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 types and functions of restriction enzymes through a Self-Quiz. To begin, click on an 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. This is a featured article. Click here for more information.
As a consequence, the DNA repair process is constantly active as it responds to damage in the DNA structure. The rate of DNA repair is dependent on many factors, including the cell type, the age of the cell, and the extracellular environment. The DNA repair ability of a cell is vital to the integrity of its genome and thus to the normal functionality of that organism. DNA damage repair and protection. 10,000 to 1,000,000 molecular lesions per cell per day. While this constitutes only 0.
These modifications can in turn disrupt the molecules’ regular helical structure by introducing non-native chemical bonds or bulky adducts that do not fit in the standard double helix. The replication of damaged DNA before cell division can lead to the incorporation of wrong bases opposite damaged ones. DNA base is stitched into place in a newly forming DNA strand, or a DNA base is skipped over or mistakenly inserted. Damage caused by exogenous agents comes in many forms. X-ray damage and oxidative damage are examples of induced damage. Whenever a cell needs to express the genetic information encoded in its nDNA the required chromosomal region is unravelled, genes located therein are expressed, and then the region is condensed back to its resting conformation. Therefore, the induction of senescence and apoptosis is considered to be part of a strategy of protection against cancer. It is important to distinguish between DNA damage and mutation, the two major types of error in DNA.