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What is differential gene expression?
the process by which cells with identical genomes become specialized by activating or silencing specific sets of genes
What are probes in a microarray?
single-stranded DNA or RNA molecules immobilized in high-density, orderly spots on a solid surface
What does red mean in microarray analysis?
Red indicates that a gene is expressed or "upregulated" in the sample (e.g., cancer)
What does the microarray test?
Microarrays test mRNA, which is first extracted and transcribed into cDNA
Normalization
A crucial data analysis step to eliminate systemic variance in microarray experiments
What conclusions can you make from microarray data?
Identify genes expressed differently in 2 cells by comparing a single gene
How does a DNA microarray work?
based on the hybridization of complementary nucleic acid strands
What does green indicate?
Green indicates the gene is "downregulated" or expressed in the reference sample (e.g., healthy cells) but not in the test sample.
What happens after the DNA is applied?
The cDNA hybridizes with complementary single-stranded DNA molecules on the microarray slide
Mircoarray
a laboratory tool used to detect and measure the expression of thousands of genes simultaneously
What are the advantages of microarray technology?
enabling rapid, genome-wide comparisons of molecular activity (such as healthy vs. diseased tissue) and providing high reproducibility for clinical research
What are microarrays used for in biology and medicine?
to analyze thousands of genetic sequences simultaneously, primarily for measuring gene expression (RNA) and detecting DNA mutations or copy number variations.
What does yellow mean?
What is the importance of the hybridization process?
It is crucial for specifically detecting gene expressions by binding labeled sample molecules to probes
what does a positive coefficient correlation mean?
Means gene expression behaves similar. The higher the coefficient, the stronger the relationship.
What are the limitations of microarrays?
reliance on pre-defined probe sequences, preventing the detection of novel or unknown genetic variations
How are fluorescent dyes used in microarrays?
to label DNA or RNA samples, allowing researchers to detect and quantify gene expression or identify mutations by scanning for light signals on a chip
What does black mean?
Black signifies that the gene is not expressed in either sample
Why use different colored dyes?
Two-color microarrays (red and green) allow for the direct comparison of two samples on a single chip. A red spot indicates higher expression in sample 1, green indicates higher expression in sample 2, and yellow indicates equal expression in both.
What is gene expression profiling?
a laboratory technique that measures the activity (expression levels) of thousands of genes simultaneously to create a global snapshot of cellular function
How do microarrays contribute to personalized medicine?
enabling high-throughput analysis of thousands of genes or proteins simultaneously, allowing clinicians to tailor medical treatment to an individual’s unique genetic profile.
What are the main steps involved in a microarray experiment?
sample collection, mRNA isolation, creation of labeled cDNA, hybridization, and data collection/analysis
What do the ratios of colors represent?
The ratios show the relative level of expression, helping to identify how much or how little a gene is expressed in each sample
Sample Collection of what?
Tissue or cells (e.g., tumor vs. normal) are collected to isolate mRNA.
Oligonucleotides
Short, single-stranded synthetic DNA sequences used as probes on the microarray