Pre-AP Biology Energy and Matter Study Guide #2

Transcription

1 Pre-AP Biology Energy and Matter Study Guide #2

2 1. Which number represents the amount of activation energy required without an enzyme? 2. With an enzyme? 3. Summarize the effect of an enzyme on activation energy? reactants products

3 1. Which number represents the amount of activation energy required without an enzyme? 3 2. With an enzyme? 2 3. Summarize the effect of an enzyme on activation energy? Lowers it reactants products

4 Use complete sentences and the terms 1-7 (below) to describe the steps in the enzyme-cycle: 1 Enzyme 2 Active site 3 Substrate 4 Induced fit 5 H 2 O molecule 6 Hydrolysis 7 Products

5 Enzyme-Cycle Diagram

6 C D B A Describe and explain the rate at A D And, what was the Vmax you calculated for the graph?

7 Slow rate due to lag-time substrate must get into liver cells Rate zero because ran out of substrate Rate slows as substrate starts to run out Highest rate is between 5 and 20 min. because substrate is abundant: 17.3 µmol/ml min. (c)

8 1. Maximum rate (steepest slope) 1 10 s = 2. Rate 40 to 50 s = 3. Why the difference in rate 0 10 s vs s? 4. Change to maintain initial high rate: 5. Effect of doubling enzyme on rate:

9 1. Maximum rate (steepest slope) 1 10 s = 0.7 moles/second 2. Rate 40 to 50 s = 0 moles/second 3. Why the difference in rate 0 10 s vs s? 0 10 s = abundant substrate = substrate ran out 4. Change to maintain initial high rate: Add more substrate 5. Effect of doubling enzyme on rate:

10 1.Use the data table to calculate the rate of reaction 0 10 min.: 2.Calculate the rate of reaction min.: 3.Add the label (A) to the graph to indicate the period of maximum enzyme rate. 4.Add the label (B) to the graph to indicate the period of deceleration of the enzyme. 5.Add he label (C) to the graph to indicate the period when the enzyme s rate became zero because it ran out of substrate. 6.Add a line to the graph that would show the rate of reaction if the [enzyme] was doubled:

11 B C A 1. Rate of reaction 0 10 min. (5.1 0)/(10 0) = 0.51 μm/min. 2. Rate of reaction min. ( )/(20 10) = 0.35 μm/min.

12 Describe and explain the relationship between temperature and enzymatic reaction rate:

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14 1. Identify the optimal temperature for most human enzymes? How does this compare with body temp.? 2. Identify the optimal temperature for enzymes from thermophilic bacteria? 3. Explain why the optimal temperatures are different for these two species:

15 1. Identify the optimal temperature for most human enzymes? How does this compare with body temp.? 37⁰C about the same 2. Identify the optimal temperature for enzymes from thermophilic bacteria? 78⁰C 3. Explain why the optimal temperatures are different for these two species: Human enzymes best adapted for our body-temperature while thermophilic bacteria live in hot-springs so their enzymes have evolved through natural selection to function at high temperature.

16 ph above or below optimal will break Hydrogen and ionic bonds, causing enzyme to denature. 1. Why is the 3-D structure of an enzyme important to its function? 2. Why can ph above or below an enzyme s optimal change the enzyme s structure? 3. How does denaturation affect an enzyme s function & rate of reaction?

17 ph above or below optimal will break Hydrogen and ionic bonds, causing enzyme to denature. 1. Why is the 3-D structure of an enzyme important to its function? Enzyme s must have a lock-key-fit with their substrate to interact with it 2. Why can ph above or below an enzyme s optimal change the enzyme s structure? Bonds that hold the enzyme s 3-D shape together can break 3. How does denaturation affect an enzyme s function & rate of reaction? When an enzyme denatures, it unravels, and its lock-key-shape is lost and it can not connect with its substrate, so it loses function.

18 1. Identify the optimal ph for pepsin? 2. Infer what the ph of the stomach is likely to be: 3. Identify the optimal ph for trypsin: 4. Infer what the ph of the small intestine is likely to be: 5. Explain why the optimal ph is different for the 2 enzymes:

19 1. Identify the optimal ph for pepsin? Infer what the ph of the stomach is likely to be: acidic: Identify the optimal ph for trypsin: 8 4. Infer what the ph of the small intestine is likely to be: slightly basic: 8 5. Explain why the optimal ph is different for the 2 enzymes: the enzymes have adaptations to be most effective in the phenvironment in which they are found

20 How can we measure how much energy (kcal) is in our rapid plants? Bombcalorimetry: 1 g rapid plant = 4.35 kcal watch?v=eagbknidkno

21 The dry-mass of 200 rapid-plant seeds: g The initial (wet) mass of 200, 21 day-old rapid-plants: g The dry-mass of those plants: 9.91 g 1 g of rapid-plant = 4.35 kcal 1. What % of the living plants was biomass (not water): (dry mass/wet mass) How much mass was added through photosynthesis from seeds to adult plants (use dry mass to calculate)? 3. Where did the added mass come from? 4. How much energy in kcal was added by the rapid plants through photosynthesis?

22 1. What % of the living plants was biomass (not water): (9.91 g/ g) 100 = 8.5% 2. How much mass was added through photosynthesis from seeds to adult plants (use dry mass to calculate)? 9.91g 0.492g = 9.42 g 3. Where did the added mass come from? The mass came from the reactants of photosynthesis. The majority came from CO 2 gas and H 2 O contributed the mass of the hydrogen atoms. 4. How much energy in kcal was added by the rapid plants through photosynthesis? 9.42 g rapid plant 4.35 kcal/g = kcal (energy)