Energy and Metabolism
,The Energy of Life
• The living cell generates thousands of different reactions
• Metabolism
• Is the totality of an organism’s chemical reactions
• Arises from interactions between molecules
• An organism’s metabolism transforms matter and
energy, subject to the laws of thermodynamics
,Metabolic Pathways
• Biochemical pathways are the organizational units of metabolism
• Metabolism is the total of all chemical reactions carried out by an organism
• A metabolic pathway has many steps that begin with a specific molecule and
end with a product, each catalyzed by a specific enzyme
• Reactions that join small molecules together to form larger, more complex
molecules are called anabolic.
• Reactions that break large molecules down into smaller subunits are called
catabolic.
Enzyme 1 Enzyme 2 Enzyme 3
A B C D
Reaction 1 Reaction 2 Reaction 3
Starting Product
molecule
, Metabolic Pathway
• A sequence of chemical reactions, where the product of one
reaction serves as a substrate for the next, is called a metabolic
pathway or biochemical pathway
• Most metabolic pathways take place in specific regions of the cell.
,The Energy of Life
• The living cell generates thousands of different reactions
• Metabolism
• Is the totality of an organism’s chemical reactions
• Arises from interactions between molecules
• An organism’s metabolism transforms matter and
energy, subject to the laws of thermodynamics
,Metabolic Pathways
• Biochemical pathways are the organizational units of metabolism
• Metabolism is the total of all chemical reactions carried out by an organism
• A metabolic pathway has many steps that begin with a specific molecule and
end with a product, each catalyzed by a specific enzyme
• Reactions that join small molecules together to form larger, more complex
molecules are called anabolic.
• Reactions that break large molecules down into smaller subunits are called
catabolic.
Enzyme 1 Enzyme 2 Enzyme 3
A B C D
Reaction 1 Reaction 2 Reaction 3
Starting Product
molecule
, Metabolic Pathway
• A sequence of chemical reactions, where the product of one
reaction serves as a substrate for the next, is called a metabolic
pathway or biochemical pathway
• Most metabolic pathways take place in specific regions of the cell.
