2.1.1. Chronicles of a Genetic Counselor
The genetic code is extremely important when examining diseases. Genetic disease are due to mutations in this genetic code. There are four categories of genetic disorders: single-gene disorders, multifactorial disorders, chromosomal disorders, and mitochondrial disorders. Single-gene disorders are due to changes that occur in the DNA sequence of one gene. Multifactorial disorders are caused by environmental factors and mutations in several genes. Chromosomal disorders are due to missing/extra copies of genes or break, deletions, and rejoining of chromosomes. Lastly, mitochondrial disorders are caused by mutations in the nonchromosomal DNA of the mitochondria.
- Cystic fibrosis: caused by a defect in the CFTR gene that is supposed to make a protein that controls movement of salt and water in and out of body cells
- Huntington's Disease: caused by faulty gene where CAG repeats that leads to involuntary movements, cognitive problems, and behavioral symptoms
- Duchenne Muscular Dystrophy: caused by a defective gene that is supposed to keep muscle cells intact called dystrophin
- Alzheimer's Disease: caused by brain cell death that makes it harder for the brain to communicate with the body and function properly
- Down Syndrome: caused by nondisjunction which leaves a sperm or egg cell with an extra copy of chromosome 21 before or at conception
- Leber Hereditary Optic Neuropathy: caused by degeneration of retinal ganglion cells and their actions which leads to acute or subacute loss of central vision
- Cystic fibrosis: caused by a defect in the CFTR gene that is supposed to make a protein that controls movement of salt and water in and out of body cells
- Huntington's Disease: caused by faulty gene where CAG repeats that leads to involuntary movements, cognitive problems, and behavioral symptoms
- Duchenne Muscular Dystrophy: caused by a defective gene that is supposed to keep muscle cells intact called dystrophin
- Alzheimer's Disease: caused by brain cell death that makes it harder for the brain to communicate with the body and function properly
- Down Syndrome: caused by nondisjunction which leaves a sperm or egg cell with an extra copy of chromosome 21 before or at conception
- Leber Hereditary Optic Neuropathy: caused by degeneration of retinal ganglion cells and their actions which leads to acute or subacute loss of central vision
2.1.2. Copy Your Genes
Polymerase Chain Reaction (PCR) is the process of denaturation, annealing, and extension on strands of DNA to produce thousands of copies that can later be used or screening, testing, etc. The steps of PCR are denaturation, annealing, and extension. In denaturation dsDNA is turned into ssDNA, this "unzips" the double strand of DNA or RNA. Annealing is when the primer attaches to the ends of the strands. This allows extension which is when Taq polymerase attaches to the primer at 3' and starts synthesizing the new DNA strand toward the 5'.
In this activity our group was responsible for performing PCR on the strand that ran through the PCR machine 10 times. As a group we first began by obtaining a 0.5 mL PCR reaction tube. Then we tapped the tube to put the bead at the bottom so wouldn't lose it. Next we added 10 µl DNA Template for Amplification, 10 µl Primer Mix, and 7 µl Enzyme Grade Ultrapure Water. After we added those components we mixed it by tapping the tube gently. Then we inserted the PCR tube into the thermal cycler and programmed it so the sample would cycle through 94°C for 45 seconds then 45°C for 45 seconds and finally 72°C for 45 seconds. Finally we stopped it after the 10th cycle and removed the tube.
In this activity our group was responsible for performing PCR on the strand that ran through the PCR machine 10 times. As a group we first began by obtaining a 0.5 mL PCR reaction tube. Then we tapped the tube to put the bead at the bottom so wouldn't lose it. Next we added 10 µl DNA Template for Amplification, 10 µl Primer Mix, and 7 µl Enzyme Grade Ultrapure Water. After we added those components we mixed it by tapping the tube gently. Then we inserted the PCR tube into the thermal cycler and programmed it so the sample would cycle through 94°C for 45 seconds then 45°C for 45 seconds and finally 72°C for 45 seconds. Finally we stopped it after the 10th cycle and removed the tube.
This image is of our gel with the DNA we performed PCR on. In the first lane is the marker at 10 ul. The second lane is the marker again but at 15 ul. The third lane is the control sample at 15 ul. Next is the sample that was spun in 10 cycles at 20 ul. In the fifth lane is the sample spun in 20 cycles at 20 ul. Finally, in the last lane is the sample that was spun in 30 cycels at 20 ul. This gel was done to test how many fragments of DNA were in each sample. The markers were comparisons to determine the weight of the bands on the gel. I predicted that the control would be the lightest blue because it had the lowest concentration and that the sample spun 30 times would be the darkest blue due to it having the highest concentration of DNA fragments.
2.2.1. Gene Therapy
Gene therapy is an experimental technique that uses genes to treat and prevent genetic diseases and malformations. There are several pros and cons with this therapy. The pros are the potential for future success, it replaces defective cells, it can eradicate diseases, prolong life, and help animals as well. However, gene therapy also modifies human capabilities, can damage someone's gene pool, causes a rise in disorders, have unintended side effects, and it's not a permanent solution. I believe that there should be some limitations for gene therapy though. For example, an athlete shouldn't be allowed to use gene therapy to make them faster or stronger. Gene therapy should only be used to treat serious, life-threatening conditions so that it improves life expectancy and improves someones quality of life.
The disease I researched was hemophilia. Hemophilia is an inherited bleeding disorder that results in an absent or reduced clotting factor (VIII or IX). VIII is hemophilia A or classic hemophilia. IX is hemophilia B or Christmas disease. Hemophilia is found on the X chromosome and affects mainly boys because they only have one X chromosome. Women are usually carriers and pass it onto their children. The disease is classified based on the amount of clotting activity present. People without hemophilia have a factor level from 50% -100%. Those with mild hemophilia have a factor level >5% - <40%. 1% - 5% factor level is moderate hemophilia. Finally, sever hemophilia is less than 1% factor level.
2.2.2. Reproductive Technology
Therapeutic cloning is when the nucleus of a cell is removed from a somatic cell and is injected into an unfertilized egg without a nucleus. It then divides and the stem cells are removed and cultured in a lab. Therapeutic cloning is done for either research or therapy. Reproductive cloning is when a formed embryo resulting from a therapeutic cloning is inserted into a woman’s womb which could theoretically develop into a fetus.