Focus on: u Elements in each molecule u How molecules are linked and unlinked u Examples and functions of each type of molecule

Chapter 3 The Chemical Building Blocks of Life

Macromolecules u Large molecules formed by joining many subunits together. u Also known as “polymers”.

Monomer u A building block of a polymer. AP Biology

Condensation Synthesis or Dehydration Synthesis u The chemical reaction that joins monomers into polymers. u Covalent bonds are formed by the removal of a water molecule between the monomers.

Hydrolysis u Reverse of condensation synthesis. u Hydro- water u Lysis - to split u Breaks polymers into monomers by adding water.

Four Main Types Of Macromolecules u Carbohydrates u Lipids u Protein u Nucleic acids

For each Macromolecule know the following: u Elements it contains u Monomer units and structures u Examples u Uses or roles

Carbohydrates u Used for fuel, building materials, and receptors. u Made of C,H,O u General formula is CH 2 O u C:O ratio is 1:1

Types Of Carbohydrates u Monosaccharides u Disaccharides u Oligosaccharides u Polysaccharides

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

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

Examples u Glucose u Galactose u Ribose u Fructose

- OSE u Word ending common for many carbohydrates.

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

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

Oligosaccharides u joined simple sugars. u Used in cell membranes.

Polysaccharides u Many joined simple sugars. u Used for storage or structure. u Examples: u Starch u Cellulose u Glycogen

 glucose and  glucose

Starch  Made of 1-4 linkages of  glucose. u Linkage makes the molecule form a helix. u Fuel storage in plants.

 glucose

Cellulose  Made of 1-4 linkages of  glucose. u Linkage makes the molecule form a straight line. u 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). u Another example of the link between structure and function.

Glycogen u “Animal starch” u Similar to starch, but has more 1-6 linkages or branches. u Found in the liver and muscle cells.

Glycogen Starch

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

Fats and Oils u Fats - solid at room temperature. u Oils - liquid at room temperature.

Fats and Oils u Made of two kinds of smaller molecules. u Fatty Acids u Glycerol

Fatty Acids u A long carbon chain (12-18 C) with a -COOH (acid) on one end and a -CH 3 (fat) at the other.

AcidFat

Neutral Fats or Triacylglycerols u Three fatty acids joined to one glycerol. u Joined by an “ester” linkage between the -COOH of the fatty acid and the -OH of the alcohol.

Saturated Fats Unsaturated Fats u Saturated - no double bonds. u Unsaturated - one or more C=C bonds. Can accept more Hydrogens. u Double bonds cause “kinks” in the molecule’s shape.

Question u Why do fats usually contain saturated fatty acids and oils usually contain unsaturated fatty acids? u The double bond pushes the molecules apart, lowering the density, which lowers the melting point.

Fats u Differ in which fatty acids are used. u Used for energy storage, cushions for organs, insulation.

Question ? u Which has more energy, a kg of fat or a kg of starch? u Fat - there are more C-H bonds which provide more energy per mass.

Phospholipids u Similar to fats, but have only two fatty acids. u The third -OH of glycerol is joined to a phosphate containing molecule.

Result u Phospholipids have a hydrophobic tail, but a hydrophilic head. u Self-assembles into micells or bilayers, an important part of cell membranes.

Steroids u Lipids with four fused rings. u Differ in the functional groups attached to the rings. u Examples: u cholesterol u sex hormones

Proteins u The molecular tools of the cell. u Made of C,H,O,N, and sometimes S. u No general formula.

Uses Of Proteins u Structure u Enzymes u Antibodies u Transport u Movement u Receptors u Hormones

Proteins u Polypeptide chains of Amino Acids linked by peptide bonds.

Amino Acids u All have a Carbon with four attachments: u -COOH (acid) u -NH 2 (amine) u -H u -R (some other side group)

R groups u 20 different kinds: u Nonpolar - 9 AA u Polar - 6 AA u Electrically Charged u Acidic - 2 AA u Basic - 3 AA

Amino Acids

R groups u Contain the S when present in a protein. u Cysteine or Cys u Methionine or Met u The properties of the R groups determine the properties of the protein.

Polypeptide Chains u Formed by dehydration synthesis between the carboxyl group of one AA and the amino group of the second AA. u Produce an backbone of: (N-C-C) X

Levels Of Protein Structure u Organizing the polypeptide into its 3-D functional shape. u Primary u Secondary u Tertiary u Quaternary

Primary u Sequence of amino acids in the polypeptide chain. u Many different sequences are possible with 20 AAs.

Secondary u 3-D structure formed by hydrogen bonding between parts of the peptide backbone. u Two main secondary structures:   helix u pleated sheets

Tertiary u Bonding between the R groups. u Examples: u hydrophobic interactions u ionic bonding u Disulfide bridges (covalent bond)

Quaternary u When two or more polypeptides unite to form a functional protein. u Example: hemoglobin

Is Protein Structure Important?

Denaturing Of A Protein u Events that cause a protein to lose structure (and function). u Example: u pH shifts u high salt concentrations u heat

Comment u Many other amino acids are possible (change the R group) u Whole new group of proteins with new properties can be made u Genetic engineering can use bacteria to make these new proteins

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

Nucleic Acids u Polymers of nucleotides u Nucleotides have three parts: u nitrogenous base u pentose sugar u phosphate

Nitrogenous Bases u Rings of C and N u The N atoms tend to take up H + (base). u Two types: u Pyrimidines (single ring) u Purines (double rings)

Pentose Sugar u 5-C sugar u Ribose - RNA u Deoxyribose – DNA u RNA and DNA differ in a –OH group on the 2 nd carbon.

Nucleosides and Nucleotides u Nucleoside = base + sugar u Nucleotide = base + sugar + Pi

DNA u Deoxyribonucleic Acid. u Makes up genes. u Genetic information for life.

RNA u Ribonucleic Acid. u Structure and protein synthesis. u Genetic information for a few viruses only.

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

Summary u Role of hydrolysis and dehydration synthesis u For each macromolecule, know the following: u Elements and monomers u Structures u Functions