BIOMI 2900 Midterm

Robert Hooke

first to describe microbes

Antonie van Leeuwenhoek

first to describe bacteria

Pasteur

first to cultivate microbes, disproved spontaneous generation

inoculated sterile medium - no pathogens grew unless he added something

how did Pasteur disprove spontaneous generation?

Koch

developed pure culture techniques, proved that microbes cause disease

pure culture

a growing collection of cells derived from one type of microorganism

Koch's postulates

ID diseased animal, grow pathogen in pure culture, reinoculate pathogen into healthy animal (must cause disease!), reisolate pathogen (must be the same as the original)

Beijerinck & Winogradsky

developed enrichment culture technique, discovered microbial metabolic diversity

microbes!

which are more diverse, microbes or plants/animals?

Watson, Crick & Franklin

developed field of DNA structure

Sanger

developed DNA sequencing technique - helped us understand evolutionary history

Woese

developed the universal "tree of life"

rRNA, compared amongst many organisms

basis of the "tree of life"

Whitaker

developed an early model of the "tree of life" - showed most of evolution was microbial in nature

microbial

most of evolution was...

microbes!

which are older, microbes or plants/animals?

Haeckel

with Darwin, developed the earliest model of the "tree of life"

phylogeny

using molecular sequences to study the evolutionary history of life - reveals microbial diversity!

Mullis

developed PCR

Pace

developed cultivation-independent techniques with rRNA

light microscopy

limited by wavelengths of light... includes bright field, phase contrast and dark field

bright field light microscopy

light microscopy method w/ low contrast, need staining to see structures

phase contrast light microscopy

light microscopy method w/ increased contrast of live bacteria

dark field light microscopy

light microscopy method with increased contrast of refractile sample

simple staining (used in bright field light microscopy)

stain cells all with one thing (e.g. crystal violet)

compound staining (used in bright field light microscopy)

stain different things differently in order to differentiate structures (e.g. Gram stain)

transmission electron microscopy (TEM)

pass e- (NOT light) through sample, visualize cell structures in sectioned samples

***100x more detail than light microscopy!

scanning electron microscopy (SEM)

coat specimen with metal and observed whether or not e' bound off (yields 3D black and white image)

fluorescence microscopy

can send light of any wavelength (not just white) - structures are visible if mcls are excited (emit light, photons) --> HIGH CONTRAST

centi

10^-2

milli

10^-3

micro

10^-6

nano

10^-9

pico

10^-12

femto

10^-15

100 micrometers

close to visible with the naked eye

0.02 micrometers

size of ribosomes

0.2 - 0.6 micrometers

size of bacteria

2 micrometers - 2 centimeters

size of eukaryotic microbial cells

10 micrometers

size of human blood cell

10-100 micrometers

size of most plant/animal cells

viscous sources >> inertial sources

why is it hard for microbes to move through fluids @

via diffusion (unlike humans)

how do microbes get necessary mcls?

(cell size)^2

variation of microbial metabolic rate

less, less

the greater the size of a microbe, the _______ its SA:V ratio and the ________ its rate

prokaryotic, eukaryotic, and viral

major types of microorganisms

prokaryotic cells

include bacteria and archaea, 0.2-700 micrometers, no organelles needed, no nucleus, and DNA forms "nucleoid"

eukaryotic cells

include just eukarya, 0.2 micrometers - 10 cm, has organelles, DNA in membrane-bound nucleus

endosymbiosis

hypothesis that chloroplasts and mitochondria are prokaryotic descendents which were engulfed by eukaryotic anscestors

***evidence = mitochondria and chloroplasts have BACTERIAL DNA, rRNA & lipids!

cytoplasmic membrane, cytoplasm, ribosomes, dsDNA genomes

things all types of cells share

viruses

NOT cells, 0.02 - 0.6 micrometers (SMALL!), have capsid shell &(potentially) envelope, obligate parasites

coccus

rod, bacilus

spirillum

spirochete

describes shape AND phylum, flagella on INSIDE of membrane, good at corkscrewing through things

budding & appendaged bacteria

help with attachement, PROECTIONS allow greated SA:V

rosettes

lots of budding/appendaged bacterial cells attached together

filamentous bacteria

long, skinny bead-shaped cells, each just a slice

ex) cyanobacteria

bacterial sheath

"house" in which to protect bacteria, effects relationship with nutrients and environment

cell envelope

the first things an antibiotic must encounter upon entering a cell

gram positive cell envelope

has teichoic and lipoteichoic acids (covalently bound to lipids), thick peptidoglycan layer (retains purple stain)

gram negative cell envelope

FAs present, has periplasm, LPS & outer membranes, turns pink with gram stin b/c of a thin peptidoglycan layer

periplasm

most enzymatic processes occur here, so many proteins are localized here

LPS / outer membrane components

porins, lipid A, core polysaccharide, O-polysaccharide

***the outermost surface of interaction, makes up MOST of cell wall!

lipid A

acts as an endotoxin for some pathogens in LPS layer of gram-negative cell envelope

O polysaccharide

provokes a strong immune response in people, found in LPS layer of gram-negative cell envelope

porins

transmit hydrophilic, low MW substances (differ in selectivity)

peptidoglycan

moveable, but gives protection and strength, unique to bacteria, chain of polysaccharides w/ peptide side chains, x-link = covalent peptide bond, can be L or D

direct crosslinks

transpeptidation in Gram negatives

peptide interbridges

transpeptidation in Gram positives

peptide bonds

vertical bonds in peptidoglycan

glycosidic bonds

horizontal bonds in peptidoglycan

autolysis, transpeptidase

how is a new peptidoglycan made?

transpeptidase

adds new peptide x-links to make new peptidoglycan

autolysins

cuts B-1,4 bonds of the polysaccharide backbone so new polysaccharide can be added

lysozyme

antimicrobial enzyme that cleaves the B-1,4 bonds of the peptide backbone

B-lactam antibiotics

antimicrobials that bind and inhibit transpeptidase

cytoplasmic membranes

act as permeability barrier, anchor proteins and conserve E via PROTON MOTIVE FORCE

proton motive force

H+ gradient drives E

nonpolar, small (e.g. O2, N2, H2O)***(+) nutrients the cell wants, via transporters!

what molecules can pass through the cell membrane w/o help?

polar, charged

what molecules can't pass through the cell membrane?

bacterial membranes

phospholipid bilyare w/ hydrophobic head/hydrophilic tail, glycerol-phosphate backbone, FA connected to head via ESTER BOND ***properties vary based on differing side chains & FAs

archaeal membranes

ETHER-linked phospholipids, lipids composed of ISOPRENE units (not FAs), have both GLYCEROL DIETHERS and TETRAETHERS ***may have lipid MONOlayers, BIlayers, or a MIX of both

integral membrane proteins

embedded in the membrane, can act as channels

peripheral membrane proteins

1 part anchored to the membrane, function associated with the membrane

active membrane transport

transport that uses energy (ATP or Proton Motive Force)

Lac permease (example of ACTIVE transport)

transports lactose to E.Coli via proton motive force

Phototransferase (example of ACTIVE transport, E.Coli)

type of group translocation --> substance = chemically modified during transport, used to transport GLUCOSE, FRUCTOSE and MANNOSE, requires 5 proteins ***E = from phosphate bond in phosphoenol pyruvate

ABC Transporter (ATP-binding cassette)

>200 diff systems, highly substrate-specific

*gram (-) have PERIPLASMIC binding pro

*gram (+) have SUBSTRATE binding pro

passive transport

transport via diffusion

across membrane, through integral membrane pro

diffusion can occur (2 ways)...

2 solutes go till = [ ] on each side of membrane

end result of diffusion

uniporters

1 mcl transported passively in 1 direction

antiporter

2 mcls transported passively in opposite directions

symporters

2 mcls transported passively in the same direction (1 of them is going down its concentration gradient)

archaeal cell envelope

***NO peptidoglycan! + usually no outer membrane, often have and S-layer, and some have pseudomeurein (regardless of presence of S-layer)

S-layer

tough, paracrystalline structure in archaeal cell envelopes, composed of pro or glycopro

pseudomurein

polysaccharide in archaeal cell envelopes, similar to peptidoglycan, but has NO D-AAs & has B-1,3 (not B-1,4) bonds between sugars

poly-B-hydroalkanoate (PHA)

internal cell structure -> polyester, C & E storage

glycogen

internal cell structure -> glucose polymer, C & E storage