Question 1 

1. Most scientists who use DNA      microarrays obtain them 

from companies that mass produce them   

from the government 

by making them in their labs 

by exploiting ambitious graduate   students 

4 points   

Question 2 

1. “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.” 

only the top layer 

only the bottom layer 

a mixture of top and bottom layers 

none of the options listed 

4 points   

Question 3 

1. The purpose of the vortex      instrument is to 

vigorously shake the tissue sample in   the solvent so that it dissolves. 

spin the tissue/solvent mixture   around to separate the solids 

cause the mRNA to bind to the pellets   

dispose of biohazardous waste safely 

3 points   

Question 4 

1. “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:” 

“mRNA sticks to the beads, while   rRNA and tRNA run right through the column” 

“tRNA sticks to the beads, while   mRNA and rRNA run right through the column” 

“rRNA and tRNA stick to the   beads, while mRNA runs right through the column” 

 
none of the options listed 
4 points   

Question 5 

1. “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:” 

reverse transcriptase 

tyrosine hydroxylase 

alcohol dehydrogenase 

ATP kinase 

4 points   

Question 6 

1. A DNA copy of a mRNA transcript is      known as 

complementary DNA (abbreviated cDNA) 

copied DNA (abbreviated cDNA) 

mitochondrial DNA (abbreviated mtDNA)   

recombinant DNA (abbreviated rDNA) 

3 points   

Question 7 

1. Each spot on the DNA microarray in      embedded with 

copies of DNA from one particular   gene 

copies of DNA from several different   genes with similar functions 

copies of DNA from several different   genes with different functions 

copies of mRNA from one or more genes   

4 points   

Question 8 

1. “When we say that the cDNA      derived from our sample has hybridized to a particular spot on the array,      we mean that: ” 

The cDNA from the sample has stuck to   the DNA on the microarray at that point. 

The cDNA from the sample is jumbled   and cannot be trusted. 

The cDNA has been used to make an   mRNA copy 

You need to buy microarrays from   different manufacturers and triangulate the results 

4 points   

Question 9 

1. “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      ___________. ” 

cancerous; normal 

normal; cancerous 

normal; normal 

cancerous; cancerous 

3 points   

Question 10 

1. “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 ” 

genes expressed by both normal or   cancerous skin cells. 

genes that were not expressed at all   in either normal or cancerous skin cells 

“genes expressed by cancerous,   but not normal skin cells” 

“genes expressed by normal, but   not cancer skin cells. ” 

4 points   

Question 11 

1. “In interpreting the results      of this study, spots on the microarray that are red correspond to:” 

genes that are turned up by cancer 

genes that are turned down by cancer 

genes that are unaffected by cancer 

genes that aren t expressed in normal   or cancerous cells 

4 points   

Question 12 

1. “In interpreting the results      of this study, spots on the the microarray that are green correspond to      genes that are ” 

  
genes that are turned down by cancer 
 
genes that are turned up by cancer 
 
genes that are unaffected by cancer 
 
genes that aren t expressed in normal   or cancerous cells 
3 points   

Question 13 

1. “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 ” 

the turned up genes are likely   controlled by a gene that has gone bad 

all of these genes are genes that   have gone bad themselves 

even just one mutation in any of   these affected genes would have been sufficient to cause the disorder 

the cytoplasm has too many free   radicals in it 

4 points   

Question 14 

1. A gene shown by the microarray to      be expressed is : 

“probably making protein, but a   protein expression analysis would be needed to know for sure” 

definitely making protein 

definitely not making protein 

probably making protein but there’s   no way to know for sure 

4 points   

Question 15 

1. “In the application of this      technique to skin cancer, a gene that has gone bad ” 

“may or may not be identified at   all, but the overall pattern of results can give important clues” 

can almost always be identified via   DNA microarray