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Rdna Prac 4

This document summarizes the results of gel electrophoresis of PCR samples. Lane 3 shows a large band at 100-50 bp indicating the presence of an Alu insert in the DNA sample. Lanes 4, 5, and 7 did not migrate as far as the negative control in lane 6, suggesting unsuccessful amplification. Figure 1 shows the gel and Figure 2 graphs the relationship between DNA fragment size and distance migrated through the gel. Improving buffer pH and resistance would enhance electrophoresis quality by providing stable conditions over long durations.

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Mthetheleli Nxele
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240 views2 pages

Rdna Prac 4

This document summarizes the results of gel electrophoresis of PCR samples. Lane 3 shows a large band at 100-50 bp indicating the presence of an Alu insert in the DNA sample. Lanes 4, 5, and 7 did not migrate as far as the negative control in lane 6, suggesting unsuccessful amplification. Figure 1 shows the gel and Figure 2 graphs the relationship between DNA fragment size and distance migrated through the gel. Improving buffer pH and resistance would enhance electrophoresis quality by providing stable conditions over long durations.

Uploaded by

Mthetheleli Nxele
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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PRACTICAL 4: GEL ELECTROPHORESIS OF AMPLIFIED PCR SAMPLES

NAME: MTHETHELELI

SURNAME: NXELE

STUDENT NO: 221040133

1 2 3 4 5 6 7

2642 bp

1000 bp 530 bp

500 bp 550 bp

300 bp

200 bp 290 bp

100bp 100-50 bp

Figure 1: Agarose (1%) gel electrophoresis of multiple PRC reaction. PRC control with water instead of
DNA in reaction mix can be seen in lane 2. PRC reaction mix with DNA template can be seen in lane 3-
7.
The gel image of PCR result under the u.v light. Base pairs of each sample are represented by bp. The
number of base pairs decrease as the distance from the origin increases. The negative control buffer
with water travelled to about 290 bp while the DNA lane 3 travelled to 100-50 with one large band
thus showing the Alu insert, DNA on lane 4,5 and 7 did not travel down father but DNA in lane 6 show
almost the same as negative control. Gel electrophoresis is the most common method used to detect
products from PCR. Each gel electrophoresis should contain a positive control and a negative control.
The positive control should consist of a segment of DNA of known size (preferably of the same size as
the target amplicon). The negative control was only buffers (GelRed) and reagent water. The PCR
positive and negative controls can be used as the positive and negative gel electrophoresis controls,
respectively. The DNA ladder (a mixture of DNA fragments of known sizes), was also run on the gel to
provide a standardized gauge of the size of DNA fragments seen in the test samples and controls. The
size of the expected product should be within the size range covered by the standard. Extrapolation
beyond the range of the standard should not be performed.
Log MW vs Distance Travelled
4

3.5

2.5
logMW

1.5

0.5

0
0 10 20 30 40 50 60 70 80
distance traveled cm

Log MW Expon. (Log MW)

Figure 2: is the graph of logMw Vs Distance travelled in cm, in agarose, the migration distance of
fragments of DNA is inversely proportional to their size: the smaller the DNA molecule, the farther it
migrates through the gel.
An individual is heterozygous +/- if there are two bands that match the +/- control. The person is
homozygous -/- if there is one band that matches the -/- control, and homozygous +/+ if there is one
band that matches the +/+ control.
To improve the quality of the electrophoresis result, the first problem demanding a solution is the pH
condition. Change in the pH makes it impossible for long-duration electrophoresis. Therefore, the
buffer’s resistance should be improved. An environment that supports a stable ionic bond structure
and measuring range during the whole experiment.

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