Through this unit we studied genetics and how they function. While we studied normal functioning of genetics, we also learned some about what an happen when genes aren't coded properly. From these genetic disorders I chose to do further research on Down Syndrome. Through my life I have known several individuals with Down Syndrome, and have noticed that they all seem to be affected in different ways. I wanted to know more about why this is the case and whether it was just my perception, or if there was in fact a spectrum of effects of the disorder.
Down Syndrome is a genetic disorder caused by tripling of the 21st chromosome that is named after the physician who first described it. It wasn't until the mid twentieth century that Down Syndrome was identified as caused by chromosomal error. Although all Down Syndrome is caused by the presences of additional 21st chromosome is does not always happen in the same manner. There are three different causes of Down Syndrome. The first is called Trisomy 21, where through meiotic nondisjunction or error during the production of germ cells in the parent. The second form is called Mosaic Down Syndrome. In this form mutation happens to genetics after fertilization occurred and so some cells have the extra 21st chromosome, for a total of 47, while others have the normal 46 chromosomes. This is different from Trisomy 21 because in that case, all cells have the extra 47th chromosome. The third type of Down Syndrome is called Translocation Down Syndrome. Translocation Down Syndrome can occur because of mutations to a germ cell before fertilization, or from mutations that take place at the time of conception. In this form, the person has the two regular 21st chromosomes, but then also has a copy of a portion of the 21st chromosome that has been translocated, and attached onto another chromosome. Because there is such variation in the cause of Down Syndrome, the effects on the person can vary greatly as well. Most show similar symptoms, but for some physical and learning delays are more severe than others. Typical symptoms of Down Syndrome include certain facial structure, including flattened nose bridge, and slanted eyes, low muscle tone, and an increased risk of various medical conditions, vision, and hearing loss. Those with the condition typically are delayed in their development and achieve physical milestones later, as well as facing learning challenges.
Although we tend to group Down Syndrome together as a single disorder, there several different causes for it. Although everyone with Down Syndrome is unified by the addition of an extra chromosome 21, the effects on the person's life can be very different. I am really glad to have a greater understanding of the causes of Downs and some of the challenges that people who have it face. My children are in dance class with a girl who has Down Syndrome and absolutely love her, but have asked some questions from time to time. I hope that now I will better be able to help them understand why she is different and beautiful, and that they will continue to help her in class and be friends with such a lovely girl.
Sources:
Mayo Clinic Staff. Down Syndrome Causes. Mayo Clinic. http://www.mayoclinic.com/health/down-syndrome/DS00182/DSECTION=causes. Accessed 27 March 2013.
Down Syndrome. Kids Health. http://kidshealth.org/parent/medical/genetic/down_syndrome.html#. Accessed 27 March 2013.
Genetic Causes of Down Syndrome. Linda Crnic Institute for Down Syndrome. http://www.ucdenver.edu/academics/colleges/medicalschool/institutes/lindacrnic/Education/LearnMoreAboutDownSyndrome/Pages/GeneticCauses.aspx. Accessed 27 March 2013.
International Down Syndrome Coalition. http://www.theidsc.org/. Accessed 27 March 2013.
Part 2. Thinking About the Course
1. What one assignment or activity you performed in this unit are you the most proud of?
I really enjoyed doing the flip-a-coin genetics lab. Although it could be completed on my own, I thought it would be more fun to have my husband help with the lab so each of us could be a parent for the data collection. It was a really interesting experience reading through the information on what facial traits are dominant and recessive, and seeing how that played out through the process. I was really proud of how my drawing for this assignment of our "child" turned out. I felt like it really represented the genetics well, and the project was fun as well as very informative. It led to discussion of our own kids and what the genetic probability was for each of them to end up with the traits they have. My husband was adopted so we don't know much about his genetics. He has brown eyes, so we were surprised when 3/4 of our kids have light colored eyes. The new understanding that I took from the project was really huge for me, and I'm proud not only of what I produced, but of how I was able to apply it in a bigger way to my own life.
2. What do you now understand best about the information in this unit?
Before this unit of study I had no idea that some traits, such as eye color were controlled by multiple genes. The way that genes function and how they produce the variations they do became a lot clearer to me through doing the work for this class. The way that genes function and impact both geneotype and phenotype was fascinating and is something I definitely understand better.
3. What actions did you take for yourself to enhance learning or enjoyment of the material?
I like being able to use what I've learned to teach my kids things as well. Although I had learned some basic genetics ideas before, (primarily Mendelian Genetics) I had never gone as in depth as this course. My daughter recently attended a genetics lecture for her 4-H rabbit project, and was very confused by all the things they threw at her. Having read the course material, and completed the labs on genetics I was able to talk with her about it, and help her to have an understanding of the basics of how genetics works. It's an important thing for her to understand since she is planning on breeding her rabbit later this year, and we can look at the traits in the mother, father, and young, and have some hands on genetics training then as well. I find that retelling, or teaching information is a great way to reinforce what you have learned, so I feel like this helped me to study some as well.
4. When did you feel most “connected” with the course? Most distanced?
I really feel connected with the course through all the interactive learning. I like being able to do lab projects that aren't overly complicated but demonstrate a portion of the work very well. I really feel like the hands on aspect connects me with the material and helps me to understand it and process it in a different way. I did feel a little distanced from the class through this as well though, because on some labs I think it might be helpful to be able to see other students results as well.
5. What could I offer you to help your understanding or enjoyment of the material?
I would have loved for there to be a way to share our drawings form the coin-flip lab with our classmates. Since we all had the exact same odds on our coin flips to determine the traits of our "children" I think it would have not only been fun to see what others ended up with, but could really have reinforced the concept of the diversity of human genetics.
