METABOLISM

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Questions and Answers

What is the definition of metabolism?

Metabolism refers to all processes through which living systems acquire and utilize free energy to carry out their various functions, by coupling exergonic reactions to endergonic processes.

Living organisms exist in a state of equilibrium.

False

What are the two main phases of metabolism?

Catabolism and anabolism.

Which of the following processes are considered endergonic processes? (Select all that apply)

Active transport of molecules against concentration gradients Signup and view all the answers

The energy produced during is utilized during to synthesize complex molecules.

catabolism, anabolism Signup and view all the answers

Which of the following molecules can be used as fuel in catabolism? (Select all that apply)

Fats Signup and view all the answers

What is the name of the process that converts glucose into pyruvate?

Glycolysis. Signup and view all the answers

What is the primary product of glycolysis?

Pyruvate. Signup and view all the answers

Glycolysis requires oxygen.

False Signup and view all the answers

Which of the following statements are true about glycolysis? (Select all that apply)

It breaks down complex molecules into simpler ones. Signup and view all the answers

Match the following terms with their correct definitions:

Catabolism = The breakdown of complex molecules into simpler ones, releasing energy Anabolism = The synthesis of complex molecules from simpler ones, requiring energy Glycolysis = The breakdown of glucose into pyruvate, generating ATP and NADH Citric acid cycle = A series of chemical reactions that oxidizes acetyl-CoA, generating ATP, NADH, and FADH2 Electron transport chain = A series of protein complexes that transfer electrons from NADH and FADH2 to oxygen, generating a proton gradient that drives ATP synthesis Signup and view all the answers

What is the role of the citric acid cycle in cellular metabolism?

The citric acid cycle oxidizes acetyl-CoA, which is derived from the breakdown of carbohydrates, fats, and proteins, generating ATP, NADH, and FADH2, which are crucial for energy production. Signup and view all the answers

The citric acid cycle requires oxygen.

True Signup and view all the answers

Where does the citric acid cycle take place?

Mitochondria. Signup and view all the answers

The electron transport chain generates the majority of ATP produced during cellular respiration.

True Signup and view all the answers

What is the role of NADH in cellular respiration?

It donates electrons to O2 to generate energy. Signup and view all the answers

During one complete turn of the citric acid cycle, which of the following is produced?

Three NADH, one FADH2, and one GTP Signup and view all the answers

What is the main purpose of exergonic reactions in living organisms?

To provide energy for endergonic processes. Signup and view all the answers

How does the active transport of molecules function in living systems?

It allows movement against concentration gradients using energy. Signup and view all the answers

What do living organisms require to maintain order in their systems?

A continuous influx of free energy. Signup and view all the answers

Which statement best describes the conditions under which metabolic reactions occur?

Most reactions are reversible and can fluctuate. Signup and view all the answers

What happens to the products of glycolysis during cellular respiration?

They undergo further oxidation and ATP synthesis. Signup and view all the answers

Study Notes

SEEC-101 Module 8 - Metabolism

Living organisms are not in equilibrium
They require a continuous influx of free energy to maintain order in a universe that maximizes disorder

Key Metabolic Questions

How does a cell extract energy and reducing power from its environment?
How does a cell synthesize the building blocks of macromolecules and the macromolecules themselves?

Metabolism Definition

Metabolism is the process by which living systems acquire and utilize free energy to carry out various functions
This is achieved by coupling exergonic reactions of nutrient oxidation to endergonic processes needed to maintain life
Examples of endergonic processes include:
- performance of mechanical work
- active transport of molecules against concentration gradients
- biosynthesis of complex molecules

Metabolic pathways are complex networks of chemical reactions within cells that convert nutrients into energy and synthesize biomolecules. They enable organisms to adapt energy use based on resources and environmental conditions. Categorized by the type of molecule processed, these interconnected pathways highlight the efficiency of cellular metabolism.

The diagram effectively showcases the intricate and highly organized network of metabolic pathways that encompasses the transformation and utilization of various biomolecules, including carbohydrates, lipids, and amino acids, revealing how these pathways interact and contribute to cellular function and energy production. The pathways include metabolism of complex carbohydrates, complex lipids, carbohydrates, lipids, amino acids, cofactors, vitamins, nucleotides, and other substances.

Catabolism and Anabolism

Catabolism is the breakdown of fuel (carbohydrates, fats) to produce CO2, H2O, and usable energy.
Anabolism uses energy from catabolism to build complex molecules from simpler precursors.

Glycolysis

Glucose is a central molecule for energy production
It can be broken down via oxidation pathways (pentose phosphate pathway and glycolysis) or stored as glycogen, starch, or sucrose
Glycolysis is a pathway that converts glucose to pyruvate, yielding a small amount of ATP
The accompanying diagram shows the steps and intermediates in glycolysis, including glucose 6-phosphate, fructose 6-phosphate, fructose 1,6-bisphosphate, triose phosphate isomerase, dihydroxyacetone phosphate, Glyceraldehyde 3-phosphate, 1,3-Bisphosphoglycerate, 3-Phosphoglycerate, 2-Phosphoglycerate, Phosphoenolpyruvate, and Pyruvate. Glycolysis also involves enzymes such as hexokinase, phosphofructokinase, aldolase, triose phosphate isomerase, glyceraldehyde 3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglycerate mutase, enolase, and pyruvate kinase.

Payoff Phase of Glycolysis

This phase of glycolysis produces ATP and NADH.

Citric Acid Cycle (Krebs Cycle)

This cycle further oxidizes acetyl-CoA to generate ATP, NADH, and FADH2.
The cycle includes many steps employing various enzymes and coenzymes for energy production. These molecules include oxaloacetate, citrate, isocitrate, a-ketoglutarate, succinyl-CoA, succinate, fumarate, and malate. Enzymes involved include citrate synthase, isocitrate dehydrogenase, a-ketoglutarate dehydrogenase, succinyl-CoA synthetase, succinate dehydrogenase, fumarase, and malate dehydrogenase.
The diagram highlights the steps in the cycle.

Electron Transfer

Electron transfer from NADH and FADH2 to oxygen in the mitochondria provides energy for ATP synthesis via oxidative phosphorylation.
This process involves the respiratory complex and generates a significant amount of ATP.