Tay-Sachs disease (TSD) is a fatal genetic disorder, that results in progressive destruction of the nervous system. Tay-Sachs is caused by a mutation in the gene that codes for an enzyme called hexosaminidase-A (Hex-A). Hex A CDNA from normal and a Tay-Sachs individual was sequenced using the same primer. This is the coding strand and starts in-frame at amino acid position #78. Results are shown below. Read the darkest band in each row. Normal Tay-Sachs (-) ATG C ATG C (+) a. Write each coding strand DNA sequence, normal and Tay-Sachs 5' to 3' b. Write the amino acid sequence that will be translated from each sequence, normal and Tay-Sachs C. Describe the type of mutation? Predict the effect of this mutation on the He> A protein.

DNA is extracted from the blood cells of two different humans, individuals 1 and 2. In separate experiments, the DNA from each individual is cleaved by restriction endonucleases A, B, and C, and the fragments are separated by electrophoresis. A hypothetical map of a 10,000 bp (base pair) segment of a human chromosome is shown (1 kbp= 1,000 bp). Individual 2 has point mutations that eliminate restriction recognition sites B* and C*. After the 10kbp segment is digested with each restriction endonuclease A, B, and C one by one, samples are loaded onto an agarose gel for electrophoresis for analysis. I would like you to draw the result of gel electrophoresis. To answer the question, first, draw the whole gel image (on the right) on your answer sheet, then indicate where you expect to see the bands on the gel. (Hint1: Same-size bands will appear at the same position. Hint 2: On the gel bands from individuals 1 and 2 might be at different positions.) The left lane (with an M label on the…

STR sites are the basis of the FBI Laboratory's Combined DNA Index System (CODIS). One STR site that is used in CODIS is TPOX, named for its location within an intron of the thyroid peroxidase gene located on human chromosome 2. Different versions of the TPOX site are known, due to varying number of repeats of the short sequence "AATG". For TPOX, the number of repeats found on different chromosomes varies from 6 to 13. Hence the "alleles" of this site are called "6", "7", "8", "9", "io", "11", "12" and "13". Any given individual can be homozygous for any one of these eight different alleles or heterozygous for two different alleles of this set. The frequency of any given genotype, however, depends upon the individual frequency of each of these eight alleles in the population. For example, allele "6" occurs at a frequency of less than 5%, allele "11" at a frequency of 20% and allele 8" at a frequency of about 46%. See below for the double stranded DNA sequence of the *11" allele and a…

Duchenne muscular dystrophy is caused by a mutation in a gene that comprises 2.5 million base pairs and specifies a protein called dystrophin. However, less than 1% of the gene actually encodes the amino acids in the dystrophin protein. On the basis of what you now know about gene structure and RNA processing in eukaryotic cells, provide a possible explanation for the large size of the dystrophin gene.