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Question 1

How is the base sequence of DNA determined by electrophoresis.

Answer 1

Sequencing DNA is used to determine the exact base sequence of a segment of DNA.

This uses modified nucleotides that cause
different strand lengths to be produced, depending on the nucleotide (A,T,C,G).

The sequence can be determined using gel electrophoresis.

Question 2

What is GEL ELECTROPHORESIS

Answer 2

A process that separates DNA fragments according to their size, resulting in a
banding pattern.

Question 3

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What are the steps to gel electrophoresis

Answer 3

1. DNA samples are placed into wells at one end of a block of agar gel, which has electrodes at each end of it.
2. An electric current is turned on, and the DNA fragments move towards the positive
   electrode (because DNA fragments are negatively charged). Smaller fragments move
   faster, so the different sized fragments are separated.
3. The accumulation of the different sized fragments produces a banding pattern on the gel, which can be interpreted.

Question 3

Info about electrophoresis displayed in an electropherogram

Answer 3

• Sequencing can now be automated using capillary gel electrophoresis.
• Results are shown with an electropherogram.
• Base sequence is read from left to right