Biochemistry Quiz: Enzymes and Metabolism

Enzymes act as biological catalysts that direct metabolic events, exhibit specificity toward substrates, and regulate metabolism.

Proteins are formed through the dehydration polymerization of amino acids, where each amino acid is linked by peptide bonds.

The three-dimensional structure of proteins is crucial because it determines their biological activity and functionality.

<p>Protein denaturation is the unfolding and disorganization of a protein's structure, often irreversible, leading to loss of biological function.</p> Signup and view all the answers

<p>Carbohydrates can be classified into monosaccharides, disaccharides, and polysaccharides.</p> Signup and view all the answers

<p>A disaccharide is made up of two monosaccharides joined by glycosidic linkages, while a monosaccharide is the simplest sugar unit.</p> Signup and view all the answers

<p>The type, nature, and number of amino acids in a protein determine its characteristic properties and functions.</p> Signup and view all the answers

<p>Carbohydrates provide energy and act as storage molecules of energy in living organisms.</p> Signup and view all the answers

<p>The primary function of ATP is to provide energy for various biochemical reactions in the cell.</p> Signup and view all the answers

<p>β-oxidation is the metabolic pathway where fatty acids are broken down in the mitochondria to generate acetyl-CoA, NADH, and FADH2.</p> Signup and view all the answers

<p>Free energy refers to the energy available to do work in a system, which determines the spontaneity and equilibrium of biochemical reactions.</p> Signup and view all the answers

<p>The electron transport chain generates a proton gradient that drives ATP synthesis through oxidative phosphorylation.</p> Signup and view all the answers

<p>Uncouplers disrupt the proton gradient, leading to the dissipation of energy as heat rather than producing ATP.</p> Signup and view all the answers

<p>The Kreb's cycle, also known as the citric acid cycle, plays a central role in the oxidation of acetyl-CoA to generate electron carriers NADH and FADH2.</p> Signup and view all the answers

<p>Cyanide is a respiratory poison that inhibits cytochrome c oxidase in the electron transport chain, preventing ATP production.</p> Signup and view all the answers

<p>Lipid digestion involves emulsification by bile salts and hydrolysis by lipases, followed by absorption of fatty acids and monoglycerides into intestinal cells.</p> Signup and view all the answers

<p>Zymogen activation is the process where inactive enzyme precursors are converted into their active forms through hydrolysis, such as pepsinogen converting to pepsin.</p> Signup and view all the answers

<p>Reversible covalent modification regulates enzyme activity by adding or removing phosphate groups, as seen in the phosphorylation of phosphorylase kinase by protein kinases.</p> Signup and view all the answers

<p>Allosteric modulation involves small molecules binding to an enzyme at sites distinct from the active site, causing conformational changes that either enhance or inhibit catalytic activity.</p> Signup and view all the answers

<p>Feedback inhibitors are end products that inhibit the activity of enzymes in a metabolic pathway, effectively stopping the pathway when enough product is produced.</p> Signup and view all the answers

<p>Positive allosteric effectors enhance the enzyme's catalytic activity, while negative effectors decrease it.</p> Signup and view all the answers

<p>Vmax represents the maximum reaction rate of an enzyme, which can be increased or decreased by allosteric effectors, influencing overall enzyme efficiency.</p> Signup and view all the answers

<p>Km is the substrate concentration at which an enzyme reaches half its Vmax; allosteric effectors can raise or lower Km, affecting enzyme affinity for substrates.</p> Signup and view all the answers

<p>Feedback inhibition is common because it prevents overproduction of metabolites, ensuring that pathways are finely tuned to the cell's current needs.</p> Signup and view all the answers

<p>Class I oxidoreductases catalyze oxidation-reduction reactions. An example is lactate dehydrogenase.</p> Signup and view all the answers

<p>Class II transferases catalyze the transfer of functional groups other than hydrogen. An example is the reaction of ATP with D-hexose to form D-hexose-6-phosphate.</p> Signup and view all the answers

<p>Class III hydrolases catalyze the hydrolysis of various bonds using water. A specific example is β-galactosidase acting on β-D-galactoside.</p> Signup and view all the answers

<p>Class IV lyases catalyze the removal of groups from substrates, forming double bonds without hydrolysis. An example is malate hydro-lyase.</p> Signup and view all the answers

<p>Class V isomerases facilitate the interconversion of isomers. An example is triosephosphate isomerase, which converts D-glyceraldehyde-3-phosphate to dihydroxyacetone phosphate.</p> Signup and view all the answers

<p>Class VI ligases catalyze the joining of two compounds while breaking a pyrophosphate bond. An example is the formation of L-glutamine from ATP, L-glutamate, and ammonia.</p> Signup and view all the answers

<p>Hexokinase catalyzes the reaction between ATP and D-hexose, producing ADP and D-hexose-6-phosphate.</p> Signup and view all the answers

<p>Class III hydrolases can act on ester, ether, peptido, glycosyl, or other types of bonds using water. A general example is the hydrolysis of glycosidic bonds.</p> Signup and view all the answers

<p>Feedback regulation ensures that enzymes function optimally at the earliest irreversible step in the pathway.</p> Signup and view all the answers

<p>They are classified into enzymes secreted by organs and those released during normal cell turnover.</p> Signup and view all the answers

<p>Tissue damage due to diseases results in increased release of intracellular enzymes into the plasma.</p> Signup and view all the answers

<p>Plasma lipase levels may be low in liver disease, Vitamin A deficiency, and certain malignancies.</p> Signup and view all the answers

<p>α-Amylase catalyzes the breakdown of dietary starch and glycogen to maltose.</p> Signup and view all the answers

<p>α-Amylase levels are primarily used to diagnose acute pancreatitis.</p> Signup and view all the answers

<p>Elevated trypsin levels in plasma may indicate acute pancreatic disease.</p> Signup and view all the answers

<p>Measurement of enzyme concentrations can provide valuable information about diseases affecting their tissues of origin.</p> Signup and view all the answers

<p>Pancreatic amylase hydrolyzes terminal α-(1,4) glycosidic linkages in polysaccharides and oligosaccharides.</p> Signup and view all the answers

<p>Lactose is hydrolyzed to glucose and galactose.</p> Signup and view all the answers

<p>Adults who lack lactase cannot digest lactose, leading to fermentation by bacteria, causing diarrhea and abdominal pain.</p> Signup and view all the answers

<p>Maltase has a pH range of 5.8 to 6.2 and catalyzes the hydrolysis of maltose into two glucose molecules.</p> Signup and view all the answers

<p>Sucrase hydrolyzes sucrose to form glucose and fructose.</p> Signup and view all the answers

<p>Carbohydrate absorption occurs via simple diffusion, dependent on concentration gradients, and active transport, which requires energy.</p> Signup and view all the answers

<p>Only monosaccharides are small enough to be absorbed directly into the bloodstream from the intestine.</p> Signup and view all the answers

<p>Fructose is absorbed faster than pentoses but slower than glucose and galactose.</p> Signup and view all the answers