microbio exam 1

microorganisms

have simple structures that lack differentiated tissues, too small to be seen with the naked eye

characteristics of microorganisms

• can reproduce quickly

• can be grown in high numbers in labs

• can be analyzed through indirect means

examples of cellular microorganisms

• fungi

• protists

• bacteria

• archaea

characteristic of bacteria

single-celled with no true nucleus

archaea

“old world” bacteria, been on Earth for a long time

characteristics of cellular microorganisms

can eat and reproduce itself

characteristics of acellular microorganisms

more of viruses that reproduce with each other to multiply in numbers

prokaryotes

prenucleus cells, such as bacteria and archaea

eukaryotes

“true” nuceus cells

characteristics of eukaryotes

• many are single-celled but larger in size

• others are highly complex multicellular organisms

• make up 1% of life on earth

• have organelles

organelles

small membrane-bound structures with specific functions, can be both micro and macro

Endosymbiosis / Endosymbiotic Theory

interaction between two organisms where one lives inside of the other

examples of endosymbiosis

mitrochondria and chloroplasts: both have their own DNA and ribosomes

• DNA can also be used to trace back lineage to ancestors

cocci shape

can be perfect spheres or oval/bean shaped

cocci arrangement

• single

• diplococci (pairs)

• tetrads (in groups of 4)

staphylococci arrangement

clusters

streptococci arrangement

chains

bacillus shape

rods, ex. found in anthrax

coccobacillus shape

short and plump rods

vibro

slightly occurring bacillus rods that are gently curved

spirillium shape

curled/spiral rods, rigid helix, twisted >2+ along its axis like a corkscrew

spirochete shape

spiral cells, flexible and resembles a spring that can dig through surfaces

mycoplasma

smallest self-replicating organism with the smallest genome of ~650 genes

result of small genome in mycoplasma

• loss of metabolism where it cant digest complicated sugars or produce amino acids

• intracellular parasite: gets its nutrients and survives inside of a host cell

biggest bacteria

e. fishelsoni, has multiple genomes all in different locations

definition of cell envelope

has 2-3 basic layers with distinct functions, acts as a protective unit

layers of the cell envelope

1. cytoplasmic membrane

2. cell wall

3. outer membrane (in some bacteria)

plasma membrane structure

• thin

• 2 lipid sheets

• phospholipids (amphipathic)

cytoplasmic membrane structure

selectively permeable membrane, a lipid bilayer with embedded proteins

what is the cytoplasmic membrane used for

• energy reactions

• nutrient acquisition

• signals from environment

• transport of waste and nutrient regulation

heat's impact on membrane fluidity

increases membrane fluidity

cold’s impact on membrane fluidity

decreases membrane fluidity

characteristics of unsaturated fatty acids

has double and triple carbon bonds, can also have kinks in chain

characteristics of saturated fatty acids

straight carbon chains

impact of unsaturated fatty acids on membrane fluidity

increases fluidity because the chains can’t compact together

impact of saturated fatty acids on membrane fluidity

decreases fluidity because the chains can compact together, creating thicker layers of these chains

how do saturated fatty acids compact

bonds through van der waal forces

• the longer the chain, the more VDR forces

• the more interaction, the more dense

function of bacterial cell wall

• maintain bacterium shape

• protect cell from osmotic (water) lysis and toxic materials

peptidoglycan

rigid structure lying outside plasma membrane, is a mesh-like polymer of sugar in long linear strands

sugars found in peptidoglycan

• NAG

• NAM

function of peptide cross bridge

holds NAM and NAG together, which then holds the peptidoglycan together

how is the peptide cross bridge formation catalyzed

• with 2 terminal D-alamines

• kicks 1 D-alamine off

• transpeptide bond formed between other D-alamine and m-diaminopimelic acid

example of natural strategy

blocking peptide cross bridging

function of penicillin binding protein

a cross-bridge enzyme that catalyzes formation of the peptide bonds

gram - bacteria layers

1. outer plasma membrane

2. thin peptidoglycan

3. plasma membrane

gram + bacteria layers

1. thick cell wall

2. plasma membrane

periplasm

space between the outer plasma membrane and plasma membrane that helps regulate transport into the cell

• makes up for lack of cell wall in gram - bacteria

gram - bacteria characteristics

• prone to desiccation

• prone to chemical disinfectants

• shows a PINK stain

gram + bacteria characteristics

• prone to antibiotics

• more physically protective

• shows PURPLE/BLUE stain

step 1 of gram stain

use crystal violet for 1 minute and water rinse

step 2 of gram stain

iodine for 1 minute and water rinse

step 3 of gram stain

alcohol to decolorize for 10-30 seconds and water rinse

step 4 of gram stain

safranin (counterstain) for 30-60 seconds and water rinse and blow dry

gram - exclusives

• periplasm

• porins

• lipopolysaccharide (LPS)

porins function

allows molecules into periplasm, advantageous for food selectivity and reactions

3 different units of lipopolysaccharide (LPS)

• O side chain / O antigen

• Core polysaccharide

• Lipid A

O side chain / O antigen of LPS

• unique to different strains of bacteria

• carries a negative charge outside of bacteria to protect against host defenses

core polysaccharide of LPS

structural, links lipid A and the unique O antigen

lipid A of LPS

an endotoxin that anchors molecules to the outer membrane

• it being an endotoxin makes LPS dangerous because it is part of or resides inside of the cell

deadly global immune system infection LPS can result in

sepsis, meaning that it is a gram - bacterial infection

glycocalyx

a more universal specialized surface coating, a repeating polysaccharide or glycoprotein unit (a sugar coat)

• combines to make a biofilm

slime layer

• loose glycocalyx, protects against loss of water and nutrients

• allows for gliding motility (helpful for gram + bacteria)

• helps protect from phagocytosis (eats bacteria as food)

capsule

• tightly packed glycocalyx, dense and thick

• allows for adherence to surfaces (sticky)

• increases bacteria size

bacterial biofilms

• pool/combo of bacteria with glycocalyx

• limits access to nutrients and slows growth

• offers massive resistance to phagocytosis and antimicrobials/antibiotics

• responsible for colonizing medical devices like catheters and pacemakers

pili

“hair,” tubes to form structures

• fimbriae

• sex pilus

• secretion systems

fimbriae

thin and hair-like, mediates adherence to surfaces and tissue

sex pilus

connects cells during DNA sharing (conjugation)

secretion systems

injects toxins into target cells (like a bee stinger)

vegetative cell

metabolically active cell

sporulation

the process of making a bacteria an endospore, induced by environmental conditions

endospores

• resists extreme heat, drying, freezing, radiation, and chemicals that would kill vegetative cells otherwise

• biologically invincible

• doesnt conduct any life processes because it’s dormant

• because it’s dormant it cant CAUSE disease, but can be the source of infection

endospore cortex

• a spore coat of several protein layers

• densely packed layer of peptidoglycan

• core comes with DNA and ribosomes and can germinate into a vegetative cell when conditions see fit

C. difficile spores

• persistent and recurring

• causes pseudomembrous colitis (shedding of the colon)

• natural microbiota essentiall for competing with this

• antibiotics kills good bacteria in microbiota, can worsen this

metabolic currencies

ATP and Proton Motive Force (PMF)

process of PMF

1. bacteria pumps proton across membrane via ETC and proton pumps

2. creates 2 concentration gradients (-/+) simultaneously

3. creates stored potential energy at the membrane and a strong force for protons to equalize gradient

how PMF is spent

1. secondary transport

2. ATP synthase

3. flagella movement

passive/simple diffusion

• molecules move from a region of high concentration to low concentration

• requires large concentration gradient for adequate nutrient uptake

• rate decreases as nutrients increase in cell

• h2o, o2, and co2 easily diffuses

facilitated diffusion

• helps diffuse larger molecules and charged ions

• requires membrane transport proteins

• passive b/c no energy is being used, only creates a path for these molecules by opening protein channels

primary active transport

• solute binds to surface of channel (with surface-binding proteins) and goes through channel

• ATP » ADP + Pi

secondary active transport

• paired with import (typically with protons) or with export of other molecules (usually waste)

directions through the channels of molecules in secondary active transport

• symporter: up/up or down/down

• antiporter: up/down

• an advantage over passive transport

group translocation

energy-dependent transport that chemically modifies molecules as it is brought to the cell

PTS

a group translocation system that prevents sugar from exiting the cell by putting a phosphate on it

• makes glucose-6-phosphate

• reduces energy spent trying to fight against the concentration gradient

monotrichous

one flagellum

peritrichous

flagella spread over the entire surface of the cell

spirochetes

corkscrew-shaped bacteria caused by periplasmic flagella or axial filaments

filament of periplasmic flagella

made of flagellin protein subunits, long

basal body/anchor of periplasmic flagella

flexible joint, connects filament of motor

hook of periplasmic flagella

flexible joint, connects filament of motor

MotA/B of flagella motor structure

H+ move through drive rotation, stationary

MS ring of flagella motor structure

the rotor, spins the connected filament

FliG of flagella motor structure

electrostatically interacts with H+ to generate spinning

C ring of flagella motor structure

cytoplasmic switch complex that controls direction of spinning

flagella movement

flagella first runs, then tumbles when changing direction of rotation

chemotaxis

flagella movement direction by concentration gradients

positive chemotaxis

flagella movement towards favorable chemical stimulus

• in presence of an attractant, flagella tumbling frequency decreases and runs towards the attractant are longer

negative chemotaxis

flagella movement away from a repellent

• in presence of a repellant, tumbles are more frequent, and there’s less changes in location

chemotaxis sensor proteins

• senses sensation of concentration gradient

• regulates and uses the same system for “best” direction of flagella movement

• have different channels for certain molecules like O2 and galactose

CheA

chemotaxis sensor kinase

CheY

response regulator correlated with attractants