Microbiology Exam 1

Microbiology

the study of organisms too small to be seen without a microscope

Why are phytoplankton important?

perform photosynthesis and produce oxygen

What is the most effect way to eliminate biofilm of medical devices?

physical removal

An emerging infectious disease can be described as…

a disease that is new, changing, or increasing in incidence

Binomial naming system

Genus: capitalized and italicized

Species: lowercase and italicized

Leeuwenhoek'

first observation of living microbes (“animalcules”)

Modern cell theory

all living things are made of cells, which arise from preexisting cells

Pasteur’s experiment

Spontaneous generation vs. Biogenesis

microbes only come from other microbes

Koch’s postulates

Germ theory: microbes cause disease

postulates that linked specific microbes to specific diseases

First widely used antibiotic by Alexander Fleming

Penicillin

Jenner’s vaccine for smallpox

cowpox provided immunity to smallpox

Eukaryotic cells

include animals, plants, fungi

larger, complex cells with defined nucleus containing linear DNA and membrane-bound organelles, cell wall made of cellulose (plants) or chitin (fungi)

Prokaryotic cells

include bacteria and archaea

simpler cells which are single, circular chromosomes, no membrane bound organelles, has cell wall made of peptidoglycan

How is archaea distinguished from bacteria by their cell walls?

archaea cell walls do not contain peptidoglycan

Evidence for evolution relationships / Phylogeny

rRNA, fossils, anatomy

Taxonomic hierarchy

Dear King Phillip Came Over For Good Soup

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Gram stain

staining method that distinguishes bacteria based on cell wall composition

Enterotube

rapid identification method allowing multiple biochemical tests to be run

Gram positive vs Gram negative

+: purple “grampa-sitive”, thick peptidoglycan layer that retains color, cells are color with clear bkg

-: pink, thin layer and outer membrane that loses primary stain but has pink counterstain, cells are color with clear bkg

based on ability to retain stain after decolorization (cell wall structure)

Rickettsia

intracellular parasite transmitted to humans by arthropods (lice, ticks, fleas)

Bordtella pertussis

may cause whooping cough

Gram + bacteria that form endospores

- Bacillus anthracis (anthrax)

- Clostridium tetani: tetanus, lock jaw

- Clostridium botulinum: botulism paralysis

- Clostridium difficile: severe colitis

Archaea often live as extremophiles…

hyperthermophiles, methanogens, extreme halophiles

What macronutrient is required in large amounts for microbial growth?

nitrogen

Endocytosis

eukaryotic cells engulf “eat” external substances by wrapping the plasma membrane around them, forming internal vesicles

• cells with cell walls cannot endocytose (prokaryotes)

Archaea and bacteria reproduce by…

binary fission

Stages: Lag, Log, Stationary, Death

Equation for growth

Nt=N0*(2^n)

Nt = population at time t, in cells

N0 = population initial, in cells

n = number of generations

Equation for dilution

# colonies / (dilution) = CFU/mL
CFU (colony forming unit)

dilution: 1/10, 1/1000

Wavelength and resolution

Wavelength decreases when resolving power (resolution) increases

—> N.A numerical aperture also increases with resolution

Use of immersion oil for 100X objective lens

Match the refractive index of glass and reduce light refraction

Light microscopes

• Bright-field: dark cells, bright bkg

• Dark-field: bright cells, dark bkg

• Phase contrast: enhances contrast between intracellular structures

• Fluorescence: specimens stains with fluorochromes glow in dark

Electron microcopes

• TEM: transmission, 2D

• SEM: scanning, 3D

Negative stain

ACIDIC stain that - charge dyes the bkg

Positive stain

BASIC stain that + charge dyes the specimen

Differential stain

divides microorganisms into groups based on staining properties

Cell membrane

composed of phospholipid bilayer, proteins, and haponoids

• Fluid Mosaic model: phospholipid bilayers has polar (hydrophilic) head, and fatty acid (hydrophobic) tails

Fimbriae

short/hair-like protein appendages, present in large numbers on cell surface, allow bacteria to attach to surfaces

Pili

longer, thicker protein appendages, 1-2 per cell, specialized for DNA transfer (conjugation)

Flagella in prokaryotes

long, thick protein appendage, drives locomotion by run/tumble (chemotaxis) “like a motor”

Endospores

formed inside certain bacteria as a survival mechanism against harsh conditions

Cilia and flagella

in eukaryotes, move like waves, 9+2 arrangement made of microtubules

What holds line chromosomes (DNA)?

nucleus

RER rough endoplasmic reticulum

• Ribosomes: site of protein production

  • Eukaryotes: complete 80S, smaller 60S and 40S “even”

  • Prokaryotes: 70S

SER smooth endoplasmic reticulum

this ER lacks ribosomes, closer to the periphery of cell

Golgi apparatus

similar to ER, no ribosomes but proteins made are transported here

• Cisternae: modifies and packages proteins and lipids into vesicles

Mitochondria

site of cellular respiration and powerhouse that makes ATP

• contains its own DNA, evolved from ancient bacteria supported by endosymbiotic theory

Organic compounds

must contain both C and H

Monomer of protein

amino acid

Ionic bond

bond between ions of opposite charges

Covalent bond

bond that shares one or more pairs of electons

Hydrogen bonds

bonds between polar molecules NOF

• stabilizes DNA base pairs

Dehydration synthesis

monomers are combined by removal of OH from A and H from B, produces water

Hydrolysis

monomers are released by addition of water, adding OH to A and H to B

Carbohydrates

Chitin, starch, cellulose, glycogen, dextran

Lipids

phospholipid, steroids, oils, fats, waxes, component of cell membrane

Proteins

amino group + R group (side chain) + carboxyl group

• R group makes unique protein

  • amino acids are bonded by peptide bonds (dehydration synthesis)

Primary structure

sequence of AA chain

Secondary structure

H-bonding of peptides causes AA to fold in repeating pattern

Teritary structure

3D folding due to side chain interactions

Quaternary structure

protein consisting of more than one AA chain

Nucleic acids

Genetic material, energy

• Nucleotides: sugar + phosphate group + nitrogen containing base

  • AGTCU

DNA

A—T, C—G, sugar phosphate backbone, double helix

RNA

A—U, G—C, single stranded

Substrate level phosphorylation

addition of phosphate to any molecule or protein, catalyzed by kinase

Oxidative phosphorylation

energy released from ox to another by red, generates ATP in electron transport chain ETC

Chemiosis

in eukaryotes, pump H+ and harness the energy stored in the H+ gradient to make ATP (NADH and FADH2)

• inner mitochondrial membrane

Photophosphorylation

light causes chlorophyll to give up e- to carrier molecules and generate ATP

Role of enzymes

decrease activation energy

Induced fit model

active site of enzyme changes shape as the substrate binds

Apoenzyme, Cofactor, Coenzyme, Holoenzyme

• Apoenzyme: inactive protein component

  • Requires Cofactor: non protein to be active

• Then becomes Coenzyme: activates apoenzyme

• Then becomes Holoenzyme: the complete, active enzyme

What happens to most enzymes at temperatures above their optimal range?

they denature and lose function

Competitive inhibitors

bind to active site on the enzyme and prevents substrate binding

Noncompetitive inhibitors

bind to another part of the enzyme (allosteric site) which changes the shape (wrong lock/key, but reversible)

Roles of microbes

human health (disease, medicine), environment (decomposition), biotechnology (drugs, enzymes), food (fermentation)

Normal microbiota

microbes in human bodies that do not cause disease

• compete with pathogens

• aiding digestion

  • stimulating the immune system

Three-Domain system

bacteria, Archaea, Eukarya

Endosymbiotic theory

theory for origin of eukaryotic cells came from prokaryotic cells

• Mitochondria evolved from aerobic bacteria

• Chloroplasts evolved from photosynthetic bacteria

  • Evidence: own DNA, bacterial-like ribosomes, double membranes

Identification methods

Morphology, staining techniques, biochemical tests, DNA sequencing

Common Gram - bacteria

E.coli, salmonella, neisseria, legionella

Nonproteobacteria

cyanobacteria: photosynthetic, major oxygen producers in aquatics

Measuring growth

Direct: plate counts, microscopic counts, most probable number MPN

Indirect: turbidity (optical density)

Culture media

• Defined: exact chemical composition known

• Complex: comp not fully known

• Selective: inhibit SOME organisms

• Differential: distinguish organisms by reaction

• Enriched: support growth of fastidious microbes

Mesophiles

bacteria that grow best at moderate temperature ~37*C

Obligate aerobes

requires oxygen, grows at top

• + SOD, + catalase

Obligate anaerobes

no oxygen, grows at bottom

• - SOD, - catalase

Facultative anaerobes

prefers but can grow without oxygen, most growth at top

• + SOD, + catalase

Aerotolerant anaerobes

tolerate oxygen

• - catalase

Microaerophiles

prefers specific oxygen conc, growth only at that specific level

• + SOD, ± catalase