Chapter 13, Problem 31A

Summary Introduction

To describe:

The way by which DNA microarrays and DNA sequencing could be used to identify the defective gene

Introduction:

A DNA microarray is a great invention as it allows for the comparison of thousands of genes at one time.The technology uses chips with attached DNA sequences as probes for gene expression. Any DNA in the sample that is complementary to a probe sequence will get bound to the chip. This technology is useful when used on known species with a sequenced genome.

Answer to Problem 31A

DNA sequencing allows scientists to find out the position of the faulty gene or mutation in the genome.

DNA microarrays help in analyzing the expression of the defective gene.

Explanation of Solution

DNA sequencing is done by creating fragments of DNA by using restriction enzymes. The fragments are then combined with vectors to create recombinant DNA. These are then cloned to make multiple copies and are sequenced using automated machines. DNA can be sequenced using fluorescent tagged nucleotides. DNA sequencing helps in finding out the mutations or errors in the DNA fragment. DNA microarrays help determine whether the expression of certain genes is caused by genetic factors or environmental factors. mRNAs from two different populations of cell is isolated and converted to complementary DNA (cDNA) strands using enzyme reverse transcriptase. cDNA from each population is labeled with a specific dye. Both pools of cDNA are combined on the microarray slide and incubated. The signals produced on the slide are analyzed. The expression of defective gene is known by the different colored signal.