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content/Biokemi/Gamla tentor/2024-08-01/35.md

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+---
+tags:
+  - biokemi
+  - provfråga
+  - plasmid
+---
+**Uppgift**
+
+A gene of interest was amplified and verified using the blue/white screening method. The
+plasmids from two bacterial colonies, one blue colony and one white colony, were purified. Then
+restriction enzyme digestion was performed, and the samples were run on a gel as follows: white
+uncut, white cut, blue uncut, blue cut (see figure below). After imaging the gel, we can conclude
+that while there is plasmid DNA in all samples, the white sample was probably mixed with the
+blue sample. Explain what finding in the gel indicates the white sample was probably mixed with
+the blue sample by referring to the size/number of bands. Account for the other source of error
+for this outcome besides pipette tip contamination from sample to sample. (4p) (Max 200 words)  
+OBS! This question needs to be answered in English.
+
+**Answer**
+
+the findings in the gel that indicate that the samples were mixed are the lines in
+the white uncut sample. It has two visible bands, with one lining up quite nicely
+with the blue uncut bands in size. If the plasmid is uncut, than there shouldn't
+be two distinct bands because the sample only consists of an uncut product. The
+white uncut should also have a larger amount of base pairs than the blue
+uncut because we have transformed a gene of interest into it, but they seem to
+have the same amount.  
+a source of error for this outcome could be that the colony picked for the white
+cut may have been close to a blue colony - causing a small amount of the blue
+colony to be accidentaly picked.  
+
+Ord: 131  
+Totalpoäng: 4