Most enzymes do in fact work on a single substrate in most cases, this is because of the enzyme - substrate specificity. Certain reactant molecules acting as substrates can only fit in the "lock" of particular enzymes and undergo a conformational change and result in Unique products to be released after the reaction has occurred.
Triglycerides and cholesteryl esters are transported in the core of plasma lipoproteins. The intestine secretes dietary fat in chylomicrons, lipoproteins that transport triglyceride to tissues for storage. Dietary cholesterol is transported to the liver by chylomicron remnants which are formed from chylomicrons.
DNA microarrays allow the rapid and simultaneously SCREENING of many thousands of genes.
