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Mechanism of enzyme action

By: HWC, Views: 7593

■ The substrate makes contact with the active site. ■ A change in the shape of the enzyme occurs resulting in the transformation of the substrate. ■ A substrate may undergo decomposition, have its atoms rearranged, or two substrates may be synthesized. ■ The products of the reaction...

Muscle cell structures - actin, myosin and titin filaments

By: HWC, Views: 7873

Once the muscle cell has been excited it will contract. • A muscle action potential will trigger the release Of Ca2+ ions into the sarcoplasm. • The Ca2+ ions bind to the regulatory proteins and trigger contraction. • Within skeletal muscle cells are structures that provide the ability...

Helper T cell receptors, activation, proliferation, differentiation & action

By: HWC, Views: 7813

• Most cells which have CD4 on their surface become Helper T cells (TN cells). • The CD4 1 cells only recognize a foreign antigen when it is presented with an antigen presenting immune cell (APC) that includes MHC-II protein. • The Helper T cell antigen receptor must match the presented...

Lipid digestion - mouth, stomach and small intestine

By: HWC, Views: 7785

• Lipid digestion takes place primarily in the small intestine; some occurs in the mouth and stomach. • Lipases are enzymes that break down triglycerides and phospholipids. • Lingual and gastric lipases hydrolyze a small amount of triglycerides. • End products are fatty acids and...

Pores and Ion Channels

By: HWC, Views: 6907

Transmembrane channels, also called membrane channels, are pores within a lipid bilayer. The channels can be formed by protein complexes that run across the membrane or by peptides. They may cross the cell membrane, connecting the cytosol, or cytoplasm, to the extracellular matrix. Membrane po...

Cytotoxic T cell receptors, activation, proliferation, differentiation & action

By: HWC, Views: 8033

• Most cells which have CD8 on their surface become cytotoxic T cells (Tc cells). • CD8 T cells recognize a foreign antigen when it is presented in conjunction with the protein, MHC-I. • Nearly all nucleated cells in the body express MHC-I molecules. • T cells that recognize self-pe...

Polysaccharides

By: HWC, Views: 7309

More complex sugars are called polysaccharides (from "poly" meaning "many" and "saccharum" meaning "sugar"). Many things in nature are made of polysaccharides. Here we show one of the polysaccharides in corn, another in wood, and another in the exoskeletons of insects like grasshoppers. How are a...

Mechanisms of capillary exchange (transcytosis & bulk flow)

By: HWC, Views: 7399

■ This method of capillary exchange is mainly used to transport small amounts of large, lipid-insoluble (water soluble) molecules, such as large proteins. ■ Substances, packaged in vesicles, move through endothelial cells via endocytosis and exocytosis. ■ This method of exchange is th...

Krebs cycle : Formation of acetyl coenzyme A and Electron transport chain

By: HWC, Views: 7809

The oxidation of glucose to produce ATP is cellular respiration. Four sets of reactions are involved: Glycolysis Formation of acetyl coenzyme A Krebs cycle reactions Electron transport chain reactions • The second pathway of glucose catabolism, formation of acetyl coenzyme A, is a transi...