Four important elements
Carbon C
Nitrogen N
Oxygen O
Hydrogen H
4
3
2
1
Four kinds of biomolecules
Carbohydrates (sugars: simple sugars; starch, cellulose, etc.)
monosaccharides, oligosaccharide (few monomers), polysaccharide
(hundreds or thousands)
Lipids
(non-polar, water insoluble, long carbon chains; fats,
waxes, steroids)
Proteins
(versatile/diverse, made up of 20 amino acids) amino acid
is the monomer; polymer: peptides chains
Nucleic acids
(DNA, RNA, ATP, etc.) monomer is nucleotide, polymer
is DNA or RNA
Dehydration synthesis two monomers (smallest subunits, e.g. glucose) are
joined, produces a water molecule
Hydrolysis water is added, bond is broken
Many monomers together form a polymer
CARBOHYDRATES
1C:2H:1 O
Glucose (major energy source)
Starch (long chain of glucoses; stored by plants; easy to digest, easy to break
the bonds between glucoses)
Cellulose (also a long chain of glucoses; grass, leaves, cotton, wood, lettuce)
Glycogen (branched chains of glucose, stored by animal in liver)
Chitin (structural material: insects, fungi)
LIPIDS
Fats, oils, waxes, steroids (all water insoluble)
Fats: triglycerides (high energy content per unit mass; twice that of
carbohydrates and proteins)
Phospholipid: have one polar phosphate group; two non-polar fatty acids
Waxes: large molecules, solid
Cholesterol and other steroids: cholesterol (important in membranes);
steroids (testosterone, estrogen)
PROTEINS
Amino acid
Chain of amino acids= peptide
One or more peptide with a function = protein
Four levels of proteins structure:
Primary: the sequence of amino acids (e.g. lysine-valine-glutamic acid)
Secondary: hydrogen bonds between amino acids; small scale, repeated
shapes (alpha helix and pleated sheets)
Tertiary: big bends/folds in peptide chain
Quaternary: more than peptide stuck together
NUCLEIC ACIDS
DNA, RNA, ATP
One sugar, phosphate group, N containing base (variable, 4 kinds)
DNA: adenine, thymine, cytosine, guanine (A, T, C, G)
DNA forms a double strand, the two strands are anti-parallel
A always with T
C always with G
TATGAT
ATACTA
RNA ribose instead of deoxyribose
Single stranded
Uracil takes the place of thymine
ATP Adenosine triphosphate (3 phosphate groups); release third phosphate,
energy releases ATP  ADP + P + energy