Types & Applications
Which microarray type uses larger DNA fragments?
cDNA microarrays
What does a red dot indicate?
Increased gene activity in the diseased sample.
What type of molecules are embedded on the microarray surface?
DNA probes representative of genes
What does a microarray measure?
The expression levels of thousands of genes at once
Microarrays can only assess genes for which what exists?
probes
Which type uses shorter DNA sequences and is made by Affymetrix?
Oligonucleotide microarrays
What does a green dot indicate?
Increased gene activity in the healthy sample
What happens to unbound cDNA molecules after hybridization?
They are washed away
What is the surface of a microarray usually made of?
A glass slide containing thousands of DNA probes
What issue makes microarrays weaker at detecting very low transcript levels?
Their limited dynamic range
What do SNP arrays analyze?
Single nucleotide polymorphisms (DNA variations)
What does a yellow dot indicate?
Equal expression levels in both samples.
What device reads fluorescence signals on a microarray?
A laser scanner
What does the intensity of each microarray spot represent?
How actively a gene is being expressed.
What problem occurs when a probe binds to the wrong sequence?
Cross-hybridization
What is one medical use of microarrays mentioned in the presentation?
Predicting tumour types based on gene-expression profiles. (one of them)
What does a black dot indicate?
Little to no gene expression in either sample.
In the diagram, what two kinds of cell tissues are compared?
Normal, and Cancerous tissue
What type of DNA binds to the probes on the microarray?
Fluorescently labelled cDNA
What does RNA sequencing detect that microarrays often can't?
Novel transcripts (new RNA sequences not previously identified)
What is a key theme of microarray studies compared to single-gene techniques?
Finding large-scale expression patterns
What can researchers determine by analyzing upregulated and downregulated genes?
Which pathways are involved in the condition being studied.
Why are two fluorescent dyes (usually red and green) used?
To compare expression levels between healthy and diseased samples
What principle allows microarrays to work: DNA binding to what?
DNA binds to its complementary sequence
Despite limitations, why are microarrays still widely used?
They allow simultaneous analysis of thousands of genes and complement methods like RNA-seq