+ Pathogens - MCC Year 12 Biology
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Transcript + Pathogens - MCC Year 12 Biology
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Chapter 7: Infection and disease 1
EL: To explore what a disease is and what causes them
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Study design – key knowledge
detecting ‘self’ and ‘non-self’ molecules: antigens and membrane receptors
– pathogens: non-cellular agents, cellular agents; controls;
physical and chemical barriers to infection in plants and animals;
immune response
– structure and overall function of the lymphatic system
– non-specific: inflammatory response; phagocytosis; blood clotting
– specific immune response: T-cell lymphocytes and cell-mediated
response; B-cell lymphocytes and humoral response, antigens and
antibodies; memory cells;
disorders of the immune response: autoimmunity; hypersensitivity, allergens
and allergic responses;
acquired immunity: natural, artificial including vaccines and antibody
serums.
Chapter 7: Pre-test
Question
What is a disease?
What is a pathogen
What is a cellular agent?
What is a non-cellular
agent?
Start of unit
End of unit
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Disease
Any
condition that interferes with how an
organism or any part of it functions
Can
be acquired through:
Genetic causes – inherited from parents
Pathogens and parasites
+ Pathogens
disease
causing organism or agent
(frequently but NOT always a MO)
Non-cellular
Prion
virus
Cellular
pathogens
pathogens
bacteria
fungi
protozoa
exo- and endo-parasites
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Nature of Disease
Intensity of pathogenic effect: VIRULENCE
Due to special characteristics of the pathogenic organism,
such as ability to produce toxins
Individuals
level of susceptibility to pathogen:
RESISTANCE
Varies with age, state of health, immunity
Some
pathogens are able to survive outside the host,
others are not
Time
between infection and symptoms: INCUBATION
PERIOD
Depends on pathogen achieving sufficient numbers, reaching target
tissue, toxin accumulation etc
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Nature of Disease: Transmission
Infective
agents can be transmitted from
one host to another by:
Direct contact
Droplets in air breathed or sneezed by host
Sexual contact (e.g. STIs)
Contaminated food or water
A carrying vector (e.g. rats carrying fleas)
An injecting vector (e.g. mosquitoes carrying malaria
parasites)
Injection with infected needles and syringes
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Non cellular pathogens: Viruses
A virus is a non-cellular agent composed of a protein
coat (capsid) and nucleic acid (RNA OR DNA)
Rely on living cells to function and replicate:
Not able to respire
OBLIGATE intracellular parasites
Often integrated into host chromosomes and replicated during cell
division
Highly specific to host cell or organism it infects (e.g.
adenovirus specific to lung cells
-> common cold)
All organisms on Earth are susceptible
to virus infection (e.g. bacteriophages)
http://www.youtube.com/watch?v=Rpj0emEGShQ
Chicken pox
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Shingles
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Rubella
or
German
measles
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Mumps
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Cold sore
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Warts
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Verruca
+ Polio
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Small pox – a killer
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Non cellular pathogens: Prions
Proteinaceaous
GENOME
infectious particles: NO
Deviant
versions of a normal cell surface
protein that are transmissable
Disease
caused by accumulation of abnormal
protease-resistant protein
Diseases
include BSE
(or mad cow), CJD,
Kuru
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Cellular pathogens: Bacteria
Prokaryotic
Contain
organisms lacking organelles
circular DNA molecule
Can
be classified according to metabolic
characteristics and/or shape
Round
Rod-shaped
Spiral
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Cellular pathogens: Bacteria
Cell
wall contains PEPTIDOGLYCAN
and is chemically and
morphologically complex
Can
have flagellum, capsules or
spores
Reproduce
rapidly by binary fission in
favourable conditions
http://www.youtube.com/watch?v=gE
wzDydciWc&NR=1
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Eye infection
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Leprosy
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Tetanus
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Plant blight
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NOB Activity 7.1 & 7.2
One
group will set up activity 7.1 pg 58-59
(procedure 1-5)
One
group will set up activity 7.2 part A pg
61-62 (procedure 1-8)
One
group will set up activity 7.2 part B pg
63 (procedure 1-6)
We
will make observations next lesson
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Homework – Chapter 7
Quick
check qu 1-25
Biochallenge
Chapter
1
Review qu 2
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Reflection
What
did you learn about infection and
disease today?
What
was the most disgusting disease
today?
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Chapter 7: Infection and disease 2
EL: To examine our bacteria investigations
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Activity 7.1 & 7.2
Everyone will complete:
Activity
7.1 pg 59, procedure 6-8, qu 1-7
Activity
7.2 part A pg 63, procedure 9, qu 1-
8
Activity
10-15
7.2 part B pg 63, procedure 7, qu
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Homework – chapter 7
Quick
check qu 26-30
Biochallenge
Chapter
qu 2
review qu 4, 5, 6, 8
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Reflection
Were
you surprised by the results of any of
the experiments and why?
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Chapter 7: Infection and disease 3
EL: To further explore the causes of disease
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Expected learning
To
further explore the causes of disease
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Cellular pathogens: Fungi
Eukaryotic heterotrophs
break down organic matter by secreting enzymes and
other chemicals
These chemicals are the main cause of the disease
Primarily
moisture
terrestrial, but need
Reproduce
Cell
using spores
wall made of chitin
Filamentous
moulds and
unicellular yeasts
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Athletes foot
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Oral Thrush
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Frogs – chytrid fungus
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Cellular pathogens: Protists
Unicellular
Very
eukaryotic organisms
diverse
Usually
motile (i.e. flagella, cilia)
Heterotrophic
Reproduce
May
sexually and asexually
have specialist life cycle
involving different hosts
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Protist Life Cycle
http://www.youtube.com/watch?v=Q_nCHDry0s8
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Endoparasites: worms
Flat
and round worms may be parasitic, but
aren’t necessarily pathogenic
Pathogenic
worms include tapeworms,
roundworms
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Endoparasites: worms
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Ectoparasites: arthropods
Generally
parasitic, but aren’t necessarily
pathogenic
Pathogenic
arthropods include head lice
and body lice
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Nelson Activity 5.2
Complete
activity 5.2 and hand in
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Reflection
Why
do you think parasites have evolved
such a complex life cycle?