Lab on chemical and physical processes of digestion

20 terms by iwmaetmsiulpy 

Ready to study?
Start with Flashcards

Create a new folder

Advertisement Upgrade to remove ads

Carbohydrate digestion:
Which substance is the enzyme and which is the substrate? What is the product?

The enzyme is salivary amylase (an enzyme produced by the salivary glands and secreted into the mouth). The substrate is starch and the product is maltose.

STARCH + WATER --AMYLASE--> MALTOSE

Carbohydrate digestion:
At what pH did you see the highest activity of salivary amylase? Why?

At pH 7 the highest activity of salivary amylase occurred. The IKI test shows that pH 7 is optimal for activity because the most starch was digested here (a negative result) and the Benedict's Test showed the amount of glucose that was broken down from the starch and it yielded the most glucose (+2). Also, in the mouth, the optimum pH is 7 and so the optimum pH for the highest activity of salivary amylase is pH 7.

Carbohydrate digestion:
How do you know that the amylase did not have any contaminating maltose?

The Benedict's Test tested for glucose (maltose), and test tubes 2,5,6 & 7 showed the presence of maltose while test tubes 1,3 & 4 did not. Test tube five had maltose, water, and pH 7 buffer being used as a control because it proved that since maltose was added, maltose would also be a produce. Where test tube 3 didn't have maltose and only had amylase, water & buffer, this showed that maltose couldn't be contaminated with the enzyme since it didn't show up in the products.

Carbohydrate digestion:
What effect did boiling have on an enzyme activity? Why?

Boiling ended the enzyme activity (as seen by test tube 1 when it was boiled before being incubated) because the head caused the reactants and enzyme to denature and stop.

Cellulose Digestion:
Did freezing have an effect on the activity of amylase? Explain.

Even though there wasn't much of a difference, the Benedict's Tests still showed 2+ (or glucose molecules) and we expected for the freezing to slow down enzyme activity and the result to be +1.

Cellulose Digestion:
Does amylase use cellulose as a substrate? Explain.

No, amylase doesn't use cellulose as a substrate. According to the Benedict's Test, there was no glucose molecules produced so the cellulose wasn't broken down because humans can't break down cellulose (it's from plants).

Cellulose Digestion:
Do you think that the bacterial suspension contained the enzyme cellulase (an enzyme that digests cellulose)? Why or why not?

The bacterial suspension does contain the enzyme cellulase because the digestion of cellulose causes the IKI test to be negative and thus hydrolysis to happen. Also, sugar molecules were produced as seen by the Benedict's Test.

Cellulose Digestion:
What is the substrate of peptidase? Explain, based on your results.

Peptidase's substrate is not starch. Peptidase breaks down peptides while starch is broken down by amylase. IKI test was positive because starch wasn't broken down and Benedict's Test was negative because no glucose molecules were formed.

Protein Digestion by Pepsin:
At which pH did you see the highest activity of pepsin? How does this correlate to the location of pepsin in the body?

Pepsin had the highest rate of activity in a pH of 2.0. This correlates with pepsin's location in the stomach, which also has a low pH.

Protein Digestion by Pepsin:
What effect did boiling have on pepsin?

Boiling pepsin denatured the enzyme causing it to have no effect on BAPNA.

Protein Digestion by Pepsin:
What is the substrate in this experiment? What is the usual substrate for pepsin, and what subunits (products) are formed with pepsin activity?

The substrate is BAPNA, a synthetic peptide, and pepsin usually hydrolyzes polypeptides found in food. The presence of pepsin hydrolyzes polypeptides into peptides and free amino acids.

Protein Digestion by Pepsin:
What was the effect of decreasing the incubation time on the optical density results?

Decreasing the incubation time of the test tubes would result in lower optical densities since pepsin would have less time to hydrolyze BAPNA.

Protein Digestion by Pepsin:
What effect would decreased incubation temp. have on pepsin activity? Why?

The effect it would have on pepsin activity is that it wouldn't give the right optical density because of the decreased incubation temp. The optical densities would all be low (at zero) because the enzyme will denature at very low temps and thus not hydrolyze the protein as much.

Protein Digestion by Pepsin:
What was the significance of using 37 degrees C for the incubation?

The significance of using 37 degrees C for the incubation is that it is body temp. and so the reactions happen optimally at body temp. because the reactions occur in the body.

Fat Digestion by Pancreatic Lipase and the Action of Bile:
Why do lipids pose special problems for digestion?

Lipids are not water-soluble/poorly soluble so they aren't easily digestible.

Fat Digestion by Pancreatic Lipase and the Action of Bile:
Describe the activity of lipase with and without the addition of bile salts.

The lipase with the addition of bile salts caused the pH to decrease when the pH only decreased slightly without the bile salts which helps to digest easier/faster.

Fat Digestion by Pancreatic Lipase and the Action of Bile:
Is the activity of bile a chemical or physical process? Explain.

Bile is a physical process which breaks up fats so there is more surface area for lipase to work on digesting fats.

Fat Digestion by Pancreatic Lipase and the Action of Bile:
What pH resulted in the maximum pancreatic lipase activity? How does this optimal pH correlate to the enzyme's location in the body?

A pH of 7 resulted in the maximum pancreatic lipase activity by showing the largest change from pH of buffer to pH of solution. This change is important because lipase activity creates fatty acids which are acidic, thus lowering the pH. The small intestine has a pH of 7.8 so it makes sense why the most activity was in a pH of 7.

Fat Digestion by Pancreatic Lipase and the Action of Bile:
Explain whether of not we can determine fat hydrolysis in tube 5. Why or why not?

We can not determine fat hydrolysis in tube 5 because there is no change in pH because it was so acidic and can't get much more acidic.

Fat Digestion by Pancreatic Lipase and the Action of Bile:
What is the substrate in this experiment? What subunits (products) does lipase form?

The substrate in the experiment is vegetable oil (triglycerides). Two subunits are monoglyceride and two fatty acids.

TRIGLYCERIDE --BILE--> (EMULSIFICATION) MINUTE TRIGLYCERIDE DROPLETS

TRIGLYCERIDE --LIPASE--> MONOGLYCERIDE + 2 FATTY ACIDS

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set