BIMM 120 Midterm 2

Example of gram negative cell

Proteobacteria

Example of gram positive cell

Firmicutes

What is cell wall made of?

Mur-NAc and Glc-NAc (sugar) crosslinked with short peptides

What does penicillin do?

Interferes with the synthesis of cell walls

Penicillin example of antibiotic resistance

Penicillin is a B-lactam, resistance cleaves B-lactam ring not allowing penicillin to interfere with sythesis of cell walls

Vancomycin

Binds terminal D-Ala-D-Ala dipeptide and prevents cross-brindge formation. (Another anti-biotic)

Gram positive bacteria contains:

Teichoic acids: (Chains of ribitol or glycerol linked by phosphodiester bonds)

S layer: Tough layer of many copies of a single protein

Periplasm: Contains digestive enzymes between plasma membrane and peptidoglycan

Porin

Passage of hydrophilic molecules

Lipopolysaccharide Phospholipid

On outer membrane and prevents diffusion of hydrophobic solutes into bacteria

Lipoprotein

globular proteins that are anchored to a membrane by a lipid moiety (molecule)

Mycobacterium

Cause tuberculosis and leprocy

Not gram (+) or (-)

Thick cell walls which make it hard to stain

Acid fast staining needed

Acid fast staining

Use heat to drive pink stain into cell

decolorized with acid-alcohol

Counterstain with methylene-blue

Monotrichous

A single flagellum, usually at one pole

Amphitrichous

A single flagellum at both ends of the organism

Lophotrichous

Two or more flagella at one or both poles

Peritrichous

Flagella over the entire surface

chemotaxis

Movement of an organism in response to a chemical stimulus

Bacteria Macronutrients

C, H, O, N, P, S

Needed for amino acids, nucleotides

Bacteria Micronutrients

Co, Cu, Mn, Mo, Ni, Zn

Prototroph

Can make all its own biological molecules

Auxotroph

Must be supplemented with biological molecules to survive

Phototrophs

Use sunlight to get energy

Chemotrophs

Oxidize chemicals to get energy

Oxidation

Loss of e-

Reduction

Gain of e-

Organotroph

Gets electrons from organic compunds

Glucose, amino acids, lipids

Lithotroph

Gets electrons from inorganic sources

H20, H2S, H2, Fe2+, NH3, NO2-

Autotrophs

Produce nutrients from inorganic materials (producers)

Heterotrophs

Consumes nutrients from other organisms (consumers)

Agar

Mixed polysaccharides derived from seaweed

Streak Plates

method to isolate colonies

Chemostat

Bioreactor which grows cells permanently in the exponential phase

Serial dilution

Dilution of colony forming units with each subsequent plate containing less concentration than the previous

Confluent lawn of bacteria

Heavy uniform growth of bacteria and obscures individual colonies

Psychrophile

Bacteria which live in cold temperature

Mesophile

Bacteria which live in moderate temperature

Thermophile

Bacteria which live in hot temperature

Acidophile

Bacteria which can or must live in acidic conditions (Low pH)

Alkaphile

Bacteria which can or must live in basic conditions (High pH)

Aciduric

Bacteria which can withstand acidic conditions, but prefer to grow in neutral conditions

Halophile

Bacteria which can live in saline conditions

Anaerobe

Bacteria which can live without oxygen

Faculatative anaerobe

Bacteria which can live in the presence or absense of oxygen

Aerobe

Bacteria which need oxygen to live

Microaerophile

Bacteria which requires lower level of oxygen to live

Barophile

Bacteria which lives in high-pressure environments

Barotolerant

bacteria which can tolerate high-pressure environments

Radioresistant

bacteria resistant to radiant energy (radiation)

Example of radioresistant bacteria

Deinococcus radiodurans

Antomicrobial measures

Refigeration/ freezing

Heat (Pasteurization)

Steam

Pressure

Filtration (0.2 micrometer filter)

Dehydration (drying, sugar honey, salting)

Bactericidal antibiotics

Kills bacteria

Bacteriostatic antibiotics

Suppresses growth of bacteria

Regulon

A collection of operons that are coordinately regulated

Quinolones

Antibiotic that poisons bacterial topoisomerases

Core polymerase

a2, b, bʹ

Required for initiation and elongation

Sigma factor

s

Required for initiation phase only

Holoenzyme

Core polymerase and sigma factor

Rifamycin B

Binds to bacterial RNA polymerase and inhibits transcription initiation

Actinomycin D

Nonselectively binds to DNA and inhibits transcription elongation

Messanger RNA (mRNA)

Encodes proteins

Ribosomal RNA (rRNA)

Forms ribosomes and is catalytic (carries our enzymatic reactions)

Transfer RNA (tRNA)

Shuttles amino acids for translation

Small RNA (sRNA)

Regulates transcription or translation

tmRNA

Frees ribosomes stuck on damaged mRNA

RNA degradosome

RNase that hydrolyzes RNA to nucleotides

Tetracycline

Inhibits aminoacyl-tRNA binding to the ribosome A site

Chloramphenicol

Inhibits peptidytransferase

Streptomycin

Inhibits 70s ribosome formation

Puromycin

Triggers peptidyltransferase prematurely

Erythromycin

Causes abortive translocation

Fusidic acid

Prevents translocation

Polysome

Enable increased protein production and help protect the mRNA from RNases