Lipids: Fats & Oils

long term energy storage Lipids long term energy storage concentrated energy German scientists said on Sunday they have shown how a gene long associated with obesity might make people fat, a finding that could lead to new drugs to help control weight. Mice without the FTO gene did not become obese and had less fat tissue overall because they burned off more calories even though they moved less and ate more, according to the study published in the journal Nature. FTO has been long linked to obesity. Studies have shown people with two copies of the "obese" version of the gene on average weigh nearly 7 lbs (3 kg) more and are about 70 percent more likely to be obese than those with other versions. 2006-2007

Lipids Lipids are composed of C, H, O “Family groups” long hydrocarbon chains (H-C) “Family groups” Fats Phospholipids Steroids Waxes Do not form polymers big molecules made of smaller subunits not a continuing chain Made of same elements as carbohydrates but very different structure/ proportions & therefore very different biological properties

Making Butter How do the molecules join? Dehydration Synthesis http://sciencehack.com/videos/category/2- Making Butter also a You Tube Video

dehydration synthesis Fats Structure: glycerol (3C alcohol) + fatty acid fatty acid = long HC “tail” with carboxyl (COOH) group “head” enzyme Look at structure… What makes them hydrophobic? Note functional group = carboxyl glycerol (countable and uncountable; plural glycerols) (organic chemistry) 1,2,3-trihydroxy-propane or propan-1,2,3-triol; a trihydric alcohol A syrupy sweet liquid obtained as a by-product in the manufacture of soap from animal or vegetable oils and fats; it is used as an antifreeze, a plasticizer, and a food sweetener and in the manufacture of dynamite, cosmetics etc. Fatty acid: A carboxylic acid derived from or contained in an animal or vegetable fat or oil. All fatty acids are composed of a chain of alkyl groups containing from 4 to 22 carbon atoms (usually an even number) and characterized by a terminal carboxyl group - COOH. The generic formula for mentioned acetic is CH3(CH2)xCOOH (the carbon atom count includes the carboxyl group). Fatty acids may be saturated or unsaturated (olefinic), and solid, semisolid, or liquid. They are classed among the lipids, together with soap and waxes.³ H2O dehydration synthesis

Building Fats Triacylglycerol 3 fatty acids linked to glycerol ester linkage = between OH & COOH hydroxyl carboxyl BIG FAT molecule!! Ester: Any of a class of often fragrant organic compounds that can be represented by the formula RCOOR´ and that are usually formed by the reaction between an acid and an alcohol with elimination of water.² 6tfd

Dehydration synthesis H2O dehydration synthesis enzyme H2O Pulling the water out to free up the bond enzyme H2O enzyme H2O

Why do humans like fatty foods? Fats store energy Long HC chain polar or non-polar? hydrophilic or hydrophobic? Function: energy storage concentrated all H-C! 2x carbohydrates cushion organs insulates body think whale blubber! What happens when you add oil to water Why is there a lot of energy stored in fats? • big molecule • lots of bonds of stored energy So why are we attracted to eating fat? Think about our ancestors on the Serengeti Plain & during the Ice Age. Was eating fat an advantage?

Saturated fats All C bonded to H No C=C double bonds long, straight chain most animal fats solid at room temp. contributes to cardiovascular disease (atherosclerosis) = plaque deposits Mostly animal fats

Unsaturated fats C=C double bonds in the fatty acids plant & fish fats vegetable oils liquid at room temperature the kinks made by double bonded C prevent the molecules from packing tightly together Mostly plant lipids Think about “natural” peanut butter: Lots of unsaturated fats Oil separates out Companies want to make their product easier to use: Stop the oil from separating Keep oil solid at room temp. Hydrogenate it = chemically alter to saturate it Affect nutrition? mono-unsaturated? poly-unsaturated?

Saturated vs. unsaturated  Olive Oil Unhealthy when Heated? Answer: Unfortunately this idea about olive oil tends to come up now and then. Overall olive oil is a very healthy unsaturated fat choice. When cooking with olive oil at home, the heat will evaporate the alcohols and esters which make up the delicate taste and fragrance of this type of oil, but it should not change its health aspects. It makes sense for cooking to use a less expensive olive oil which doesn't have much flavor to begin with and then chose a more flavorful olive oil like extra virgin after cooking or at the table. The thought that heating olive oil may cause it to become an unhealthy trans fat stems from the fact that when oils are heated they can hydrogenate. This really only happens to any appreciable extent when the oil is heated to very high temperatures repeatedly, as would be the case in commercial frying in a restaurant setting. The fact that olive oil is monounsaturated does help increase its resistance to oxidation and hydrogenation. Studies have shown oxidation and hydrogenation occurs to a lesser degree in olive oil than in other oils. But in any case, the amount of hydrogenation is miniscule and no home cook would ever experience this problem unless you heated the oil so hot that it reached a smoking point.

It’s just like a penguin… Phospholipids Structure: glycerol + 2 fatty acids + PO4 PO4 = negatively charged It’s just like a penguin… A head at one end & a tail at the other!

Phospholipids Hydrophobic or hydrophilic? fatty acid tails = PO4 head = split “personality” hydrophobic hydrophillic “attracted to water” Come here, No, go away! interaction with H2O is complex & very important! “repelled by water”

Phospholipids in water Hydrophilic heads “attracted” to H2O Hydrophobic tails “hide” from H2O can self-assemble into “bubbles” bubble = “micelle” (pronounced "my sell" or "my seal”) can also form a phospholipid bilayer early evolutionary stage of cell? water Classroom Demonstration: Oil droplets in Water bilayer water

Why is this important? Phospholipids create a barrier in water define outside vs. inside they make cell membranes! http://www.johnkyrk.com/cellmembrane.html

Steroids Structure: 4 fused C rings + ?? different steroids created by attaching different functional groups to rings different structure creates different function examples: cholesterol, sex hormones cholesterol

Cholesterol Important cell component animal cell membranes precursor of all other steroids including vertebrate sex hormones high levels in blood may contribute to cardiovascular disease Difference between HDL(healthy) and LDL(unhealthy)

Cholesterol Important component of cell membrane helps keep cell membranes fluid & flexible

From Cholesterol  Sex Hormones What a big difference a few atoms can make! Same C skeleton, different functional groups

Let’s build some Lipids! 2006-2007

Ghosts of Lectures Past (storage) 2007-2008

Phospholipids & cells Phospholipids of cell membrane Required Reading Phospholipids of cell membrane double layer = bilayer hydrophilic heads on outside in contact with aqueous solution outside of cell and inside of cell hydrophobic tails on inside form core forms barrier between cell & external environment Phospholipid bilayer Note other molecules in membrane… http://intro.bio.umb.edu/111-112/111F98Lect/soapandoil.html How does soap work?