Enzyme Function and Mechanisms Quiz

<p>Partial proteolysis (A)</p> Signup and view all the answers

<p>Holoenzymes (C)</p> Signup and view all the answers

<p>Transfer of the phosphate group (B)</p> Signup and view all the answers

<p>Analog of the substrate (D)</p> Signup and view all the answers

<p>ALT (D)</p> Signup and view all the answers

<p>Phosphoenolpyruvate (D)</p> Signup and view all the answers

<p>Formation of glyceraldehyde-3-phosphate (C)</p> Signup and view all the answers

<p>Oxidative phosphorylation (D)</p> Signup and view all the answers

<p>Oxidative phosphorylation (D)</p> Signup and view all the answers

<p>Anaerobic glucose oxidation (D)</p> Signup and view all the answers

<p>3 mole (C)</p> Signup and view all the answers

<p>Lactate concentration (B)</p> Signup and view all the answers

<p>Oxidative phosphorylation (A)</p> Signup and view all the answers

<p>Phosphofructokinase (A)</p> Signup and view all the answers

<p>ATP (B)</p> Signup and view all the answers

<p>Glucose-6-phosphate (B)</p> Signup and view all the answers

<p>Anaerobically (B)</p> Signup and view all the answers

<p>Aerobic glycolysis (A)</p> Signup and view all the answers

<p>1,3-bisphosphoglycerate (D)</p> Signup and view all the answers

<p>Formation of NADPH2 (A)</p> Signup and view all the answers

<p>Glucose-6-phosphate dehydrogenase (B)</p> Signup and view all the answers

<p>They reduce the rate of enzymatic reactions. (B)</p> Signup and view all the answers

<p>Vitamin PP (A)</p> Signup and view all the answers

<p>To bind to the active site of the enzyme. (C)</p> Signup and view all the answers

<p>Decomposition of substances with energy release. (A)</p> Signup and view all the answers

<p>Oxidative decarboxylation of keto acids. (C)</p> Signup and view all the answers

<p>Synthesis of complex molecules from simpler ones. (D)</p> Signup and view all the answers

<p>Acetyl-CoA (D)</p> Signup and view all the answers

<p>The Krebs cycle and oxidative decarboxylation of pyruvate. (D)</p> Signup and view all the answers

<p>ribose-5-phosphate (B)</p> Signup and view all the answers

<p>purine and pyrimidine nucleotides (C)</p> Signup and view all the answers

<p>ribose-5-phosphate (C)</p> Signup and view all the answers

<p>glyceraldehyde-3-phosphate, fructose-6-phosphate (A)</p> Signup and view all the answers

<p>oxidative stage of the pentose phosphate cycle (C)</p> Signup and view all the answers

<p>glucose-6-phosphate dehydrogenase (B)</p> Signup and view all the answers

<p>glucose-6-phosphate (C)</p> Signup and view all the answers

<p>lactate, amino acids, glycerol, fatty acids, glycerol-3 phosphate (B)</p> Signup and view all the answers

<p>amylo-1,4 → 1,6-glucosyltransferase (A)</p> Signup and view all the answers

<p>UDP-glucopyrophosphorylase (A)</p> Signup and view all the answers

<p>glucose-6-phosphatase (B)</p> Signup and view all the answers

<p>aldolase (A)</p> Signup and view all the answers

<p>gluconeogenesis (D)</p> Signup and view all the answers

<p>immature chylomicrons (A)</p> Signup and view all the answers

<p>both glucagon and epinephrine (B)</p> Signup and view all the answers

<p>fats deposited in adipocytes (C)</p> Signup and view all the answers

Proteolytic enzymes break down proteins. They are also called proteinases or peptidases. These enzymes are found in various biological systems and have important roles in digestion, cell function, and regulation.

The shape of the active site in an enzyme matches the shape of the substrate, allowing for specific binding. This lock-and-key mechanism ensures that the enzyme interacts only with its specific substrate.

Isomerases catalyze the rearrangement of atoms within a molecule, converting one isomer to another. They don't break or form bonds, just change the spatial arrangement.

Pepsin is produced in the stomach as pepsinogen (inactive). It gets activated by hydrochloric acid and a small cleavage, removing a part of the molecule, resulting in active pepsin.

Holoenzymes are complete, active enzyme complexes. They consist of an apoenzyme (protein portion) and a cofactor (non-protein component like a coenzyme).

Kinases transfer a phosphate group from a donor molecule (like ATP) to an acceptor molecule. This phosphorylation often activates or deactivates the acceptor molecule.

Competitive inhibitors resemble the substrate and bind to the enzyme's active site, preventing the actual substrate from binding and blocking the reaction. This competition can be overcome by increasing the substrate concentration.

Serum, the liquid portion of blood after clotting, is often used to measure enzyme activity for diagnostic purposes. It provides a sample of enzymes circulating in the body, reflecting potential tissue damage or disease.

A site on an enzyme molecule where molecules other than the substrate bind.

Substances that reduce the rate of enzymatic reactions by binding to the enzyme and preventing it from working properly.

The active form of vitamin B6, involved in amino acid metabolism, specifically in aminotransferases.

Vitamins function as cofactors by binding to enzymes through weak bonds, usually non-covalently, to help the enzyme perform its activity.

A derivative of vitamin PP, also known as NAD+, involved in various dehydrogenase reactions, which remove hydrogen atoms.

The breakdown of complex molecules into simpler ones, releasing energy.

The synthesis of complex molecules from simpler ones, requiring energy.

Pyruvate, the product of glycolysis, is a central intermediate in metabolism, connecting carbohydrate, lipid, and protein pathways.

The process of converting glucose into pyruvate in the absence of oxygen. It produces a net gain of 2 ATP molecules, which is much less efficient than aerobic respiration.

The enzyme responsible for catalyzing the reaction of substrate phosphorylation, a key step in anaerobic glycolysis.

The primary energy source for brain cells. Brain cells are highly dependent on glucose for their metabolic needs.

A decrease in blood plasma pH is often caused by insufficient activity of this process. This is because the buildup of lactic acid, a byproduct of anaerobic glycolysis, lowers the pH.

The ratio of ATP to ADP is a key regulator of glycolysis. When ATP levels are high, glycolysis is slowed down to conserve energy. Conversely, when ADP levels are high, glycolysis is stimulated to produce more ATP.

The process of making ATP by transferring a phosphate group from a high-energy molecule to ADP. This happens during anaerobic glycolysis and also in other metabolic pathways.

The process that enables erythrocytes (red blood cells) to produce ATP. This happens because red blood cells lack mitochondria, the primary site of aerobic respiration.

The completion of glycolysis with the formation of phosphoenolpyruvate.

Ribose-5-phosphate is the product formed in the non-oxidative stage of the pentose phosphate pathway of glucose conversion.

Pentoses formed in the pentose phosphate cycle are used for the formation of purine and pyrimidine nucleotides, which are the building blocks of DNA and RNA.

Ribose-5-phosphate, a product of the pentose phosphate pathway, is directly involved in the synthesis of nucleic acids.

The pentose phosphate pathway produces ribose-5-phosphate and xylulose-5-phosphate, which are necessary for the synthesis of glucose, particularly during gluconeogenesis.

The reduction of NADP occurs during the oxidative stage of the pentose phosphate cycle, a crucial step in generating reducing power for biosynthesis.

Glucose-6-phosphate dehydrogenase is the key regulatory enzyme of the pentose phosphate pathway, controlling the rate of the pathway and the production of NADPH.

The pentose phosphate pathway uses glucose-6-phosphate as its primary substrate to generate NADPH and pentose sugars.

Gluconeogenesis primarily utilizes lactate, amino acids, glycerol, and glycerol-3-phosphate as substrates to produce glucose, especially during periods of low glucose levels.

Amylo-1,4 → 1,6-glucosyltransferase is an enzyme that catalyzes the formation of alpha-1,6-glucosidic bonds, branching points in glycogen.

UDP-glucopyrophosphorylase catalyzes the formation of UDP-glucose, an important precursor for glycogen synthesis.

The enzymes involved in glycogen synthesis are: hexokinase, UDP-glucopyrophosphorylase, glycogen synthase.

Aldolase catalyzes the cleavage of fructose-1,6-bisphosphate into two phosphotrioses, dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, in glycolysis.

In the liver, alanine is used for gluconeogenesis, the process of synthesizing glucose from non-carbohydrate sources.

Lipoproteins, such as chylomicrons and VLDL, are responsible for the transport of lipids by blood and lymph.

Immature chylomicrons are synthesized in enterocytes, cells lining the small intestine, after absorption of dietary fats.

The enzyme triacylglycerol lipase is activated by glucagon and epinephrine, hormones that signal the need for energy mobilization.

Phosphofructokinase (PFK) is a key regulatory enzyme in glycolysis. It catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, a committed step in glycolysis. PFK's activity is tightly controlled to ensure proper glucose metabolism.

ATP, a product of glycolysis, acts as an inhibitor of phosphofructokinase (PFK). When ATP levels are high, the enzyme is inhibited, slowing down glycolysis. This negative feedback mechanism prevents the overproduction of ATP.

Glucose-6-phosphate, a product of hexokinase, inhibits the activity of the enzyme. This feedback inhibition prevents the overaccumulation of glucose-6-phosphate.

In the first minutes of muscle contraction, glucose is broken down for energy without the use of oxygen, a process called anaerobic glycolysis. This rapid energy production process is vital for short bursts of intense activity.

During prolonged physical activity, energy production shifts to aerobic metabolism, where glucose is completely oxidized to CO2 and H2O, yielding a much larger amount of ATP. This process occurs in the mitochondria.

Substrate-level phosphorylation is a direct transfer of a phosphate group from a substrate molecule (like 1,3-bisphosphoglycerate) to ADP, generating ATP. This occurs in glycolysis and is a less efficient ATP production mechanism compared to oxidative phosphorylation.

The pentose phosphate pathway is a crucial metabolic pathway in red blood cells, where it primarily produces NADPH2, a reducing agent essential for the detoxification of reactive oxygen species. NADPH2 also helps maintain the integrity of red blood cells.

The pentose phosphate pathway generates both pentose sugars like ribose-5-phosphate and NADPH2. Pentose sugars are essential components of nucleic acids, while NADPH2 is involved in reductive biosynthesis and detoxification reactions.