2) Myoclonal epilepsy and ragged red fiber disease (MERRF) is a human condition named for the ragged red fibers of skeletal muscle cells and myoclinic epilepsy in affected individuals. People with this disorder have a mutation in a mitochondrial gene for a tRNA, specfically that for lysine. Why are affected individuals always heteroplasmic?

2b) What anticodon would a suppressor tRNA have to have to suppress a 5'UAA3' stop codon?

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.

1) The plot to the right shows the Oxygen Saturation of Hemoglobin (Hb) versus O2 concentration. a) The Kd between HBa and HBB chains is 100 nM. When L35S mutation (Leucine 35 → Serine) is introduced into the Hba chain the Kd changes to 300 mm. \^^^^^A^A Draw a dashed curve on the figure to the right that represents how this mutation would likely change the curve. Note: that I am asking for how a change in affinity between HBa and HBB chains will impact HB binding to O2 1.00 0.75- HB Y 0.50 HBa L35S HBa L35S D101P 0.25 0.00 0 2 4 po₂ (kPa) 6 b) How might this specific mutation alter the interaction between HBa and HBB chains? I am asking you to predict what Leu specifically might be doing here. 8 c) Now imagine that a second mutation is added to the HB¤ L35S mutant to generate an HBa L35S D101P double mutant. A measure of the double mutant shows that it has a Kg = 2 kPa, but does not change the binding of HBa and HBB. Draw a dotted line on the figure above that shows the resulting…

In this chapter you were introduced to nonsense suppressor mutations in tRNA genes. However, suppressormutations also occur in protein-coding genes. Using thetertiary structure of the β subunit of hemoglobin shownin Figure 9-3(c), explain in structural terms how a mutation could cause the loss of globin protein function. Nowexplain how a mutation at a second site in the same protein could suppress this mutation and lead to a normalor near-normal protein.

1. (a) By binding one L-tryptophan molecule/monomer, the trp repressor binds to DNA to sup- press synthesis of L-tryptophan in E. coli. Below is the amino acid sequence of the helix - reverse turn - helix region of the trp repressor that binds to DNA compared to the sequence of the corresponding DNA binding motif of the Prl protein. A diagram of the trp repressor dimer is also shown. Trp Prl Trp Prl 80 -Gly-Glu-Met-Ser-Gln-Arg-Glu-Leu-Lys-Asn-Glu-Leu-Gly-Ala-Gly-Ile- -Ser-Glu-Glu-Ala-Lys-Glu-Glu-Leu-Ala-Lys-Lys-Cys-Gly-Ile-Thr-Val- trp helix 5 70 trp helix 4 Prl helix 80 Prl helix Ala-Thr-Ile-Thr-Arg-Gly-Ser-Asn-Ser-Leu-Lys-Ala-Ala- Ser-Gln-Val-Ser-Asn-Trp-Phe-Gly-Asn-Lys-Arg-Ile-Arg- reverse turn 90 Comparing the two protein sequences above, identify all amino acid pairs that differ in electrostatic charge due to proton dissociable groups (assume pH 7). Indicate the charge of both residues for each such pair. (b) Circle the pair of residues for which the electrostatic charge due to…

Hurler syndrome is due to a mutation in a gene that encodes aprotein called α-l-iduronidase. This protein functions withinlysosomes as an enzyme that breaks down mucopolysaccharides(a type of polysaccharide that has many acidic groups attached).When this enzyme is defective, excessive amounts of the mucopolysaccharides dermatan sulfate and heparin sulfate accumulatewithin the lysosomes, especially in liver cells and connectivetissue cells. This accumulation leads to symptoms such as anenlarged liver and spleen, bone abnormalities, corneal clouding,heart problems, and severe neurological problems. The pedigreebelow contains three members affected with Hurler syndrome,indicated with black symbols. Based on this pedigree, does thissyndrome appear to follow autosomal recessive, autosomaldominant, X-linked recessive, or X-linked dominant inheritance?Explain your reasoning.

Consider the mechanism of the enzyme RNase:   What would happen to the Km (i.e., would it increase, decrease, or stay the same) if the his12 was mutated to a lysine? Explain.   What would happen to the Kcat (i.e., would it increase, decrease, or stay the same) if the his12 was mutated to a valine? Explain.

1).   In the absence of this enzyme, a substance called ceroid lipofuscin accumulates in lysosomes in the brain, resulting in seizures, blindness, decline in cognitive function and motor skills, dementia, and death by the late teens or early 20’s. The TPP1 gene is 6695 bp in length. Think about the characteristics of Batten disease, and then suggest an approach to gene therapy that might be effective for this specific genetic disorder.  You may assume that your research team is working in the U.S. and your research is funded by a grant from the National Institutes of Health (NIH).  Please EXCLUDE the use of CRISPR from consideration. A. Will you use germline or somatic cell gene therapy? Please NAME and DEFINE the form of gene therapy selected, then explain WHY this is the most appropriate choice.

Which of the following mutations in the protein-coding region of a gene is more likely to lead to complete loss of function of the encoded protein: an insertion of six nucleotides or a deletion of two nucleotides? Briefly explain your answer.