DNA to mRNA

protein synthesis

biosynthesis

promoter

RNA (pol)ymerase

Sigma (σ) Factor

RNA pol + σ factor

synthesizes RNA

5 protein subunits

1. RNA Holoenzyme binds to DNA (forms Closed Complex)

2. DNA is unwound

(Start of Open confirmation)

1. Ribosome binds to mRNA at Shine-Delgarno sequence

2. AUG is first codon

1. Aminoacyl-tRNA arrives at A site

2. Transpeptidation reaction occurs between P and A sites

3. Translocation

– Empty tRNA exits from E site

– tRNA with growing chain moves from A to P

– New tRNA comes into the A site

1. E site (exit site)

2. P site (peptidyl, or donor site)

3. A site (aminoacyl, or acceptor)

+lipids= lipoproteins; gram -

+sugars= glycoproteins; gram +

two or more genes transcribed from 

a single promoter

• Regulatory regions are upstream of 

genes; one regulatory region can control grouped genes

Transcriptional-  change in gene expression levels by altering transcription

rates.

Translational - control of the levels of protein synthesized from its mRNA.

Protein- how much the mRNA is translated into proteins.

Diauxic Growth of E. coli-

transition occurs; glucose genes off, lactose genes on

when a regulatory protein promotes transcription initiation; activator protein binds upstream and promotes RNA Holoenzyme binding

when a regulatory protein inhibits transcription initiation; repressor protein binds to operator to prevent transcription

Mutation: induced/spontaneous

Recombination: leads to newcombintations of genes on a chromosome

point mutation

alteration of base pair resulting in SAME amino acid

Prion

infectious proteins that lack nucleic 

acids

mad cow

point mutation

alteration of base pair resulting in DIFFERENT amino acid;

Auxotroph- nutritional mutant that requires an additional growth factor

Prototroph- parent of an auxotroph

Fast, easy to idenitify mutagens; an increase in reversion rate = potential 

mutagen/carcinoge

bacterial sex

plasmid DNA  carries gene for sex pilus; F⁺

cell-cell contact required

– Temperature

– Nutrients

– Water (osmotic balance)

– Appropriate atmosphere

– pH

stops bacterial growth

-static/-stasis = standing still

D value; decimal reduction time

time require to kill 90% of microbes or spores

ribosomes

DNA

Enzymes

Cell wall

Membranes

intensity/concentration- lowers D-value

Microbial load- number of microbes; D-value same rate, increased time to do so

Population Compostition- mixture of microbes

Temperature- increased temperature, more active

Environment- type of material contaminated

autoclave- moist heat, under pressure. More quantity, more time

Boiling- moist heat, not under pressure

pasteurization- sub-boiling temps; high temp short time, ultra high temp,

Hot air

incinteration

physical

DNA damaged

ionzing- gamma rays/xrays

non-ionizing- UV light

physical

seperates bacteria from liquid

HEPA filtration for air

ultra filtration- filters out lipopolysaccharide endotoxins from dead gram -

chemical

Bactericidal or bacteriostatic depending on 

concentration

higher concentration = bacterialcidal

– Increases membrane permeability

– Denatures protein

Chemical

Oxidizing agent, inactivates key proteins

Iodine – very effective germicide

 Chlorine

chemical

• Antibacterial and effective against algae and 

fungi

• Mode of action

– Inactivate enzymes - react with –SH group

toxic

chemical

Surface active compounds (“surfactants”)

– Damage cell membranes

– Denature protein

chemical

disinfecting, sanitizing, and antisepsis

compounds (natural or synthetic) 

that inhibit specific metabolic processes in 

cells

Paul Ehrlich- syphillis antibiotic

Alexander Fleming- penecillin

antibiotic targets

• Cell wall synthesis

• Membrane function

• Protein synthesis

• Metabolite antagonism

Active against Gram positives

– Natural or semi-synthetic

– Allergies and pathogen resistance

ex PENECILLIN 

Quinolones (nalidixic acid, ciprofloxacin) – Inhibit DNA gyrase; Very broad spectrum

Mitomycin – Cross-links with DNA; Induces endonuclease activity

Enzyme inhibitors

ex. Sulfonamide

• Humans and animals

• Plant pathogens

 • Pests

CO2 fixation and O2 evolution on Earth

Lichens

a unique symbiotic life form 

consisting of fungi and algae (actually 

cyanobacteria)

Protozoology: study of protozoa

Eukaryotic, unicellular animals

Motile by cilia, flagella, or amoeboid motility

Require host machinery to multiply

1 nucleic acid- DNA or RNA

acellular

capsid- some have lipid envelope

Nucelocapsid

Virion- complete individual virus

10nm - 300nm

helical- tube shape

polyhedral- multi-sided

• Attachment: adhesion to target site

• Entry: Virus injects nucleic acid into host

• Replication: early viral proteins shut down host metabolism, then replicates

• Maturation/assembly: Capsids/nucleic acids; sometimes host DNA picked up

• Release: Virions are released; Cell lysis; budding

attachment/entry- same; except DNA becomes circular

Repression- phage represses lytic cycle

Integration- phage inserts into host DNA; prophage

attainment- prophage replicates with chromosome; repressor protein blocks lytic

Entry- to lytic cycle; prophage expressed

contain envelopes with Glycoprotein spikes

'naked' virion = non-enveloped

Immune system- immunity from current/previous infection.

Vaccination: exposure to virus (inactivated or 

portion of virus)

Fever: increased temp inactivates some viral 

proteins

Interferon: antiviral produced by the body, blocks viral protein synthesis