Goal of lesson - Learners will apply a DNA microarray analogy to determine the expression level of multiple genes in a genome.

Objectives

1. Learners will determine how a football field is like a DNA microarray.
2. Learners will know what a DNA microarray is.
3. Learners will have a better understanding of transcription and gene expression.

Using the latest technology of DNA microarrays, scientists are now able to simultaneously look at the expression level of multiple genes in a genome. A DNA microarray is a very small piece of plastic or glass (also known as a "chip") onto which single-stranded segments of DNA have been attached in a microscopic array.

We can use a football field analogy to explain these "chips."

To find out which pages are photocopied the most, all of the pages out of the library that are used in photocopying are laid down side by side on the field. These pages represent the gene sequences that are used in a microarray.

If someone puts glow in the dark paper into the copy machine, the copies that are made (the genes that are transcribed) will glow in the dark.

Each copy is then laid onto its representative page on the field. Pages that have been copied many times (analogous to genes that are transcribed many times) will have higher stacks.

These high stacks represent highly transcribed genes. A page that is not photocopied at all will have no glow in the dark pages placed upon it. This represents a gene that is not transcribed.

After the sun goes down, one can look at the field and see which pages (genes) are glowing. Those that have been photocopied the most will have the highest stacks and will glow the brightest. These represent the genes that have the greatest expression.

Just as there is variation in the pages on our football field, there is variation in gene expression. Variation in gene expression in the genome is linked to the phenotypic variation in cells.

Using DNA microarrays the variation in abundance of each gene's transcript can be surveyed. In other words, it is easy to identify which genes are transcribed the most (i.e. have the greatest expression).

Back to Top