Enzyme rate and controlled measurements
導入済み| English | 意味 |
|---|---|
| enzyme/ˈenzaɪm/ | 酵素 |
| denaturation/ˌdenətʃəˈreɪʃn/ | 変性 |
What would explain this observation?
- An enzyme 酶 works quickly at one temperature and slowly at another. Heating can increase successful collisions, but excessive heat can change the active site.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- An enzyme is a biological catalyst. The substrate binds at an active site whose shape and chemical properties support the reaction. A catalyst increases rate without being used up overall.
- enzyme: A biological catalyst; denaturation 变性: A structural change that disrupts function.
Which change best tests the effect of pH?
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Testing pH means changing only pH. Buffers of different pH at one fixed temperature isolate pH as the variable; changing temperature or enzyme concentration at the same time would mix two variables and the result could not be attributed to pH.
Match each technical term to its precise meaning.
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Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Measure rate using product formed per unit time or a fixed endpoint. For an endpoint test, 1/time is a rate proxy if the same amount of product or substrate change defines the endpoint each time.
- For starch digestion, equilibrate enzyme and starch in a water bath, control pH with buffer, mix measured volumes, and test samples with iodine at fixed intervals. Use a clean spot for each test. Do not put iodine into the reaction mixture.
Which two habits make the investigation or model in this case more defensible?
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Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: the endpoint is reached in 40 s. Use rate proxy = 1/time. Rate proxy = 1/40 = 0.025 per second. At 20 s the proxy is 0.050 per second, twice as large. This comparison is valid only if the same endpoint and starting concentrations are used.
A fixed endpoint takes 50 s. Calculate the rate proxy 1/time. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A fixed endpoint takes 50 s. Calculate the rate proxy 1/time.
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The result is 0.02 1/s. Known: the endpoint is reached in 50 s. Use rate proxy = 1/time. Rate proxy = 1/50 = 0.02 per second. This proxy is comparable with the 40 s worked case (0.025 per second) only because the same endpoint definition is used.
Check the conclusion and its limits
- An optimum is specific to the enzyme and conditions. Low temperature usually slows the reaction; it does not necessarily denature the enzyme. Endpoint intervals limit precision.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
A low temperature always permanently denatures an enzyme. This claim is false: Low temperature usually only slows an enzyme because molecules collide less often; the active site is unchanged and warming restores activity. Denaturation is a structural change from excessive heat or extreme pH, not a guaranteed result of cooling.
Enzyme rate and controlled measurements: Measure rate using product formed per unit time or a fixed endpoint. For an endpoint test, 1/time is a rate proxy if the same amount of product or substrate change defines the endpoint each time.
A low temperature always permanently denatures an enzyme.
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
Low temperature usually only slows an enzyme because molecules collide less often; the active site is unchanged and warming restores activity. Denaturation is a structural change from excessive heat or extreme pH, not a guaranteed result of cooling.
A biological catalyst: write the technical term.
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enzyme means A biological catalyst.