1. Which DNA nitrogenous bases pair with each other? Which bases are purines, and which
are pyrimidines?
Adenine and guanine are the purines and Cytosine and Thymine are the pyrimidines.
2. How is DNA information used to make proteins? What are the steps of this process?
Enzymes read the inform...
Student Name:
Access Code (located on the underside of the lid of your lab kit):
Pre-Lab Questions
1. Which DNA nitrogenous bases pair with each other? Which bases are purines, and which
are pyrimidines?
Adenine and guanine are the purines and Cytosine and Thymine are the pyrimidines.
2. How is DNA information used to make proteins? What are the steps of this process?
Enzymes read the information in a DNA molecule and transcribe it into an
intermediary molecule, mRNA. The information contained in the mRNA molecule is
translated for amino acids, which are the building blocks of proteins.
3. Give an example of a scenario in which you would perform PCR vs a scenario in which
you would use recombinant DNA technology.
For PCR, it is when I have an unknown DNA isolated from a specimen in small
concentration, and I want to amplify it so it can be identified through gel electrophoresis.
For DNA technology it would be to identify the function of a gene.
4. What occurs during each of the three steps involved in the PCR cycle? How has the use
of PCR changed biotechnology?
PCR is based on 3 steps required for any DNA synthesis reaction; 1) denaturation of the
template into single strands, 2) annealing of primers to each original strand for new
strand synthesis, 3) extension of the new DNA strands from the primers.
5. How could you take a protein with a known sequence of amino acids and use it to
create an artificial gene?
With help from known protein sequences, you can make its most probable nucleotide
sequence based on the frequency of tRNA that is present in the organism in which we
need to express the proteins. We will then artificially make the sequence and amplify it
by using PCR.
, EXPERIMENT 1: DNA Extraction
Post-Lab Questions
1. What is the purpose of the following reagents in the experiment?
a. Salt (in the DNA extraction solution): Helps to make debris like proteins, lipids
and RNA clump together.
Lab 7 Microbial Genetics & Genetic Engineering BIO250L b.
Detergent (in the DNA extraction solution): Pulls apart the membrane surrounding the cells
and the nucleus releasing the DNA from the cell.
c. Ethanol: Promotes ionic bonds and causes precipitation, which then takes the
DNA out of the solution.
2. What else might be in the ethanol/aqueous interface? How could you eliminate this?
RNA and soluble salt might be in the ethanol/aqueous interface. This could be
eliminated by using a centrifuge, RNase enzymes, or crushing it in a bag and
draining it through a cheesecloth.
3. What is the texture and consistency of the DNA?
Fragile,sticky and slimey
4. Is the DNA soluble in the aqueous solution or in the alcohol?
It is soluble in aqueous solution.
Insert a photo of your DNA. Include your name and access code handwritten in the
background of your photo.
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