Biochemistry Chapter 5 Quiz

The breakdown of glucose into pyruvate, generating a net gain of 2 ATP and 2 NADH molecules.

A 3-carbon molecule formed during glycolysis, which can be further broken down for energy or used in other metabolic pathways.

The enzyme that phosphorylates glucose, trapping it inside the cell and activating it for metabolism.

An isomer of glucose-6-phosphate, a key intermediate in glycolysis.

The enzyme that phosphorylates fructose-6-phosphate, creating fructose-1,6-bisphosphate, a key step in glycolysis.

The process of adding a phosphate group to a molecule, often coupled with the release of energy.

A type of phosphorylation where energy is directly transferred from a substrate molecule to ADP, producing ATP.

A high-energy electron carrier molecule that is reduced during glycolysis, carrying electrons to the electron transport chain for ATP production.

The process of breaking down glycogen into glucose. This process is activated when energy demands are high, such as during exercise or rapid growth.

The process of building up glycogen from glucose. This process is activated when there is a surplus of glucose in the body, typically after a meal.

The storage of glucose in a branched polymer, allowing for rapid release of glucose when needed. It also minimizes the osmotic burden of high blood glucose.

The liver and skeletal muscles are the primary sites for glycogen metabolism. The liver plays a critical role in maintaining blood glucose levels, while skeletal muscles use glycogen for their own energy needs.

Glycogenolysis and glycogenesis utilize different enzymes. This separation allows for tight regulation of glycogen metabolism, ensuring that glucose is released when needed and stored when in excess.

Fructose is metabolized more rapidly than glucose, and its uptake by organs is not dependent on insulin or ATP investment.

Fructose metabolism in the liver involves multiple steps, utilizing the enzyme fructokinase, while in muscle, it occurs in a single step using hexokinase.

The metabolic fate of fructose depends on the body's nutritional state. When fructose is abundant, it can be used for fatty acid synthesis.

Galactose, another dietary sugar, is converted to glucose-6-phosphate through the Leloir pathway, involving four enzymes.

Gluconeogenesis is the metabolic process of synthesizing glucose from non-carbohydrate sources, such as pyruvate, lactate, and amino acids.

The process where pyruvate is not converted to acetyl-CoA but instead reduced to lactate, regenerating NAD+ for continued glycolysis.

This type of glycolysis uses oxygen to generate energy and involves the complete oxidation of glucose to CO2.

The enzyme that catalyzes the reduction of pyruvate to lactate, regenerating NAD+ for continued glycolysis under anaerobic conditions.

Systems that shuttle electrons across the mitochondrial membrane, regenerating NAD+ for continued glycolysis.

A shuttle system that utilizes malate and aspartate to transport electrons across the mitochondrial membrane.

A shuttle system that transports electrons across the mitochondrial membrane using glycerol 3-phosphate.

The total number of ATP molecules produced per molecule of substrate during cellular respiration.

The process of uncoupling oxidative phosphorylation (OXPHOS), reducing the efficiency of ATP production.

The energy generated by the proton motive force (PMF) that can be used for ATP synthesis.

Glucose can be broken down via two pathways:

• Anaerobic glycolysis - occurs in the absence of oxygen, yielding 2 ATP and lactate.
• Oxidative glycolysis - utilizes oxygen, produces 2 ATP and pyruvate, which is then used in the Krebs cycle for further energy production.

Lactate dehydrogenase is an enzyme crucial for the conversion of pyruvate to lactate in anaerobic glycolysis. This process occurs when oxygen supply is low, preventing a buildup of pyruvate and allowing for continued ATP production.

The enzyme that converts pyruvate to lactate is called lactate dehydrogenase, or LDH. It does this by adding a hydrogen ion to pyruvate thanks to the reducing power of NADH. This reaction is reversible, but the direction it favors is determined by the ratio of NADH to NAD+.

Disaccharides like sucrose, lactose, and fructose are broken down into simpler monosaccharides like glucose, fructose, and galactose by specific enzymes (sucrase, lactase) during digestion. These simple sugars are then absorbed and further processed by the body.

Complex carbohydrates like starch and glycogen are broken down into glucose monomers by enzymes called amylases. This process occurs during digestion, allowing the body to readily absorb and utilize glucose for energy.

The process of synthesizing glucose from non-carbohydrate sources, such as amino acids, glycerol, and lactate.

The main source of energy for the brain, even during fasting.

When the body uses stores of glycogen to maintain blood glucose levels for approximately 12-18 hours.

The liver, kidney cortex, and small intestine are the primary sites of gluconeogenesis.

The primary source of alanine for gluconeogenesis in the liver.

The process of converting pyruvate to alanine, which is then transported to the liver for gluconeogenesis.

A molecule produced during anaerobic glycolysis, serving as a substrate for gluconeogenesis in the liver.

The process of converting lactate to pyruvate using the enzyme lactate dehydrogenase.

The key steps in gluconeogenesis that cannot be reversed easily, requiring different enzymes for forward and reverse reactions.

An enzyme that converts pyruvate to oxaloacetate, initiating gluconeogenesis.

An alternative pathway for glucose metabolism, providing precursors for biosynthesis and reducing power in the form of NADPH.

A key molecule in metabolism, serving as a branch point for various pathways like glycolysis, glycogen synthesis, and the pentose phosphate pathway.

The primary role of the pentose phosphate pathway in providing reducing power for various biosynthesis and redox regulation processes.