DNA Microarray

Question 1

What is DNA microarray?

Answer 1

A tool that uses microscopic DNA spots on a solid surface to analyze DNA

Question 2

What are the main stages of DNA microarray?

Answer 2

1. Sample preparation
2. Hybridisation
3. Washing
4. Analysis

Question 3

Explain sample preparation in DNA microarray

Answer 3

Collect and purify RNA
RNA converted to cDNA or cRNA
Fluorescent probe attached

Question 4

What does the microarray look like?

Answer 4

Small solid surface with 1000s of microscopic spots containing DNA sequences (probes)

Question 5

What are the probes?

Answer 5

Short oligonucleotide sequences each complementary to a gene sequence.

Question 6

Please explain the hybridisation step.

Answer 6

Labelled cDNA/cRNA is added to the microarray.
If the cDNA/cRNA is complementary to a oligonucleotide, it will hybridise.

Question 7

What does the strength of the signal of each spot indicate?

Answer 7

How much of the target sample hybridized to the probe

Question 8

Please explain the washing step

Answer 8

Array is washed to remove any unbound or non-specifically bound cDNA/cRNA

Question 9

Why is the array scanned with a laser scanner?

Answer 9

To excite the fluorescent labels attached to the bound cDNA/cRNA.

Question 10

What does the detector measure?

Answer 10

Detector measures the intensity of the fluorescence, which correlates with gene expression level.