Ch. 3: Biochemistry Section 2

Molecules of Life Four main classes of organic compounds are essential for life processes of living things: Carbohydrates Lipids Proteins Nucleic Acids

Carbohydrates Carbohydrates- Organic compounds composed of carbon, hydrogen and oxygen 1:2:1 ratio Serve as sources of energy or structural components Monosaccharides, disaccharides, and polysaccharides

Carbohydrates Monosaccharides Disaccharides Polysaccharides Simple sugar; 1:2:1 ratio of atoms Disaccharides Monosaccharides combine to form a double sugar Polysaccharides Complex molecule of 3 or more monosaccharides

Carbohydrates

Types of Polysaccharides Glycogen Animals store glucose in the form of glycogen Used for energy storage Starch Plants store glucose in the form of starch Cellulose Plants use cellulose as a structural component Gives strength and rigidity to plant cells

Proteins Proteins: composed mainly of carbon, hydrogen, oxygen, and nitrogen Formed by the linking of monomers called amino acids Ex: hair, horns, skin, muscles, enzymes (catalysts)

Proteins Amino Acids 20 different amino acids All share the same basic structure Central carbon Single hydrogen Carboxyl group (--COOH) Amino group (NH2) R group (what distinguishes different amino acids)

Proteins R groups Can be simple or complex Differences among the R groups of amino acids gives proteins their different shapes Different shapes allow proteins to carry out many types of activities

Proteins Dipeptide Polypeptide Two amino acids linked together through a peptide bond Polypeptide Long chains of amino acids Polypeptide chains and resulting proteins can have different shapes depending upon types of bonds, temperature, solvents, etc.

Proteins Enzymes RNA or protein molecules that act as biological catalysts Essential for any cell to function properly Many enzymes are proteins

Proteins Enzymes Enzyme reactions depend on a physical fit between the enzyme and its specific substrate, the reactant being catalyzed Enzymes have folds, called an active site, where the substrate fits. Only specific substrates are acted upon Only that substrate fits in that active site

Proteins Enzymes Continued Enzymes bind to a substrate, the enzyme changes shape slightly  weakening bonds of substrate One way enzymes reduce activation energy Once reaction is completed, the enzyme releases the new product IMPORTANT: the enzyme itself remains unchanged, and can be used many times

Enzyme Reaction

Lock and Key

Lipids Lipids: large, nonpolar organic molecules Include triglycerides, phospholipids, steroids, waxes, and pigments Do not dissolve in water Large amounts of C-H bonding means they store more energy per gram than any other macromolecule per

Lipids Fatty Acids Unbranched carbon chains that make up most lipids The two ends of a fatty acid have different properties Head (carboxyl group C-O-O-H) is hydrophilic (water loving) Tail (C-H chains) are hydrophobic (water hating)

Lipids Saturated vs. Unsaturated

Lipids Triglycerides Three fatty acids attached to an alcohol glycerol Can be saturated and unsaturated

Lipids Phospholipids Two fatty acids attached to a glycerol molecule The cell membrane is made up of two layers of phospholipids, called the lipid bilayer Hydrophobic tails and hydrophilic heads Forms a barrier between outside and inside of cell

Lipids Waxes: waterproof, and help provide a protective coating for plants’ outer surfaces. Human ex: ear wax helps protect ear canal Steroids: Fused carbon rings; many animal hormones are steroids. Most common animal hormone is cholesterol

Nucleic Acids Nucleic Acids: very large and complex molecules that store and transfer information in the cell DNA: contains info about characteristics or organisms and directs cell activities RNA: stores and transfers info from DNA in order to manufacture proteins. Can also act as enzymes

Nucleotide: made of sugar, nitrogenous base, and phosphate group

Monomers and Polymers of Macromolecules