Transcript Microbes and disease

Option F:
Microbes and Biotechnology
(HL only)
F.6 Microbes and Disease
F.6.1 List 6 methods by which pathogens are transmitted and gain
entry to the body
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Food
Water
Aerial
Animal vectors
Puncture wounds
Sexual contact
F.6.2 Distinguish between intracellular and extracellular bacterial
infection using Chlamydia and Streptococcus as examples
Intracellular
Extracellular
Example
Chlamydia
Streptococcus
Location
Lives inside cell
Lives outside cells
Toxins
None
Yes
Damage to cells
Indirect; long term
problems
Direct damage (invasin)
Immune system
Not targeted (hidden)
Immediately targeted
F.6.3 Distinguish between endotoxins and exotoxins
F.6.4 Evaluate methods of controlling microbial growth by
irradiation, pasteurization, antiseptics and disinfectants
Irradiation: gamma rays/microwaves/UV rays used to destroy nucleic acids
Pasteurization: heating to a specific temperature to ensure that pathogenic
bacteria are destroyed (i.e. milk)
Antiseptics: mild chemicals used to kill bacteria without damaging skin and
mucous membranes (i.e. 50-80% ethanol)
Disinfectants: Kill bacteria but no endospores; damaging to skin and mucous
membranes (i.e. bleach, Lysol)
F.6.5 Outline the mechanism of the action of antibiotics, including
inhibition of synthesis of cell walls, proteins and nucleic acids
1. Cell wall synthesis inhibition: interferes with
peptidoglycan/cell wall cross linkages (penicillin)
2. Protein synthesis inhibition: binds to 70S ribosomes
(streptomycin)
3. Nucleic acid inhibition: inhibits synthesis of nucleic
acids (Rifampicin)
F.6.6 Outline the lytic life cycle of the influenza virus
Put these in order
• Virus uncoats in endosome
• The virus is taken up into an endosome via endocytosis
• The nucleocapsid recognises specific points on cell membrane
where viral proteins have become inserted and buds off to
release new virus particles
• Viral RNA is transported to nucleus
• Viral RNA is released into cytoplasm
• Transcription of viral mRNA occurs
• Some viral mRNA is transported back to cytoplasm where
translation of viral proteins occur. Some serves as template for
more RNA
• Viral envelope proteins are packaged at Golgi apparatus and
transported to cell membrane
• The virus attaches to specific cell surface receptors on host cell
• The ER makes viral envelope proteins in cytoplasm
Put these in order
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The virus attaches to specific cell surface receptors on host cell
The virus is taken up into an endosome via endocytosis
Virus uncoats in endosome
Viral RNA is released into cytoplasm
Viral RNA is transported to nucleus
Transcription of viral mRNA occurs
Some viral mRNA is transported back to cytoplasm where
translation of viral proteins occur. Some serves as template for
more RNA
• The ER makes viral envelope proteins in cytoplasm
• Viral envelope proteins are packaged at Golgi apparatus and
transported to cell membrane
• The nucleocapsid recognises specific points on cell membrane
where viral proteins have become inserted and buds off to
release new virus particles
F.6.7 Define epidemiology
• The study of the occurrence, distribution and control of disease
in a population
F.6.8 Discuss the origin and epidemiology of one example of a
pandemic
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Definition
Name example
Cause of occurrence
Mode of transmission
Symptoms
Effect
Health measures
International factors
TOK consideration/correlation and cause
F.6.9 Describe the cause, transmission and effects of malaria, as
an example of disease caused by a protozoan
Cause: Plasmodium
Transmission: Female Anopheles mosquito
• Plasmodia reproduce in mosquito gut and egg sac ruptures to
release sporozoites which travel to its salivary glands
Effects:
• Anaemia
• Fever chills
• Shivering
• Headache
• Pain in joints
F.6.10 Discuss the prion hypothesis for the cause of spongiform
encephalopathies
Scrapie
Bovine spongiform
encephalopathy
(BSE)
Variant CreutzfeldtJackob disease
(vCJD)
F.6.10 Discuss the prion hypothesis for the cause of spongiform
encephalopathies
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Prions are infective agents that are made of protein only
It is believed that this is the cause for neurodegeneration
It is believed that it causes BSE/CJD/scrapie
The transmission of the disease did not fit any conventional
theory
Transmission can occur by eating infected foods
Prions cause other normal proteins to fold abnormally
Two forms: PrPsc (misfolded) and PrPc (wild type)
PrPsc cause of disease
PrPsc can cause PrPc to misfold
PrPc found naturally in brain cell membranes but function is
unknown