Biochemistry Quiz on Lipid Metabolism

A molecule with a positive and negative end due to uneven electron distribution.

A weak bond between a slightly positive hydrogen atom and a slightly negative atom, like oxygen.

The ability of water molecules to stick to each other.

The ability of water molecules to stick to other molecules or substances.

The amount of heat energy required to raise the temperature of 1 gram of a substance by 1 degree Celsius.

A substance that dissolves other substances.

A substance that can donate a proton (H+) to a base.

A substance that can accept a proton (H+) from an acid.

The process of water molecules donating and accepting protons, resulting in the formation of hydronium ions (H3O+) and hydroxide ions (OH−).

A solution that resists changes in pH upon the addition of an acid or base.

The first step in the urea cycle, catalyzed by carbamoyl phosphate synthase I (CPS I), consumes ATP and is the rate-limiting step.

N-acetylglutamate (NAG) is a crucial activator of carbamoyl phosphate synthase I (CPS I), the enzyme responsible for the first step in the urea cycle.

High levels of arginine lead to increased N-acetylglutamate (NAG) production, which in turn activates carbamoyl phosphate synthase I (CPS I).

A metabolic condition characterized by elevated ammonia levels, leading to toxicity. It can be caused by genetic defects in the enzymes involved in the urea cycle.

Defects in the enzyme ornithine transcarbamoylase, which is involved in the second step of the urea cycle, lead to a specific type of hyperammonemia.

Glucogenic amino acids can be converted to glucose via gluconeogenesis because their carbon skeletons can enter the pathways of carbohydrate metabolism.

Ketogenic amino acids can be broken down into acetoacetyl-CoA or acetyl-CoA, which can be used for the synthesis of ketone bodies but not glucose.

The carnitine shuttle is a transport system that moves fatty acyl-CoA molecules, which are activated fatty acids, from the cytoplasm into the mitochondria.

The β-oxidation pathway is a metabolic process that breaks down fatty acids into acetyl-CoA, which can be used for energy production in the citric acid cycle.

Fatty acids are activated by being converted to fatty acyl-CoA in the cytoplasm using ATP, which is needed to start the β-oxidation process.

A type of globular protein found in red blood cells (erythrocytes) that plays a crucial role in transporting oxygen throughout the human body.

Hemoglobin's affinity for oxygen increases as the partial pressure of oxygen rises, leading to increased oxygen binding in the lungs.

Hemoglobin's affinity for oxygen decreases as the partial pressure of oxygen falls, leading to increased oxygen release in tissues.

A protein structure within hemoglobin responsible for binding oxygen.

Each hemoglobin molecule can bind up to four oxygen molecules.

Glycolysis is the breakdown of glucose into pyruvate, generating energy in the form of ATP. This process occurs in the cytoplasm of cells and is a fundamental pathway for cellular energy production.

The preparatory phase of glycolysis involves steps 1-5, where glucose is activated and prepared for cleavage. These steps consume ATP but prepare the molecule for the energy-generating stage.

The payoff phase of glycolysis encompasses steps 6-10, where energy is harvested through oxidation and substrate-level phosphorylation, resulting in the production of ATP and NADH.

In step 1 of glycolysis, glucose is phosphorylated into glucose-6-phosphate. This is catalyzed by hexokinase and uses ATP as the phosphate donor. This step traps glucose inside the cell and is irreversible.

Step 2 of glycolysis involves the isomerization of glucose-6-phosphate into fructose-6-phosphate. This reaction is catalyzed by glucose-6-phosphate isomerase and makes the molecule easier to phosphorylate in the next step.

Step 3 of glycolysis involves the phosphorylation of fructose-6-phosphate into fructose-1,6-bisphosphate. This step is catalyzed by phosphofructokinase-1 (PFK-1) and uses ATP as the phosphate donor.

Step 4 of glycolysis involves the cleavage of fructose-1,6-bisphosphate into two triose phosphates: dihydroxyacetone phosphate and glyceraldehyde 3-phosphate. This reaction is catalyzed by aldolase, creating the starting point for the payoff phase.

Step 5 of glycolysis involves the isomerization of dihydroxyacetone phosphate into glyceraldehyde-3-phosphate. This reaction is catalyzed by triose phosphate isomerase and completes the preparatory phase.

Step 6 of glycolysis involves the oxidative phosphorylation of glyceraldehyde-3-phosphate into 1,3-bisphosphoglycerate. This reaction is catalyzed by glyceraldehyde-3-phosphate dehydrogenase and produces NADH.

Step 7 of glycolysis involves the transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP. This is catalyzed by phosphoglycerate kinase and results in the production of ATP and 3-phosphoglycerate.

Step 8 of glycolysis involves the isomerization of 3-phosphoglycerate into 2-phosphoglycerate. This reaction is catalyzed by phosphoglycerate mutase and involves moving the phosphate group from C-3 to C-2.

Step 9 of glycolysis involves the dehydration of 2-phosphoglycerate into phosphoenolpyruvate. This reaction is catalyzed by enolase (phosphopyruvate hydratase), removing water to create a high-energy compound.

Step 10 of glycolysis involves the transfer of a phosphate group from phosphoenolpyruvate to ADP. This is catalyzed by pyruvate kinase and results in the production of ATP and pyruvate. This is the second ATP-generating step and is irreversible.

Hexokinase, phosphofructokinase-1 (PFK-1), and pyruvate kinase are the key regulatory enzymes in glycolysis. These enzymes are regulated by factors such as substrate availability, feedback inhibition, and allosteric effectors, ensuring that glycolysis functions optimally for energy production.

Glycolysis is a highly efficient metabolic pathway that provides a constant source of energy for the cell. Its key products, ATP and NADH, are essential for various cellular functions. It is a fundamental process that has evolved over time to ensure the survival and functioning of all living organisms.

The initial stage of β-oxidation where FAD removes two hydrogen atoms from acyl-CoA, forming trans-Δ²-enoyl-CoA. This step generates FADH₂ which is a key player in ATP production.

An enzyme responsible for catalyzing the first step of β-oxidation. It facilitates the removal of hydrogen atoms from acyl-CoA.

The process where water is added across the double bond in trans-Δ²-enoyl-CoA, forming L-3-hydroxyacyl-CoA. It prepares the molecule for further oxidation.

An enzyme vital for the hydration step in β-oxidation, adding water to the double bond of trans-Δ²-enoyl-CoA.

The third stage of β-oxidation where the hydroxyl group on L-3-hydroxyacyl-CoA is oxidized to a carbonyl group, using NAD⁺ as an electron acceptor. This produces NADH, another key molecule for ATP synthesis.

The enzyme that catalyzes the oxidation of the hydroxyl group in the third step of β-oxidation. It uses NAD⁺ for this oxidation.

The final stage of β-oxidation where 3-ketoacyl-CoA is broken down into acetyl-CoA and a shorter acyl-CoA through the addition of CoA. This process generates acetyl-CoA, the main energy unit for the Krebs cycle.

The crucial enzyme that catalyzes the breakdown of 3-ketoacyl-CoA during thiolysis in β-oxidation.

The complete breakdown of a fatty acid molecule through repeated cycles of β-oxidation yields numerous acetyl-CoA molecules, FADH₂ molecules, and NADH molecules. These products then enter the electron transport chain to produce ATP.

β-oxidation is regulated by factors such as the availability of substrates like fatty acids, the energy demands of the cell, and the levels of key enzymes involved in the process.

A type of enzyme that catalyzes the joining of two molecules through the formation of a new chemical bond. They play a crucial role in the continuity of nucleic acids and in various metabolic processes.

This specific type of ligase helps to bind DNA strands by sealing nicks in the sugar-phosphate backbone.

RNA ligase joins RNA fragments. This is important for certain RNA processing events.

This particular type of ligase catalyzes the attachment of amino acids to their corresponding tRNAs, forming aminoacyl-tRNA complexes.

These ligases catalyze the joining of various biomolecules in metabolic pathways.

Non-protein chemical compounds that assist enzymes in catalyzing biochemical reactions. They can be coenzymes, metal ions, or prosthetic groups.

A type of non-protein organic molecule that binds to an enzyme and is essential for its activity. They're often derived from vitamins and associate temporarily with the enzyme.

Inorganic molecules that can be essential for the activity of many enzymes. They help stabilize structures, facilitate electron transfer and participate in catalytic reactions.

A non-polypeptide unit that tightly binds to an enzyme, essential for its activity. They remain attached to the enzyme throughout the reaction.

Inactive precursors of enzymes that require activation to function. They are often activated through proteolytic cleavage or chemical modifications.

Enzymes that differ in amino acid sequence but catalyze the same chemical reaction. They can have different affinities for substrates, different rates of reaction, and may respond differently to inhibitors or activators.

Represents the maximum number of substrate molecules converted to product by one enzyme molecule per second when the enzyme is fully saturated. It's a measure of enzyme efficiency.

Describes the rate of enzymatic reactions by relating reaction velocity (V) to substrate concentration ([S]). It helps in understanding the relationship between substrate concentration and enzyme activity.

The substrate concentration when half of the enzyme's active sites are filled. It indicates the affinity of the enzyme for its substrate; a lower Km means higher affinity.

The maximum reaction velocity achieved by an enzyme when all active sites are saturated with substrate. It represents the enzyme's capacity to catalyze the reaction.