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Biology: Saturated vs. Unsaturated Fats


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  • Type: Video Tutorial
  • Length: 9:29
  • Media: Video/mp4
  • Use: Watch Online & Download
  • Access Period: Unrestricted
  • Download: MP4 (iPod compatible)
  • Size: 101 MB
  • Posted: 07/01/2009

This lesson is part of the following series:

Biology Course (390 lessons, $198.00)
Biology: Inorganic and Organic Chemistry (34 lessons, $51.48)
Biology: Lipids and Nucleic Acids (4 lessons, $6.93)

Taught by Professor George Wolfe, this lesson was selected from a broader, comprehensive course, Biology. This course and others are available from Thinkwell, Inc. The full course can be found at The full course covers evolution, ecology, inorganic and organic chemistry, cell biology, respiration, molecular genetics, photosynthesis, biotechnology, cell reproduction, Mendelian genetics and mutation, population genetics and mutation, animal systems and homeostasis, evolution of life on earth, and plant systems and homeostasis.

George Wolfe brings 30+ years of teaching and curriculum writing experience to Thinkwell Biology. His teaching career started in Zaire, Africa where he taught Biology, Chemistry, Political Economics, and Physical Education in the Peace Corps. Since then, he's taught in the Western NY region, spending the last 20 years in the Rochester City School District where he is the Director of the Loudoun Academy of Science. Besides his teaching career, Mr. Wolfe has also been an Emmy-winning television host, fielding live questions for the PBS/WXXI production of Homework Hotline as well as writing and performing in "Football Physics" segments for the Buffalo Bills and the Discover Channel. His contributions to education have been extensive, serving on multiple advisory boards including the Cornell Institute of Physics Teachers, the Cornell Institute of Biology Teachers and the Harvard-Smithsonian Center for Astrophysics SportSmarts curriculum project. He has authored several publications including "The Nasonia Project", a lab series built around the genetics and behaviors of a parasitic wasp. He has received numerous awards throughout his teaching career including the NSTA Presidential Excellence Award, The National Association of Biology Teachers Outstanding Biology Teacher Award for New York State, The Shell Award for Outstanding Science Educator, and was recently inducted in the National Teaching Hall of Fame.

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Remember that lipids are big time energy storage molecules. They have other functions, but I want to talk to you right now about some lipids that are out there and some controversies you may have heard of. You've probably heard of saturated fats versus unsaturated fats and which one is good and which on isn't good and the uses of fats. Let's take a quick review here of what a fat is all about. Fats are triglycerides. A glycerol backbone hooked, generally, to three fatty acids. The fatty acids can be any length. The thing I want to talk to about right now is this whole idea of what is a fatty acid and what does the term saturated mean versus unsaturated.
Well, quick review of carbon chemistry. Remember that carbon has four bonding sights. Using the Lewis dot notation, we have our four balance electrons. Remember that carbon tends to form chains. So, one carbon can hook up with hydrogens and completely saturate its bonds with hydrogens. Oh, did you hear that word? Completely saturate its bonds with hydrogens. On the other hand, many carbons, as in what you seem to see right here, where the carbon is hooked to a carbon, hooked to a carbon, hooked to carbon, and the hydrogens are filling those free bonding sights that are not part of the carbon chain, will hook with another carbon. We'll make his electrons x's. So, our chains can grow. We could go with a hydrogen here and a hydrogen here. So, blah, blah, blah, blah, blah, all the way down to the end where we can illustrate the end of a fatty acid molecule with CH[3.]
Well, I want to talk to you about makes something a saturated fatty acid or saturated fat, as opposed to an unsaturated one. If you remember much about carbon chemistry, you remember that carbon can sometimes form double bonds. Remember that carbon isn't--and you know what? Carbon can form triple bonds even. We don't find that a lot in living systems. It's these double bonds that are very, very important. So, carbon can actually, as it's making its chain--if we were to pop off one of these hydrogens--if this were going to be part of a fatty acid and we were going to pop off one of these hydrogens, well now, this carbon in my hand has one, two, three bonding sights filled. It indeed does have a fourth one to continue on in the chain way.
However, when that happens, you'll notice that we have lost a hydrogen. In losing that hydrogen, we've lost our idea of being saturated with hydrogen. So, what starts to happen in a situation like this, is you get something that looks like this. So, here's my carbon and I'm going to illustrate all of the hydrogens with just plain old straight lines now. I'll throw in the hydrogen, so--okay? Now, here's what's going to happen. Here's a carbon and we're going to put that here and we're going to put that here. Now, what we're going to do is on my next carbon, we are going to double bond it to that one.
Now let's see what happens. Check this out. This carbon is using--let's see how many bonds it's using. One, two, three. So, it only has room for one hydrogen right there. Continuing the chain, this carbon is already using one, two, three. So, it only has room for one hydrogen there. We have lost this idea of being saturated. So, we now have an unsaturated fat. What do you think polyunsaturated fats are? You got it. Polyunsaturated fats are fats that have several sights with double bonds. Well, what's up with this controversy, saturated versus unsaturated fats and why do we care?
Well, here's the problem. Your bodies are lacking something and what they do is we lack the ability to make double bonds. We can't make those double bonds. When we synthesize fats, we can only make those big old long saturated fats. But the problem is that we need unsaturated fats in our cell membranes. We need--you see what happens when you make--there's a lot to learn still about lipids and cell membranes and things like that, but we need--one simple thing I want you to know for the purpose of where we're going here, is that our cell membranes need unsaturated fats. The second thing I want you to remember is this. We can't make them. We can't make them.
So, guess what. We need to take some in. Now, that doesn't mean start eating a whole lot of ice cream. Oh good, I'm going to eat ice cream and take in all this fat. But, the bottom line is we do need to take in some fats. Of course, our diets are way too fatty. But this isn't a course in nutrition. Oh man. Don't push that button, because I feel very strongly, sometimes, about some of the things you guys take in. Here's the problem. The problem is this. Saturated fats--well, wait a minute. I call this a problem. It shouldn't be a problem, but you're going to see some people who've made it a problem. Watch this. Saturated fats: those fats that have no double bonds. Saturated fats are more solid at room temperature.
In other words, a saturated fat is less likely to be a liquid at room temperature. So, we're going to say solid. Unsaturated fats at the temperature that we often will consider to be roomy temperature will be more liquid. All right, here's the problem. The problem is peanut butter. I don't know if peanut butter is your problem, but it's the problem we're going to talk about right now. Peanut butter has--peanut oil, has unsaturated fats in it. Peanut oil. Unsaturated fats. Okay, is that good or is that not good? Think. Yes, that's right. That's good, because we need these guys. We need unsaturated fats. They're unsaturated, which means they're liquid at room temperature. Right?
Guess what. Some of you guys, maybe it's not you, maybe it's like, the other consumers. But they go--we have our high tech flask. They go to the grocery store where things are stored at room temperature and they look in the grocery store. They take a look at this peanut butter and they say, "Man this peanut butter is spoiled, because it has all this gross grease on top." So, they don't buy it, unless they're a wizened consumer. Unless they're listening to me. Because, you see, that's unsaturated fats. That's good. Well, that's not bad. Okay?
Now, what has the peanut butter industry done? Those of you, who are watching from the peanut butter industry, don't take this personally. What they have done, is they take peanut oil and they hydrogenate it. Hydrogenate it. In other words, they add hydrogen. So, you know those double bonds? They're breaking them and putting hydrogens on them instead and making it into a single bond by bombarding that thing with hydrogens. So, instead of oily peanut butter--well, you still do get oily peanut butter, but now instead of--and we only use the best here. We open this fresh for you guys, because we want you to see that we're not making this up. Instead, look, no oil.
It's nice and solid and it's saturated. It's not going to do you much good unless you're real skinny and you need to fatten up a little bit. Because you're not going to use this in your cell membranes. You are going to use this in your cell membranes. Don't take in too much of it. So, saturated, unsaturated, one looks better. Which one? I don't know. You know, I don't get grossed out by this. This one, everybody thinks, looks a lot better, but this one is better. Remember that next time you go grocery shopping.
Inorganic and Organic Chemistry
Lipids and Nucleic Acids
Saturated vs. Unsaturated Fats Page [1 of 2]

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