lipids structure and function Flashcards
Characteristics
They are insoluble in water, dissolve in organic solvents, act as nutrients and provide energy to the body 9 kilocalories per cell. They contain a COOH group at the end of a long carbon chain.
Mistake commonly made about lipids
They were originally thought to cause people to become fat but instead the lack of lipids in the body causes carbohydrates to break down to produce saturated fat to make up for their absence. Saturated fat can’t be stored in membranes so instead it is stored in adipose tissue.
Functions
- make up membranes
- Send signals between cells in the body, let body know if their is membrane damage
- control metabolism of carbohydrates-makes sure they are not broken down to make saturated fat
- Precursors to prosthogladins and sterioid hormones
Functions in food
- Provide lubricity-slip and slide feeling on tounge
- Provide viscosity- thickness
- shortening and areation for baked goods
- acts as a flavor, and aroma carrier
- act as neurological trigger to let you know if you are satisfied or not with what you ate
- act as emulsifier
- involved in oxidative degradation-limits shelf life of food
3 classes
- metabolically and chemically derived forms-fatty acids, cholestrol and sterols
- Neutral lipids
- Complex compound lipids
nomenclature
w system: write down number of carbons first, number of carbons starting from ch3 group to double bond and number of double bonds that come after that (not the location)
Delta system: Write down number of carbons first, and then the location of all the double bonds based on the first carbon they are attached to.
Fatty acid and glycerol reaction
The fatty acid replaces all of the OH groups on the glycerol with ester groups transforming it into a triacyglycerol molecule (very hydrophobic). The triacyglycerol molecule can then be broken down to produce mono and diacyglycerol molecules which can act as emulsifiers
Squalence molecule
This is a type of hydrocarbon with frequent double bond which can be used to bind to molecules only found on cell membranes so they can react with them
Three chemical groups
- Chemically derived lipids-fatty acids which consist of unsaturated or saturated molecules that are heavily reactive and provide energy to the body.
-Cholesterols
-sterols
-Fat soluble vitamins A, E, D &K
Hydrocarbons-squalenes - Neutral lipid storage molecules- when fatty acids are converted to esters when reacted with glycerol and other alchols.
-Free fatty acids react with glycerol to produce triacyglycerols (storage molecule). Mono and diacyglycerols can be used as emulsifiers because of their amphiplilic nature
Complex or compound lipids
These are both polar and non polar and are used to produce membranes and transport fatty acids throughout the body. These include phospholipids and glycolipids.
Phosphoplids formation and types
glycerol-3-phosphate reacts with fatty acids to produce phosphatic acid whose oH group can be replaced with an inositol ring, a serine, choline or ethanolomine structure
Inositol-very hydrophobic and useful in creating the membrane of nerve tissue. Contains aromatic ring filled with attached OH groups that ionize often
Serine-protonted amine and deprotonated carboxyl under biological conditions which are used to actively metabolize organ tissue.
ehtanolomine- Interspersed between choline to help keep all phospholipids packed together despite not being charged. Binds to molecules using h bonding. Amide bonded to H and not charged
Choline- can bind to H20 and everything with the charge that it has. (what do these molecules need to bind to?) +charged N group
Waxes
These are neutral lipids formed by the reaction of a long fatty acid with a long chain alchol producing a long carbon chain ester which have a hydrophobic effect strong enough to act as a barrier to protect against surface water from getting into a food. It can also prevent moisture from getting from one part of the food into another part of the food by seperating each layer with natural plant based wax.
