Question

We have been studying a SNP in the PTC Taste Receptor. Please 1) define what a SNP is, using language that someone who is NOT a biology major could understand and 2) hypothesize WHY the SNP we are studying could affect someone’s ability to detect bitterness.

Answer 1

What are single nucleotide polymorphisms (SNPs)?

Single nucleotide polymorphisms, frequently called SNPs (pronounced “snips”), are the most common type of genetic variation among people. Each SNP represents a difference in a single DNA building block, called a nucleotide. For example, a SNP may replace the nucleotide cytosine (C) with the nucleotide thymine (T) in a certain stretch of DNA.

SNPs occur normally throughout a person’s DNA. They occur once in every 300 nucleotides on average, which means there are roughly 10 million SNPs in the human genome. Most commonly, these variations are found in the DNA between genes. They can act as biological markers, helping scientists locate genes that are associated with disease. When SNPs occur within a gene or in a regulatory region near a gene, they may play a more direct role in disease by affecting the gene’s function.

Most SNPs have no effect on health or development. Some of these genetic differences, however, have proven to be very important in the study of human health. Researchers have found SNPs that may help predict an individual’s response to certain drugs, susceptibility to environmental factors such as toxins, and risk of developing particular diseases. SNPs can also be used to track the inheritance of disease genes within families.

The ability to taste bitter is done through G-protein coupled receptors. The chemicals in bitter foods trigger the G-protein coupled receptors to release a messenger protein that sends the signal to the brain to activate the bitter taste buds. Phenylthiocarbamide (PTC) is an organosulfur that has a unique property in that it either tastes very bitter or is tasteless to humans. The gene for this PTC receptor is TAS2R38. One of the factors that can affect to the ability to taste PTC, or not to taste PTC, is a Single Nucleotide Polymorphism (SNP).

Single Nucleotide Polymorphisms are the most common type of genetic variations among people. A SNP is a in a building block of DNA, more specifically called a nucleotide. In this case, Guanine (G) is replaced with Cytosine (C) at a specific position. So the receptor for pt will change and thus it will become tasteless.