Focus on:

Elements in each molecule How molecules are linked

and unlinked Examples and functions of

each type of molecule

Chapter 3 The Chemical Building

Blocks of Life

Macromolecules

Large molecules formed by joining many subunits together.

Also known as “polymers”.

Monomer

A building block of a polymer.

AP Biology

Condensation Synthesis or Dehydration Synthesis

The chemical reaction that joins monomers into polymers.

Covalent bonds are formed by the removal of a water molecule between the monomers.

Hydrolysis

Reverse of condensation synthesis.

Hydro- water Lysis - to split Breaks polymers into

monomers by adding water.

Four Main Types Of Macromolecules

Carbohydrates Lipids Protein Nucleic acids

For each Macromolecule know the following:

Elements it contains Monomer units and

structures Examples Uses or roles

Carbohydrates

Used for fuel, building materials, and receptors.

Made of C,H,O General formula is CH2O C:O ratio is 1:1

Types Of Carbohydrates

Monosaccharides Disaccharides Oligosaccharides Polysaccharides

Monosaccharides

Mono - single Saccharide - sugar Simple sugars. 3 to 7 carbons. Can be in linear or ring forms.

Monosaccharides

Can be “Aldoses” or “Ketoses” depending on the location of the carbonyl group.

Examples

Glucose Galactose Ribose Fructose

- OSE

Word ending common for many carbohydrates.

Disaccharides

Sugar formed by joining two monosaccharides through a “glycosidic linkage”.

Examples

Maltose = glucose + glucose Lactose = glucose + galactose Sucrose = glucose + fructose

Oligosaccharides

2 - 10 joined simple sugars. Used in cell membranes.

Polysaccharides

Many joined simple sugars. Used for storage or structure. Examples:

Starch Cellulose Glycogen

glucose and glucose

Starch

Made of 1-4 linkages of glucose.

Linkage makes the molecule form a helix.

Fuel storage in plants.

glucose

Cellulose

Made of 1-4 linkages of glucose.

Linkage makes the molecule form a straight line.

Used for structure in plant cell walls.

glucose

Comment

Most organisms can digest starch (1- 4 linkage), but very few can digest cellulose (1- 4 linkage).

Another example of the link between structure and function.

Glycogen

“Animal starch” Similar to starch, but has

more 1-6 linkages or branches.

Found in the liver and muscle cells.

Glycogen

Starch

Lipids

Diverse hydrophobic molecules. Made of C,H,O No general formula. C:O ratio is very high in C.

Fats and Oils

Fats - solid at room temperature.

Oils - liquid at room temperature.

Fats and Oils

Made of two kinds of smaller molecules. Fatty Acids Glycerol

Fatty Acids

A long carbon chain (12-18 C) with a -COOH (acid) on one end and a -CH3 (fat) at the other.

Acid Fat

Neutral Fats or Triacylglycerols

Three fatty acids joined to one glycerol.

Joined by an “ester” linkage between the -COOH of the fatty acid and the -OH of the alcohol.

Saturated FatsUnsaturated Fats

Saturated - no double bonds. Unsaturated - one or more

C=C bonds. Can accept more Hydrogens.

Double bonds cause “kinks” in the molecule’s shape.

Question

Why do fats usually contain saturated fatty acids and oils usually contain unsaturated fatty acids?

The double bond pushes the molecules apart, lowering the density, which lowers the melting point.

Fats

Differ in which fatty acids are used.

Used for energy storage, cushions for organs, insulation.

Question ?

Which has more energy, a kg of fat or a kg of starch?

Fat - there are more C-H bonds which provide more energy per mass.

Phospholipids

Similar to fats, but have only two fatty acids.

The third -OH of glycerol is joined to a phosphate containing molecule.

Result

Phospholipids have a hydrophobic tail, but a hydrophilic head.

Self-assembles into micells or bilayers, an important part of cell membranes.

Steroids

Lipids with four fused rings. Differ in the functional groups

attached to the rings. Examples:

cholesterol sex hormones

Proteins

The molecular tools of the cell. Made of C,H,O,N, and

sometimes S. No general formula.

Uses Of Proteins

Structure Enzymes Antibodies Transport Movement Receptors Hormones

Proteins

Polypeptide chains of Amino Acids linked by peptide bonds.

Amino Acids

All have a Carbon with four attachments:

-COOH (acid) -NH2 (amine) -H -R (some other side group)

R groups

20 different kinds: Nonpolar - 9 AA Polar - 6 AA Electrically Charged

Acidic - 2 AA Basic - 3 AA

Amino Acids

Amino Acids

R groups

Contain the S when present in a protein. Cysteine or Cys Methionine or Met

The properties of the R groups determine the properties of the protein.

Polypeptide Chains

Formed by dehydration synthesis between the carboxyl group of one AA and the amino group of the second AA.

Produce an backbone of: (N-C-C)X

Levels Of Protein Structure

Organizing the polypeptide into its 3-D functional shape. Primary Secondary Tertiary Quaternary

Primary

Sequence of amino acids in the polypeptide chain.

Many different sequences are possible with 20 AAs.

Secondary

3-D structure formed by hydrogen bonding between parts of the peptide backbone.

Two main secondary structures: helix pleated sheets

Tertiary Bonding between the R groups. Examples:

hydrophobic interactions

ionic bonding Disulfide bridges

(covalent bond)

Quaternary When two or more

polypeptides unite to form a functional protein.

Example: hemoglobin

Is Protein Structure Important?

Denaturing Of A Protein

Events that cause a protein to lose structure (and function).

Example: pH shifts high salt concentrations heat

Comment Many other amino acids are

possible (change the R group) Whole new group of proteins

with new properties can be made

Genetic engineering can use bacteria to make these new proteins

Nucleic Acids

Informational polymers Made of C,H,O,N and P No general formula Examples: DNA and RNA

Nucleic Acids

Polymers of nucleotides Nucleotides have three parts:

nitrogenous base pentose sugar phosphate

Nitrogenous Bases

Rings of C and N The N atoms tend to take up

H+ (base). Two types:

Pyrimidines (single ring) Purines (double rings)

Pentose Sugar

5-C sugar Ribose - RNA Deoxyribose – DNA RNA and DNA differ in a –

OH group on the 2nd carbon.

Nucleosides and Nucleotides

Nucleoside = base + sugar Nucleotide = base + sugar + Pi

DNA

Deoxyribonucleic Acid. Makes up genes. Genetic information

for life.

RNA

Ribonucleic Acid. Structure and protein

synthesis. Genetic information for a few

viruses only.

DNA and RNA

More will be said about DNA and RNA in future lessons.

Summary

Role of hydrolysis and dehydration synthesis

For each macromolecule, know the following: Elements and monomers Structures Functions