mod two - microbiology (morphology and arrangement of bacterial cell)

Morphology Bacilli

• rod shaped

• diplo, strepto

Morphology - Cocci

• sphere

  • staph, strep (types are determined after morph)

Morph - Spiral

• vibrio, spirochete, sprillium

Arrangement Staph V Strep

Gram POSITIVE Cocci

• Staph = cluster

• strep = chain

Gram negative cocci

Gonorrhea

Gram positive bacilli

Anthrax, clostridium (C.DIFF/CDAD)

Gram negative bacilli

• e.coli (Escherichia), shigella

• salmonella

• food poisoning

Spirochaete

lime disease, sphilis

Vibrio

cholera

Structure of A bACTERIAL cell

External

Appendages:

• flagella, pili/fimbriae

Surface

• Slime layer, glycocalyx (around the cell / capsule)

Cell Envelope

• outer membrane

• cell wall

• cytoplasmic membrane

Internal

• cytoplasm

• ribosomes

• inclusions

• nucleoid/chromosome

• cytoskeleton

• endospores

• plasmid - extra chromosomal DNA

• microcompartment

ALL bacteria cells will have

• membrane

• chromosomes

• ribosomes

Glycocalyx

• gelatinous mass covers cell

• polysacchirides and/or polypeptide

Two types

• capsule - neatly organized + firmly attached

• slime layer - unorganized and loose

Glycocalyx Virulence

• causes pneumococcal pneumonia infection

• Capsules prevent phagocytosis

Biofilm formation will increase

• bacteria stick together; produces chemicals that protect the bacteria inside

• fights against antibody and immune system

Flagella (move away from danger)

• propel bacteria

Chemotaxis - attraction to chemicals

Fimbriae

• hairlike

• increased virulence

• made of protein

• Attachment device = bacteria attach to target cell and establish infection

• major factor in Gonorrhea (attaches to genitals)

• increases pathogenesis

Pili

• motility (glide + twitch)

• Conjugation pili - DNA transfer

• made of protein

• increases pathogenesis by passing antibiotic genes

Horizontal Gene Transfer (HGT)

Pili connect to other cells to pass new DNA

Structure of Bacterial Cell Wall

Peptidoglycan

• polymer of polysaccharide rows

• N Acetylglucosamine (NAG)

• N Acetylmuramicacid (NAM)

  • rows are linked by polypeptides

Gram POSITIVE cell wall

thick polypeptide laer

Tecichoic acids

Gram Negative Cell Wall

• thin polypeptide wall

Outer-membrane

• contains Lipopolysaccharides (LPS)

• Lipid A, LPS, endotoxin

Periplasmic space

• between the outer and cell membrane (transports molecules)

• Porins (gates/channels - 2nd layer of protection)

Atypical Cell Wall / No cell wall

Acid-fast bacillus wall

• thick and waxy (Mycobacterium - TB)

Mycoplasmas - no cell wall

Archea - cell wall of pseudomurein

Murein = peptid.

Damage to the cell wall

lysosome hydrolyzes bonds in peptid.

• Penicillin breaks peptide bridges in peptidoglycan

• cell wall protects cell from osmotic distress and maintains its shape

Plasma / Cytoplasmic Membrane

Phospholipid bilayer

• proteins embedded or attached

Fluid mosaic model

• membrane is not rigid

• allows flow of lipids and proteins

Ligand Receptor Concept

• ligands on surfcace of cell

• something comes to interact with ligands

Gram POSITIVE

• purple

• keeps color

• thick

• teichoic acid

• granular

• NO LPS

Gram Negative

• decolonized

• pink/red

• thin

• periplasm space

• LPS is high