energy and metabolism

bioenergetic

• The study of energy transformations in organisms 

metabolism

refers to the sum of all chemical reactions occurring within an organism or cell.

enzyme

Each step of metabolism is generally catalyzed by a specific

catabolism

break down complex molecules into simpler molecules

catabolism

These reactions generally: 

• Break chemical bonds

 • Release energy 

• Often transfer energy to ATP and electron carriers

 • Convert large molecules into smaller molecules 

catabolism

Digestion of food

c o a

catabolism

Breakdown of glycogen into glucose

catabolism

Cellular respiration

catabolism

Breakdown of fats into fatty acids and glycerol

ATP

Energy released during this process (catabolism) is captured, primarily in the form of

Anabolism

-construct complex molecules from simpler molecules 

anabolism

These reactions generally:

• Require an input of energy

• Build new chemical bonds

• Produce larger and more complex molecules

• Support growth, repair, and storage

anabolism

Protein synthesis from amino acids

c o a

anabolism

Glycogen synthesis from glucose

c o a

anabolism

DNA synthesis from nucleotides

c o a

anabolism

Fat synthesis from fatty acids and glycerol

c o a

anabolism

Photosynthesis, which synthesizes organic molecules using energy from sunlight

c o a

energy

the capacity to cause change or perform work

catabolic reaction

→ release energy → energy captured in ATP → ATP provides energy for 

anabolic reaction

Thus, that supplies much of the energy needed for this 

kinetic energy

the energy associated with motion 

thermal energy

 a form of kinetic energy associated with the random movement of atoms and molecules 

potential energy

stored energy resulting from an object's location or structure 

chemical energy

potential energy stored in chemical bonds 

first law of thermodynamics

Energy cannot be created or destroyed; it can only be transferred or transformed.

second law of thermodynamics

Every energy transfer or transformation increases the entropy of the universe.

entropy

• often described as a measure of disorder or randomness, although it is more accurately related to the dispersal of energy 

spontaneous process

• can occur without requiring an external input of energy. This does not necessarily mean that the reaction occurs rapidly 

Nonspontaneous process

• requires an input of energy 

ATP

Cells accomplish many nonspontaneous processes by coupling them with energy-releasing reactions. The major energy-coupling molecule in cells is

Free energy

•  the portion of a system's energy that can perform work under the conditions found in living cells 

exergonic reactions

•  releases free energy 

exergonic reactions

General form Reactants → Products + Energy 

endergonic reactions

is a specific type of non-spontaneous reaction that absorbs free energy from its surroundings

endergonic reactions

General form Reactants + Energy → Products