DNA Extraction & Gel Electrophoresis

DNA extraction requires _________to lyse the epithelial cells and to degrade compounds inhibitory to amplification

• freezing

• heat treatment

• enzyme

• mechanical shearing

What can you observe on the agarose gel after electrophoresis if you do not treat your sample with RNAse ?

• protein

• RNA

• mitochondria

• phospholipids

The ratio of absorption at 260nm to absorption at 280nm is commonly used to assess….

• Whether your DNA or RNA is contaminated with organic substances.

• The purity of DNA and RNA with respect to protein.

• The concentration of protein in your sample.

Put the following types of naturally occurring RNA in order according to their abundance in cellular or total RNA. (First listed is most abundant)

• mRNA, rRNA, tRNA

• rRNA, tRNA, mRNA

• tRNA, rRNA, mRNA

• tRNA, mRNA, rRNA

When evaluating the purity of extracted DNA, deoxyribonucleic acid, what should the optical density, or its light-blocking ability, be at 260nm and 280nm be? (The 260nm/280nm ratio)

• < 1.6

• 2.0 - 2.3

• >2.0

• 1.6 - 2.0

What is the purpose of a buffer system in electrophoresis?

• Alternate the current

• Carry the current, maintain a stable pH for the separation of molecules and protect the sample

• disrupt the contaminants

• stop the migration process

How can DNA fragments be separated using gel electrophoresis ?

• DNA carries a negative charge and large fragments are pulled more strongly than small fragments towards the positive electrode

• DNA carries a negative charge and small fragments are able to travel more quickly than large towards the positive electrode

• DNA carries a positive charge and large fragments are pulled more strongly than small fragments towards the negative electrode

• DNA carries a positive charge and small fragments are able to travel more quickly than large towards the negative electrode

Where would you find DNA, the genetic material, in an animal cell?

• In the centriole

• Only in the mitochondria

• In the mitochondria and the nucleus

• In the cytoplasm

Eukaryotic chromosomes are thousands of times longer than a typical cell. How can chromosomes fit inside a eukaryotic nucleus?

• The genetic material remains distributed in the nucleus, mitochondria, and chloroplast.

• The genome is present in a looped structure; thus, it fits the size of the nucleus.

• The DNA remains coiled around proteins to form nucleosomes.

• The genetic material remains bound to the nuclear envelope, forming invaginations.

What is the first step in isolating DNA?

• Generating genomic DNA fragments with restriction endonucleases

• Introducing recombinant DNA into an organism by any means

• Overexpressing proteins in E. coli

• Lysing the cells in the sample