L9 - Bacteria Growth Metabolism Respiration Flashcards
What is catabolism and how is it demonstrated by pryuvate
Large molecules -> small molecules
Initial oxidation to pyrubate and then de gratin of pyruvate. Electron accepted by NAD+ cycles e- and makes energy through respiration and fermentation
Picks up H+ to reduce acidity
Explain the ETC
- when each e- is transfereed between membrane protein, a H+ is released and a proton gradient is built up
- proton motive force is built up and ATP synthase uses this energy to turn ADP to ATP (chemical energy)
Why does bacteria need energy?
Flagella movement, active transport etc
What is the key molecule in generating energy
ATP synthase
Describe aerobic respiration in bacteria
- similar to mitochondria
- dehydrogenases, quinones, cytochromes and one terminal oxidase
- e- transfer enabled by presence of hemes and sulphur clusters
- capture e- to the electron acceptor protein and is transferred to another protein and this transfer creates energy
- cytochrome oxidase = final electron acceptor that turns oxygen to water
What happens in anaerobic respiration
Final e- acceptor is an inorganic compound other than O2
- nitrate is reduced to nitrite via nitrate reductase
Why is total ATP yield less in anaerobic vs aerobic
Only part of the Krebs cycle operates under anaerobic conditions due to less redox potential of final electron acceptor
Explain how fermentation works
- releases energy from oxidation of organic molecules
- does nto use teh Krebs cycle or the ETC
- substrate level phosphorylation
No energy
Pyruvate is reduced which then undergoes a series of processes that releases acid as byproduct
How is bacteria classified depending on their method of respiration
Aerobes - obligate, facultative, microaeropillic
Anaerobes - aerotolerant, obligate
Describe how mycobacterium tuberculosis combates immune system
Captured by macrophages bacteria avoids vesicles and continues to live and replicate
- 2 tings prevent the pass of oxygen
Why does mycobacterium tuberculosis have to change the mode of metabolism? How?
Host cell lipids are essential carbon sources during infections. So they switch from carbohydrate based metabolism to metabolism of lipid substrates via glyoxylate shunt enzyme
How does mycobacterium tuberculosis survive under energetically unfavourable and poorly oxygenate conditions?
- they move to another cytochrome that has higher afffinity for oxygen
- moves to anaerobic respiration, does part of TCA cycle to avoid losing carbon
Give an example of how fermentation leads to dental disease.
- gram positive bacteria
- commonly found in the mouth and is part of our microbiome
- high sugar diet → bacteria can ferment the sugar, they use the sugar and turns it into lactic acid
- permease system takes up sugar and undergoes fermentation
- decreases pH in our mouth (due to lactic acid)
How do bacterias grow?
Increase in number of cells not teh size of a single bacterium through binary fission
Explain in detail how binary fission is achieved
- elongation of cell wall, cell membrane and overall volume starts chromosome duplication
- septum wall grows inward chromosomes are pulled towards opposite ends
- septum is synthesised and cell membrane start to separate cell chambers
What are Fts proteins and what is their significance?
They are filamentous temperature sensitive proteins and it divides in 37 degrees and becomes filamentous at 42
- they interact to form the divisome which forms the septal ring and defines cell division plane
- Fts ring produced in the middle, sits in the internal part of the membrane
- other proteins attach to it and is in charge of producing diff components of cell wall
- the combination of all the proteins for this function is called the divisome
How does Fts find the middle?
- these proteins r involved in finding the middle
- one theory suggests that MinD and MinC is bound to the poles of the bacteria that prevents the formation of the ring
- the centre has no inhibition of FtsZ so a ring is able to be formed
Explain the bacterial life cycle and how the replication is started.
DnaA binds to DNA origin of replication (oriC) to initiate formation of the DNA replication complex.
tightly regulated for diff factors to ensure we have an exact copy of the original one
During adverse conditions, endospores are formed. Describe this:
- endospore pormatio acts as a survival mechanism
- resting stages highly resistant to heat, desiccation etc
- may survive thousands of years
- bacterial genome is sequestered in a safe place until environmental conditions improve
Describe the structure of the endospore formation
Mother cell secretes protein coat to protect spore and then lyses to release spore.
- spores have a very simple structure (just DNA and some ribosomes)
- assymetric division forms the forespore and it developes into a spore which separates
Describe the cellular structure of a spore
Core - DNA, RNA, proteins
Inner membrane
Spore wall
Cortex
Outer membrane
Protein coat
Exoporium
what is the protein coat used to protect spores?
Calcium dipocolinate
Difference vegetative cell vs endospores
- presence of calcium dipocolinic acid
- enzymatic activity and macromolecular synthesis
- heat resistance and chemical resistance
- sensitivity to lysozyme
- absent in V present in E
- present in V absent in E
- low in V high in E
- sensitive in V and resistant in E
Only what kind of bacteria forms endospores?
Positive
