Microarrays and Gene Expression Arrays

Francisco Millan, Michelle Measar, Gurleen Kaur

Introduction to Microarrays

We are doing research on gene expression of an anomaly cell compared to a normal cell.

Gene mutations lead to abnormal cell behavior. This results in altered gene expression which affects cell function.

Microarrays is a technique used to analyze the expression of more than one gene within a cell.

Using microarrays, differences in gene expression between two different cells types can be pinpointed.

Using a microarray chip is highly efficient in that it can test for multiple genes at once.

We save time, effort and resources.

So what is a Microarray?

How a Microarray chip is made. 1. We need the entire sequenced genome of an

organism.2. Design primers to replicate

each gene. 3. PCR to make multiple copies

of genes that will be used as probes.

4. Denature the duplex DNA into single strands.

5. Place microscopic spots of each single-stranded DNA

gene into ordered rows and columns on a slide.

Types of Microarrays1.DNA

a.(Gene Expression)2.Protein3.Carbohydrates4.Antibodies5.Metabolites

Gene Expression arrays look to see if certain genes are being expressed in a cell.

Microarray Methods

1.Collect Tissue2.Isolate RNA3.Isolate mRNA4.Make Labeled DNA

copy (cDNA)5.Apply cDNA6.Scan Microarray7.Analyze Data

Advantages of Microarrays.1.They provide information on thousand of

genes in a single experiment.2.Mostly used for gene expression studies.3.Saves time, effort, resources and are easier to

use. They are cost-effective and relatively cheap- within the reach of many individual researchers.

4.With this technology, we are developing improvements in therapy, faster cancer diagnosis and prognosis.

5.It is still improving and advancing.

Disadvantages of Microarrays

1.Faulty probe sequences can lead to faulty hybridization and false positive.

2.Reverse transcriptase activity may produce cDNA mutant and give a false negative.

3.A faulty translation mechanism may not detect gene expression or proper proteins for cellular function.

How gene expression and microarray relate to our article

1. Why gene expression array was used in our article?

To analyze gene expression patterns between monozygotic twins of different ages.

2. What was the conclusion of the gene expression array?

Gene expression changes with age due to multiple factors (life-style, environment, etc…).

Fig. The older MZ twins display the greatest differences in gene expression profiles between siblings. (Left) Scatter plots showing expression profiles of 3- and 50-year-old twin pairs. (Right) Number of overexpressed and repressed genes obtained by DNA array analyses in the 3-year-old compared with the 50-year-old twin pair.