Question

I have a test soon coming up and I really don’t understand this, please be very detailed and guide me

Q5B. A sample of albumin was treated as shown below for 10 minutes. After the treatment, 5 drops of Ninhydrin reagent was added and heated for 5 min. Explain the observations for EACH tube. 2m Tube Added components Result No. 2 ml Albumin 1 ml distilled water colorless 2 ml Albumin. 1 ml Pepsin + 2 drops of 0.1N HCI Light purple Q5C. A fat free carton of milk was tested for casein content. The precipitate obtained after addition of 1 tablespoon lemon juice to 30 ml of warm milk (700F) was filtered and dried completely. The weight of the dried casein was found to be 1.1 gm. The label shows that one serving size (240 ml) has 8 gm protein Determine if the label is accurate and if not, then calculate the % error. Show calculations 2m

both questions

take your time

Answer 1

Ans 1: As described in the table in the first tube has the protein and distilled water and its gives no color that means no free amino acids is present in the tube because ninhydrin reagent basically deaminates the amino acid and produce a substance called diketohydrin which has a purple appearance. Since this tube has no such peptidase that’s why it does not contains any free amino acids and hence no color appears. Hence it will act as the control or we can say the origin point.

In second tube we have the protein albumin, the endopeptidase pepsin which cuts at the amino side of aromatic amino acids. So this tube must contain free amino acids which react with the Ninhydrin reagent and this gives the light purple appearance.

Ans 2: From the experiment we conducted we got the result that 30 mL contains 1.1 gm of Casein which means 240 mL contains 8.8 gm of Casein, but the label mentioned that 240 mL contains 8 gm of Casein. So the label is not accurate and % error is (|Approx-Exact|/Exact)*100= |8-8.8|/8.8*100= 9.09% error.