Biochemistry Hormones and Enzymes Quiz

A hormone that primarily promotes glycogen synthesis, aiding in the storage of glucose in the liver and muscles.

An enzyme that catalyzes the conversion of glucose 6-phosphate to glucose 1-phosphate, essential for glycogen synthesis and breakdown.

A vitamin that is NOT a coenzyme in the pyruvate dehydrogenase (PDH) complex, which is crucial for converting pyruvate to acetyl-CoA for the citric acid cycle.

The step in the citric acid cycle where FADH2 is produced during the oxidation of succinate to fumarate.

A characteristic of ketone bodies, which are alternative fuel sources produced during prolonged fasting or starvation.

Bile salts are produced by the liver and secreted into the small intestine. They emulsify dietary lipids, breaking them down into smaller droplets for easier digestion and absorption.

A hormone that stimulates the release of bicarbonate from the pancreas, which neutralizes stomach acid in the small intestine, aiding in digestion.

Complex II in the electron transport chain couples the oxidation of succinate with the reduction of ubiquinone (CoQ), a crucial step in transferring electrons and generating a proton gradient.

The inner mitochondrial membrane is selectively permeable, controlling the passage of specific molecules and ions, essential for maintaining the proton gradient for ATP synthesis.

Hormones are primarily produced and released from various tissues in the body, acting as signaling molecules that regulate diverse physiological processes.

A mutation affecting citrate synthase disrupts a key step in the citric acid cycle, preventing acetyl-CoA from combining with oxaloacetate to produce citrate. This leads to reduced ATP production contributing to fatigue.

The enzyme malfunctioning in a patient having trouble converting succinate to fumarate in the citric acid cycle is succinate dehydrogenase, which is a part of Complex II.

A defect in Complex IV of the electron transport chain disrupts the final step of electron transfer, preventing the reduction of oxygen to water and causing the proton gradient to collapse, resulting in reduced ATP synthesis. This leads to fatigue because of insufficient energy production.

A defect in Complex III disrupts electron flow from ubiquinol to cytochrome c, causing the proton gradient to collapse, leading to impaired ATP production, and causing muscle weakness and fatigue.

A 16-carbon fatty acid undergoing beta-oxidation and entering the citric acid cycle will produce a total of 31 NADH molecules. Each cycle of beta-oxidation yields 1 NADH and 1 FADH2, and the complete oxidation of the 16-carbon fatty acid produces 8 acetyl-CoA molecules, each of which produces 3 NADH during the citric acid cycle.

Glycerol kinase is the enzyme that catalyzes the first step in the conversion of glycerol into a glycolytic intermediate, specifically dihydroxyacetone phosphate (DHAP).

The urea cycle primarily occurs in the liver, where ammonia produced by the breakdown of amino acids is converted into urea, which is less toxic and can be excreted by the kidneys.

Glycogen phosphorylase is the key enzyme that initiates glycogen breakdown into glucose by catalyzing the phosphorolytic cleavage of glycosidic bonds in glycogen, releasing glucose-1-phosphate.

Insulin binds to its receptor, a tyrosine kinase receptor, triggering a cascade of intracellular signaling events that ultimately lead to the activation of GLUT4, a glucose transporter protein, which facilitates glucose uptake into cells.

Elevated blood glucose and triglyceride levels often indicate an imbalance in hormones, with increased glucagon activity and decreased insulin activity being a primary cause.

PDH complex activity is regulated by numerous factors, including the ratios of ATP/ADP, NADH/NAD+, and the availability of CoA, but NOT Zn2+.

Malate dehydrogenase is the enzyme that catalyzes the oxidation of malate to oxaloacetate generating NADH, a key step in the citric acid cycle.

The heme group belongs to a C-type cytochrome, specifically cytochrome c, a mobile electron carrier in the respiratory chain, crucial for transferring electrons between Complex III and IV.

Succinate dehydrogenase, an enzyme of the citric acid cycle, also functions as Complex II in the electron transport chain, playing a crucial role in oxidizing succinate and transferring electrons to ubiquinone (CoQ).

Lipoprotein lipase (LPL) is activated by apoC-II in the capillary, where it hydrolyzes triacylglycerols into free fatty acids and monoacylglycerols, essential for transporting dietary lipids to various tissues.

A person severely lacking biotin could exhibit signs of propionic acidemia, a genetic disorder affecting the metabolism of propionyl-CoA, which can lead to developmental delays, neurological problems, and metabolic acidosis.

Vigorous muscle activity triggers glycogen phosphorylase b kinase, which activates glycogen phosphorylase b by phosphorylation. This leads to the breakdown of glycogen into glucose-1-phosphate, providing a readily available energy source for muscle contraction.

The glycogenin mechanism begins with the formation of a glycosidic bond between the glucose of UDP-glucose and a tyrosine (Tyr) residue on glycogenin. This initiates the formation of a new glycogen molecule.

Trypsin activates trypsinogen, a zymogen, along with precarboxypeptidases A and B, to form active forms of carboxypeptidases A and B. These enzymes are essential for digesting proteins in the small intestine.

Beige adipocytes, unlike white adipocytes, are not limited to cold exposure to convert. They share similarities with brown adipocytes in terms of increased mitochondrial concentration and UCP1 production, promoting thermogenesis. However, they differ in their appearance, with beige adipocytes displaying multiple lipid droplets compared to the single lipid droplet of brown adipocytes.

Phosphoglucomutase catalyzes the conversion of glucose-1-phosphate to glucose-6-phosphate, enabling the utilization of glucose-1-phosphate, mainly produced from glycogen breakdown, in the glycolytic pathway in both muscle and liver cells.

UTP is the nucleotide used to commit glucose to glycogen synthesis. It provides the energy required to link the glucose molecule to the growing glycogen chain.

ATP inhibits the PDH complex by allosterically activating PDH kinase, thus blocking the conversion of pyruvate to acetyl-CoA, slowing down the citric acid cycle. This is an example of feedback regulation, as high ATP levels signal the cell to reduce energy production.

Lipoate is a coenzyme used in the citric acid cycle. It is a carrier of electrons and acyl groups, playing a crucial role in the oxidative decarboxylation of α-ketoglutarate and pyruvate.

Ketone bodies are mainly created in the liver from fatty acids during periods of prolonged fasting or starvation. They serve as an alternative fuel source for tissues like the brain.

Carnitine acyltransferase 1 (CAT1) is located on the outer mitochondrial membrane and catalyzes the transfer of a fatty acyl group from CoA to carnitine, creating acylcarnitine, which can then pass through the membrane into the mitochondrial matrix.

Glutamate is the key amino acid for amino acid oxidation, acting as a central hub for amino group transfers during amino acid catabolism and nitrogen excretion.

Complex I, the first complex of the electron transport chain, acts as a proton pump. It transfers electrons from NADH to ubiquinone (Q) and translocates protons across the inner mitochondrial membrane, contributing to the proton gradient.

Heme b in Complex II is a molecule that plays a role in substrate channeling, facilitating the interaction between the components of the complex, but it doesn't contribute to proton pumping, free radical neutralization, or NADH synthesis.

The liver is where epinephrine, insulin, and glucagon are all produced and released. These hormones play crucial roles in regulating glucose metabolism, including glycogen storage, breakdown, and gluconeogenesis.

Glucose-6-phosphate inhibits hexokinase by allosteric feedback inhibition, which is a non-competitive inhibition. It binds to a regulatory site on hexokinase, altering the enzyme's conformation and reducing its affinity for glucose without competing for the active site.

AMP accumulates during muscular contraction, triggering a cascade of events that activates glycogen breakdown. AMP binds to the allosteric site of inactive glycogen phosphorylase b, changing its conformation to the active state, glycogen phosphorylase a. This ultimately leads to a faster breakdown of glycogen into glucose, providing energy for muscle contraction.

AMP and Ca²⁺ are the two allosteric activators of glycogen phosphorylase. They bind to the enzyme and stimulate its activity, promoting the breakdown of glycogen into glucose, which can be used for energy production in muscle cells.