sci 115 please answer all questions
Most scientists who use DNA microarrays obtain them
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from companies that mass produce them |
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from the government |
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by making them in their labs |
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by exploiting ambitious graduate students |
In this study, cancerous and normal skin tissue samples were excised with a scalpel. Each skin sample was then placed into a sample tube along with solvent, shaken on a vortex and centrifuged. When the sample tubes came out of the centrifuge, there was a top layer and a bottom layer. For our purposes, we went on to use ______________ for further processing.”
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only the bottom layer |
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none of the options listed |
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a mixture of top and bottom layers |
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only the top layer |
The purpose of the vortex instrument is to
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vigorously shake the tissue sample in the solvent so that it dissolves. |
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spin the tissue/solvent mixture around to separate the solids |
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cause the mRNA to bind to the pellets |
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dispose of biohazardous waste safely |
“Once the RNA is isolated from the DNA, proteins and other materials, the solvent/RNA mixture is run through a column of all beads. Each bead has several short strands of polyT RNA sticking out of it. In this step:”
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“mRNA sticks to the beads, while rRNA and tRNA run right through the column” |
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“rRNA and tRNA stick to the beads, while mRNA runs right through the column” |
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none of the options listed |
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“tRNA sticks to the beads, while mRNA and rRNA run right through the column” |
“Once the mRNA is isolated, you make a DNA copy of it using by adding polyT primers, labeled DNA nucleotides, and an enzyme known as:”
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reverse transcriptase |
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tyrosine hydroxylase |
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alcohol dehydrogenase |
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ATP kinase |
A DNA copy of a mRNA transcript is known as
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copied DNA (abbreviated cDNA) |
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complementary DNA (abbreviated cDNA) |
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recombinant DNA (abbreviated rDNA) |
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mitochondrial DNA (abbreviated mtDNA) |
Each spot on the DNA microarray in embedded with
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copies of DNA from one particular gene |
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copies of DNA from several different genes with similar functions |
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copies of DNA from several different genes with different functions |
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copies of mRNA from one or more genes |
“When we say that the cDNA derived from our sample has hybridized to a particular spot on the array, we mean that: “
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The cDNA from the sample has stuck to the DNA on the microarray at that point. |
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The cDNA from the sample is jumbled and cannot be trusted. |
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You need to buy microarrays from different manufacturers and triangulate the results |
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The cDNA has been used to make an mRNA copy |
“In this particular experiment, we used red-labeled DNA to process the sample from _____________ tissue and the green-labeled DNA to process the sample from ___________. “
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cancerous; normal |
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normal; cancerous |
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normal; normal |
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cancerous; cancerous |
After scanning the green labeled areas and the red labeled areas, when we combine the two images, the spots that show up as yellow correspond to “
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genes that were not expressed at all in either normal or cancerous skin cells |
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genes expressed by both normal or cancerous skin cells. |
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“genes expressed by cancerous, but not normal skin cells” |
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“genes expressed by normal, but not cancer skin cells. “ |
“In interpreting the results of this study, spots on the microarray that are red correspond to:”
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genes that are turned up by cancer |
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genes that are turned down by cancer |
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genes that are unaffected by cancer |
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genes that aren t expressed in normal or cancerous cells |
“In interpreting the results of this study, spots on the the microarray that are green correspond to genes that are “
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genes that are unaffected by cancer |
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genes that aren t expressed in normal or cancerous cells |
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genes that are turned down by cancer |
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genes that are turned up by cancer |
“When the DNA microarray study tells us that a large number of genes have been turned up (or turned down) by a disorder, the most likely explanation is that “
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the turned up genes are likely controlled by a gene that has gone bad |
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all of these genes are genes that have gone bad themselves |
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even just one mutation in any of these affected genes would have been sufficient to cause the disorder |
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the cytoplasm has too many free radicals in it |
A gene shown by the microarray to be expressed is :
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definitely making protein |
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“probably making protein, but a protein expression analysis would be needed to know for sure” |
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probably making protein but there’s no way to know for sure |
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definitely not making protein |
In the application of this technique to skin cancer, a gene that has gone bad “
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“may or may not be identified at all, but the overall pattern of results can give important clues” |
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can almost always be identified via DNA microarray |
