Metabolism

Laws of Thermodynamics

The transfer and transformation of thermal energy

First Law

Energy cannot be created or destroyed, but it can be transformed from one type into another

Energy cannot be created or destroyed, but it can be transformed from one type into another

Example:
-atoms have potential energy
-when atoms form a bond, potential energy is transformed into thermal energy

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Second Law

During any process, the universe tends toward disorder (law pertains to the transformation of potential energy into heat or m

During any process, the universe tends toward disorder
(law pertains to the transformation of potential energy into heat or molecular motion)

Example:
-more likely a stack of books will tumble over than arrange themselves to form a stack

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Thermodynamics and Metabolism

ATP
(Energy of the cell)

Composed of:
Nitrogenous base Adenine
Ribose sugar
Three Phosphate Groups

Phosphates are negative

Releases energy when hydrolyzed

ADP is released when 1 bond is broken

Electron Carriers

Compounds that pick up electrons from energy-rich compounds and donate them to low-energy compounds

Example:
NAD⁺ (oxidized form), NADH (reduced form)
FAD (oxidized form), FADH₂ (reduced form)

Redox reactions are coupled reactions

Reduced molecules (gained electrons) have higher energy levels compared to oxidized molecules

Types of Energy

Kinetic Energy

Energy of motion (moving objects perform work by causing other matter to move)

Potential Energy

Stored energy (energy that is available but not yet released)

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Bond Energy

Energy required to break (or form) a chemical bond

Exothermic Reaction:
a reaction accompanied by the release of energy in the form of heat

Example:
-cellular respiration

Endothermic Reaction:
a reaction or process accompanied by or requiring the absorption of energy in the form of heat

Example:
-photosynthesis

2 Types of Energy

Anabolism

Using energy to build large molecules

Catabolism

Breaking down compounds into smaller molecules to release energy

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Anabolic reactions are endothermic because it takes in energy within the reaction and uses it. It builds larger molecules from smaller ones and absorbs energy from the surroundings of heat.

Catabolic reactions are exothermic because the energy is released. Large molecules are broken down into smaller ones releasing energy in the form of heat.