structural basis for lipopolysaccharide recognition by peptidoglycan ...
Bacteria. Cell wall Made of a peptidoglycan called murein. This is laid down as a network of...
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Transcript of Bacteria. Cell wall Made of a peptidoglycan called murein. This is laid down as a network of...
Prokaryotic cellsBacteria
The parts of a prokaryotic cell
Cell wallMade of a peptidoglycan called murein. This is laid down as a network of polysaccharide fibres.
A strong layer that prevents the cell from bursting and excludes certain substances
Cell surface membrane Normal fluid mosaic structure
Controls the passage of substances in and out of the cell. Can be folded inwards to give additional surface area to house molecules involved in respiration reactions
Genetic material A circular strand of DNA To control the cell
Ribosomes These are a smaller type (70S) than those found
in eukaryotic cells
Protein synthesis
Capsule Protects against chemicals and
desiccation. Also protects the bacterium
from attack by phagocytic cells such as our white blood cells.
flagellum Made of a single, long fibre up to 20 µm long. These may be present singly, at one or both
ends or even all over the cell.
Parts continued
pili Fine threadlike structures attached to
the capsule or cell wall. Up to 1 µm long
For attachment to surfaces
plasmids Small loops of DNA Carry some additional genes. This is where genes giving antibiotic resistance would be found. Used in genetic engineering for
transferring foreign genes into bacterial cells
Oil droplets/glycogen granules
As a food store
Parts continued
Microorganisms can cause disease by damaging the cells of the host and by producing toxins
Mycobacterium tuberculosis is a Gram-positive, rod-shaped bacterium and the cause of
tuberculosis in humans
Tuberculosis is primarily an airborne disease; it is spread from person to person
by droplet infection when an active TB sufferer coughs and sneezes
The most common salmonellosis is enterocolitis, caused principally by Salmonella enteriditis and
Salmonella typhimurium.
Food poisoning caused by S. enteriditis and S. typhimurium occurs when these bacteria are present in sufficient numbers in consumed food. A bacterial load of 100,000 per gram of food is
sufficiently high for many of the bacteria to survive the digestion process, and to continue multiplying within the gut.