BMS2052 Lecture Notes - Lecture 1: Drug Resistance, Virulence Factor, Tubulin
30 May 2018
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Week 1. Introduction to microbes and host-pathogen
interactions
• Microbes (particularly) bacteria are virtually everywhere
• Gut bacteria contributes about 1kg of your total body mass
-most are in large intestines
-50% of feces is bacteria
• We have co-evolved with microbes – less than 5% of them cause disease
• oral flora a eoe pathoges if gie the opportuity
• Antimicrobial resistance is a major global problem – hard to diagnose
• Colonisation does not equal infection
• The smaller the microorganism, the more difficult/complex it is and the more expensive it is to
analyse (i.e. need special microscopy)
• Similarities and differences of Archaea with Bacteria and Eukarya:
Archaea
Bacteria
Eukarya
Similarities
o Anucleate
o Cell envelope
o Usually only single circular
chromosome
o Varies in shape and sizes
o DNA replication, transcription
and translation is more similar
than with bacteria
o Histones
o Many enzymes involved in DNA
replication are more similar
than in bacteria
Differences :
-Archaea has unique
membrane lipids
o Different plasma membrane
o Archaea lack peptidoglycan
o Different plasma membrane
find more resources at oneclass.com
find more resources at oneclass.com
• Archaea and human disease:
o Diversity in the human body is lower (unlike bacteria which is abundant)
o Virtually no known bone fide pathogens of humans (do not cause human disease)
with possible exception of Methanosphaera oralis
o Most are extremophiles
o Mostly known for producing methane in cattle – major contribution to climate change –
indirect impact on our health
find more resources at oneclass.com
find more resources at oneclass.com
BACTERIA
• Prokaryote
• Morphology:
o 4 basic shapes:
1. Spherical/round – cocci
2. Rod-shaped – bacilli
3. Spiral – spirochaete
4. Curved – oas
o Pleomorphic bacteria: can have no shape or different shapes depending on
environment)
Mycoplasma and Ureaplasma
No cell wall
Smallest species of bacteria cells yet discovered
o Arrangement: single cells, pairs, chains or clusters
• Difference between bacteria and eukaryotes:
Bacteria
Eukaryote
o No internal structure
o Generally single cell
o Ope floor pla
o Lack:
1. Membrane bound nucleus
2. Internal membranous structures
i.e. ER, golgi
3. Cytoskeleton
o However some bacteria have these
things – no longer strictly true
o Membrane bound organelles
o Generally multicellular
• Controversy: should the term prokaryote be abandoned
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Introduction to microbes and host-pathogen interactions: microbes (particularly) bacteria are virtually everywhere, gut bacteria contributes about 1kg of your total body mass. Bacteria: anucleate, cell envelope, usually only single circular chromosome, varies in shape and sizes, different plasma membrane, archaea lack peptidoglycan. Eukarya: dna replication, transcription and translation is more similar than with bacteria, histones, many enzymes involved in dna replication are more similar than in bacteria, different plasma membrane. Bacteria: prokaryote, morphology, 4 basic shapes, spherical/round cocci, rod-shaped bacilli, spiral spirochaete, curved (cid:272)o(cid:373)(cid:373)a(cid:859)s, pleomorphic bacteria: can have no shape or different shapes depending on environment) Smallest species of bacteria cells yet discovered: arrangement: single cells, pairs, chains or clusters, difference between bacteria and eukaryotes: Cell wall: outside the plasma membrane, rigid, determines/maintains shape, strong structural support (rigid but elastic) In gram negative bacteria only: an outside layer of the cell wall.
