3 1 4Microarray Student

Topics: DNA, Gene expression, Cancer Pages: 12 (3958 words) Published: January 22, 2015

Activity 3.1.4: DNA Microarray
Equipment

Computer with Internet access
Laboratory journal
Carolina Biological DNA CHIPS: Genes to Disease Kit
Glass slide
Genes 1-6 Dropper Bottles
cDNA Mixture Dropper Bottle
Permanent marker
Colored pencils or markers
Micropipettor (20-200 µl)
Micropipettor (0.5-10 µl)
Disposable micropipette tips
70°C hot water bath
Digital camera (optional)
Safety goggles
Latex or nitrile exam gloves
Procedure
Part 1: DNA Microarray Virtual Lab
1. Go to a review of transcription and translation at http://learn.genetics.utah.edu/content/begin/dna/transcribe/ Complete the activity and answer the following questions. a. Describe the process of transcription (be sure to mention the molecules involved). Transcription is the process of making an RNA copy of a gene sequence. This copy, called a messenger RNA (mRNA) molecule, leaves the cell nucleus and enters the cytoplasm, where it directs the synthesis of the protein, which it encodes. b. What is different about the base pairing between the two sides of DNA and between DNA and RNA? One major difference between DNA and RNA is the sugar, with the 2-deoxyribose in DNA being replaced by the alternative pentose sugar ribose in RNA, whereas is DNA pairing, the bases, Adenine, Guanine, Cytosine, Thymine pair with their base pair match. c. Describe the process of translation (again mention all of the molecules involved). Translation is the process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids during protein synthesis. The genetic code describes the relationship between the sequence of base pairs in a gene and the corresponding amino acid sequence that it encodes. In the cell cytoplasm, the ribosome reads the sequence of the mRNA in groups of three bases to assemble the protein. d. What is the resulting primary sequence of the protein you made in the interactive? Methionine, Leucine, Aspartic Acid, Valine, Phenylalanine 2. Go to the “DNA Microarray Virtual Lab” found at the University of Utah’s Learn.Genetics: Genetic Science Learning Center’s website: http://learn.genetics.utah.edu/content/labs/microarray/ 3. Click on the microarray slide to begin. Then choose Chapter 2 “Measuring Gene Expression” and go on through Chapter 3 “The Experiment”. Complete the interactive a first time without writing anything down. 4. Answer the following questions as you work through the virtual DNA microarray a second time. a. What can scientists look for to see which genes are turned on in a particular cell? Provide an example. Scientists use DNA microarrays that used techniques allowing the amount of mRNA transcribed by each gene which allows scientists to determine which genes are expressed to a cell. To do so, they use PCR to make copies of a gene and then DNA is placed on the microarray. An example of this is when the DNA microarrays can be used to detect single nucleotide polymorphisms (SNPs). b. Why are tissue samples from healthy and cancer cells taken from the same patient? Both samples are collected to be able to compare the cells, look at differences in gene expression in cells that have the exact genetic blue print. c. How is RNA separated from the rest of the tissue? In order to be separated, RNA samples are mixed with organic solvents, and then they run through a vortex and centrifuge. d. Describe the process used to isolate mRNA from the other types of RNA. mRNA is different from other types of RNA because it is the only type that has Poly-A tails, having several adenine amino acids at the end of the molecule. e. Explain how samples are marked. Cancerous cells are red and healthy cells are green. f. Why is it necessary to make a cDNA copy? Why is mRNA not used? RNA is not used because DNA is a more stable compared to RNA. Making a cDNA copy is necessary to visualize the cDNA later on. This is possible because when you make the cDNA copy, you incorporate a fluorescent label in the molecule. g....
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