Chem 210 Test 3-with 100% verified answers-2024-2025.docx, Exams of Chemistry

Download Chem 210 Test 3-with 100% verified answers-2024-2025.docx and more Exams Chemistry in PDF only on Docsity! Chem 210 Test 3-with 100% verified answers-2024-2025 Test #3 CORRECT ANSWERS IN RED Question 1 True or False: The amino acids cysteine and serine both contain sulfur atoms. True False Question 2 True or False: The following secondary structure shown below is an example of an Antiparallel beta sheet. True False Question 3 True or False. The side chain of leucine is bonded to the backbone nitrogen atom. True False Question 4 True or False: The name of the molecule that binds to an enzyme is called the apoenzyme. True False Question 5 True or False: An inhibitor that binds at the active site is an uncompetitive inhibitor. True False D. E. Question 12 Which of the following correctly matches the amino acid with its one letter abbreviation? Glutamic acid, E Isoleucine, S Lysine, L Phenylalanine, P Arginine, A Question 13 By convention, polypeptides are read in which order? N to C-terminus C to N- terminus 5’ to 3’ 3’ to 5’ Smallest to largest amino acid by weight Question 14 In one turn of a helix, there approximate amino acids. 2.3 3.6 4.2 5.4 None of the above Question 15 In an alpha helix, the R groups on the amino acid residues: Alternate between the inside and outside of the helix Cause only left-handed helices to form Generate the hydrogen bonds that form the helix Stack within the interior of the helix Are found on the outside of the helix spiral Question 16 Motifs are classified primarily by their: Amino acid sequence Evolutionary relationships Content and arrangement of the secondary structure Content and arrangement of the tertiary structure Subunit content and arrangement Question 17 The secondary structure shown below is an example of a(n): Parallel beta sheet Antiparallel beta sheet alpha helix beta-turn alpha-turn Question 18 The overall three-dimensional shape of a single folded polypeptide is structure. Primary Secondary Tertiary Quaternary Motif Question 19 How many classes of enzymes are recognized by the IUBMB? 3 4 5 6 7 Question 20 An enzyme requires Cr+3 for catalysis. Under conditions of chromium deficiency, when the enzyme lacks chromium, this enzyme would be referred to as a(n): Holoenzyme Apoenzyme Active enzyme Inhibitor Competitive inhibitor Question 21 As a substrate reacts to become a product, it goes through the , which is a high potential energy state. Conversion State Stable mode Unstable mode Conversion Mode Transition state Coenzyme Bienzyme Both B and C Question 26 (short response) A) Is the following protein globular or fibrous? Explain. B) Identify the types of secondary structure present in the following protein. A) It is a globular protein because of its ball-like shape. Fibrous proteins are usually long and extended. B) There is one alpha helix in front and some in the back. Also present is a beta sheet; there seems to be both parallel and antiparallel strands here. Beta turns may be present, but are not required in the answer. Question 27 (short response) Hemoglobin is said to be a tetramer. A) What is a tetramer? B) Structurally, a tetramer describes what level of protein organization? A) Simply it means that hemoglobin has four subunits or four independent polypeptide chains interacting non-covalently. Each protein molecule is composed of two copies each of two different subunits a and b. We say that hemoglobin is a tetramer because it has four polypeptide chains. B) It is describing the quaternary structure, which has two or more independent polypeptide chains that associate with one another to form a quaternary structure. Question 28 (short response) There are collections of protein structure that fit between true secondary and true tertiary structure. What is the name of the collections of protein structure? Explain this type of structure. Motifs occupy a position between secondary and tertiary. Motifs are particularly stable arrangements of secondary structure, including the connections between them. Motifs are found in a variety of proteins from across all organisms. Question 29 (Short response) A. What is the lowest level of protein structure? And B) How do scientists communicate information about this level? The primary level is the order of amino acids covalently bonded together, including disulfide bonds, in a polypeptide chain. The primary sequence is written, for proteins, from N to C terminal using the one- letter or three-letter abbreviations. Question 30 What is the spot on an enzyme where reactions take place? Explain the characteristics of this spot. The active site is the spot on the enzyme where catalysis takes place. This area is often small when compared to the overall size of the protein. In fact, about 10 amino acids make up the active site.