Structure - Bacterial Alternate Structures Flashcards
Cell Inclusions
Cellular energy reserves and carbon reservoirs.
Why do bacteria prefer carbon stored in insoluble form?
Reduction of osmotic stress due to reduced cytoplasmic substance dissolution
General structure of poly-beta-hydroxybutyric acid/
Hydroxybutyrate polymerised via Ester linkages
What is the variable length of hydroxybutyrate?
C3-C18.
What is hydroxybutyrate generally referred to as?
poly-beta-hydroxyalkanoate.
When are poly-beta-hydroxyalkanoate synthesised?
When cell is saturated with carbon, to be used as an energy source.
What can cell inclusions store?
Carbon, sulfur, phosphate etc.
What form do Cell Inclusions store phosphate in?
Polyphosphate form.
Why are phoshpate cell inclusions important?
Phosphate is often a limiting nutrient
Magnetosomes
Allow certain magnetotactic bacterial cells to move towards the magnetic field of earth.
What is the main component of a magnetosome?
Fe3O4
Why is Fe3O4 important?
Guides cells twoards earths magnetic field to lower O2 levles.
Gas Vesicles
Increase cell buoyancy by decreasing cell density.
What is an example of where gas vesicles are used?
Planktonic organisms floating within nutrient rich locations.
What does the structure of the gas vesicle allow for its function?
Gas difusion but water impermeability.
What proteins make up the vesicle structre?
GvpA forms watertight vesicle shells that are small, hydrophobic and rigid whilst GvpC links these GvpA together
What is the mechanism of Gas Vescile buoyancy?
Contain 1/10 cell density, inflating decraasing overall density, increasing buoyancy.
In what process are endospores produced.
During sporulation
What are some chemical characterisitcs of endospores?
Resistinat to heat, harsh chemical and radiation.
What is the function of endospores?
Allow an organisms to endure unfavourable conditiosn
What organisms are endospores usually foudn in?
Bacillus or soil bacteria.
What happends to VG during sporulation?
It enters a dormancy like stage without growth but high resistance.
What are the three steps of endospore invigoration after formation?
Activation, Germination, Outgrowth.
What happens in endospore activation?
Heat endospores elevates temeprautres.
What happens in endospore Germnination?
Nutrient supplication which decreases resistance due to increaseing refractility.
What happens in endospore Outgrowth?
Water uptake, DNA/RNA/PROTEIN synthesis, cell emergence from broken endospores.
How are endospores observed in culutre?
Impermeable to dyes, seen as unstained regions, special stains used.
What are the four layers distinct in endospores from VG?
Exosporium, spore, cortex then core.
How much of endospore dry weight is dipicolinic acid?
10%
What does Dipicolinic acid do?
Binds free water to dehydrate the cell and stabilses DNA against heat denaturation, inserting between bases.
How does the endospore core differe from VG cytoplasm?
Less water and small acid soluble spore protiens.
What is the important of less water in endospore core?
Increases gel-like consistency allowing heat resistance of their macromolecules.
What are the functions of SASSP?
Protecting DNA from UV damage, compacting it from B form to A form and as carbon source in outgrowht.
How many proteins are required for sporulation?
over 200 requiring differential protein synthesis.
What happens genetically in sporulation?
Activation of endospore specific genes and inactivation of VG genes.
What is the first stage in sporulation?
Asymmetric cell divions forming forespore and mother cell
What is the second stage of sporulaiton?
TF control each gene expressive fates.
When does sporulation occur?
After DNA replication completes one round so chromosome copies are available.
What happens when division occurs in sporulation?
Forespore is engulfed by mother cell
How does forespore engulfing occur?
Proteins facilitate membrane migration around forespore.
