BIOL243 L1

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  • Created by: Katherine
  • Created on: 03-04-17 10:04
Name the features of the bacterial cell:
Capsule, Cytoplasm, Ribosomes, Cell Wall, Plasma Membrane, Nucleoid, Plasmid, Flagella, Fimbriae, Inclusion.
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Why is the nucleoid important?
It is an irregularly shaped region that is the location of the chromosome. There is usually 1 per cell.
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Why are plasmids important?
Usually small, circular DNA molecules. Exist and replicated independently of chromosome. Not required for growth and reproduction. May carry genes that confer selective advantage (e.g. drug resistance). Important tool in molecular biology.
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What are inclusions?
They are granules of organic or inorganic material that are reserved for future use. e.g. glycogen, PHB, polyphosphate granules or sulphur granules. They take up alot of the cell volume so there is an advantage to have them when there is large storag
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What is the cytoplasmic membrane?
It is a phospholipid bilayer (permeable barrier) and contains integral and peripheral membrane proteins.
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What colour is a stained gram positive cell wall?
Blue/purple
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Why is the peptidoglycan structure important?
It gives structure to the cell and there a repeating units. It is rigid because of the peptide cross links. If you break the cross links the cell becomes leaky.
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What make up the peptide cross links in peptidoglycan structure?
N Acetylglycosamine (NAG), N Acetylmuramic acid (NAM) and NAM-NAG polymer chains linked via peptide bridges.
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What are the features of a Gram Negative cell wall?
Polysaccharides, Lipopolysaccharides, Phospholipid Bilaer, Lipoproteins. Peptidoglycan
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What are the features of a Gram positive cell wall?
TO BE FILLED IN
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How does a Mycobacterial cell wall differ to a gram negative?
It has a similar structure, but there are also mycolic acids on the outer part of the wall. In nature, Mycobacterial withstand advverse environments.
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What is the capsule made from?
Extracellular polysaccharides (EPS)
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What does the capsule do?
It protects from host defences (e.g. phagocytosis) and from harsh environmental conditions (e.g. desiccation and over production).
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What is an S layer and what does it do?
Surface Layer - it is a part of the cell envelope and consists of a monomolecular layer composed of identical proteins or glycoproteins.
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What is the flagella used for?
For swimming and attachment to surfaces
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What are the different names for flagellum and what do they mean?
Polar flagellum (flagellum at end of cell), Monotrichous (one flagellum) Amphitrichous (One flagellum at each end of cell), Lophotrichous (Cluseter at 1 or both ends), Peritrichous (Spread over entire cell surface).
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What are fimbriae? What are they used for?
Appendages that are short and thin (hair like). Used for recognition and attachment to surfaces.
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What are the differences between Pili and Fimbriae?
Pili are longer and thicker and are in lower numbers.
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What are pili used for?
Required for mating and attachment to surfaces.
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What are surface associated communities of bacteria called?
A biofilm
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Why doe we identify and classify oranisms?
To bring a sense of order to the huge diversity of bacteria, to enhance communication, to provide the means for accurate identification for treatment.
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If a species is more closely related, what will theire 16S rRNA sequence be like?
More similar to each other
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What is the procedure of determining how closely related organisms are?
Sequence the 16S rRNA gene and compare sequences and generate phylogenetic tree.
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GO OVER COMPARIOSON OF 16S RNA
OK
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What are the 3 domains which we can determine using universal phylogenetic tree derived from 16S rRNA?
Bacteria, Archaea, Eukarya
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What did Carl Woese's tree look like and why is it different to our modern adaptation of the phylogenic tree?
It had 3 domains, whereas they now have 2.
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Of Taxonomic hierarchies, which are italicised?
Genus, Species and strain
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What are the 5 classes of the phylum: Proteobacteria?
Alpha-proteobacteria, Beta - , Gamma - , Delta - and Epsilon -.
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Gamma proteobacteria contain how many orders, which include...
14 Orders, including Enterobacteriales.
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The order Enterobacteriales contain which family and which genera?
Enterobacteriacae, and many genera including Escherichia.
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What is a taxonomic dichotomous key (decision tree)
It is a tool used to determine the identity of strains, asking YES/NO questions.
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Classical taxonomy and identification relies on what?
Relies on phenotypic analyses: morphology, O2 tolerance, G+C content of DNA, physiology and metabolism (nutrient source, relationship to pH, temp, salinity, products formed and presence of certain enzymatic activities).
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What shape are cocci and what shape are bacilli?
Cocci are circular while bacilli are small rods.
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What shape is staphylococci?
A cluster of circles
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What shape is streptococci?
A line of circles
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What shape is streptobacilli?
A line of rods,
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What shape is filamentous?
A thin worm like shape
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What it an obligate aerobe?
It must have oxygen to survive
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What is an anaerobe?
It can survive in the absence of oxygen.
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What is a facultative aerobe?
It is an aerobe that can survive in the absence of oxygen
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What is a Microaerophile?
It
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What is an aerotolerant anaerobe?
It is an anaerobe that is tolerant of oxygen.
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What is an endospore?
It is a surival form produced under unfavourable conditions.
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How long can endospores survive?
100s if not 1000s of year.
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Why are endospores tolerant to heat, drying, radiation and chemicals?
Very low water content, contain calcium dipicolinat, special protens protect DNA.
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What is a motility test?
Gram negative bacteria will not spread in the solution while positive will.
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How is a catalase activity test done?
Important detoxifying H202 is produced during aerobic metabolism and in this test, H202 is converted to H2O and 1/2 O2. A marker for the test are bubbles.
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How is an oxidase test done?
It detects the presence of cytochrome c and associated oxidase using Kovac's reagent. Oxidase negative bacteria is colourless when reduced. And oxidase positive bacteria is purple (oxidised)
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How is G+C content (%) determined?
G + C = G + C / G + C + A + T X 100.
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What does a higher GC content mean?
It means that more energy is required for separation of DNA strands (3 hydrogen bonds between G and C).
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Other cards in this set

Card 2

Front

Why is the nucleoid important?

Back

It is an irregularly shaped region that is the location of the chromosome. There is usually 1 per cell.

Card 3

Front

Why are plasmids important?

Back

Preview of the front of card 3

Card 4

Front

What are inclusions?

Back

Preview of the front of card 4

Card 5

Front

What is the cytoplasmic membrane?

Back

Preview of the front of card 5
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