Human Biochemistry

Amino Acids and Proteins

there are about 20 amino acids that occur naturally they are the basic “building blocks” of life/proteins

NH 2 CHRCOOH

condensation reactions will link amino acids together to form polypeptides and eventually proteins water is formed and they link together with a peptide bond peptide bonds YouTube (1:14)

Primary Structure determined by the number, kind, and order of a.a. in the polypeptide held together by simple peptide bonds Proteins have a complex structure which can be explained by defining four levels of structure What is a protein video 3:38

Secondary Structure the polypeptide then spontaneously folds into regular, repeating structure because of hydrogen bonding

Tertiary Structure highly specific looping and folding of the polypeptide because of the following interactions between their R-groups: –covalent bonding –hydrogen bonding –ionic bonding –London dispersion forces this tertiary level is the final level of organization for proteins containing only a single polypeptide chain

Quaternary Structure linkage of two or more polypeptides to form a single protein in precise ratios and with a precise 3-D configuration. Protein folding

Quaternary Structure example

Carbohydrates most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Monosaccharides simplest sugars (single sugars) two common isomers of monosaccharides (C 6 H 12 O 6 ) glucose fructose

Disaccharides two monosacharides bonded together by a condensation reaction that creates a glycosidic linkage

three common disaccharides 1. sucrose - common table sugar 2. lactose - major sugar in milk 3. maltose -

Polysaccharides condensation of many glucose molecules

serve principally as food storage and structural molecules in plants

three types of polysaccharides 1. Starches (plants) – serve as storage depots of glucose 2. Cellulose (plants) – plant cell walls 3.Glycogen – serve as a form of energy storage in animals and fungi

Lipids

3 Main Types of Lipids

1. Triglycerides (fats and oils) found in fatty tissue a condensation reaction called ester linkage

Saturated vs. Unsaturated fatty acids (2:51)

2. Phospholipids major structural components of cell membranes polar “heads” love water (hydrophilic) uncharged “tails” avoid water (hydrophobic) + _

+ _

3. Steroids cholesterol is the most abundant and important steroid