Chemical Reactions
Process that changes set of chemicals into another set of chemicals
Reactants yields
Products
6CO2 + 6H20  C6H12O6 + 6O2
Slow
Fast
Metabolism:
Chemical processes occurring within a living cell necessary to maintenance life
Catabolism - Breaking Down molecules
Anabolism – Building Molecules
Reaction Energy
• Energy is Released when chemical bonds Break
• Energy is Absorbed when chemical bonds Form
• Reactions that release energy
Spontaneous
• Reactions that require energy
Non Spontaneous
Energy requirements in chemical reactions
Energy-Releasing Reaction
Burning a Log
C6H12O6 → CO2 + H2O
Activation energy
Reactants
Products
Enzymes
• Chemical reactions in the human body require
energy
• Enzymes serve as a CATALYST
• Speed up reactions that take place in cells
a lot of
Reaction using Enzyme
Candy Bar
Reaction pathway
without enzyme
Reactants
Reaction pathway
with enzyme
Activation energy
without enzyme
Activation
energy
with enzyme
Products
Chapter 02D.mpg
CARBOHYDRATES
Characteristics of Carbohydrates
• Consist of carbon, hydrogen, & oxygen
• Energy containing molecules
• Some provide structure: Celulose
• Basic building block is a monosaccharide (CH2O)n ; n = 3,5,6
• Two monosaccharides form a disaccharide
Three Monosaccharides
C6H12O6
Dehydration Synthesis
of a Disaccharide
Formation of Disaccharides
Hydrolysis of a Disaccharide
Important Polysaccharides: Starch
• Consists of glucose
subunits
• Plant energy
storage molecule
• Glycogen is a very
similar molecule in
animals.
• Starch and glycogen
can be digested by
animals.
Important Polysaccharides: Cellulose
• Composed of glucose
subunits
• Different bond
formed than starch
• Structural component
in plants
• Cannot be digested
by animals
LIPIDS
Characteristics of Lipids
• Composed of:
Carbon, Hydrogen, and Oxygen
• Includes:
Fats, Oils, Phospholipids, and Cholesterol
• Phospholipids part of cell membrane
• Building blocks:
• Fatty Acids and Glycerol.
• Energy storage molecules
Fatty Acid Structure
•Carboxyl group (COOH) forms the acid.
•“R” group is a hydrocarbon chain.
A Representative Fatty Acid
Unsaturated
Fatty Acid
Saturated
Fatty Acid
Glycerol
Synthesis of a Fat
A Phospholipid
PROTEINS
Characteristics of Proteins
• Contain:
• Carbon, Hydrogen, Oxygen, Nitrogen, sulfur
• Function:
• Structural components of animals
• Control molecules (enzymes)
• Transport and messenger molecules
• Basic building block is the amino acid
Amino Acid
• Amine group acts like a base, tends to be positive.
• Carboxyl group acts like an acid, tends to be negative.
• “R” group is variable, from 1 atom to 20.
• Two amino acids join together to form a dipeptide.
• Adjacent carboxyl and amino groups bond together.
Some Amino Acids
Some More Amino Acids
Still More Amino Acids
Formation of a Dipeptide
Dehydration synthesis
Amino Acid + Amino Acid --> Dipeptide
Amino Acid + Dipeptide --> Tripeptide
A.A. + A.A. + …..+ Tripeptide --> Polypeptide
A protein consists of one or more
polypeptide chains.