For this protein gel, molecular weight markers were loaded in the first well. Molecular weight marker bands are labeled 1 - 5. The markers contain aprotinin (6 kDa), trypsin inhibitor (21.5 kDa), lactate dehydrogenase (36.5 kDa), bovine serum albumin (66.2 kDa), and myosin (200 kDa).

Sample X and sample Z were loaded in the second and third wells, respectively. Sample protein bands are labeled A - F.

A) Which MW band represents trypsin inhibitor?
[ Select ]
3
2
5
1
4

B) What is the approximate molecular weight of the protein in band C?
[ Select ]
30 kDa
50 kDa
200 kDa
5 kDa
80 kDa

Question

For this protein gel, molecular weight markers were loaded in the first well. Molecular weight marker bands are labeled 1 - 5. The markers contain aprotinin (6 kDa), trypsin inhibitor (21.5 kDa), lactate dehydrogenase (36.5 kDa), bovine serum albumin (66.2 kDa), and myosin (200 kDa).

Sample X and sample Z were loaded in the second and third wells, respectively. Sample protein bands are labeled A - F.

A) Which MW band represents trypsin inhibitor? 
[ Select ]
3
2
5
1
4

B) What is the approximate molecular weight of the protein in band C? 
[ Select ]
30 kDa
50 kDa
200 kDa
5 kDa
80 kDa

BlackTom AI · Accepted Answer

Let’s tackle the two parts of this question in sequence, carefully mapping markers to their known molecular weights and then applying that to the gel bands.
Option A reasoning:
- The molecular weight markers are given as five values: 6 kDa, 21.5 kDa, 36.5 kDa, 66.2 kDa, and 200 kDa. They are labeled in the order 1 through 5. That means band 1 corresponds to 6 kDa, band 2 corresponds to 21.5 kDa, band 3 corresponds to 36.5 kDa, band 4 corresponds to 66.2 kDa, and band 5 corresponds to 200 kDa.
- The question asks which MW band represents trypsin inhibitor. The markers list explicitly states that trypsin inhibitor is 21.5 kDa, which matches band 2.
- An alternate route to the same conclusion is to check the progression: 21.5 kDa is the second smallest marker, so it maps to band 2. Therefore, band 2 is the trypsin inhibitor marker.
Option B reasoning:
- Band C on the gel lies between the bands labeled by the markers corresponding to 21.5 kDa and 36.5 kDa, since C is drawn at an intermediate position between those two marker references on the typical gel ladder progression.
- The two marker weights surrounding this region are 21.5 kDa and 36.5 kDa. An approximate value that lies between them and is commonly used in many problems is 30 kDa, which matches one of the provided choices.
- The alternative choices—30 kDa, 50 kDa, 200 kDa, 5 kDa, 80 kDa—fit differently: 50 kDa would be closer to the mid-ladder, but not anchored between 21.5 and 36.5 unless the band is placed accordingly; 200 kDa is far too large for a middle band like C; 5 kDa is smaller than the smallest marker; 80 kDa is not clearly aligned with the C position on the schematic. Hence 30 kDa is the best approximate.
In summary, for Part A the band representing trypsin inhibitor is band 2, and for Part B the approximate MW for band C is 30 kDa.

W25 BIOL D006B 01Y Cell & Molecular Biology Lab Quiz 4

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