SSCE VCE Biology Scientific Investigation and Research Methods: The student wanted to investigat

Question

The student wanted to investigate the effect of two different endonucleases (restriction enzymes) on a linear DNA fragment.
The student used three tubes containing a buffered solution of linear DNA fragments, each fragment being 9500 base pairs in length.

Two different endonucleases were available: BamHI and HindIII.

Step 1 – 2 μL of BamHI was added to the sample in Tube 1.
Step 2 – 2 μL of HindIII was added to the sample in Tube 2.
Step 3 – 2 μL of HindIII and 2 μL of BamHI were added to the sample in Tube 3.
Step 4 – The three tubes were incubated for one hour at a constant temperature of 37 °C.
Step 5 – A 1% agarose gel was placed into an electrophoresis chamber and the gel was covered with buffer solution.
Step 6 – 40 μL of a DNA ladder with fragments of known sizes was added to the first well of the 1% agarose gel.
The known sizes of the fragments were 10000 bp, 8000 bp, 6000 bp, 5000 bp, 4000 bp, 3000 bp, 2000 bp, 1500 bp, 1000 bp, 500 bp and 250 bp.

Step 7 – 40 μL of the contents of each of the tubes was loaded into three separate wells of the 1% agarose gel.
Step 8 – An electric current of 100 V was run through the gel for 45 minutes.

after 45 minutes the student obtained the results shown below.

[DNA ladder image]

Source: results based on a 1 kb DNA ladder from TEquipment, www.tequipment.net.

The student wanted to investigate the effect of two different endonucleases (restriction enzymes) on a linear DNA fragment - VCE - SSCE Biology - Question 11 - 2020 - Paper 1

Worked Solution & Example Answer:The student wanted to investigate the effect of two different endonucleases (restriction enzymes) on a linear DNA fragment - VCE - SSCE Biology - Question 11 - 2020 - Paper 1

What effect did each endonuclease have on the linear DNA fragment?

What might account for the absence of a band in Tube 1?

What might account for the single band in HindIII/Tube 2?

What factors could affect the size or length of the fragments produced?

What is a suitable safety precaution in this experiment?

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