Dr. Moalem explains in Chapter 2: "A Spoonful of Sugar Helps the Temperature Go Down" that Diabetes allowed for certain people in the Young Dryas, an Ice Age that occurred 13,000 years ago, to survive and reproduce, relating to Big Idea 1: "The process of evolution drives the diversity and unity of life.". First, explain what Diabetes is by using words such as blood sugar, pancreas, and insulin.
Next, explain the specific variations of alleles in the population that lived during the Young Dryas that Dr. Moalem describes. How does increased blood sugar help people survive in freezing temperatures? How does sugar affect the freezing point of water? What is Brown Fat?
Explain how random mutation and certain meiotic events could have caused this variation of alleles in the population during the Young Dryas. Finally, by referring to your evolution flow chart from the beginning of the year, explain how adaptations arise by using words such as variation, selective pressure, selected for, selected against, and microevolution. (Jeremy Bush jbush3@students.d125.org)
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ReplyDeleteDiabetes is a condition where the pancreas has trouble producing insulin. In type 1 diabetes, the body has an autoimmune disorder where the immune system destroys the insulin producing cells. Type 2 diabetes is when the body develops resistance to the effects of insulin. These two effects lead to lower than normal levels of insulin, so there is nothing to help move glucose into cells. Instead, there is a higher glucose concentration in the blood stream.
ReplyDeleteDr. Moalem describes the adaptation of the Young Dryas to the climate of Europe following a brief warming period after the ice age. There were slight variations in the alleles of the Young Dryas during the short period of extreme cold in Europe, such as varied ability to deal with the cold, but what is most important is that the ones that were able to survive were the ones that could thrive in the cold. These ones "flourished across Europe during periods of significant cold" (29). These are the ones that were naturally selected for during the ice age and, thus, were the ones left during the short cold period.
Increased blood sugar plays a crucial role in survival of humans in cold periods. Increased blood sugar in the blood stream decreases the freezing temperature of the blood, allowing people to survive longer in the cold. This is one application of big idea 1: the process of evolution drives the diversity and unity of life. Those with high blood sugar were selected for at the time due to environmental pressures, creating similar traits in people because these traits were the ones that allowed people to survive and reproduce. What makes brown fat special is that “brown fat has much smaller droplets and is specialized to burn them, yielding heat. Brown fat cells are packed with energy generating powerhouses called mitochondria that contain iron—which gives them their brown color.”
http://directorsblog.nih.gov/brown-fat-white-fat-good-fat-bad-fat/
Random mutations and meiotic events such as crossing over could create genetic variation in the Young Dryas. These change the genetic code of the cells, which change the alleles and the traits that each cell expresses. “For one thing, it became clear that any given trait was usually the product of many genes rather than a single one. A mutation to any one of the genes involved could create small changes to the trait rather than some drastic transformation.” But since this happens on such a small scale, many changes will occur over time to develop a large enough change to increase the ability to survive and reproduce of an individual.
http://evolution.berkeley.edu/evolibrary/article/history_19
Adaptations arise over time due to evolution. For microevolution to occur, a specific population of a certain species must be in an environment with selective pressures such as weather, predation, and competition. These different pressures will select for traits expressed by certain individuals that allow them to survive and reproduce. Those that are selected against will die out, removing the alleles that put individuals at a disadvantage from the gene pool.
Post by Jeremy Bush on Sunday march 10
By Daniel Majeed dmajeed4@students.d125.org