AP Bio Unit 3

Describe the role of energy in biological processes.

Energy is the capacity to do work and is required for life processes.

Define metabolism in the context of living organisms.

Metabolism encompasses all chemical reactions involved in maintaining the living state of cells and organisms.

Explain the difference between autotrophs and heterotrophs.

Autotrophs produce complex organic compounds from simple inorganic molecules using light or chemical energy, while heterotrophs utilize organic compounds produced by other organisms for energy and building materials.

What is bioenergetics and what does it study?

Bioenergetics is the study of how organisms manage their energy resources, including the storage, transfer, and utilization of energy.

How do the laws of thermodynamics apply to biological systems?

The first law states that energy cannot be created or destroyed, only transformed, while the second law states that every energy transfer increases the entropy of the universe.

List the various forms of energy that exist in biological systems.

Energy exists in forms such as chemical, electrical, light, mechanical, and thermal energy.

Define potential energy and provide examples.

Potential energy is stored energy due to an object's position or chemical composition, such as chemical bonds and water behind a dam.

What is kinetic energy and give examples of it.

Kinetic energy is the energy of motion, with examples including light, heat, and a flowing river.

Explain the significance of chemical reactions in energy transformation.

Chemical reactions involve the making and breaking of chemical bonds, which absorb or release energy.

Differentiate between exergonic and endergonic reactions.

Exergonic reactions release energy and are spontaneous, while endergonic reactions require an input of energy to proceed and are non-spontaneous.

Provide examples of exergonic reactions.

Examples of exergonic reactions include cellular respiration and the breakdown of glucose.

What are endergonic reactions and provide examples

Endergonic reactions require an input of energy to proceed; examples include photosynthesis and the synthesis of proteins.

Describe how coupled reactions function in cellular processes.

Coupled reactions link endergonic and exergonic reactions, allowing cells to perform necessary endergonic reactions by utilizing the energy released from exergonic reactions.

Describe the structure of ATP.

ATP consists of an adenosine molecule bonded to three phosphate groups.

Explain the significance of the high-energy bonds in ATP.

The high-energy bonds between the phosphate groups store a significant amount of potential energy.

How is ATP produced in cells?

ATP is produced through substrate-level phosphorylation, oxidative phosphorylation, and photophosphorylation.

What happens during the hydrolysis of ATP?

Hydrolysis of ATP to ADP and inorganic phosphate releases energy for cellular work.

Define the ATP/ADP cycle.

The ATP/ADP cycle allows for the efficient storage, transfer, and utilization of energy in biological systems.

List some cellular processes powered by ATP.

ATP powers processes such as synthesis of complex molecules, active transport of molecules, muscle contraction, and nerve impulse transmission.

Describe the role of enzymes in biochemical reactions.

Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process.

How do enzymes affect activation energy?

Enzymes lower the activation energy required for a reaction to occur, making it more likely to happen under cellular conditions.

What determines the function of an enzyme?

The specific three-dimensional structure of an enzyme determines its function.

Explain the concept of the active site in enzymes.

The active site of an enzyme is a specific region where the substrate binds and the reaction occurs.

How specific are enzymes in their function?

Enzymes are highly specific, often recognizing only one substrate or a small group of related substrates.

What factors influence enzyme activity?

Enzyme activity is influenced by temperature, pH, and substrate concentration.

Describe the optimal conditions for enzyme activity.

Optimal conditions allow for maximum enzyme activity.

What is allosteric regulation in enzymes?

Allosteric regulation is when the binding of a molecule at a site other than the active site alters enzyme activity.

Describe competitive inhibition in enzyme activity.

Competitive inhibition occurs when a molecule similar to the substrate binds to the active site of an enzyme, preventing the actual substrate from binding.

Explain feedback inhibition in metabolic pathways.

Feedback inhibition is a regulatory mechanism where the end product of a metabolic pathway inhibits an earlier enzyme in the pathway, thus controlling the production of the product.

Define cellular respiration.

Cellular respiration is the process by which cells break down organic molecules to release energy in the form of ATP.

How is glucose utilized in cellular respiration?

Glucose is the most common substrate for cellular respiration, but other organic molecules like fatty acids and amino acids can also be used.

List the three main stages of cellular

respiration.

The three main stages of cellular respiration are glycolysis, the citric acid cycle, and the electron transport chain.

Describe the process of glycolysis.

Glycolysis takes place in the cytosol and partially breaks down glucose into two pyruvate molecules, producing a small amount of ATP and NADH.

Explain the citric acid cycle's role in cellular respiration.

The citric acid cycle occurs in the mitochondrial matrix and completely oxidizes pyruvate, generating CO2, NADH, FADH2, and a small amount of ATP.

How does the electron transport chain contribute to ATP production?

The electron transport chain generates the majority of ATP through oxidative phosphorylation, using electrons from NADH and FADH2 to create a proton gradient.

Describe the function of ATP synthase in cellular respiration.

ATP synthase uses the proton gradient created by the electron transport chain to drive the synthesis of ATP.

What is the overall equation for the complete oxidation of glucose in cellular respiration?

The overall equation is C6H12O6 + 6O2 →6CO2 + 6H2O + energy (ATP).

Define the two phases of glycolysis.

Glycolysis has two phases: the preparatory phase, which consumes 2 ATP to convert glucose into fructose-1,6-bisphosphate, and the payoff phase, which splits fructose-1,6-bisphosphate into two three carbon molecules, generating 4 ATP and 2 NADH.

Explain the preparatory phase of glycolysis.

The preparatory phase of glycolysis consumes 2 ATP to convert glucose into fructose-1,6-bisphosphate.

Describe the payoff phase of glycolysis.

The payoff phase of glycolysis splits fructose 1,6-bisphosphate into two three-carbon molecules, which are then oxidized to form pyruvate, generating 4 ATP and 2 NADH

Describe the net yield of glycolysis per glucose molecule.

The net yield of glycolysis per glucose molecule is 2 ATP and 2 NADH.

Explain the role of fermentation under anaerobic conditions.

Fermentation regenerates NAD+ from NADH, allowing glycolysis to continue in the absence of oxygen.

Define lactic acid fermentation and its occurrence.

Lactic acid fermentation occurs in exercising muscle cells when oxygen demand exceeds supply, leading to muscle fatigue and soreness.

How is pyruvate converted before entering the citric acid cycle?

Pyruvate is converted into acetyl-CoA by the pyruvate dehydrogenase complex before entering the citric acid cycle.

What is the first compound formed in the citric acid cycle?

The first compound formed in the citric acid cycle is citrate, which is created when acetylCoA combines with oxaloacetate.

Explain the net yield of one turn of the citric acid cycle.

The net yield of one turn of the citric acid cycle is 2 CO2, 3 NADH, 1 FADH2, and 1 ATP (or GTP) per acetyl-CoA molecule.

Describe the function of NADH and FADH2 produced in the citric acid cycle.

NADH and FADH2 produced in the citric acid cycle are used in the electron transport chain to generate more ATP.

What is the location of the electron transport chain in cellular respiration?

The electron transport chain consists of a

series of protein complexes and mobile

electron carriers that facilitate the transfer of

electrons from NADH and FADH2.`

The electron transport chain is located in the inner mitochondrial membrane.

How does the electron transport chain function?

The electron transport chain consists of a series of protein complexes and mobile electron carriers that facilitate the transfer of electrons from NADH and FADH2.`

Define the citric acid cycle and its alternative names.

The citric acid cycle is also known as the Krebs cycle or tricarboxylic acid (TCA) cycle, and it is the second stage of cellular respiration.

Explain the significance of the citric acid cycle in metabolism.

The citric acid cycle is a central metabolic hub, with intermediates being used for the synthesis of amino acids, nucleotides, and other important biomolecules.

What happens to citrate during the citric acid

cycle?

Citrate is oxidized through a series of eight enzyme-catalyzed reactions, releasing CO2 and generating NADH, FADH2, and a small amount of ATP.

Describe the role of NADH and FADH2 in the electron transport chain (ETC).

NADH donates electrons to Complex I, while FADH2 donates electrons to Complex II in the ETC.

Explain how the proton gradient is created during the electron transport chain process.

As electrons move through the complexes of the ETC, protons (H+) are pumped from the mitochondrial matrix into the intermembrane space, creating an electrochemical gradient.

How does ATP synthase utilize the proton gradient for ATP synthesis?

Protons flow back into the mitochondrial matrix through ATP synthase, causing it to rotate and catalyze the formation of ATP from ADP and inorganic phosphate (Pi).

Define the final electron acceptor in the electron transport chain and its significance.

Oxygen serves as the final electron acceptor in the ETC, combining with protons to form water, which is crucial for maintaining the flow of electrons through the chain.

What is the efficiency of the electron transport chain and oxidative phosphorylation in ATP production?

The ETC and oxidative phosphorylation are highly efficient, generating approximately 34 ATP per glucose molecule, assuming 2.5 ATP per NADH and 1.5 ATP per FADH2.

Describe the process of chemiosmosis in relation to ATP synthesis.

Chemiosmosis is the process by which the proton gradient generated during the ETC is utilized for ATP synthesis through ATP synthase.

Explain the regulation of the electron transport chain and oxidative phosphorylation.

The ETC and oxidative phosphorylation are tightly regulated to maintain cellular energy balance and prevent the formation of harmful reactive oxygen species (ROS).