CHEM210 / CHEM 210 Module 3: (Latest Update 2026 / 2027) Organic Chemistry | Questions & Answers | Grade A | 100% Correct – Portage Learning

CHEM210 / CHEM 210 Module 3: (Latest Update 2026 / 2027) Organic Chemistry | Questions & Answers | Grade A | 100% Correct – Portage Learning Q: True or False: the amino acids serine and methionine both contain sulfur atoms. Answer false Q: True or False: The following secondary structure shown below is an example of a beta-turn. Answer False Q: True or False: The side chain of proline is bonded to the backbone nitrogen atom. Answer True Q: True or False: The name of the molecule that binds to an enzyme is called the apoenzyme. Answer False Q: True or False: An inhibitor that binds at the active site is an uncompetitive inhibitor. Answer False Q: Which amino acids differ by only one atom? Ser and Thr Leu and Ile Ala and Ser Asp and Asn Ser and Cys Answer Ser and Cys Q: The formation of a peptide bond between two amino acids is an example of a(n) ________ reaction. Answer Condensation Q: The peptide Ala-Glu-Gly-Ala-Leu-Arg has __________. A disulfide bond Five peptide bonds Four peptide bonds A proline residue No C-Terminal Answer Five peptide bonds Q: Formally, when there are 100 or more amino acids covalently linked together that is called a __________. Answer Protein Q: What is used by biochemists to indicate the mass of a protein? Answer kDa or Da Q: All of the 20 standard amino acids contain an R-group that is attached to the: Answer Alpha Carbon Q: 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 Answer Glutamic Acid, E or Aspartic Acid, D Q: The order of amino acids in a protein is written_________. Answer N to C-Terminus Q: Roughly how many amino acids are there in one turn of an alpha helix? Answer 3.6 Q: In an alpha helix, the R groups on the amino acid residues: Answer are found on the outside of the helix spiral Q: Motifs are classified primarily by their: Answer Content and arrangement of the secondary structure Q: A single folded polypeptide has a globular shape, which describes its ______________ structure. Answer Tertiary Q: How many classes of enzymes are recognized by the IUBMB? Answer 6 Q: An enzyme requires Cr+3 for catalysis. When the enzyme contains the Cr+3 its called a(n) ________________. Answer Holoenzyme Q: When a substrate has just started its conversion to a new molecule, it is said to be in the ______________. Answer Transition state Q: Which of the following would change the rate of an enzyme-catalyzed reaction? Amino acids, concentration, temp ph, concentration, temp ph, polarity, concentration polarity, concentration, temp ph, polarity, temp Answer ph, concentration, temp Q: The concept of induced fit refers to the fact that: Answer Substrate binding induces a conformation change in the enzyme Q: The ES stands for: Answer Enzyme substrate Q: any molecule or ion that is necessary for an enzymes function is called a ___________. Answer cofactor Q: Is the following protein globular or fibrous? Explain. Also identify the types of secondary structures present in the following protein. Answer Its a globular protein due to its ball-like shape. Fibrous proteins are long and extended. The types of secondary structures present are alpha helices, beta sheets and turns. 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 the type of structure. Answer 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. What is the lowest level of protein structure? How do scientists communicate information about this level? Answer 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. What is the spot on an enzyme where reactions take place? Explain the characteristics of this spot. Answer the spot of 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. The secondary structure shown below is an example of a(n): Answer Parallel beta sheet Staphylokinase is said to be a dimer. What is a dimer? Structurally a dimer describes what level of protein structure? Answer A dimer contains two polypeptide chains interacting covalently. This describes the quaternary structure which has two or more polypeptide chains. Why are proteins the most important macromolecule? Answer They perform most of the work in cells. How many different proteins are found in humans? Answer At least 20,000 different proteins What are some functions of proteins? Transport Hormones Catalysis Structure Protection Answer Transport Proteins help to move molecules around the cell and organism. i.e. hemoglobin - blood based protein that carries oxygen from the lungs to the tissues Hormones these molecules communicate messages between cells i.e. relaxin - a protein that helps women during childbirth by relaxing pelvic ligaments to make delivery easier Catalysis (proteins also known as enzymes) speed up chemical reactions i.e. protease - breaks down proteins in cells and help organisms recycle unneeded proteins; also added to laundry detergent to degrade stains with protein (blood, food) Structure give strength to cells, organelles, and tissues i.e. collagen - found in cartilage, skin, and tendons Protection ability to fight foreign invaders (outside proteins and toxins) i.e. antibodies Amino acids monomers used as building blocks contain both an amine functional group and a carboxylic acid functional group; both functional groups are connected to an alpha carbon What permits all amino acids to link together in a protein? each amino acid has the same HN3, CH, COO- groups What makes amino acids unique? the unique part of each amino acid is indicated by the R, which is called the side chain side chains differ in composition, size, and charge while each amino acid has a different side chain, they can be classified by their commonality in structure its is common to group the side chains by charge, size, and polarity True or False: All proteins are constructed from the same 20 amino acids True What is physiological pH? 7.4 Non-polar aliphatic (straight chain amino acids) relatively small - permits them to interact with other groups found in the interior of the protein, away from water, nestled with other aliphatic groups *Proline is a unique amino acid that deviates from the general structure as the side chain bonds to the backbone N; only amino acid with this type of structure (not flexible - advantage and disadvantage in protein structure) Non-polar aromatic group of amino acids similar to aliphatic in that they are non-polar, but the side chains of these compounds contain a ring of carbons as an aromatic functional group more rigid and not as small as the aliphatic group Polar, but neutral amino acids contain side chains that have a dipole, and most can H-bond this permits these amino acids to interact strongly with water and are often found on the outside of the protein and in contact with water Acidic amino acids have side chains with pKa values smaller than 7, which indicates they lose their proton in the acidic pH range this property also means that at physiological pH these amino acids are negatively charged Basic amino acids have a pKa that is near or greater than 7, which means their side chains are normally positively charged these molecules are often found in contact with water because they H-bond they are often located near acidic residues in proteins to take advantage of favorable interactions between positive and negative charges Histidine does not have a charged group on its side chain At a slightly lower pH, it would appear as depicted - the pKa of the side HN+ group (indicated by the double dagger) is 6.00, so it typically has no charge at pH 7.4 True or False: cysteine is a unique amino acid that is neutral and polar with an uncharged side chain that can form disulfide bonds by their sulfur atoms covalently bonding True disulfide bonds stabilize a protein structure when present not all proteins contain these bonds, but they are common in proteins that exist outside of the cell i.e. keratin - protein component of hair; straight or curly hair holds its shape through disulfide cross linking between strands of hair, these bonds are strong which permits hair to maintain its shape polypeptides long chains of amino acids (99 residues or less) True or False: As macromolecules, proteins are synthesized from an average of 100 to 300 amino acids into a large chain True What dictates the exact sequence of amino acids? cell's DNA Where does synthesis of proteins occur? in the ribosomes, amino acids are covalently linked together to form a protein in a highly coordinated process Synthesis reaction of amino acids the same reaction for each amino acid occurs b/c of the functional groups common to each amino acid the amino functional group of one amino acid reacts with the carboxylic acid functional group of a second resulting in the two monomers joining together to produce a dipeptide with the release of water -- condensation rxn since one O from the carboxylic acid group and 2 H from the amino group are lost as water What kind of bond is formed between two amino acids? Peptide bond the ends of the dipeptide formed have reactive amine and carboxylic groups, which permit them to form additional peptide bonds peptide/oligopeptide describes a short chain of amino acids usually from two to twenty amino acids has an amino-terminal end (N-terminal end) and a carboxylic-terminal end (C-terminal end) protein backbone all the peptide bonds in a protein which link all the amino acids together residues term used to refer to the molecule remaining after the condensation rxn takes place what classifies a molecule as a protein instead of a polypeptide? 100 residues What is the mass for a protein that has 100 amino acids? 10,000 g/mol (Da - Dalton) or 10 kDa supramolecular chemistry the chemistry of large compounds conformation 3D structure of proteins biologically active conformational structures most proteins adopt a conformation that, when folded, is either fibrous or globular True or False: shape is important to function when adopting a specific conformation. True intrinsically disordered portions of proteins may exist in a random conformation What are the four standard levels of protein structure? 1. Primary 2. Secondary 3. Tertiary 4. Quaternary Primary Structure refers to the order of amino acids covalently bonded together, including disulfide bonds, in a polypeptide chain True or False: scientists routinely use the one-letter abbreviations to show amino acid sequence. True i.e. the first 60 amino acids in the sequence for insulin depicted Scientists write the sequence, starting with the N-terminal amino acid residue on the left, and continue writing the sequence to the right in the direction of the C-terminal True or False: proteins contain at least 100 amino acids, but they may contain thousands of residues in one chain True How do scientists write out the sequence of a protein? Secondary Structure used to examine the local 3D structure of amino acid residues close in linear sequence; there are 3 types of secondary structures (3) beta-turns Secondary Structure - alpha helices (1) alpha-helices: coiled structures where the backbone atoms form H-bonds to stabilize this sequence; standard helix has 3.6 amino acids/residues per each "turn" while rising 5.4 angstroms per turn (1 angstrom = 1x10-10m); interior of helix has no space; side chains (R groups) point out of the helix so they can interact with water and other chemical species Secondary structure - beta-sheets (2) beta-sheets: repetitive sheet-like structure; zig-zag orientation that puts adjacent side chain groups as far apart as possible; formed by individual beta-strands that interact by H-bonding to one another; parallel and anti-parallel anti-parallel forms when one beta-strand ends and the amino acid sequence turns back around on itself, then an additional beta-strand can join other strands to form anti parallel sheets parallel beta-sheets have beta-strands going in the same direction differences: H-bonding partners are different and the distance of each repeat is unique - parallel repeats every 6.5A while the anti-parallel repeats every 7.0A True or False: About 30% of amino acids are found in turns True these turns are changes in the direction of the N and C terminals of the primary sequence these turns permit proteins to form secondary structures immediately next to one another secondary structure - beta turn a four-residue unit that turns 180 degrees the turn is seen as a "rope" connecting the two strands beta-turns can form with both the alpha helix and beta sheet motif collection of particularly stable groups of secondary structures occupy a position b/w secondary and tertiary structures but are not one of the four levels specified by scientists i.e. helix-turn-helix composed of an Alpha helix, followed by a turn, and then another alpha helix Tertiary structure the overall 3D structure of the folded polypeptide non-covalent forces and disulfide bonds maintain tertiary structure in the proper conformation necessary for function i.e. myoglobin depicted is critical for our muscle cells for binding and storing O2 prosthetic group a non-amino acid portion of the molecule necessary for the structure and function of the protein fibrous protein exists in a long, extended structure of alpha helices quaternary structure describes macromolecules that have two or more independent polypeptide chains associated with one another, the number and orientation of these independent chains constitute the quaternary structure i.e. staphylokinase, hemoglobin Dimer two polypeptides (two subunits) tetramer protein with 4 subunits -in ending used for proteins that are not enzymes i.e. hemoglobin, myoglobin -ase ending used for proteins that are enzymes i.e. protease, staphylokinase enzymes proteins that accelerate/speed up chemical reactions have a high specificity for one molecule, or a collection of molecules, due to their structure (conformation) How to enzymes speed up chemical reactions? reactants bind to the enzyme, primarily in the interior, and then undergo a chemical transformation this binding helps to speed the reaction along by lowering the energy needed to get the reaction started enzymes do this better than inorganic catalysts due to their complementary structure the result is that reactions speed up 1000 times or more compared to the rate of uncatalyzed reactions substrate the chemical species that bind to the enzyme and are converted to another compound lyase catalyze the forming or breaking of double bonds oxidoreductases catalyze oxidation and reduction reactions i.e. luciferase found in lightning bugs transferals catalyze the transfer of a group from one molecule to a second hydrolases catalyze the breaking, or hydrolysis, of bonds isomerases catalyze the rearrangement within a single molecule ligases catalyze the joining of two molecules, or two parts of a molecule How many classes of enzymes exist? 6 co-factor non-protein components that are critical for activity i.e. metal ions such as fumerase requires Mg2+ for activity coenzymes organic compounds that function as cofactors; aid enzymes by assisting in the transfer of chemical groups from one compound to a second i.e. Vit C, niacin apoenzyme an enzyme without the cofactor (either ion or coenzyme) holoenzyme when the cofactor is added to the apoenzyme to produce a functional enzyme active site specific spot on the enzyme where catalysis takes place composed of 10 amino acids that form non-covalent interactions with the substrate which helps to generate a favorable energy change to enhance the reaction induced fit small movements of the amino acids in the enzyme to bind specifically to the substrate interactions at the active site of the enzyme that provide energy to change the conformation of the enzyme to accommodate the substrate transition state the structure of the molecule in its transition into a new molecule most unstable part of the reaction d/t high potential energy true or false: increasing the concentration of enzyme generally increases the rate of the reaction true True or False: unfolding renders the enzyme inactive, which means it does not catalyze a reaction True What is the optimal temperature for human function? 37 degrees celsius inhibitors slow down or stop enzyme reactions by binding to the enzyme via non-covalent interactions; reversible inhibitors 1. competitive petitive