BIOCHEM C785 Readiness Exam/Latest Complete Solution/Questions & Answers

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The LEP gene codes for an anorexigenic hormone. Interestingly, breastfeeding has been shown to alter methylation of the promoter of this gene, leading to increased LEP expression. What is likely happe... ning in response to breastfeeding? (ANS- Breastfeeding decreases the methylation of the promoter of the LEP gene, increasing the spacing between nucleosomes. A patient with xeroderma pigmentosum is prone to developing multiple skin cancers starting in childhood. This occurs because of a mutation in a gene that codes for enzymes that help repair DNA damage through the nucleotide excision repair (NER) pathways. How does NER differ from other repair mechanisms? In NER: (ANS- The error in one strand of DNA is removed as well as several nucleotides on either side of the error. The gap that was removed is filled in by DNA polymerase Several components of cigarette smoke, including benzopyrene, insert themselves (intercalate) into the DNA and lead to several types of mutations such as frameshift mutations, including both insertions and deletion. Which of the following repair pathways would be used to repair this type of damage? (ANS- Nucleotide excision repair is used to repair deletions, insertions, and helix-distorting lesions, such as thymine dimers Interaction between the two amino acids shown below can help stabilize the structure of a protein. What kind of interaction is this? (ANS- Hydrophobic Interaction Which of the following forces can lead to aggregation as a result of protein misfolding? (ANS- Hydrophobic interactions Which of the following statements about protein structure and stability is true? (ANS- Ionic bonds between the side chains of the charged amino acids stabilize the protein structure Primary structure consists of the order of ______ in a protein. These are held together with ______ bonds that are formed by a ______ reaction. (ANS- Amino acids, peptide, dehydration What type of reaction breaks peptide bonds apart? (ANS- Hydrolysis Reaction A particular amino acid in a protein helps to stabilize the protein by forming disulfide bonds. What amino acid is likely to form this type of bond? (ANS- Cysteine Aggregation of proteins is the main reason behind many neurodegenerative diseases. Which one of the following mutations will likely cause a neurodegenerative disease? (ANS- Replacing a polar amino acid with a non polar amino acid Chymotrypsin is a digestive enzyme that has optimal activity at a pH of 7.8 and a temperature of 37 degrees Celsius. Which of the following statements is true? (ANS- The reaction rate for chymotrypsin at a pH of 9.5 is lower than the reaction rate for chymotrypsin at a pH of 7.8. A patient presents with a fever of 110°F. Which interaction(s) would be disrupted within a neuronal protein if the fever is not resolved quickly? (ANS- Hydrophobic Interactions [Show More]

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