Physio Ex Exercise 8 Activity 3 - Assessing Pepsin Digestion of Proteins PDF

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PhysioExo - Assessing Pepsin Digestion of Proteins...

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7/10/2020

PhysioEx Exercise 8 Activity 3

PhysioEx Lab Report Exercise 8: Chemical and Physical Processes of Digestion Activity 3: Assessing Pepsin Digestion of Protein Name: Date: 10 July 2020 Session ID: session-0bc05dc9-6ffe-8acf-05c6-c85fa8002b99

Pre-lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly. 1 Where in the body does protein digestion begin? You correctly answered: the stomach. 2 The substrate for pepsin is You correctly answered: protein and peptides. 3 In this activity the substrate you will be using to detect protein digestion is You correctly answered: BAPNA. 4 Negative results with the negative controls You correctly answered: are expected and validate the experiment. 5 A spectrophometer measures You correctly answered: optical density.

Experiment Results Predict Question 1 Predict Question: At which pH do you think pepsin will have the highest activity? Your answer: pH 2.0. Stop & Think Questions 1 Which of the following tubes are negative control tubes? You correctly answered: tubes 3 (pepsin, deionized water, pH 2.0 buffer) and 4 (deionized water, BAPNA, pH 2.0 buffer). 2 An optical density greater than zero indicates that https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex8/act3/

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7/10/2020

PhysioEx Exercise 8 Activity 3

You correctly answered: BAPNA digestion has occurred and pepsin is active. Experiment Data Tube No.

Reagent 1

Reagent 2

Reagent 3

Boiled

Time (min)

Temp (°C)

Optical Density

1

Pepsin

BAPNA

pH 2.0 Buffer

+

60

37

0.00

2

Pepsin

BAPNA

pH 2.0 Buffer

-

60

37

0.40

3

Pepsin

Deionized Water

pH 2.0 Buffer

-

60

37

0.00

4

Deionized Water

BAPNA

pH 2.0 Buffer

-

60

37

0.00

5

Pepsin

BAPNA

pH 7.0 Buffer

-

60

37

0.03

6

Pepsin

BAPNA

pH 9.0 Buffer

-

60

37

0.00

Post-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1 Pepsin would be most active You correctly answered: in the stomach. 2 Which two tubes validated the results of the experiment? You correctly answered: tubes 3 (pepsin, deionized water, pH 2.0 buffer) and 4 (deionized water, BAPNA, pH 2.0 buffer). 3 With more enzyme activity the optical density You correctly answered: increased. 4 If pepsin were digesting an actual protein substrate, the product would be You correctly answered: peptides and amino acids.

Review Sheet Results 1 Describe the effect that boiling had on pepsin and how you could tell that it had that effect. Your answer: Boiling inactivated the pepsin. There was no activity observed in Tube 1 but it was very active in Tube 2. https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex8/act3/

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PhysioEx Exercise 8 Activity 3

2 Was your prediction correct about the optimal pH for pepsin activity? Discuss the physiological correlation behind your results. Your answer: Pepsin is the most active. My prediction was a pH of 2.0 was correct. 3 What do you think would happen if you reduce the incubation time to 30 minutes for tube 5 (pepsin, BAPNA, pH 7.0 buffer)? Your answer: If the incubation time was reduced to 30 min for Tube 5, I think there would be no digestion of protein.

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