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Fall SAVY 2016 (Day 4) – Intro to Macromolecules

Posted by on Monday, October 17, 2016 in Grade 3, Grade 4, SAVY.

This week in Intro to Macromolecules, we began by reviewing our carbohydrate lab results from the previous week. We chose to analyze our results visually by creating a Venn diagram as a group, with the two overlapping circles being labeled “monosaccharides” and “starch.” We noticed that some foods contained just monosaccharides (ex. galactose) or just starch (ex. corn starch), while others contained both (ex. yellow squash). The students analyzed the data and tried to draw some generalizations about which types of foods contain which types of sugar. Some observations included that sweet-tasting foods usually contain monosaccharides and that many vegetables, especially ones that grow underground, contain starch. We also sought to put our carbohydrate knowledge to practical use by addressing questions in small groups about issues such as “low-carb” diets, what to eat to get energy quickly after exercise, the basis for lactose-intolerance, and the structural and caloric differences between artificial and natural sugars. I encourage you to ask your student about which question his/her group had and what they proposed as an answer.

Next we began studying our second class of macromolecule—lipids. Just as carbohydrates are classified as “macromolecules” because they are composed of repeating sugar monomers, lipids are macromolecules because they are usually composed of multiple fatty acids joined together. We compared the structures of the three different categories of lipids (triglycerides, phospholipids, and steroids) and discussed the correlation between their structures and their names. We also compared the structure of fatty acids with and without double bonds using a molecular modeling kit. The students were quick to point out that addition of a double bond put a “kink” in what had previously been a relatively straight molecule and that addition of the double bond resulted in removal of two hydrogen atoms. Fatty acids lacking double bonds are called saturated fats (saturated with hydrogen atoms), while fatty acids containing double bonds are called unsaturated fats. After comparing the forms and sources of each type of fat (saturated vs. unsaturated), we had the opportunity to extract fat from three different types of food using acetone (an organic solvent in which lipids will dissolve). I am looking forward to next weekend when we will analyze our results. In the meantime, discuss with your student what types of fat he/she thinks will be present in mini chocolate chips, potato chips, and sunflower kernels. Also ask your student how he/she will be able to identify the type of fat present.

See you next week!