Which of the following statements about V0, Vmax, [S] and Km values is not true?单项选择题

题目图片
A

a. An enzyme with a Km value much lower than the concentration of its substrate in the cell (Km << [S]) would be well suited to a ‘housekeeping’ role that needs to be maintained all the time.

B

b. An enzyme with a high Vmax necessarily has a high Km.

C

c. An enzyme with a Km value much higher than the concentration of its substrate in the cell (Km >> [S]) would be well suited to a role that needs to respond to variations in [S].

D

d. Many enzymes have a Km fairly close to the concentration of their substrate in the cell, so they usually work at a significant fraction of their Vmax but can respond to changes in [S] if required.

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类似问题

Question text SECTION A: ENZYMATIC REACTIONS This section contains a total of 7 marks. You should allow 7-10 mins to answer the questions in this section. Jeroen is an honours student working in the La Trobe Institute for Molecular Sciences. He is testing the efficacy of a new compound "X" that he hopes inhibits the activity of the enzyme he is interested in, Lockdownase. He conducts a Michaelis-Menten assay where his enzyme, Lockdownase, is incubated in the presence of increasing concentrations of substrate, with a constant concentration of inhibitor X. He obtains the following Lineweaver-Burk plot: Using the data above, answer the following questions (1 mark each): Q1. A. Calculate the Km for the enzyme alone (give your answer to 3 decimal places). Answer 1 Question 1[input] Q2. Calculate the Kmfor the enzyme + inhibitor (give your answer to 3 decimal places). Answer 2 Question 1[input] Q3. Calculate the Vmax for the enzyme alone (give your answer to 3 decimal places).Answer 3 Question 1[input] Q4. Calculate the Vmax for the enzyme + inhibitor (give your answer to 3 decimal places).Answer 4 Question 1[input] Q5. What is the type of inhibitor used in this experiment? Answer 5 Question 1[select: , Competitive, Irreversible, Uncompetitive, Covalent] Q6. What would you alter in the reaction mixture to increase the activity of enzyme back to normal levels (i.e. to before compound X was added) even in the presence of the inhibitor? Answer 6 Question 1[input] Q7. Which of the following conditions are important to keep constant when measuring enzyme activity? Select all that apply.pHvolumetemperatureoxygen levels Ensure that you have entered and checked all your answers before pressing "Next page" as you will not be able to return to this page and these questions.

The Vmax of an enzyme is:

Is the following statement true or false?'There is an inverse relationship between the Km and an enzyme’s affinity for its substrate'.

Question textFollow the instructions in your laboratory manual (page 24, Questions 1-4) to complete the following protocol table for this study on the effect of substrate concentration on enzyme activity. Give all your answers as numbers only. [table] Assay # | Final concentration of Ethanol(mM) | Volume of 0.6 M ethanol stock required(μL) | Volume of 15 mM NAD+ stock required to give final concentration of 0.5 mM(μL) | Volume of assay buffer(μL) | Water to provide a total volume of 290 μL(give your answer in μL) | Volume of ADH enzyme required(μL)(add last) | Total volume(μL) 1 | 0 | Answer 1 Question 14 | Answer 2 Question 14 | 200 | Answer 3 Question 14 | 10 | 300 2 | 5 | Answer 4 Question 14 | Answer 5 Question 14 | 200 | Answer 6 Question 14 | 10 | 300 3 | 10 | 回答第7题第14题 | 回答第 8 题第 14 题 | 200 | 答案 9 问题 14 | 10 | 300 4 | 14 | 回答第10题第14题 | 答案 11 问题 14 | 200 | 答案 12 问题 14 | 10 | 300 5 | 20 | 答案 13 问题 14 | 答案 14 问题 14 | 200 | 答案 15 问题 14 | 10 | 300 6 | 30 | 答案 16 问题 14 | 答案 17 问题 14 | 200 | 答案 18 问题 14 | 10 | 300 7 | 50 | 答案 19 问题 14 | 回答第 20 题第 14 题 | 200 | 答案 21 问题 14 | 10 | 300 8 | 100 | 答案 22 问题 14 | 答案 23 问题 14 | 200 | 答案 24 问题 14 | 10 | 300 [/table]

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