovered the first antibiotic, penicillin by accident

- accidental because microbes naturally produced as a defense

chronological list of people during golden age

-pasture

- lister

- koch

- gram

- ehrlich

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Limitations of antibiotics

- resistance

- allergies

- toxicity

- strains

- don't work on viruses

What do Microbiologists Currently Study?

Antibiotic resistance and immune system

How are Microbes Beneficial to Us and the World?

- decomposers: for digestion and sewage treatment

- growth factors: vitamins, edited genes for insulin production, food production

- O2, carbon fixation, Nitrogen fixation (prokaryotes) and biofules

Normal Microbiota

- Microbes normally present in and on the human body

- Includes "good" microorganisms and some pathogens

- Bacteria, some archaea, and eukaryotes (often fungi). Also viruses.

Importance of Microbiota (4 reasons)

1. Immune System Development

2. Digestion

3. Production of growth factors (e.g. vitamins B and K)

4. Resistance- ability of the body to prevent growth of pathogens and ward off disease

Biofilms

- Microbes attach to solid surfaces and grow into masses

- Grow on tissue, teeth, and medical implants

- Can cause infections and are able to resist antibiotics and disinfectants

Infectious Disease

A disease in which pathogens invade a susceptible host, such as a human or an animal

Emerging Infectious Diseases

New or changing diseases or diseases increasing in incidence

Emerging Infectious Diseases factors

- Evolution (e.g. V. cholera)

- Changing ecology of the pathogen (e.g. Powassan Virus)

- Modern transportation

- Ecological changes (e.g. deforestation)

prokayotic cell size

- 0.2 - 8 μm in diameter or length

- Volume is ~100-1000 times smaller than Eukaryotic cells

prokayotic cell shape

common shapes = Bacillus (Rod), Coccus (Spherical)

spiral shapes = spirochete, lomger flexible cell wall w/ axial filament

star shapes = aquatic bacteria have weird shapes to adapt

cell envelope of prokaryotes

- includes capsule (if present)

- call wall (2 if gram -)

- Cell membrane

Arrangement of Cocci

Arrangement of Cocci:

- Diplococci: Pairs of cocci

- Streptococci: Chains

Tetrads - Groups of four

- Sarcinae: Cubelike groups of eight

Staphylococci clusters

Arrangement of Bacilli

- Single bacillus

- Diplobacilli: Pairs of rods

- Streptobacilli: Chains of rods

- Coccobacillus: oval shaped rods

3 Structures External to bacterial Cell Wall

1. Glycocalyx

2. Pili and Fimbriae

3. Bacterial Flagella

Glycocalyx

- "sugar shell" external to cell wall made by mostly polysaccharides, sometimes polypeptides

- provides aiding in attachment, prevent phagocytosis and help form biofilms for initial attachment

2 types of Glycocalyx

1. capsules: neatly organized and

firmly attached

2. Slime layer: unorganized and loose

Pili and Fimbriae

- Hair-like appendages

Made up of Pilin protein polymers

Fimbriae

- Adhering to cells or surfaces

(e.g. pellicle or biofilms)

- main function is for attachment

EX. E. coli have it to attach to our intestines

Pili

- typically longer and only 1-2 per cell and more specialized

- Conjugation (Sex pilus, specialized for transfer of DNA)

- Slight motility (twitching and gliding)

Bacterial Flagella

- Long protein structures used in most prokaryotic motility

- filament made of flagellin protein

- spins like propeller in both directions

- Mobility helps with Photo- and

Chemotaxis

Bacterial Flagella propeller powered by...

proton motive force (H gradient)

flagella can be...

- polar (one at one end/both ends) or

- peritrichous (multiple). Form bundle when together, to go opposite direction form tumble.

Eukaryotic Flagella and Cilia

- Structures used for eukaryotic cell motility

- Made up of bundles of microtubules (cytoskeleton)

- located under cell membrane

- movement is whip-like, powered by ATP

Spirochete (bacteria) Flagella

- specialized flagella

- difference from normal bacteria flagella due to it being coiled around cell itself under outer membrane (axial fillament)

- Bundles of "endoflagella" anchored

at one end

- Rotation creates corkscrew motility

How does spirochete Flagella help infection? (virulence factor)

- increased motility allows it to get to more viscous tissues.

Bacterial Cell Wall

- made of Peptidoglycan in bacteria

- Permeable to sugars, amino acids, etc.

- Protects cell membrane and prevents lysis in hypotonic solutions

2 components of Peptidoglycan

- glycan

- tetrapeptide

Glycan

- Polymer of a repeating (NAG)-(NAM) disaccharide

Tetrapeptide

- side chain: link the glycan polymers together

Additional Peptide Cross-bridge (Gram-Positive Cells)

Gram Positive Bacteria

- Stain purple

- have thick peptidoglycan layer

- Have granular layer (aqueous space)

- Teichoic (& lipoteichoic) acid: help link cell wall to plasma memb. and have neg. charge to regulate movement of cations

Polysaccharides and teichoic acids

provides....

Antigenic Specificity in gram positive bacteria

Lancefield Grouping

- discovered by Rebecca Lancefield

- Serological testing of streptococci to determine antogenic specificity.

Gram Negative Bacteria

- stain red/pink

- thin peptidoglycan layer

- have periplasm

- have additional outer membrane

gram negative outer membrane

- selective

- Lipoproteins anchors

- Porin Proteins allow some

molecules to pass

- have lipopolysaccaride (LPS)

Lipopolysaccaride (LPS)

- Have 3 components and in gram neg bacteria outer mem.

- Lipid A embedded in outer membrane and is endotoxin.

- Has core polysaccharide

- Has O polysaccharide which varies and used for identification

Lipid A

- endotoxin released for inflammation

- good thing, but can get out of control

Penicillin

- antibiotic that inhibits cell wall synthesis by preventing

crosslinking of glycan chains

- gram positives generally more susceptible, penecillin cannot pass gram neg. outer membrane

Lysozymes

- Enzyme that Breaks down the glycan chain

Found in sweat, tears, and saliva.

- Gram pos. more susceptible

Gram Staining

- Differential Staining that distinguishes between 2 groups of bacteria

- gram. pos = remain purple

- gram neg. = counterstain pink

Gram Staining steps

1. crystal violet

2. iodine

3. alcohol decolorization

4. safranin (counterstain)

- step 3 is key, Breaks down Outer membrane of Gram-neg.

- In gram pos. alcohol dehydrates the thick peptidoglycan layer into

a mesh-like barrier; crystal violet-iodine is retained.

Mycobacterium

- can't be gram stained due to its waxy cell wall

Bacteria lacking a cell wall =

Mycoplasma

acid fast bacteria

- Small group of bacteria including

Mycobacterium, Nocarida

- More similar to Gram-Positives

- Waxy cell wall, Mycolic Acid

Don't Gram Stain well or at all

Cells that retain a primary red stain are...

"acid-fast". Blue is the counterstain

Mycoplasma

- Lack a cell wall

- Small and vary in cell shape (pleomorphic)

- Stronger cell membrane

containing sterols

Mycoplasma is...

less sensitive to penecillin because they have no cell wall which is pencillin target

Archaea cell walls

- have cell wall made of pseudomurein (No peptidoglycan)

- S-layers (surface layers)- Sheets of protein

or glycoprotein

- cant be gram stained

- some can lack walls however

Eukaryotes cell walls

- Algae: made of Polysaccharides (often cellulose or pectins),

or even silica or calcium in diatoms.

- Fungi: made of polysaccharides (like chitin) and glycoproteins

Fluid Mosaic Model

- Viscous like olive oil

- Proteins move freely

- Phospholipids can rotate

and move laterally

- Self-sealing

Functions of cell membrane

1. Selective Barrier

2. Anchors proteins

3. Energy production and

energy consumption

Osmosis

- movement of water across a membrane

- water always moves to area of higher solute concentration

lysis

- membrane bursts in hypotonic envrionment

Plasmolysis

- cell in hypertonic solution membrane shrinks away from wall

What type of environment are most bacteria found?

hypotonic environment

Why do we use salt as a food preservative?

- provides hypertonic environment to prevent microbial of growth

Aquaporins

- facilitates diffusion of water

Passive transport

- With the concentration

gradient (high --> low) no energy required

- Net movement until

Equilibrium is reached

- includes simple or facilitated

Simple Diffusion

- across lipid membrane

Facilitated Diffusion

- uses permeases

Active transport

- Against Concentration

gradient (low --> high)

- Need Energy Input!

- important in bacteria

Types of active transport

ATP Transporters - use ATP energy

Co-transporters (coupled)

Light-driven

Group Translocation

Co-transporters (coupled)

- use energy directly from

another gradient; bacteria often use H+