Bioenergetics and ATP Production Quiz

Bioenergetics is the branch of science that studies the transfer and utilization of energy in biological systems.

A positive ΔG indicates a reaction requires energy input to proceed. This is a non-spontaneous, endergonic reaction.

A negative ΔG indicates a reaction releases energy, making it spontaneous and exergonic. It can occur without external energy input.

ATP is the primary energy currency of cells. When hydrolyzed, it releases energy for cellular processes.

Substrate-level phosphorylation directly transfers a phosphate group from a substrate molecule to ADP, producing ATP. Occurs in glycolysis.

Oxidative phosphorylation uses an electron transport chain to generate ATP from ADP through the oxidation of electron carriers like NADH and FADH2. It occurs in the mitochondria.

Glycolysis is the breakdown of glucose into pyruvate, generating ATP and NADH. It occurs in the cytoplasm.

Gluconeogenesis is the synthesis of glucose from non-carbohydrate sources like pyruvate or amino acids. It's the reverse of glycolysis.

The pentose phosphate pathway produces NADPH and ribose 5-phosphate, a precursor for DNA and RNA synthesis, from glucose.

Glycogenolysis is the breakdown of glycogen, a stored form of glucose, into glucose. It releases glucose for energy use.

Glycogenesis is the synthesis of glycogen from glucose. It stores glucose as glycogen in the liver and muscles.

The citric acid cycle (TCA cycle) is a series of reactions that generates ATP, NADH, and FADH2 by oxidizing acetyl-CoA derived from pyruvate.

The electron transport chain (ETC) uses electrons from NADH and FADH2 to generate a proton gradient across the mitochondrial membrane, driving ATP synthesis through oxidative phosphorylation.

The pyruvate dehydrogenase complex converts pyruvate into acetyl-CoA, a key molecule for entering the TCA cycle. This is a crucial link between glycolysis and the TCA cycle.

Regulation of metabolism involves complex mechanisms to fine-tune the rates of metabolic pathways ensuring balance between energy production and use, and resource allocation.

A branched-chain polymer of glucose that serves as a major energy storage form in animals.

The process of breaking down glycogen into glucose, primarily in the liver and skeletal muscles.

The synthesis of glycogen from glucose, primarily in the liver and skeletal muscles.

A metabolic pathway in the cytoplasm of cells that generates NADPH and the precursor for nucleotide biosynthesis, ribose-5-phosphate.

The main products of the oxidative reactions of the Pentose Phosphate Pathway are NADPH and ribulose 5-phosphate.

The non-oxidative reactions of the PPP interconvert sugars, generating glycolytic intermediates and ribose 5-phosphate for nucleotide biosynthesis.

The enzyme responsible for forming glycosidic bonds to create the branching structure of glycogen.

The enzyme that breaks down glycogen, releasing glucose 1-phosphate.

NADH and FADH2 are electron carriers that deliver electrons to the ETC. They get produced during different metabolic processes like glycolysis, pyruvate oxidation, and the citric acid cycle (TCA cycle).

The ETC consists of four major protein complexes (I, II, III, IV). Electrons flow from complex I (NADH) or complex II (FADH2) to complex III, then to complex IV. This flow powers the pumping of protons across the inner mitochondrial membrane.

The number of protons pumped across the membrane depends on the electron carrier. NADH pumps three protons, while FADH2 pumps two. This difference reflects the energy levels of these carriers.

The proton gradient created by the ETC drives the synthesis of ATP via ATP synthase. ATP synthase is an enzyme that uses the energy stored in the proton gradient to generate ATP, the energy currency of the cell.

The malate-aspartate shuttle is one mechanism for transferring NADH from the cytoplasm (where glycolysis occurs) to the mitochondria (where the ETC takes place). It involves a series of reactions that regenerate NADH inside the mitochondria.

The glycerol 3-phosphate shuttle is another mechanism for transferring NADH from the cytoplasm to the mitochondria. However, this shuttle converts NADH to FADH2 inside the mitochondria, resulting in a slightly lower ATP yield.

The total ATP yield from the complete oxidation of one glucose molecule is estimated to be 36 or 38 ATP. This number depends on the shuttle used to transport cytoplasmic NADH to the mitochondria (malate-aspartate shuttle generates slightly more ATP).

Glycogen is a storage form of glucose found in the liver and muscles. It is rapidly mobilized when blood glucose levels drop, providing a readily available energy source.