Bacterial cell growth and structure

Nucleiod

Is a haploid that holds all the genetic information. (<1 - > 10million bc)

Ribosomes

Most abundant, 70s ribosomes (small subunit contains16S rRNA). Used for protein synthesis./

Cell membrane

High in protein content, Rich in fatty acids, lacks of sterols contains hopanoid. Has a selectively permeable; Respiration; protein secretion system (G-bacteria).

Cell wall

Determines the shape of the bacteria. Protects cells from osmotic pressure.

Peptidoglycan

NAM, NAG, Tetrapeptide side chains, peptide cross bridge.

O-Polysacchariode side chain

Varied among species or strains; repeating oligosaccharide unit. O-antigen. Structure of LPS

Core

Conserved among G-; containing special sugars, Hep(heptulose) and KDO(ketodeoxyoctanoic acid)

Lipid A

In outer membrane; Phosphorylated GlcN with FA; [Lipid A: endotoxin

Plasmid

Small Circular DNA containing their own origin of replication, angle to duplicate outside of the chromosome. Non- essential. Conjugation

Glycocalyx

Polysaccharide containing material outside cell wall (sugar shell). Ex: Capsule, slime layer, biofilm

Capsule

Condense layer, excludes particles. Evades host immune system (anti-phagocytosis) K-antigen. Cannot uptake dye, use negative staining method to visualize/.

Slime Layer

Loosely associated, does not exclude particles

Flagellum

Made up of entirely made of protein. Basal body, hook and filament. Locomotion: spin like propeller. Antigenic structure. Monotrichous, Lopotricchous, Peritrchous, Amphitrichous.

Pilus

Used for attachment and gene transfer. Sex Pilus and Ordinary Pilus.

Sex Pilus

Used for gene transfer ( conjugation) Ex: F pilus

Ordinary Pilus

Important for attachment, antigenic structure.

Endospores

Dormant cell(metabolically inactive form) produces by two majors Gram-positive genera: Bacilus and Clostridium. Extremely resistant to environmental stress. Major component include calcium dipicolinate and keratin like spore coat.

Endospore Triggers

limited nutrients, and germination is usually activated by physical and chemical exposure

Environmental Growth Factors

Nutrients, temperature, pH, Ionic strength/ osmotic pressure, Aeration.

Heterotrophic

Require organic carbon for growth

Nitrogen Fixation

N2→ NH3 (E.coli)

Ammonification

Delaminating of amino acids to produce NH3

Nitrate or nitrite reduction

NO3- or NO2- → HN3

Temperature

Most bacteria that interact with humans are Mesophilkes with an optimal temp of 30-37 degrees

Ph

Most bacterial pathogens are neutrophils with an optimal pH of 5-8

Ion is strength and Osmotic Pressure

Cell wall structure helps tolerate osmotic changes

Aerobic metabolism

Generate H2O2, O2 by-products with the use of the enzymes , superoxide dismutase (SOD) and catalase

Obligate Aerobes

Require oxygen and cannot survive without it. (Mycobacterium tuberculosis)

Facultative Anaerobes

Can grow grow with or without oxyacetylene but uses it if present

Microaerophiles

Require lower concentration of oxygen (2-10%)

Aerotolerant bacteria

Cannot use oxygen for their growth but are not harmed by it

Disinfection

Elimination of many or all pathogens. Includes biocides or germicides. Antiseptics: anti microbial but non toxic to living tissue.

Sterilization

Elimination of all forms of microbes. Autoclaves

Antibiotics

Substances that either kills our inhibits the growth of a bacterium.

Bactericidal

Irreversible progress

Bacteriostactic

Inhibiting multiplication (reversible)