What is the significance of double bonds in the fatty acids?
Answers:
A double bond means the fatty acid is unsaturated.
Depending on wither it is a cis (hydrogens on same side) or trans (hydrogen on alternating sides), this can either be good or bad for you :)
here is a picture
http://www.bastnet.com/fatfacts/images/c.
If it is cis, then there will be a bend in the fatty acid, and the stuff won't cling so smoothly to your arteries
If it is trans, then the chain appears straight, and that is not good for you~
Double "OO" in your fatty acids means you are beginning to look like an "O"
The double bond indicates that the fatty acid is unsaturated ( this is the definition of unsaturated.).
Double bonds tend to be less stable and this means that unsaturated fatty acids tend to "turn into something else" with single bonds.
This has an implication for people who cook with unsaturated fatty acids, as heat tends to promote this change.
If you want to know what you are eating, it is safer to cook with saturated fats - they are stable at high temperatures.
Double bonds change the shape of fatty acids. First of all, there are saturated fatty acids (in which every carbon atom makes four bonds and there are no double bonds in the hydrocarbon chain) and unsaturated (in which there are one (monounsaturated) or many (polyunsaturated) double bonds).
Saturated fatty acids are relatively linear and they can stack pretty well on top of one another like sheets of paper. These types of fats tend to be solid at room temperature (butter, shortening) because the hyrocarbon chains can fit so closely together. This also means that they can stack pretty well on top of each other in your arteries as well and clog them.
Unsaturated fats have double bonds that can come in two forms as posted earlier. A trans unsaturated fat, although the bond angles change a little around the carbon atom, is still realtively linear. A cis unsaturated fat however has a pretty dramatic kink in it. This means that the fatty acids chains can't get as close together and these fats won't pack as well together and tend to be liquid at room temperature (vegetable oils). Imagine stacking a flat sheet of paper on top of a folded one, they won't fit very tightly. So they won't pack together as well in your arteries either.
If you look at a jar of JIF and a jar of natural peanut butter, you may notice that the natural stuff has a solid component and a liquid component. This is because of the different types of fat in a peanut, the solid part is saturated fats and the liquid is unsaturated. This kind of bugs consumers since they have to mix the two together before making a sandwich, so companies now take the unsaturated fats and bombard them with hydrogen to break up those double bonds and saturate the fatty acid chains with hydrogen. That is why JIF has no liquid component to it and why is says "partially hydrogenated _____ oil" in the ingredients on the back. All so you don't have to stir it!
Three differences are important:
1) A double bond in the molecule of a fatty acid shows that the two C-atoms on either side are unsaturated and therefore more reactive. They easily react with oxygen to become rancid and with hydrogen to become saturated.
2) A double bond also reduces the melting point of fatty acids and most of them change from solid to liquid.
3) A double bond also allows the molecule to have two different shapes ie straight or bent which are called cis and trans. Nearly all the natural fatty acids are in the cis form.
Double bonds mean the fatty acid is unsaturated.
Unsaturated fatty acids tend to be more liquid than the corresponding saturated fatty acids.
Unsaturated fatty acids will therefore tend to be cooking oils, while saturated fatty acids will tend to feature in fats and lards.
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