module 1 bolded terms

limit of detection for the unaided human eye

100-200 um

robert hooke (1635-1703)

• built first compound microscope

• observed mold, fleas, cork

• published micrographia

• coined the term “cell”

micrographia

intricate drawings of samples studied (by hooke)

antonie van leeuwenhoek (1632-1723)

• built single lens magnifiers

• first to observe single-celled microbes

• called microbes ”small animals” (bc he observed motility)

spontaneous generation

living organisms arise from non-living matter

francesco redi (1626-1697)

• air + environment is important to life

• maggots on decaying meat came from fly eggs

louis pasteur (1822-1895)

• air is important to life

• disproved spontaneous generation

• applied heat to neck flask (broken neck led to growth, intact neck had no growth)

robert koch (1843-1910)

• first guidelines/postulates to establish link b/w specific microbe and disease

• studied link b/w bacillus antracis and anthrax

sergei winogradsky (1856-1953)

• studied microbes in natural habitats

• built column

• soil bacteria oxidize iron, sulfur, and ammonia to obtain energy

• can incorporate CO2 into organic matter

• how to cultivate microbes where they came from

• possible benefits and roles of microbes

resolution

ability to distinguish small objects close together

magnification

an enlarged image of an object

contrast

difference in color intensity between an object and its background

compound (light) microscope

image formed from 2 or more lenses

refraction

bending of light as it passes through an object that slows its speed

fluorochromes

stain for microbes that absorb light and emit visible fluorescent light

scanning electron microscope

uses beam of electrons to scan surface of sample, creates high res 3d image

transmission electron microscope

uses beam of electrons to transmit through a specimen to form image of internal structure

peptidoglycan

• rigid structure that lies just outside the plasma membrane

• composed of sugars/amino acids

gram positive

thick peptidoglycan layer

gram negative

outer membrane with thin peptidoglycan

cocci

spheres that can be single or can be associated in arrangements that is useful for identification

diplococci

divide and remain in pairs

streptococci

divide on 1 plane to form chains

staphylococci

divide in randome planes making grape-like clusters

tetrads

divide in 2 planes forming a square of 4 cocci

sarcina

divide in 3 planes making cubic packet of 8 cocci

bacilli

rods, length to width ratio differ

coccobacilli

short and wide bacilli

diplobacilli

bacilli divide and remain in pairs

streptobacilli

bacilli divide on 1 plane to form chains

palisades

bacilli divide on irregular plane (hinge like)

amphipathic lipids

lipids with hydrophilic and hydrophobic components

hydrophilic parts of plasma membrane

polar ends that interact with water

hydrophobic parts of plasma membrane

non polar tails that are insoluble in water and interact with each other

hopanoids

• hydrophobic molecule similar to cholesterol

• form functional membrane microdomains

• found in bacteria

functional membrane microdomains

platforms for protein complex assembly

peripheral membrane proteins

proteins loosely connected to membrane and easily removed, 20-30% of membrane proteins

integral membrane proteins

amphipathic proteins that are embedded within membrane and not easily removed

episomes

• plasmids that can integrate into the chromosome

• inherited in cell division

• carry genes that confer selective advantage in some situations

frimbriae

• short, thin, hairlike, protein appendages (1000/cell)

• mediate attachment to surfaces, motility, and dna uptake

sex pili

• longer, thicker, less numerous (10/cell)

• genetically encoded on plasmids

• required for conjugation

conjugation

sharing dna between bacterial cells

monotrichous

one flagellum

polar flagellum

flagellum at end of cell

amphitrichous

one flagellum at each end of cell

lophotrichous

cluster of flagella at one or both ends

peritrichous

spread over entire surface of cell

sacculus

• cell wall, confers shape and rigidity to the cell

• protects cell membrane

peptidoglycan

disaccharide unit of glycan with attached peptide of 4-6 amino acids

penicillin

antibiotic that targets transpeptidase

transpeptidase

enzyme that cross links amino acids in peptidoglycan

teichoic acid

• unique to gram positive

• glycerol or ribitol phosphodiester chains

• negatively charged cross threads

lipopolysaccharides (LPS)

• endotoxin in outer membrane of gram negative bacteria

• released when cell dies, overstimulates immune cells + causes cytokine storm

• consists of lipid A, core polysaccharide, and O side chain

lipid a

part of LPS buried in outer membrane

core polysaccharide

10 sugar structure joined to lipid A

O side chain (O antigen)

polysaccharide that extends outward from the core in LPS

lysis

hypotonic environment, cell rupture

plasmolysis

hypertonic environment, cell shrivels up

capsules

well organized layers made of polysaccharides that are covalently bonded and difficult to wash away

slime layers

polysaccharide layers that are unorganized and easily washed away

glycocalyx

polysaccharide extension that aids in attachment to solid surfaces

s layers

geometric pattern made of protein that aid in protecting from ion and pH fluctuations

s layer functions

• protect from ion and pH fluctuations, osmotic stress, enzymes, and predation

• maintains shape and rigidity

• promotes adhesion to surfaces

• protects from host defenses

mycolic acids

fatty acids in mycobacteria

mycobacteria

mycolic acids linked to arabinogalactan link to peptidoglycan

arabinogalactan

polysaccharide linked to mycolic acids in mycobacteria

pleomorphic

can change shape

culture medium

solid or liquid mixture of nutrients and other compounds

peptones

partial proteolytic digestion of protein sources

extracts

• aqueous extracts that contain amino acids, peptides, nucleotides, organic acids, vitamins, and minerals

• usually beef or yeast

agar

• sulfated polymer solidifying agent

• cannot be degraded by most microbes

supportive media

tryptic soy broth and agar, sustain growth of many microorganisms

enriched media

blood agar, supportive media supplemented with special nutrients

selective media

allow growth of particular microorganisms, while inhibiting growth of others

differential media

• distinguish among different groups of microbes and even permit tentative identification of microbes based on biological characteristics

• ex) macconkey agar - lactose fermenters vs nonfermenters

pure/axenic culture

population of cells arising from a single cell

colony

visible cluster of microorganisms

colony forming units

number of colonies multiplied by dilution factor

chemostat

rate of incoming medium = rate of removal of medium from vessel

turbidostat

rate of incoming media adjusted to keep a constant turbidity of sample

lag phase

• metabolically active/no increase in cell number

• adaptation; induce enzymes needed

• length varies w/ species + conditions

exponential/log phase

• population doubles each generation

• primary metabolites synthesized during

• secondary metabolites synthesized towards end

• balanced growth, cell constituents made at constant rates

  • most susceptible to antibiotics

primary metabolites

amino acids, nucleic acids, simple lipids

secondary metabolites

antibiotics, toxins, immunosuppressants

N_t = N₀ × 2ⁿ

exponential growth rate

stationary phase

• growth curve horizontal

• population growth ceases

• new cells made at same rate as old cells die (growth = death rate)

  • secondary metabolites made at beginning

death phase

exponential decline in number of viable cells

long term stationary phase

bacteria evolve or express genes to allow persistent survival, death rate approximately equal to growth rate

sessile

microbes grow attached to surfaces

planktonic

free floating microbes

biofilm

complex slime enclosed communities of microbes

extracellular polymeric substance (EPS)

formed when microbes reversibly attach to conditioned surface and release polysaccharides, proteins, and dna

halophiles

require NaCl conc above 0.2 M

obligate aerobe

requires O₂

obligate anaerobe

usually killed in presence of O₂

microaerophile

requires 2-10% O₂

facultative anaerobes

do not require O₂ but grow better in its presence

aerotolerant anaerobes

grow with or without O₂

barophilic

requires high pressure for growth