NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE Part Il Applications of DNA T
ID: 253065 • Letter: N
Question
NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE Part Il Applications of DNA Technology While you are waiting for Lee's biopsy results, you decide to do some concentrated studying for the USMLE Step 1, the exam that all second-year medical students must take to progress in medical school. Because of your interest in Lee's case, you review material related to genetic diagnosis, prevention, and treatment. You use a few reliable Internet sources on genetic conditions (http:/lghr.nlm.nih.gov/) and techniques related to molecular genetics (https://www.dnalc.org/resources/animations) as well as your good old college textbook to answer the following Questions 1. In order to test Lee for a genetic disorder, Dr. Aikenhed will probably take a sample of cells containing his genomic DNA by swabbing his cheek or taking a blood sample. Why is it important to use non-cancerous cells to test Lee for a genetic disorder instead of the biopsy tissue? 2. Describe the main technique for amplifying a segment of DNA (like the one you suspect is involved in Lees cancer) from a complex mixture of genomic DNA. Remember that the entire human genome sequence is known. (Hint: This is a technique that is commonly used by laboratories that do genetic testing and various other applications of molecular biology 3. If Dr. Aikenhed wanted to see if there was mutation within the protein-coding sequence of the gene implicated in this disorder (as opposed to mutations affecting regulatory elements), what technique involving dideoxymucleotides could be used? Briefly describe this technique. Lee and his family have inspired in you a desire to find out more about how to prevent and treat this disorder. In your medical genetics textbook, you read that some genetic disorders have specific treatments and/or prevention strategies The symptoms and progression of phenylketonuria (PKU), for example, can be mitigated with a strict diet that limits phenylalanine intake. Cystic fibrosis is treated with palpitations (tapping) of the chest to loosen mucus and with antibiotics to help prevent infection, among other strategies. Most genetic disorders, however, do not have such clear cut recommendations. A Family In Need: Interner-Enhanced Case Study on Cancer Genetics by Janet A. De Souza-HareExplanation / Answer
1. The reason why you have to take a sample from non-cancerous cells is because you need to do a comparation of the DNA from healthy cells with the DNA from cancerous cells by a process called DNA SEQUENCING, in which you can “read” the order of the nucleotides in a specific segment of DNA.
2. The technique which is employed to amplify a specific segment of DNA it is called PCR ( Polymerase Chain Reaction), using this technique you make a great number of copies of this DNA segment.
3. It is a method for DNA Sequencing called the Sanger Method, it is a process in which you use a dideoxynucleotides (ddNTPs), these nucleotides are characterized by a lack of OH molecule in the third carbon of the sugar, which is necesary for the chain elongation, so when the polymerase is synthesizing a segment of DNA it incorporates dNTPs, but when it incorporate a ddNTP it can not add a new dNTP right next to the ddNTP, because the phosphodiester bond can not be generate.
In this technique you use four tubes, label as: ddATP, ddCTP, ddTTP and ddGTP, in each tube you add your target DNA, a primer, the polymerase and dNTPs, and in the tube label ddATP, you add ddATP, in th tube ddCTP you add ddCTP and so long. Then you run a gel electrophoresis and the generated segments will be separated. You can “read” the sequence from the smallest fragment (placed in the bottom of the gel) to the largest one (placed in the top of the gel).
4. The fact of having the genetic contribution, means that the person carries the mutation that pre-dispose him or her to manifest the disease, and if he or she smoke or is obese or is inactive, etcetera all of these can contribute in a more aggressive form of the disease.
5. The technique that may help a person in order of not transmite the mutation to her or his offspring is the edition of the genes by CRISPR.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.