TA: Will Spencer

Functions of bacterial cell parts Lengeler et al. pp Cellular and subcellular organization of procaryotes

1. Protoplasm Nucleoid Ribosomes / polysomes Cytosol Storage granules

2. Bacterial cell envelopes Cytoplasmic (=inner membrane, plasma membrane), CM Outer membrane, OM Periplasm Cell wall Capsule

3. Bacterial appendages Pilus, pili Flagellum, flagella

4. Disruption of bacterial cells Boiling in SDS Sonic oscillation French pressure cell

1. Protoplasm Nucleoid: Function, Properties –Compact lobular body: skein –Loops, coils DNA –Genome –Center of cell; CM attached –1 copy / cell; > 1 copy / cell; rapidly growing

1. Protoplasm Nucleoid: Molecular composition –Circular 2 x double stranded DNA helix –4.7 x 10 6 bp –Supercoiled –Proteins: packing DNA –Proteins: remove supercoils

1. Protoplasm Ribosomes: Function, Properties –Sites of protein synthesis –mRNA  translation to protein –E. coli: 18,000 ribs / cell –Polysomes = > 1 ribosome on same mRNA

1. Protoplasm Ribosomes: Molecular composition –rRNA = 62% –Proteins = 38% –Large subunit = 50 S 2 rRNAs + 32 proteins –Small subunit = 30 S 1 rRNA + 21 proteins

1. Protoplasm Cytosol: Function and properties –enclosed by CM –1000s of proteins: metabolism –[protein] ~ 20% –Gel

1. Protoplasm Cytosol: Molecular composition –80% dry weight = protein –60 tRNA molecules –mRNA –Metabolites –Vitamins, cofactors, ATP, inorganic ions –H 2 O

1. Protoplasm Storage granules: Function and properties –Deposits –Short-term energy source Storage granules: Molecular composition –Polysaccharides: glycogen –Degradation  free sugars

2. Bacterial cell envelopes CM: Function and properties –Selectively permeable boundary –Passage of H2O, nutrients, ions –Transport systems –Nutrient E  ATP

2. Bacterial cell envelopes CM: Molecular composition –Bilayer of 7 different phospholipids –100s of proteins: > 2 x 105 / CM –30% lipid; 70% protein

2. Bacterial cell envelopes OM: Function and properties –Molecular sieve –Protection vs chemicals –Specific transport proteins: Scavenge rare nutrients

2. Bacterial cell envelopes OM: Molecular composition –Asymmetric bilayer: Inner leaflet: phospholipids Outer leaflet: lipopolysaccharide –50 proteins: 10 6 molecules / cell

2. Bacterial cell envelopes Periplasm: Function and properties –Between OM and CM –Aqueous gel –Proteins: nutrition, detoxification

2. Bacterial cell envelopes Periplasm: Molecular composition –Peptidoglycan = murein: rigidity Several layers Sacculus –Gram - = thin; Gram + = thick –Binding proteins: nutrients –Degradative enzymes

2. Bacterial cell envelopes Capsule: Function and Properties –Defense against host cell’s phagocytes –Colonization of environments –Growth conditions Capsule: Molecular composition –High mol weight complex polysaccharides –Amorphous slime

3. Bacterial appendages Pilus, -i : Function and properties –Type 1 pili; / cell Attaching to surfaces –F1 pili = sex pilus; 1 – 3 / cell Conjugation Conduit for transfer of DNA to recipient

3. Bacterial appendages Pilus, -i : Molecular composition –Pilin = single species protein –Minor protein at tip = adhesin –Carbohydrate binding –Attachment

3. Bacterial appendages Flagellum, -a: Function and properties –Cell swimming –Basal body complex: M, S, P, L rings –Central rod –Hook –Filament

3. Bacterial appendages Flagellum, -a: Molecular composition –Flagellin –Hook protein –Basal body complex: 10s of protein Rotary motor

4. Disruption of bacterial cells Boiling in 2% SDS –Cell lysate: all contents dissolved –Proteins: SDS-PAGE Sonic oscillation –Pop bacteria French pressure cell –16,000 psi