1. 1 The Chemical Building Blocks of Life Chapter 3

2. 2 Outline Biological Molecules – Macromolecules  Proteins  Structure and Denaturation  Nucleic Acids  DNA and RNA  Lipids  Fats and Phospholipids  Carbohydrates  Transport and Storage

3. 3 Biological Molecules The framework of biological molecules consists of carbon bonded to other carbon molecules, or other types of atoms. – Hydrocarbons consist of carbon and hydrogen.  Covalent bonds store considerable energy.

4. 4 Biological Molecules Macromolecules – proteins – nucleic acids – lipids – carbohydrates Functional groups – specific groups of atoms attached to carbon backbones  retain definite chemical properties Link: Functional groups

5. 5 Building Macromolecules Macromolecules are often polymers. – long molecule built by linking together small, similar subunits  Dehydration synthesis removes OH and H during synthesis of a new molecule.  Hydrolysis breaks a covalent bond by adding OH and H.

6. 6 The Many Functions of Proteins – enzyme catalysis – defense – transport – support – motion – regulation – storage

7. 7 Amino Acid Structure contain an amino group (-NH 2 ), a carboxyl group (-COOH) and a hydrogen atom, all bonded to a central carbon atom – twenty common amino acids grouped into five classes based on side groups  nonpolar amino acids  polar uncharged amino acids  charged amino acids  aromatic amino acids  special-function amino acids

8. 8 Amino Acids Peptide bond links two amino acids. – A protein is composed of one or more long chains of amino acids linked by peptide bonds (polypeptides).

9. 9 Protein Structure Protein function is determined by its shape. – Protein structure  primary - specific amino acid sequence  secondary - folding of amino acid chains  tertiary - final folded shape of globular protein  quaternary - forms when two or more polypeptide chains associate to form a functional protein

10. 10 Chaperone Proteins Chaperone proteins are special proteins which help new proteins fold correctly. – Chaperone deficiencies may play a role in facilitating certain diseases.

11. 11 Unfolding Proteins Denaturation refers to the process of changing a protein’s shape. – usually rendered biologically inactive  salt-curing and pickling used to preserve food

12. 12 Nucleic Acids Deoxyribonucleic Acid (DNA) – Encodes information used to assemble proteins. Ribonucleic Acid (RNA) – Reads DNA-encoded information to direct protein synthesis. Nucleic acids are composed of long polymers of repeating subunits, nucleotides. – five-carbon sugar – phosphate – nitrogenous base  purines  adenine and guanine  pyrimidines  cytosine, thymine, and uracil

13. 13 Nucleic Acid Structure DNA exists as double- stranded molecules. – double helix – complementary base pairing  hydrogen bonding RNA exists as a single stand. – contains ribose instead of deoxyribose – contains uracil in place of thymine

14. 14 Lipids Lipids are loosely defined as groups of molecules that are insoluble in water. – fats and oils Phospholipids form the core of all biological membranes. – composed of three subunits  glycerol  fatty acid  phosphate group

15. 15 Fats and Other Lipids Fats consist a of glycerol molecule with three attached fatty acids (triglyceride / triglycerol). – Saturated fats - all internal carbon atoms are bonded to at least two hydrogen atoms – Unsaturated fats - at least one double bond between successive carbon atoms  Polyunsaturated - contains more than one double bond  usually liquid at room temperature

16. 16 Fats as Energy Storage Molecules Fats, on average, yield about 9 kcal per gram versus 4 kcal per gram for carbohydrates. – Animal fats are saturated while most plant fats are unsaturated.  Consumption of excess carbohydrates leads to converted into starch, glycogen, or fats for future use.

17. 17 Carbohydrates Carbohydrates are loosely defined as molecules that contain carbon, hydrogen, and oxygen in a 1:2:1 ratio. – monosaccharides - simple sugars – disaccharides - two monosaccharides joined by a covalent bond – polysaccharides - macromolecules made of monosaccharide subunits  isomers - alternative forms of the same substance

18. 18 Carbohydrate Transport and Storage Transport disaccharides – Humans transport glucose as a simple monosaccharide. – Plants transform glucose into a disaccharide transport form. Storage polysaccharides – plant polysaccharides formed from glucose - starches  most is amylopectin Cellulose - plants – alpha form or beta form of ring Chitin - arthropods and fungi – modified form of cellulose