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Some mutations result in proteins that function well at one temperature but are nonfunctional at a different (usually higher) temperature. Siamese cats have such a “temperature-sensitive” mutation in a gene encoding an enzyme that makes dark pigment in the fur. The mutation results in the breed's distinctive point markings and lighter body color (see the photo). Using this information and what you learned in the chapter, explain the pattern of the cat’s fur pigmentation.
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- You are working on a protein for a research project. The protein does not express well in prokaryotic expression systems so you decide to try a eukaryotic system, baker’s yeast, instead. As part of the expression system, you add a signal peptide to the protein so that it will be exported through the endomembrane system to the outside of the yeast cell. This makes purifying the protein much simpler. During the purification, you notice that the protein is heavier than it should be during gel filtration chromatography. This is confirmed by SDS-PAGE. What could be the reason that the protein has gained mass when expressed in the eukaryotic system?arrow_forwardYou are studying a mutation in mice, which acts dominantly. Mice that have only one copy of the allele carrying this mutation have a kinky tail phenotype. You identify the gene that the mutation affects and find that the codon that encodes the second amino acid in the predicted protein has been mutated to a stop codon. Would you characterize this mutation as a loss-of-function or a gain-of-function and what specific subtype (hypermorphic, antimorphic, etc. ) within these categories? Explain your reasoning.”arrow_forward. The genetic code is thought to have evolved to maximize genetic stability by minimizing the effect on protein function of most substitution muta- tions (single-base changes). We will use the six arginine codons to test this idea. Consider all of the substitutions that could affect all of the six arginine codons. (a) How many total mutations are possible? (b) How many of these mutations are "silent," in the sense that the mutant codon is changed to another Arg codon? (c) How many of these mutations are conservative, in the sense that an Arg codon is changed to a functionally similar Lys codon?arrow_forward
- Complete the protein synthesis for the partial DNA sequence for a normal FGFR3 gene (TOP) and mutated FGFR3 gene (BOTTOM). Remember, when filling in mRNA, use capital letters only. When filling in amino acids, use three letters, with the first letter capitalized. If you do not use this format, your answer may be marked wrong. DNA CCG TTC GGG GAA ССС MRNA Amino Acid DNA CCG TTC GGG GAA TCC MRNA Amino Acidarrow_forwardWhat type of mutation is this? 1. Which type of mutation is responsible for new varia tions of a trait? Which type of mutation does not result in an abnormal amino acid sequece? Which type of mutation stops the translation of an mRNA molecule? 2. Sickle Cell Anemia Sickle cell anemia is the result of a type of mutation in the gene that codes for part of the hemoglobin molecule Hemoglobin carries oxygen in your red bloods cells. The mutation causes these red blood cells to become stife sickle-shaped when they release their oxygen. The sickled cells tend to get stuck in blood vessels, causing poin ond increased risk of stroke, blindness, damage to the heart & lungs, and other conditions. Analyze the DNA strands below to determine what amino acid is changed AND what type of mutation occurred Normal hemoglobin DNA A G TC Normal hemoglobin mRNA val• Hisolelo thr•proo Gll Normal hemoglobin AA sequence CA cGT AG A CTGAGG AC AC Sickle cell hemoglobin DNA Sickle cell hemoglobin mRNA Sickle cell…arrow_forwardSickle cell anemia is a widespread disease in many African countries and can be caused by a change in the amino acid sequence from glutamic acid to valine. A patient is diagnosed with the disease and a genetic fingerprint reveals the following DNA sequence for the gene: (a) (b) (c) (d) (e) Write down the mRNA sequence for the given DNA sense strand indicating the polarity. Derive the polypeptide from the mRNA molecule using the table of the genetic code (Table Q1 below) again indicating the polarity of the peptide chain. Indicate the position in the DNA molecule that could have caused the disease and write down all possible point mutations in the DNA sequence that could have caused it. [ The polypeptide chain is polymerized at the ribosomes using t-RNA molecules. Write down all possible t-RNA molecules with their anti-codons that are used to polymerize the amino acid VAL. Indicate the polarity. 3'-TAC TGA GCA AGA TTA CAT ACT-5' Explain what is meant by redundancy of the genetic code.…arrow_forward
- Given: eukaryotic cells can make different proteins, using only one gene. How can a eukaryotic cell make different final proteins from the same gene? Note: some of the answers are actually correct statements, but they don't have anything to do with this question. A.Eukaryotes have 3 RNA polymerases instead of just one. B.Eukaryotes cannot perform simultaneous transcription and translation. C.Eukaryotes splice RNA and can do so in various arrangements. D.Eukaryotes lack the Shine Delgarno sequence.arrow_forwardBiochemistry: Site-directed mutagenesis, in which individual amino acid residues are replaced with others, is a powerful method to study enzyme mechanisms. In experiments with particular enzyme, various lysine residues were replaced with aspartate, yielding the results summarized in the table below: Enzyme Form: Enzyme Activity (U/mg) Native enzyme: 1,000 U/mg Recombinant Lys 21 to Asp 21: 970 U/mg Recombinant Lys 86 to Asp 86: 100 U/mg Recombinant Lys 101 to Asp 101: 970 U/mg a. What might be inferred about the role of Lys 21, 86, and 101 in the catalytic mechanism of this enzyme? b. Discuss where within the enzyme one might find Lys 21 and 101. Are these residues likely to be evolutionary conserved in this enzyme? Explain c. Is Lys position 86 likely to be evolutionary conserved? Explainarrow_forward1. You are working with a known chemical that can cause a mutation in the DNA. You decide to use the Replica Plating experiment to confirm that this is the case. Please talk about how this experiment works. Also, please discuss any two types of mutations that could take place due to this mutation and what these mutations can cause when DNA is made into protein. 2. What is a difference between prokaryotic and eukaryotic gene expression? Please explain. Also, discuss briefly the significance in splicing, why this is done and how this leads into variety of different polypeptides.arrow_forward
- Using a computer algorithm that searches for sequence similarities in other organisms, you discover that hexose kinase is a highly conserved gene that is expressed by many species, both prokaryotic and eukaryotic. The most closely related prokaryotic homolog of hexose kinase has a protein sequence in which 90% of the amino acids are identical to those of the human version of the gene. To learn more about their similarity at the DNA level, you obtain segments of the genomic DNA coding for the hexose kinase gene in both humans and this prokaryotic species. After combining both DNA samples, you heat them to denature the DNA strands and then allow them to cool and reanneal. Finally, you examine the DNA hybrids you obtain under the electron microscope. Your analysis reveals that there are three different DNA hybrids in this sample, these can be seen below. You reason that one must belong to the prokaryotic species, one to the humans and the third arose when one strand from each species base…arrow_forwardGene editing is also used to explore the structure and function ofproteins. For example, changes can be made to the coding sequenceof a gene to determine how alterations in the amino acid sequenceaffect the function of a protein. Let’s suppose that you areinterested in the functional importance of a particular glutamicacid (an amino acid) within a protein you are studying. By geneediting, you make mutant proteins in which the glutamic acidcodon has been changed to other codons. You then test the encodedmutant proteins for functionality. The results are as follows: FunctionalityNormal protein 100%Mutant proteins containingTyrosine 5%Phenylalanine 3%Aspartic acid 94%Glycine 4%From these results, what would you conclude about the…arrow_forwardConsider the following DNA sequence, which codes for a short polypeptide: 5'-ATGGGCTTAGCGTAGGTTAGT-3' Determine the mRNA transcript of this sequence. You have to write these sequences from the 5' end to the 3' end and indicate those ends as shown in the original sequence in order to get the full mark. How many amino acids will make up this polypeptide? Determine the first four anticodons that will be used in order to translate this sequence.arrow_forward
- Biology Today and Tomorrow without Physiology (Mi...BiologyISBN:9781305117396Author:Cecie Starr, Christine Evers, Lisa StarrPublisher:Cengage Learning