Why does having an extra chromosome like with Down Syndrome have so many consequences?
Hi there! Here's an important concept to remember: too much or too little is bad. Too much water and you would die of water poisoning and too little of dehydration. The same holds for many biological systems, especially when it comes to chromosome counts in mammals. An extra chromosome means an extra copy of a set of genes which means more of whatever the genes are encoding, which the body may not be able to cope with. Furthermore, when you have this extra number when it comes to mitosis the pairing of the chromosomes would be strange, because you have an extra copy!
- Answer provided by Ethan Yang
What is the main cause of down syndrome?
Down syndrome is also known as "trisomy 21" where the affected individual has one extra chromosome. See http://en.wikipedia.org/wiki/Down_syndrome
- Answer provided by Dr. Sean Myles
Why is it that many patients whom have Down Syndrome often share the same facial characteristics? (ex. Flat facial expression, small chins)
Because the extra copy of chromosome 21 has myriad effects: one contributes to facial features, another to the function of the brain, a third to a heightened risk of early Alzheimer's. But it's important to note that some of these issues with Down syndrome can be dealt with. For instance, many Down's patients have trouble speaking because of anatomical differences in their tongue. But give them computers, and they can express themselves much better.
- Answer provided by Jay Ingram