VISUAL SKILLS Choose the term that correctly describes the relationship between these two sugar molecules: a. structural isomers b. cis-trans isomers c. enantiomers d. isotopes

Video transcript

Welcome back today. We'll be looking at this problem. Which one of the following statements is not true regarding glucose and fructose. That not is our reminder that we'll be looking for a false statement about these two molecules. When I look at my answer choices, I see their answers about molecular formulas and structural formulas. So a good place to start here. Might be going to my textbook and looking at the structures of glucose and fructose. So I'm going to do that and I'll put that structure right here for us to look at. When I look closely at these structures, I see that they're very similar except for the location of one thing. They both have a C double bonded to an O. But in the glucose molecule here on the left that C O double bond is on a terminal carbon at the end With a hydrogen attached to it on one side that makes this an alga hide group on fructose. However here on the right that C O double bond is on an internal carbon with carbons bonded to it on either side. That makes this a ketone group. Now coming on back over to my answer choices. Let's start with choice A. It says both have the same molecular formulas. Well, when I come back over to my structures here, I can figure out the molecular formulas that lists how many of each kind of atom or in the molecule. So for glucose here, I counted up all the seas. Os and H is I would get six carbons, 12 hydrogen and six oxygen's going over to fructose. I count them all up. I'm going to get the same thing. C6 H 12 oh six. So when I come back to choice A. Here both have the same molecular formulas That is true. Which makes this not the correct answer to our question where we're looking for a false statement. Choice B says both have different structural formulas as we saw. These structures are indeed slightly different with the location of that C. O double bond. So this is also true statement and therefore not our answer choice C says both are structural members. The definition of structural members are molecules that have the same molecular formula, but different structural formulas. So that is also true. So we are left by process of elimination with choice D. But if we want to double check choice D says both contain alga hide functional group as we saw glucose does indeed have an alga hide group with this terminal C. O bond with an H bonded to the sea. But fructose has a ketone group instead. So that is a false statement and therefore Choice D. Must be our correct answer to this problem. Hope to see you in the next video