Microbiology
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What is the name of the first oxygen producing micro-organisms?
Cyanobacteria
What 3 things is all life classified as?
Bacteria, Archaea, Eukarya
What was Pasteurs hypothesis?
Microorganisms present in putrefying material were descendants of those already present in the material or that were are carried in on dust particles in air
Knowledge that life does not arise spontaneously allows?
• Prevention of food spoilage • Prevention of infections during operations • Understanding of the causes of infectious diseases
Who helped in the prevention of food spoilage and when?
Louis Pasteur (fermentation, pasteurisation) 1864
Who helped in the prevention of infections during operations?
Lister (aseptic technique) 1867
Who helped in the understanding of the causes of infectious diseases?
Koch (Germ theory of disease & Koch’s postulates) 1876
What experiment was defined as definitive proof for biogenies?
Swan neck flask
What were Koch’s postulates?
• The suspected pathogen must be present in all cases of disease and absent from healthy animals • Suspected pathogen must be grown in pure cultures • Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal • The suspected pathogen must be reisolated and shown to be the same as the original
What did Hooke do?
First observed “cells”
What did Van Leeuwenhoek do?
Observed live micro-organisms
How did Karl Woese discover archaea?
He looked at the ribosomal DNA and recognised it was very different to that of bacteria
Features of a bacterial cytoplasm.
• Thick, semi-transparent and elastic • 80% water • Contains all the molecules required for life
Features within the bacterial cytoplasm.
• The nucleiod (DNA) - Ribosomes (site of proteins synthesis composed of RNA and protein
Features of a bacterial cell membrane.
• A thin structure inside the cell wall and enclosing the cytoplasm • Consists of a phospholipid bilayer • Contains selective carrier proteins • Acts as a semi-selective barrier that regulates the uptake of nutrients
Features of bacterial cell wall.
• Very rigid to protect cell from rupturing • Antigenic, often contains toxic molecules and is a common site for antibiotic action • Two types differentiated by gram stain
How is the strength of a bacterial cell wall provided?
A mucopeptide called peptidoglycan which is unique to bacteria
Composition of cell wall in gram negative bacteria from inside to outside
Cytoplasm, Inner membrane, Cell wall, Outer membrane, Lipopolysaccharide (LPS)
Composition of cell wall in gram positive bacteria from inside to outside
Cytoplasm, Inner membrane, Cell wall, Teichoic Acids
What do lipopolysaccharides do?
Otherwise known as endotoxin. Important virulence factor for evading phagocytosis and a barrier to certain antibiotics
What is teichoic acid?
Long anionic polymers that thread through the thick, multi layer of highly cross-linked peptidoglycan.
Describe the capsule of a bacteria
Firmly attached and highly organised
Describe the slime layer of a bacteria
Unorganised and loosely attached
What do flagella do?
Help a bacteria move by rotation