MICB 3301 Exam 1

microbiology

study of organisms too small to be seen by the unaided eye (microorganisms or microbes)

microbes require:

the use of microscopes to be seen

what is the size range for microbes?

nanometers to micrometers

what is the size range for bacteria?

micrometers

what is the size range for viruses?

nanometers

what type of small subunit ribosomal RNA (SSU rRNA) is contained in bacteria?

16S rRNA

what type of small subunit ribosomal RNA (SSU rRNA) is contained in archaea?

16S rRNA

what type of small subunit ribosomal RNA (SSU rRNA) is contained in eukarya?

18S rRNA

prokaryotic

have no membrane bound nucleus or organelles (Bacteria + Archaea)

eukaryotic

have a membrane bound nucleus (Eukarya)

what are the characteristics of viruses?

• acellular

• not prokaryotic or eukaryotic

• not in any domain of life

• use different criteria to organize

Robert Hooke

first to describe microbes (observed eukaryotic fungi)

Antony van Leeuwenhoek

first to see prokaryotic bacterial cells

microbes are considered to be…

living organisms (except for viruses)

spontaneous generation

idea that living organisms could develop from nonliving matter

Who discovered that flies don't spontaneously generate?

Francisco Redi

Who discovered that microbes don't spontaneously generate?

Spallanzani

what did Spallanzani’s experiment result in?

microbes will grow in flask of meat broth

no growth if flask is first sealed and boiled

Louis Pasteur

Swan neck flask experiment

what was the swan neck flask experiment?

Nutrient broth was boiled in S shaped flask, broth remained free of growth until flask was tilted so broth could touch S curve and growth was immediately seen —> proves microorganisms in air contaminated broth (not air itself).

Pasteurization

heat to kill microbes

Joseph Lister

surgical procedures to prevent wound infections

Robert Koch

first direct evidence that bacteria cause disease

pathogen

microbe that causes disease

Koch’s postulates

criteria used to establish link between microbe and disease

list of Koch’s postulates

• microbe must be found in all cases of disease, and absent from all healthy

• microbe must be isolated and grown in a pure culture

• same disease must result if microbe is inoculated into a healthy host

• microbe must be isolated again from innoculated individual

Jenner

material from cowpox lesions protects against smallpox, first vaccine

Metchinkoff

discovered bacteria engulfing human cells —> macrophages

Winogradsky

isolated bacterial that oxidize inorganic compounds(iron and sulfur) for energy
chemolithotrophs

Beijerinck

isolated nitrogen-fixing bacteria
- reduce atmospheric nitrogen to ammonia as a nitrogen source

prokaryotic organism habitats

terrestrial and aquatic

prokaryotic organism reproduction

asexual reproduction (binary fission)

binary fission

one bacterial cell gives rise to two identical bacterial cells

bacteria size

0.3 micrometers - 100 micrometers

Thiomargarita size

100 micrometers, one of the largest known bacteria

coccus

sphere

diplococcus

pair of spheres

streptococcus

twisted chain of cocci

staphylococcus

grape like clusters of cocci

tetrad

4 cocci in a square

bacillus

rod

vibrio

curved rod

spirillum

rigid helix (ex: Borrelia burgdorferi, causes Lyme Disease)

spherochete

flexible helix (Ex: mycoplasma)

pleiomorphic

variable shape

hyphae

long filaments that come bacteria and many fungi form

mycelium

network of hyphae

advantages to small size

high SA:V ratio —> more efficient nutrient uptake, faster growth

what makes up the bacterial cell envelope

• plasma membrane

• cell wall

• layers outside cell wall

characteristics of bacterial plasma membrane

• encompasses cytoplasm

• selectively permeable barrier

• main site of energy generation

• transport systems- bring nutrients

• signal transduction systems- sense and respond to environment

amphipathic

polar heads that are hydrophilic and interact with water, nonpolar tails that are hydrophobic

bacterial cell wall

rigid, lies just outside of the plasma membrane

bacterial cell wall functions

• shape

• protection from toxic substances

• osmosis

• prevents osmotic lysis

what color do gram + bacteria stain?

purple

what color do gram - bacteria stain?

pink

peptidoglycan

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

what is important about peptidoglycan?

important component of cell wall
polysaccharide form from subunits
two alternating sugars:
- N-acetylglucosamine(NAG)
- N-acetylmuramic acid(NAM)
sugar chains cross-linked by peptides of alternating D- and L- amino acid

gram + cell wall

thick peptidoglycan layer and plasma membrane

gram - cell wall

a thin layer of peptidoglycan sandwiched between an inner cytoplasmic membrane and an outer membrane

what are teichoic acids?

polymers of glycerol or ribitol
provides stability in gram+ cell walls

components of gram - cell wall

thin peptidoglycan surrounded by outer membrane
lipids, proteins, lipopolysaccharide
no teichoic acids
porins = channels in outer membrane

Three parts of lipopolysaccharides(LPS)

1. lipid A
2. core polysaccharide
3. O side chain(or O antigen)

importance of LPS

• protection from host defenses

• promote cell attachment and stabilize cell wall

• lipid A portion of LPS can act as a toxin

3 layers outside the cell wall

capsules

slime layers

S layers

can all be made by gram + and gram - cells

capsules

polysaccharides

organized, not easily removed

Slime Layers

polysaccharides

diffuse, unorganized, easily removed

S layers

protein, organized

cytoplasm

substance in which inclusions, chromosomes, and ribosomes are suspended. mostly water and highly concentrated

3 types of storage inclusions

• carbon

• phosphate and sulfur

• carbon and nitrogen

carbon storage inclusions

• glycogen

• poly-B-hydroxybutyrate(PHB) granules (long chains of carbon that can be assessed when microbe needs carbon)

• -used to make biodegradable plastic

phosphate and sulfur inclusions

polyphosphate(metachromatic) granules (stores of phosphate)
sulfur globules

carbon and nitrogen inclusions

cyanophycin granules - chains of amino acids (can be accessed by enzymes to break down cyanofycin as a source of carbon)

gas vacuole inclusions

• protein with hollow inside

• control buoyancy

• found in cytoplasm of some aquatic bacteria

• Ex: cyanobacteria

carboxysome microcompartment

cyanobacteria and other CO2 fixing bacteria

polyhedral shape, protein shell

what are the 2 enzymes inside carboxysomes?

RubisCo: adds CO2 to RuBP

Carbonic anhydrase
- converts carbonic acid into CO2

nucleoid

region containing chromosome

R plasmids

resistance plasmids: have genes encoding antibiotic resistance

pilli

thin protein appendages

type I pilli

attachment to surfaces

sex pilli

cell to cell attachment

type IV pilli

• twitching motility: can move the entire group of cells

• repeated extension, attachment, retraction

basal body

rod + series of rings, rod turns inside of L and P rings

hook

extends into environment

filament

made of protein

parts of flagella

filament, hook, basal body

flagella rotation

counterclockwise rotation: forward rotation (run)

clockwise rotation: disrupts run, cell stops and tumbles

chemotaxis

sensory system that enables microbes to move toward or away from specific chemicals

how does chemotaxis work?

• chemoreceptors in plasma membrane sense presence of attractants and repellents

• transmit signals to flagellum

• proteins of basal body take information from chemoreceptors to dictate direction of flagellum rotation

what direction of rotation do attractants cause?

counterclockwise rotation —> flagella bundle, cells run

what direction of rotation do repellents cause?

clockwise rotation —> flagella fly apart, cells tumble (change direction randomly)

features of archaea

• prokaryotic

• asexual reproduction

• terrestrial and aquatic habitats

• circular double stranded DNA chromosomes and plasmids

• gram + or -

• sizes similar to bacteria

do archaea have plasma membranes?

yes

some archaea may have cell walls, but they don’t include what?

peptidoglycan

if archaea don’t have cell walls, what might they have instead?

S layer

what can make some archaea motile?

flagella

methanogenesis

process unique to archaea, biological production of methane

extremophiles

can grow under extreme conditions (some archaea)

thermophiles

grow between 45-85 ºC

hyperthermophiles

grow between 85-113ºC

How are archaeal and bacterial membranes similar and different?

Similar:
- Same size and shape
- Move by flagella
- Reproduce via binary fission

Different:
- Archaea lack fatty acids in their lipids
- No peptidoglycan
- Different lipid bonding