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26 Cards in this Set
- Front
- Back
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Describe the structure of a typical bacterium... |
1. Flaggelum 2. Slime coat/Capsule 3. Photosynthetic membrane 4. Nucleoid 5. Glycogen granules/lipid droplets 6. Mesosome 7. Cell wall 8. 70s ribosomes 9. Cell membrane 10. Plasmid |
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What factor allows water to move into the bacterium? |
The contents of the bacterium are hypertonic to the solution so water moves in by osmosis. |
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What is the function if the bacterial cell wall? |
- prevents swelling and bursting - protection - support - maintains the shape |
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What is PEPTIDOGLYCAN? |
PEPTIDOGLYCAN is an important component of the cell wall. It is composed of many parallel polysaccaride chains with cross- linkages to form a net-like structure. |
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What is the structure and function of the capsule/Slime layer? |
Structure - made up of gelatin, proteins, glycolipids, starch. Function - protects from phagocytosis -Also make it easier to be pathogenic as cellular markers are hidden. |
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It is thought that the slime capsule evolved in some bacteria to tackle.... |
Dry conditons |
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Both pili and flagellae are... |
Thread like protein projections from the surface. |
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What is the function of the pili? |
Used for attaching to host cell and for reproduction |
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How can the pili make the bacteria more susceptible to viruses? |
The pili can serve as an entry point |
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What is the function of the flagellum? |
Aids the bacteria on movement. Not present in all. Moves the bacteria is rapid rotations. Made of the protein flagellin. |
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What replaces the mitochondria in bacteria? |
Bacteria have no mitochondria so some bacteria have respiratory enzymes in the cell membrane. |
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What do scientists believe that mesosomes do? (2 theories) |
1. They are artefacts of procedures done for microscopy 2. Associated with enzyme activity - separation of DNA. |
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What is the role of a PLASMID? |
Plasmids store extra genetic information that is additional to the info in the Nucleoid, This could be genes for toxins or antibiotic resistance. |
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Plasmids cannot be transferred between bacteria. True or False |
False - they can be transferred via the pili during reproduction |
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Define the Nucleoid... |
One single circular length of DNA No membrane Folded and coiled to fit the bacterium |
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What two sub units make up the 70s ribosomes? |
50s and 30s |
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Describe the structure of a Gram negative bacterium... |
1. Thin layer of PEPTIDOGLYCAN 2. No tectonic acid 3. Rich in lipids |
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Describe the structure of gram positive bacterium... |
1. Thick layer of PEPTIDOGLYCAN 2. Techoic acid |
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Why is important to discover which type of bacteria it is in the infection? |
Different antibiotics work better against different bacteria based on their cell wall composition. |
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What colour is gram positive after staining? |
Blue/purple |
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Why does gram negative loose its initial purple colouring? |
The ethanol dissolves the lipoplyscaccharides in the outer membrane, leaving the thin peptidoglycan layer exposed so the colouring runs out. |
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What are the 2 stains used gram staining called? |
1. Primary stain - Crystal violet/iodine complex 2. Counterstain - red safranin |
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What are the 4 types of antibiotics used? |
Beta lactam Aminoglycides Polypetides Glycopeptides |
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Why do glycopeptides and beta lactam antibiotics work better on gram positive bacteria? |
Glycopeptides like vancomycin target the precursors of cell wall synthesis - they are polar molecules so cannot pass through gram negatives phospholipid membranes Beta lactam targets peptidoglycan and this is more important in gram postive |
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How do polypeptides work? |
They interact with the phospholipids in gram negative bacteria which disrupts outer membrane |
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How do Aminoglycides work? |
They inhibit protein synthesis and apply oxidative stress - works on both types of bacteria but not on aerobes. |
