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DNA Sequence Variation, Epigenetics, and Gel Electrophoresis

Question 1: Describe DNA sequence variations that can be often observed among individuals of the same species. Discuss the possible phenotypic consequences of these DNA sequence variation, give examples, if possible. Discuss the technologies or methods that are often used in detect each of these variations.

Question 2: Describe the field of epigenetics study. How do epigenetic modifications affect gene expression and phenotype?

Question 3: Briefly describe the principles and applications of 2-dimensional gel electrophoresis, including 2d DIGE, for analysis of proteins.

Question 4: How does real time PCR work to quantify the initial amount of the DNA template? How should the method be modified to quantify the initial amount of RNA template extracted from tissue or cells?


Solution Preview

1) DNA variations within the same species can occur by a few different means, including translocations, polymorphisms, and amplifications/deletions. The most common of these (and probably the answer this question is looking for) is the polymorphism, also known as the single nucleotide polymorphism (SNP) or single nucleotide variation (SNV).

There are several possible consequences of a SNP. Here are a few that I can recall:
a) Nothing, sometimes a SNP is just there and acts in no capacity

b) Mutation of the amino acid that is encoded by the gene. This assumes that the SNP is not in an intron (uncoded region of DNA), but it's one of the more dramatic possibilities. You can probably imagine pretty easily how bad a mutation can get, with the result being a damaged or dysregulated protein that needs to be taken care of by the cell. Ultimately, this could result in disease

c) Frame shift - If your SNP accidentally changes an amino acid coding codon into a stop codon or something like that, then you can get a protein that is truncated. Half a protein is usually pretty useless!

d) Transcriptional/Translational changes - Even if the SNP were to cause no change to the code of the protein, the body very tightly regulates transcription and translation. Changes to the coding sequence can change how fast things are made or degraded, though it is not possible ...

Solution Summary

In this posting, we answer four different questions relating to DNA and molecular biology techniques. Each question receives a paragraph or two of coverage, with answers can explanations provided.

If you are confused about DNA mutations, epigenetics, electrophoresis, or real-time PCR, check this solution out!

4 different sources are provided throughout