Bio Lab Report A Study of Digestive Systems PDF

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A Study of Digestive SystemsIntroduction: This experiment consisted of three tests using the enzymes amylase, pepsin, and lipase. Each enzyme described the effects of a specific digestive system and its corresponding biomolecule. The enzyme amylase is emitted in both saliva from the mouth and in the...

Description

A Study of Digestive Systems Introduction: This experiment consisted of three tests using the enzymes amylase, pepsin, and lipase. Each enzyme described the effects of a specific digestive system and its corresponding biomolecule. The enzyme amylase is emitted in both saliva from the mouth and in the duodenum as pancreatic amylase and is used to break down starch. Amylase is used to cleave “large starch molecules into drexin and subsequently into smaller maltooligosaccharides (MOS) containing α-D-(1,4) linkages, isomaltooligosaccharides (IMOS) containing  α-D-(1,6) linkages, the trisaccharides maltotriose, and the disaccharide maltose” (Breslin and Gachons). Glucose molecules could be used in cellular respiration to produce ATP. A well plate was used, containing water which was the negative control and starch which was the positive control. Below were three wells that were designated to a certain amount of minutes (1, 3, and 7) each of which contained two drops of the starch plus amylase mixture and one drop of I₂Kl reagent. The hypothesis for this experiment is that the solution would change colors from blue to yellow as the amylase broke down the starch. The enzyme pepsin is used to break down proteins and polypeptides located in the stomach and the duodenum. Proteins are broken down into smaller peptides that make it easier to be transported in the body. The peptides can then be broken down into amino acids that make new functional proteins. Six test tubes contained different amounts of water, albumin, NaHCO₃, hydrochloric acid, and pepsin in order to observe protein digestion in pepsin. A biuret reagent was added to qualitatively measure the concentration of proteins. If the test tube was blue it meant there was an absence of proteins, if it was pink then there was a presence of peptides, and purple if there was a presence of proteins. After the samples were completed they were placed in 37℃ water which provided a stable environment. The hypothesis was that the test tube which contained hydrochloric acid and pepsin would result in the most color change, which would be to the color orange, since pepsin needs an acidic environment. The enzyme lipase is used to break down lipids. The digestion starts in the duodenum which means the lipase molecules break down into fatty acids and glycerol. The four test tubes used in this experiment tested the main function of lipase. The test tube contained different amounts of water, bile salts, and lipase but all contained the same amount of whole milk, NaOH, and phenol red. Phenol red has a pink color when it's in an alkaline solution, an orange color when it’s in a neutralized solution and a yellow color when it’s in an acidic solution. Once the test tubes were prepared, they were placed in 37℃ water which provided a stable environment. The hypothesis for this experiment is that the test tube that

contained the most bile salts along with the whole milk and lipase would have the most color change from pink to yellow.

Materials and Methods: The group followed the procedure as listed in the lab manual. The group used all materials as directed and did not stray from the given instructions (Malinoski, 188-192).

Results: In the experiment with amylase, the positive control (starch) turned blue and the negative control (water) turned yellow. After one minute the mixture of amylase and starch turned dark blue. After three minutes the mixture of amylase and starch turned light brown. Finally, after seven minutes, the mixture of amylase and starch turned yellow. See figure 1 on page 5. In the second experiment with pepsin, Test Tube 1 was clear, Test Tubes 2, 3, 4, and 6 were purple. Lastly, Test Tube 5 was pink. See table 2 on page 5. In the third experiment with lipase, Test Tube A and B were pink. Test Tube C resulted in a cloudy orange color and Test Tube D resulted in clear orange. See table 3 on page 5-6.

Discussion: In the first experiment, the hypothesis that the solution would change colors from blue to yellow as the amylase broke down the starch was supported because the solution changed from blue to brown to yellow over the course of seven minutes. This means that the initial concentration of starch was broken down into simpler molecules. The final yellow colors means that most of the molecules of starch were broken down because the solution was almost the same shade as the negative control of water that didn’t have any starch in it. In the second experiment, the hypothesis that the test tube with pepsin and HCL, which was Test Tube 5, would have the most colorimetric change from pink to orange was supported by the data. In mammals, the inactive form of pepsin, pepsinogen, is “secreted by chief cells in the gastric glands and is converted to pepsin by the highly acidic conditions of the stomach” (Russell). Only Test Tube 5 contained a mixture of the enzyme and an acid that could activate the functional aspect of the enzyme which means that the polypeptide was able to react with the enzyme. This broke down into peptides and amino acid chains which reacted with the biuret reagent to produce pink. Test Tube 1 remained clear but the remaining Test Tubes were purple because they either lacked pepsin or HCL which proposes the presence of protein. This means that the proteins could not be broken down because the enzyme was inactivated.

In the third experiment, the hypothesis that the test tube that had the most bile salts, which was Test Tube D, would turn from pink to yellow was not supported. Test Tube D resulted in a clear orange color which means that the solution had a neutral pH level. It was not considered that the fatty acids were just slightly acidic and the base of NaOH neutralized the pH of the overall solution. The main issue with these experimental tests is that only one trial was conducted for each. To make this experiment more reliable, multiple trials should take place in the future.

Works Referenced:

Gachons, Catherine Peyrot des, and Paul A. S. Breslin. “Salivary Amylase: Digestion and Metabolic Syndrome.” SpringerLink , Springer US, 17 Sept. 2016. Malinoski, Chris. Biology 1107: Principles of Biology-Laboratory Manual. Michigan: Hayden-McNeil, 2020. Russell, Peter J., et al. Biology: the Dynamic Science. Cengage Learning, 2017.

Figures and Tables: Table 1. The effect of amylase on a sample of starch over 7 minutes Test

Negative Control

Positive Control

Starch +

Starch +

Starch +

(dH₂O)

(Starch)

Amylase after

Amylase after

Amylase after

1 minute

3 minutes

7 minutes

Dark Brown

Light Brown

Yellow

I₂Kl

Yellow

Blue

Table 2. The effect of pepsin on samples of albumin over 15 minutes. Test Tube

dH₂O (mL)

1% Albumin

0.05M HCl

1% NaHCO₃

0.5%

(mL)

(mL)

(mL)

Pepsin

Final Color

(mL) 1

4

0

0

0

0

Clear

2

2

2

0

0

0

Purple

3

1

2

1

0

0

Purple

4

1

2

0

0

1

Purple

5

0

2

1

0

1

Pink

6

0

2

0

1

1

Purple

Table 3. The effect of lipase on multiple samples of whole milk over 15 minutes. Test

dH₂O

Whole

5% Bile

0.5%

0.1M

0.05%

Initial

Final

Tube

(mL)

Milk

Salts (mL)

Lipase

NaOH

Phenol

Color

Color

(mL)

Red

A

2

2 drops

0

0

1 drop

1 drop

Pink

Pink

B

1

2 drops

1

0

1 drop

1 drop

Pink

Pink

C

1

2 drops

0

1

1 drop

1 drop

Pink

Cloudy Orange

D

0

2 drops

1

1

1 drop

1 drop

Dark

Clear

Pink

Orange...