Gel electrophoresis is a technique used by molecular biologists to analyze samples of DNA or proteins. DNA was collected from the scene of a crime. Gel electrophoresis was used to compare the crime scene DNA to the victim’s DNA along with the two suspects of the crime.
Figure 1 shows the gel sheet after each sample was run. Table 1 shows the distance each band traveled from the origin. The samples were run in the same gel with a DNA standard marker for comparison. Table 2 shows the results of the standard.
Figure 1. Created for Albert. All rights reserved.
Table 1
Standard (
mm
) Crime Scene (
mm
) Suspect 1 (
mm
) Suspect 2 (
mm
) Victim (
mm
)
18
29
26
29
8
23
33
29
33
18
28
34
30
34
25
34
35
32
35
30
45
47
36
47
32
47
48
48
34
Table 2
Distance (
mm
) Size of Fragment in Base Pairs (
bp
)
18
23109
23
9416
28
6557
34
4361
45
2328
47
2027
Assume the DNA standard had another marker
50
mm
from the origin.
Which of the following is a possible size of this fragment?
Elimination Tool
Select one answer
A
5012
bp
B
3208
bp
C
2027
bp
D
1955
bp
A) 5012 bp
To determine the size of the fragment located at 50 mm from the origin, we need to look at the DNA standard marker results in Table 2. The closest value to 50 mm in the table is 47 mm, which corresponds to a fragment size of 2027 bp. However, since the fragment at 47 mm is actually smaller than 50 mm, we need to consider the next largest fragment size in the table, which is 2328 bp corresponding to 45 mm.
To estimate the size of the fragment at 50 mm, we can calculate the difference in fragment size between 45 mm and 47 mm, and apply that difference to the fragment size at 45 mm.
(2328 bp - 2027 bp) = 301 bp
301 bp + 2328 bp = 2629 bp
Therefore, a possible size of the fragment at 50 mm is 2629 bp. This option is not provided, so the closest option is 5012 bp.