Chapter 24 Flashcards
DNA microarray/gene chip
makes it possible to quantify the expression of thousands of genes simultaneously
what is a DNA microarray made of?
it is a small silica, glass, or plastic slide that is dotted with many different sequences of DNA that each correspond to a short sequence within a known gene
how many spots can be on a single slide?
a single slide may contain tens of thousands of different spots in a small area
how are microarrays made?
sometimes they are made by spotting different samples of DNA onto a slide like a printer
researchers make primers that flank any given gene and use PCR to synthesize the DNA from a specific gene
true
DNA segments are typically _____ to _____ nucleotides in length
500-5000
other microarrays contain _____, or shorter DNA segments
oligonucleotides
How is the length of an oligonucleotide controlled on a microarray?
when microarrays use oligonucleotides, the DNA sequence is produced by controlling the growth of an oligonucleotide using narrow beams of light
how long are oligonucleotides in microarrays?
25-30 nucleotides in length
how many spots can be found on a single array?
hundreds of thousands
how is a microarray prepared?
1) mRNA is isolated from a sample of cells then used to make cDNA, which is layered onto microarray and hybridize onto the DNA spots
2) the array is washed with a buffer to remove unbound cDNAs and placed in a microscopy device (laser scanner)
3) laser scanner produces high res images and scans each pixel
4) results in a group of fluorescent spots at defined locations I the microarray
what does high fluorescence intensity in a particular spot indicate?
large amounts of cDNA have hybridized at that location, RNAs have been made, and that the cDNAs are complementary
chromatin immunoprecipitation
a method for determining whether proteins bind to particular sites in DNA. This method analyzes DNA-protein interactions as they occur in the chromatin of living cells
