BIOL126 Lecture Notes - Lecture 10: Terbinafine, Schistosomiasis, Gram-Positive Bacteria
8 Jun 2018
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Microbiology and Body defences
• Microbiology:
o The study of microscopic organisms (microorganisms)
• Microorganisms: living organisms that need a microscope to study them
▪ First life on earth 3.8 billion years ago
▪ Created the biosphere that allowed multicellular organisms to evolve
▪ Multicellular organisms evolved from microorganisms
▪ Most of the physiological, metabolic and genetic diversity belongs to
the microbial world
▪ 50% of biomass is made of microorganisms
▪ Essential for decomposition and recycling of nutrients
▪ Exist in huge numbers but relatively few species cause disease
• Cells are generally less complex
o Two fundamental cell types
• Prokaryotes 'before nucleus'
▪ Small simple single cells
▪ No nucleus, a ring of DNA in nucleoid region of cytoplasm
▪ No membrane-bound organelles
▪ Ribosomes
▪ ATP produced by glycolysis only
▪ Plasma membrane surrounded by cell wall; (some have outer
membrane)
• Peptidoglycan in cell wall
• Eukaryotes 'true nucleus'
▪ Can be single or multicellular
▪ More complex
▪ Membrane-bound nucleus that contains DNA as chromosomes
▪ Membrane-bound organelles e.g. mitochondria
▪ Non-membrane organelles e.g. ribosomes
▪ Produce ATP by aerobic respiration and glycolysis (anaerobic
respiration)
▪ Plasma membrane
o Describe the main microbiological agents that affect human health
• Good microorganisms
▪ Food-related
• Wine, beer, bread - yeasts
• Yoghurt, milk - bacteria
• Cheese - fungal moulds
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▪ Pharmaceuticals
• Antibiotics - fungal moulds
• Vaccines - (inside viruses)
▪ Decomposition
▪ Nutrient production
• Types of microorganisms
▪ Viruses (10-900nm)
• Non living
• Smallest microbes - seen with an electron microscope
• Obligate intracellular parasites - invade host cells (specific for viral
type)
• Hijack host cell machinery to reproduce and undergo metabolism
• Can mutate easily
• Viral invasion often kills (lyse) host cells
• Antibiotics have no effect
• Structure
• Protein coat (capsid) surrounding DNA or RNA
• Some surrounded by a lipid envelope
• 600 known to infect humans
• Skin - chicken pox, measles, herpes, warts
• Respiratory - rhinovirus (cold), influenza, SARS
• Digestive - rotovirus, norovirus, hepatitis
• Urogenital - herpes, HPV
• Circulatory/immune - HIV/AIDS, mumps, dengue
• Nervous - Polio, rabies
• Prions
• Infectious proteins - abnormal folding
• Rare - familial or acquired
• Affect neural tissue - always fatal
• Hard to destroy
• Resistant to most sterilisation techniques
• Incineration is best
• e.g. CJD, BSE (mad cow disease)
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▪ Bacteria (0.5-5um)
• Prokaryotes
• Small free-living single cells
• Larger than viruses, smaller than eukaryotes
• Reproduce by binary fission, often at very high rates
• Wide range of metabolic patterns
• Some are pathogenic
• Some have virulence factors to enhance pathogenicity and
pathophysiology
• Can be treated with antibiotics
• e.g. staphylococcus, streptococcus, E. coli
• Structure
• Shape varies
• 3 main shapes
• Cocci (spherical)
• Bacilli (rod shaped cylinders)
• Spiral (curved, wavy)
• Multiple arrangements
• Pairs
• Chains
• Clusters
• Tetrad
• Curved
• Club
• Random
• Cell wall
• Major contributor to ultimate shape
• An important characteristic for bacterial identification
• Chromosomes not contained in nucleus
• Ribosomes
• Plasmids may be present
• Cell wall is a variable thickness
• Capsule may be present
• Some are motile - flagella
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find more resources at oneclass.com
Document Summary
Microbiology and body defences: microbiology, the study of microscopic organisms (microorganisms, microorganisms: living organisms that need a microscope to study them. Smallest microbes - seen with an electron microscope type: hijack host cell machinery to reproduce and undergo metabolism, can mutate easily, viral invasion often kills (lyse) host cells, antibiotics have no effect. Structure: protein coat (capsid) surrounding dna or rna. Some surrounded by a lipid envelope: 600 known to infect humans. Skin - chicken pox, measles, herpes, warts: respiratory - rhinovirus (cold), influenza, sars, digestive - rotovirus, norovirus, hepatitis, urogenital - herpes, hpv, circulatory/immune - hiv/aids, mumps, dengue, nervous - polio, rabies, prions. Infectious proteins - abnormal folding: rare - familial or acquired, affect neural tissue - always fatal, hard to destroy, resistant to most sterilisation techniques. Incineration is best: e. g. cjd, bse (mad cow disease) Larger than viruses, smaller than eukaryotes: bacteria (0. 5-5um, prokaryotes, reproduce by binary fission, often at very high rates, wide range of metabolic patterns.
