Before the discovery of insulin in 1921, being diagnosed with Type 1 diabetes was a death sentence. Despite the successful management of diabetes with purified animal insulin, potentially severe side effects were abundant, and alternative ways to produce insulin were needed. This case study guides students through the history of using insulin to treat diabetes, focusing on the development of recombinant DNA technology and the world's first bioengineered drug, recombinant human insulin, which is now used worldwide to treat diabetes. Through the course of this case, students consider the central dogma of molecular biology, the development of recombinant DNA technology, drug design, the importance of recombinant proteins to our society, and the ethical analysis and debates that occur as a result of some scientific discoveries. This case was developed as an introduction to an upper-division biotechnology course focusing on recombinant protein design and production, but could also be used in molecular biology, biochemistry, or introductory biology courses to highlight recombinant DNA and biotechnology.
The Y chromosome is only one-third the size of the X. Although the Y has a partner in X, only the tips of these chromosomes are able to recombine. Thus, most of the Y chromosome is inherited from father to son in a pattern resembling asexual, not sexual, reproduction. No recombination means no reassortment, so deleterious mutations have no opportunity to be independently selected against. The Y chromosome therefore tends to accumulate changes and deletions faster than the X. Degradation doesn't occur in X chromosomes because during female meiosis, the X has the other X as a full partner in recombination.
While genes determine most of our physical characteristics, the exact combination of genes we inherit, and thus our physical traits, is in part due to a process our chromosomes undergo, known as genetic recombination.
This initial module from the GENIQUEST project introduces the dragons and the inheritance of their traits, then delves into meiosis and its relationship to inherited traits. Students examine the effects of choosing different gametes on dragon offspring, and learn about genetic recombination by creating recombination events to generate specific offspring from two given parent dragons. Students learn about inbred strains and breed an inbred strain of dragons themselves. Lastly, students investigate a mysterious new dragon trait and use the properties of linkage and inheritance to examine the trait's relationship to other, known dragon traits.
In 3 minutes, this video tells the pertinent story of how recombinant DNA technology was used to produce human -- or synthetic -- insulin in large amounts and how it became the first biotechnology treatment approved by the FDA.
"CRACKING THE CODE"/"Cloning Paper Plasmid" activities can (1) serve as a review of the "genetic code" and the role it plays in our life; and, (2) to help students see how genes may be manipulated for genetic research, namely, gene cloning/genetic engineering.
The laboratory time, the specialized equipment and expertise to carry out recombinant DNA experiments may be lacking in the high school. Activity 2 will help students conceptualize the mechanics involved in cutting and ligating DNAs into a plasmid vector with "sticky ends" of complementary DNA base pairs.
Four talks focus on sex determination-the molecular and genetic mechanisms that determine whether an organism will be male, female or a hermaphrodite.
Meisosis animation 49:00-53:00
53:21 SRY animation Y to X crossing over
53:30 SRY transfer 54:45
2 min video A quick tutorial, showing how we use restriction enzymes to cut out a desired gene from one organism, and insert it into the plasmid of a bacterium. This allows massive production of the desired protein (in this case the hormone: insulin) in a relatively short amount of time.