Chapter 3 - Easy level - Cellular Metabolism and Biochemical Reactions Quiz

Biochemistry Review Questions and Answers

• Ribose-5-phosphate serves as the precursor for both purine and pyrimidine nucleotide synthesis, providing the sugar component of the nucleotides.
• Nitrogen fixation is the process that converts atmospheric nitrogen (N2) into ammonia (NH3), which can then be incorporated into organic compounds.
• Fatty acid synthesis primarily occurs in the cytosol of cells.
• The formation of peptide bonds during protein synthesis is energetically driven by the hydrolysis of GTP.
• Antimetabolites like 6-mercaptopurine work by inhibiting nucleic acid synthesis, thereby preventing cancer cell proliferation.
• Pyruvate is the end product of glycolysis, while glucose-6-phosphate and fructose-1,6-bisphosphate are intermediates in glycolysis.
• Rubisco catalyzes the conversion of CO2 to 3-phosphoglycerate in the Calvin cycle.
• Glutamate is directly synthesized from the citric acid cycle intermediate α-ketoglutarate.
• Oxygen is the final electron acceptor in the mitochondrial electron transport chain, forming water.
• In animal cells, glucose is stored in the form of glycogen.
• Fatty acid synthesis primarily occurs in the cytosol of eukaryotic cells, while NADP+ acts as the final electron acceptor in the light reactions of photosynthesis, where it is reduced to NADPH.

Biochemistry Review Questions

• Glycolysis involves the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, catalyzed by Phosphofructokinase.
• Nitrogen fixation is the conversion of atmospheric nitrogen (N2) to ammonia (NH3) in the nitrogen cycle.
• Protein synthesis is driven by the hydrolysis of two GTP molecules for the addition of each amino acid to the growing polypeptide chain.
• The carbon and nitrogen atoms of the purine ring in purine nucleotides are derived from both glucose and amino acids.
• The regeneration of Ribulose-1,5-bisphosphate (RuBP) in the Calvin cycle requires ATP only.
• DNA polymerase is responsible for catalyzing the addition of nucleotides during DNA synthesis.
• 6-mercaptopurine's effectiveness in cancer treatment is due to its ability to inhibit nucleic acid synthesis.
• The synthesis of the non-essential amino acid alanine from pyruvate requires amination, the addition of an amino group.
• Photosystem II's primary function in photosynthesis is to generate a proton gradient for ATP synthesis.
• The conversion of two molecules of pyruvate to one molecule of glucose in gluconeogenesis requires 6 ATP molecules.
• In polysaccharide synthesis, glucose-1-phosphate reacts with UTP to form UDP-glucose, an activated glucose intermediate.
• In the biosynthesis of fatty acids, the addition of each two-carbon unit requires two molecules of NADPH.

Cellular Metabolism and Biochemical Reactions Overview

• Chemiosmotic coupling is the process of ATP generation via proton gradients across membranes, proposed by Peter Mitchell.
• Photosynthesis is the process in which plants convert light energy into chemical energy through biochemical reactions involving light absorption, electron transport, and ATP generation.
• The biosynthesis of cell constituents includes gluconeogenesis, glycolysis, lipid synthesis, protein and amino acid synthesis, and nucleic acid synthesis pathways.
• Key experiments related to cellular metabolism cover the chemiosmotic theory, antimetabolites in cancer therapy, and biological aspects and treatment approaches for AIDS.
• ATP is the primary molecule used by cells as a source of metabolic energy, distinguishing it from glucose, NADH, and pyruvate.
• Glycolysis produces a net gain of 2 ATP molecules per molecule of glucose, not 4, 8, or 36.
• The first law of thermodynamics in biological systems exemplifies the conversion of chemical energy to mechanical energy.
• Chemiosmotic coupling in cellular respiration describes the generation of ATP through proton gradients, not direct ATP synthesis from glucose, electron transfer, or glucose breakdown.
• Gibbs free energy in biological systems predicts the direction of biochemical reactions, not the rate of enzymatic reactions, entropy change, or total energy.
• The primary outcome of the citric acid cycle in cellular metabolism is the production of ATP, NADH, and FADH2, not the synthesis of glucose, conversion of ATP to ADP, or breakdown of amino acids.
• Photosynthesis is the process that converts light energy into chemical energy in plants, not glycolysis, oxidative phosphorylation, or the Krebs cycle.
• Gluconeogenesis involves synthesizing glucose from amino acids and glycerol, not fatty acids.
• Oxygen is the final electron acceptor in the electron transport chain during aerobic respiration, crucial for the generation of water as a byproduct and the continuation of the electron transport chain.