Pearson, as an active contributor to the biology learning community, is pleased to provide free access to the Classic edition of The Biology Place to all educators and their students. The purpose of the activities is to help you review material you have already studied in class or have read in your text. Some of the material will extend your knowledge beyond your classwork or textbook reading. At the end of each activity, you can assess your progress through a Self-Quiz. To begin, click on what enzymes are important for digestion activity title.
Concept 1: How Do Restriction Enzymes Work? Concept 11: Allelic Frequency vs. Concept 3: How Do Guard Cells Function? Concept 5: The Genetic Code: RNA vs. Restriction enzymes are enzymes isolated from bacteria that recognize specific sequences in DNA and then cut the DNA to produce fragments, called restriction fragments. Restriction enzymes play a very important role in the construction of recombinant DNA molecules, as is done in gene cloning experiments. Another application of restriction enzymes is to map the locations of restriction sites in DNA. You should have an understanding of DNA structure and the principles and steps involved in constructing and analyzing recombinant DNA molecules, as presented in lectures and in your textbook. This activity is designed to enhance your understanding and retention by illustrating DNA structure, restriction enzyme digestion of DNA, analysis of digested DNA by agarose gel electrophoresis, and the principles involved in constructing a restriction map from primary data.
A 15-question multiple-choice quiz allows you to test your understanding of the material. An additional three questions test your ability to construct restriction maps from DNA fragment size data. The correct restriction maps may be viewed on-screen. The restriction mapping section includes an interactive Shockwave animation in which you can measure the migration distance of a DNA fragment after gel electrophoresis and see how that distance gives its molecular size from a calibration curve. Literature Related to Milk Composition. Literature Related to Milk and Human Health.
Literature Related to Milk Micro. Literature Related to Milk Processing. Links to Other Web Sites. This page briefly describes the general properties of enzymes present in milk.
Enzymes are proteins that have biological functions. Lipases are enzymes that degrade fats. The major lipase in milk is lipoprotein lipase. It is associated with the casein micelle. Agitation during processing may bring the lipase into contact with the milk fat resulting in fat degradation and off-flavors. Proteases are enzymes that degrade proteins. The major protease in milk is plasmin. Protein degradation can be undesirable and result in bitter off-flavors, or it may provide a desirable texture to cheese during ripening.