文档介绍：Chapter 3 The Same 20 Amino Acids Serve as Building Blocks for All Proteins in NatureHomework 2 part 1: Ch. 5 problems 2, 9, 12, Almost all chemical reactions occurring in anisms are catalyzed by Many thousands of enzymes have been discovered, each catalyzing a different kind of chemical Life would not occur without enzyme Enzymes are the most varied and most highly specialized . Proteins are extremely versatile in function and crucial in virtually all biological Many small molecules and ions are transported by specific Some proteins transport molecules from an to another, many exist in the blood plasma, ., hemoglobin (oxygen), serum albumin (fatty acids), lipoproteins (lipids), and transferrin (iron). Some proteins transport molecules across plasma membrane anelle membranes (glucose, amino acids, nucleotides, chloride, potassium, sodium ions but not water). Some proteins function as nutrient or storage proteins. For example, many of such kind exist in plant seeds, animal eggs (Ovalbumin of egg white, casein of milk). Ferritinin animal tissue function to store ion (about 4500 ions are stored in the cavity of each plex!). Some proteins are responsible for the coordinated motions (contraction, changing shape, moving about). For example, actin and myosin in muscle and nonmuscle cells. Tubulin and dyneinin eukaryotic flagella and Some proteins are responsible for mechanical support (strength and protection) Collagen in tendons (筋腱),cartilage, and Elastin in ligaments (韧带). Keratin in hair, fingernails, Fibroin in silk fibers and spider Resilin in wing hinges of some Some proteins function to defend Immunoglobins in Fibrinogen and thrombin in blood- Snake venom, bacterial toxins, and toxic plant proteins (ricin). Some proteins help regulate cellular or