AS Unit F212 - Molecules, Biodiversity, Food and Health
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Revision powerpoint with an in depth summary on the topic. Can be printed with 2-4 slides to an A4 page and then cut out to form a mini revision booklet. Very colourful. 27 slides long
AS Unit F212 - Molecules, Biodiversity, Food and Health
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, Organisms that cause disease
Communicable diseases are caused by pathogens & can be passed from one
organism to another. A pathogen is a microorganism that causes disease, it
lives in a host taking nutrition from their body & causing damage.
Types of pathogen
Bacteria- belong to kingdom prokaryotae. Their cells are
smaller than eukaryotic cells & can take many shapes e.g.
spherical (cocci). There are 2 main types of bacterial cell walls;
gram +ve & gram –ve which effects how the bacteria react to
an antibiotic. Bacteria cause disease by releasing toxins that
poison or damage the host cells. The toxins are a by-product of
the normal functioning's of bacteria. In plants, the bacteria
often live in vascular tissue & cause blackening & death of
theses tissues.
Protoctista- protists that cause disease are parasitic &
cause harm by entering host cells & feeding on the contents as
they grow. They may need a vector to transfer them to the
host or may enter the body directly through polluted water.
,Virus- viruses invade cells & take over the cell metabolism.
The viral genetic material is inserted into the host DNA
causing the cell to manufacture more copies of the virus. The
host cell eventually bursts, releasing many new viruses which
will infect healthy cells. Some viruses, called bacteriophages,
attack bacteria. The are being used to identify & treat some
diseases.
Fungi- produce hyphae which form a mycelium. The fungus
can send out specialised reproductive hyphae which grow to the
surface of the skin to release spores. This causes redness &
irritation. Parasitic fungi cause communicable disease by
digesting living cells & destroying them. Some fungi also
produce toxins. In plants, the fungus often lives in the
vascular tissue, where it can gain nutrients by releasing
enzymes from hyphae to digest surrounding tissue which causes
decay.
, bacterium
virus
fungi
Thin cell wall of
chitin
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