Metabolism and energyWhat are catabolic vs anabolic pathways, catabolism, and anabolism? What are metabolic pathways? How are metabolic pathways controlled? Metabolism is the general pathwayss for all chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments.
Overview of metabolism (article) | Khan Academy
What are metabolism, catabolism, and anabolism? What are metabolic pathways? How are metabolic pathways controlled? Metabolism is the general term for all chemical reactions that happen in the cells of living organisms to sustain life.
These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism can be divided into two general types of reactions.
Catabolism is all of the chemical reactions that break down molecules, either to extract energy or to produce simple molecules for constructing others. Anabolism refers to all of the metabolic reactions that build or assemble more complex molecules from simpler ones. Catabolism and anabolism are intimately connected, and one really cannot occur without the other. For example, when you eat protein say, in an egg at breakfast , enzymes in the stomach and intestines will digest the protein to release individual amino acids.
The chemical reactions that convert the large protein molecule into simpler amino acids are all catabolic reactions. The amino acids are absorbed from the intestine, and go through the portal vein to the liver.
Liver cells absorb amino acids and use them to synthesize new proteins that are released into the blood. The chemical reactions by which the liver cells make new proteins are anabolic reactions. Other cells in the body can take up those proteins from blood, and break them down again into amino acids catabolism which they use to make their own specialized proteins or other molecules anabolism.
Working together these processes of metabolism keep cells alive and functioning. The chemical reactions of metabolism do not happen randomly. They are organized into metabolic pathways, in which one molecule is converted through a series of steps into another molecule.
The figure below is an example of a metabolic pathway. The purple arrow shows the metabolic pathway called glycolysis, which converts glucose into pyruvate, producing ATP. Glycolysis is a catabolic pathway, and all life depends on it. It is the central metabolic pathway, and will be explored further in another branch. Metabolic pathways are interconnected.
Cells use molecules produced in one pathway to make others. The figure below shows some of the many reactions that eukaryotic cells use to maintain life. Do not try to learn all the pieces of information; that is not why this this diagram was included.
Rather, look at how the different molecules are arranged into pathways. Each pathway either breaks down molecules catabolism or produces one or more molecules that are essential for life anabolism. Also look at how all the pathways branch off from glycolysis. Some molecules have several paths coming into and going out from them. Look at glyceraldehydephosphate GAD-3P , in the center of the figure. Each step in a metabolic pathway will be catalyzed by an enzyme. These enzymes are crucial to metabolism for several reasons.
Enzymes also let cells regulate metabolic pathways in response to changes in the environment or signals from other cells. Every metabolic pathway will have at least one rate-limiting enzyme. If that enzyme is missing, the entire pathway stops. Cells can control the activity of the entire pathway by:.
Many diseases are the result of defective metabolism. You will learn about many of them as you explore other Leaves and Branches. After studying the materials in this leaf, you should be able to:. What are the chemical reactions that break down molecules called?
How do cells obtain energy from molecules other than glucose? How do inhibitors block the function of enzymes? Why is water so important to life? Why is osmosis so important in biology? How do the light-independent reactions make glucose and other carbohydrates? Why is glycolysis called the basic metabolic pathway of life? What is a catalyst? What molecules and macromolecules are essential for all life?
Daniel Johnson, Jessica Blackburn. What is the difference between metabolism, catabolism, and anabolism? This video is a silly mnemonic about catabolism and anabolism that will hopefully help you remember them. Was this page helpful? Click to show correct answer Protein biosynthesis: How are all the molecules of life produced from a small number of elements? About BioBook Learn More.