BIOL 2900 Lecture Notes - Lecture 4: Cytoplasm, Membrane Technology, Herbalism
1 Jun 2016
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oToxins
Chemicals produced by the pathogen
Harm tissues or trigger host immune responses that cause damage
oExotoxins - secreted by live bacteria
oEndotoxins - integrated into the membrane of the bacteria
Exotoxins
oProteins
Secreted by live pathogen
oAbnormal signal to cells
oDestroy cellullar and extracellular structures
oEx: cholera makes exotoxins
oMRSA
Makes many exotoxins
Abscess, cellulitis
Invasive infection - antibiotic resistance
Necrotizing faciitis
Highly drug resistant - high incidence in hopitals
Resistance to last-line antibiotics
oClostridium Difficile
Feces-filled capsules tx bacterial infection
oAnthrax
Exotoxins cause the damage in the lungs, skin and GI
Endotoxins
oGram-Negative Bacteria cell contains LPS (endotoxin)
Integrated in the membrane of the bacteria (live pathogen)
Lipoploysaccharide (LPS) layer
oO side chain - chain varied depending on bacterium
oCore Polysaccharide - relatively constant composition
oLipid A:composed of glycolipids
Associated with the toxic activity in Gram -ve
bacterium
Function of LPS Layer
oMay play a role in infection by any gram-negative bacterium
oReleased from dead cells when cell wall disintegrates
oCausing inflammation
Activate macrophages, neutrophils
Produce pyrogens : May trigger fever
oVasodilation
LPS as Endotoxins
oAcute Inflammation
Release of too much LPS
Can be induced by antimicrobial drugs that kill
bacteria
Increasing activity of the immune system
Systemic Infection (Sepsis)
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oAcitvates Blood Coagulation
oAcute Whole-Body Inflammation
Drop of blood pressure
Shock
Multi-organ failure
Prokaryotic Cell Organization and Structure
The Cytoplasm
oDNA
oProkaryotic Chromosome
Typically one large circular molecule of DNA- Only 1
chromosome
With no nuclear membrane
oMay have plasmids
Main Roles of Bacterial DNA
oContain genetic material
oTranscription
oReplication
Ribosomes
oProtein synthesis
oSome differences from eukaryotes
The ribosomes of prokarytoes are smaller than
sytoplasmic ribosomes of eukaryotes
But rbosomes can be found in eukaryotes'
mitochondria
Endospores
Structural bacterial but in a different form
Endospores are formed by a few groups of Gram positive bacteria as intracellular
structures, bt ultimatley they are released as free spores
Formed by vegetative cells in response to environmental signals that indicate a
limiting factor for vegetative growth
oEx: exhaustion of an essential nutrient
Endospores exhibit no signs of life. Although, they retain viability indefinitely
Endospores are highly resistant to environmental stresses:
oHigh temperatures, irradiation, strong acids, disinfectants, etc.
Germinate and become vegetative cells when the environmental stress is relieved
Endospore-formation is a mechanism of survival rather than a mechanism of
reproduction
Genetic Changes in Bacteria
Mutations in Bacteria
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find more resources at oneclass.com
Document Summary
Toxins o o o o o o o o o. Harm tissues or trigger host immune responses that cause damage. Endotoxins - integrated into the membrane of the bacteria. Highly drug resistant - high incidence in hopitals. Exotoxins cause the damage in the lungs, skin and gi. Endotoxins: gram-negative bacteria cell contains lps (endotoxin) Integrated in the membrane of the bacteria (live pathogen) Lipoploysaccharide (lps) layer: o side chain - chain varied depending on bacterium, core polysaccharide - relatively constant composition, lipid a:composed of glycolipids. Associated with the toxic activity in gram -ve. Function of lps layer bacterium: may play a role in infection by any gram-negative bacterium, released from dead cells when cell wall disintegrates, causing inflammation. Produce pyrogens : may trigger fever: vasodilation. Can be induced by antimicrobial drugs that kill bacteria. Systemic infection (sepsis: acitvates blood coagulation, acute whole-body inflammation. The cytoplasm o o o o o o o o.
