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25 Cards in this Set
- Front
- Back
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What does a typical photoautotroph need to function? |
Light, DIC, DIN, DIP & DOP, metals, vitamins etc. |
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Diffusion is only useful when external [salt] > internal [salt], true or false? |
True |
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In marine systems, is internal [salt] greater or less than external [salt]? |
Greater than. Internal [salt] is measured in mm, whereas external [salt] is in nm or um. |
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What do marine organisms use to create low internal [Na+] and high internal [K+]? |
Na/ K co-transporters and ATP |
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What comes in with Na+? |
Nutrients |
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What kind of curve do Michaelis-Menten Kinetics produce? |
Rectangular hyperbolic curve |
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Which is more beneficial, a low Kg and a high umax, or a high Kg and a low umax? |
A low Kg and a high umax |
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What is Kt? |
Substrate affinity |
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What is Tmax? |
Maximum transport rate |
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Stress stimulates synthesis, therefore... |
To alter Tmax, more porters are needed. |
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If DN is insufficient, what else can some cyanobacteria use? |
N2 |
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Examples of DIN? |
Ammonium and nitrate |
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Which is more costly to use, NO3- or NH4+ and why? |
NO3- because it is reduced internally to NH4+ at a 20 % cost to concurrent PS. |
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Examples of DON? |
Urea, urease |
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What do cells need urease for? |
Assimilation |
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How is synthesis controlled? |
Repression |
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When is synthesis allowed? |
When signals repressing are removed (de-repression) |
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What is metabolite repression? |
Feedback control, typically from an end product |
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What is internal NH4+ assimilated into? |
Glutamine |
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What are feedback controls for NH4+ and NO3- suggested as? |
Glutamine, or 2-oxoglutaric acid (ketoglutaric acid) |
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What is an example of feedback control in the longer term? |
Overall N-status (N:C) |
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What are the enzymes central to N-assimilation? |
- Nitrate reductase (NR; NO3- to NO2-) - Nitrite reductase (NiR; NO2- to NH4+) - Glutamine synthetase (GS; Glu + NH4 to Gln) - Glutamine, oxoglutaric acid transferase (GOGAT; Glu + 2OG to 2Glu) - 2OG made from C fixation |
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Is NO2- toxic? |
Yes |
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How is reductant made? |
It is photogenerated using NADPH2 |
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What is stress? |
Caused by something that elicits an energy/resource costing response which is otherwise not required |
