Metabolism, Nutrition, and Energy Production Overview

Metabolism

The sum of all the body's chemical reactions.

Catabolism

The phase of metabolism that breaks things down into smaller parts.

Anabolism

The phase of metabolism that synthesizes or builds larger compounds.

Exergonic

Reactions that release energy (catabolic). The product of these catabolic reactions have less energy than their reactants, thus releasing energy.

Endergonic

Reactions that require energy to proceed (anabolic). This happens because the reactants have less energy than the product and require the input of energy to proceed.

ATP

Adenosine triphosphate, the important energy provider for many physiological processes in our bodies.

Nutrients

Substances such as carbohydrates, lipids, and fats that are necessary for survival.

Metabolic pathways

Enzyme mediated reactions through which metabolism takes place.

Chemical bonds

Connections between atoms that are broken and formed during metabolic reactions.

Monomers

Small compounds that can be used by the cell in catabolic reactions.

Glucose

The fuel for cells in the body, especially in the brain and liver, produced from digested carbohydrates.

Fatty Acids

Products of lipid degradation (triglycerides) that are further catabolized by the body.

Amino Acids

Monomers produced from the breakdown of proteins in catabolic pathways.

Synthesis reactions

Reactions that convert a chemical into another chemical for cellular use.

Macromolecules

Large molecules such as proteins, complex carbohydrates, lipids, and nucleic acids that are assembled during metabolic processes.

Energy requirements

Considerations regarding the energy needed for metabolic reactions.

Law of conservation of energy

States that energy cannot be created or destroyed.

Catabolic Reaction

Reactions that release energy from the breakdown of nutrients such as glucose, fatty acids, and amino acids.

Catabolism

The breakdown of complex molecules to release energy.

Anabolism

The synthesis of complex molecules from simpler ones, requiring energy.

Endergonic Reaction

A reaction that requires energy input to proceed.

Exergonic Reaction

A reaction that releases energy.

ATP Synthesis

The process of forming ATP, which is endergonic and requires energy.

ATP Hydrolysis

The breakdown of ATP into ADP and a free phosphate group, releasing energy.

Phosphorylation

The addition of a phosphate group to a molecule, often mediated by an enzyme.

ATPase

An enzyme that catalyzes the hydrolysis of ATP.

Oxidation-Reduction Reaction

A chemical reaction where electrons are transferred between substances, involving oxidation and reduction.

OIL RIG

A mnemonic for remembering that Oxidation Is Losing electrons and Reduction Is Gaining electrons.

Glycolysis

The metabolic pathway that breaks down glucose into pyruvate, releasing energy.

Hydrolysis Reaction

A chemical reaction that involves the breaking of a bond in a molecule using water.

Electron Carriers

Molecules that transport electrons during cellular respiration.

Energy Efficiency of ATP Hydrolysis

The cell harnesses around 40% of the energy from ATP hydrolysis to perform work.

Cellular Work

Processes that require energy, such as muscle contraction and moving ribosomes.

Glucose Catabolism

The reaction that breaks down glucose to release energy for ATP synthesis.

ADP

Adenosine diphosphate, a product of ATP hydrolysis.

Phosphate Group

A functional group consisting of a phosphorus atom bonded to four oxygen atoms, released during ATP hydrolysis.

Chemical Energy

Energy stored in the bonds of chemical compounds, used by cells to perform work.

Nutrient Utilization

The process by which cells use nutrients to generate ATP.

Heat Loss in ATP Hydrolysis

The remaining energy from ATP hydrolysis that is not harnessed for work is lost as heat.

Cellular Processes

Biochemical activities within cells that require energy, such as metabolism and signaling.

Reactive Nature of ATP

ATP is reactive due to its unstable structure caused by negatively charged phosphate groups.

Citric Acid Cycle (Krebs Cycle)

Series of Reaction in the mitochondrial matrix break glucose down further to synthesize ATP.

Substrate-level Phosphorylation

Involves Transfer of a Phosphate Group (PO4-) directly to phosphate containing chemical compound (ex. ADP + p ----> ATP).

Oxidative Phosphorylation

Energy from flow of electrons during oxy-red reaction is harnessed in a process that generates ATP.

Inner Mitochondrial Membrane

Location where oxidative phosphorylation occurs.

Electron Transport Chain

Electrons stripped off glucose during glycolysis and citric acid cycle are transferred to electron carriers NADH and FADH2 which deliver them to this chain.

Glucose Catabolism

The process of breaking down glucose, which includes glycolysis.

Glycolysis

A series of 10 reactions that break down glucose and is mediated by enzymes.

Energy Investment Phase

The initial phase of glycolysis where ATP is used to phosphorylate glucose.

First Phosphorylation

Glucose is phosphorylated by ATP, yielding glucose-6-phosphate and ADP.

Second Phosphorylation

The carbon atoms in glucose-6-phosphate are rearranged and then phosphorylated by another ATP, resulting in fructose-1,6-bisphosphate and ADP.

Cleavage

The 6-carbon fructose-1,6-bisphosphate is split, forming two 3-carbon compounds.

Energy Payoff Phase

Phase of glycolysis where ATP is synthesized and NAD+ is reduced to NADH.

Oxidation

The two glyceraldehyde-3-phosphate molecules are phosphorylated and oxidized by NAD+ to produce NADH and 1,3-bisphosphoglycerate.

ATP Synthesis

The carbon atoms in the two 3-phosphoglycerate molecules are rearranged to form phosphoenolpyruvate, which donates a phosphate group to ADP yielding ATP and pyruvate.

Summary Yield of Glycolysis

Spent 2 ATP, Synthesized 4 ATP, Synthesized 2 NADH, split glucose into two three-carbon pyruvates.

Net Yield of Single Glucose Molecule

2 ATP and 2 NADH.

Intermediate Step: Fate of Pyruvate

Describes the outcomes of pyruvate under anaerobic and aerobic conditions.

Anaerobic Conditions

Pyruvate reduced to lactate when there is not enough oxygen.

Aerobic Conditions

Pyruvate moves into mitochondria, is oxidized, and enters the citric acid cycle.

Pyruvate Oxidation

In the presence of oxygen, pyruvates lose a carbon atom to become a molecule of acetate and a molecule of CO2.

Aerobic Conditions

When oxygen is present, two pyruvates enter the mitochondrial matrix for pyruvate oxidation.

Decarboxylation

The process where pyruvates lose a carbon atom to become a molecule of acetate and a molecule of CO2.

Acetyl-CoA

A molecule formed when acetate is oxidized by NAD+ and combined with coenzyme A.

Citric Acid Cycle

A series of 8 reactions that take place in the mitochondrial matrix, where oxidative glucose catabolism occurs.

Citrate Synthesis

The reaction where Acetyl-CoA combines with oxaloacetate to form citrate and CoA.

First Oxidation

Citrate is rearranged and oxidized by NAD+, generating CO2 and NADH.

ATP Synthesis

The conversion of Succinyl-CoA to succinate and CoA, while forming ATP.

Second Oxidation

Succinate is oxidized by FAD and NAD+, generating FADH2 and NADH, and is converted back to oxaloacetate.

Net Yield of Glucose Catabolism

10 NADH, 2 FADH2, and 4 ATP are produced after Glycolysis and the Krebs Cycle.

Oxidative Phosphorylation

The stage where the most ATP molecules are synthesized, consisting of three steps.

Electron Transport Chain (ETC)

A series of electron carriers contained within 4 large enzyme complexes (I-IV) embedded in the Inner mitochondrial membrane.

Electromotive Force (EMF)

The force generated in the ETC as electrons are transferred between electron carriers.

Proton Pump

Complex I uses the EMF to pump H+ into the intermembrane space against the concentration gradient.

H+ Concentration Gradient

A steep gradient established by pumping H+ from the mitochondrial matrix into the intermembrane space.

Complex IV

Transfers the electrons to oxygen, the final electron acceptor, to form H2O.

FADH2

An electron carrier generated during the second oxidation step of the Citric Acid Cycle.

NADH

An electron carrier generated during glycolysis, pyruvate oxidation, and the Krebs Cycle.

Succinate

A 4-carbon compound formed after the first oxidation of citrate.

Oxaloacetate

A 4-carbon molecule that combines with Acetyl-CoA to form citrate.

ATP

A molecule synthesized during the Citric Acid Cycle and oxidative phosphorylation.

Krebs Cycle

Another name for the Citric Acid Cycle, involved in glucose metabolism.

Glycolysis

The first step in glucose metabolism, occurring before the Krebs Cycle.

Oxygen Reduction

Oxygen is reduced and accepts electrons while combining with two hydrogen atoms to form water.

Water Formation Reaction

2 H+ + 2 e- + ½ O2 --> H2O

ATP Formation

ADP and P bind to ATP-synthase to form ATP.

ATP Synthase Function

The synthesis begins when ADP and P bind to enzyme ATP synthase, which unite them to ATP.

Release of ATP

ATP cannot be used by the cell until released from the enzyme.

Proton Motive Force

The electrochemical energy of the proton motive force spins a portion of the enzyme called the rotor.

Energy from Glucose Catabolism

The majority of energy harnessed from the oxidation of glucose is to create a hydrogen ion gradient.

Oxidative Phosphorylation Equation

C6H12O6 + 6 O2 ---> 6 H2O + 6 CO2 + 38 ATP + Heat.

ATP Yield from Glycolysis

ATP Synthesized - 2 From Glycolysis, 2 From Citric Acid Cycle, 34 Phosphorylation.

Substrate Level Phosphorylation

Can you identify the difference between substrate level phosphorylation and oxidative phosphorylation?

Glycolytic Catabolism

Do you know what glycolytic catabolism is and why it is called anaerobic catabolism?

Oxidative Catabolism

Are you able to describe oxidative catabolism and why it is called aerobic catabolism?

ATP in Glycolysis

Do you know how much ATP is expended during energy investment phase of glycolysis, and how much is generated during the energy payoff phase?

Fate of Pyruvate

Can you describe the fate of pyruvate under anaerobic conditions?

Citric Acid Cycle Products

Are you able to list the products generated by the Citric Acid Cycle for each glucose?

Role of Oxygen

Do you know the role of oxygen in glucose catabolism?

Fatty Acid and Amino Acid Catabolism

Much like glucose catabolism, cells can catabolize fatty acids and amino acids.