Lipids
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what are the 3 main roles of lipids? (S.E.M)
• specific biological functions e.g. transmission of chemical signals into and within the cell. • Energy storage. • Membrane Structure.
What are the 6 classes of lipids based on their chemical structure? (F.A,T - PGST)
Fatty Acids, Triglyceride. phospholipid, glycolipid, sterols and terpenes.
What are Fatty Acids? give examples
long unbranched hydrocarbon chains w/ a carboxyl group at the end. e.g. myristic acid
Why are Fatty Acids highly reduced?
Bc they have lots of hydrogen atoms but few oxygen atoms so yield a lot of energy upon oxidation and are a more efficient form of energy storage.
What is the tail of a Fatty Acid?
long hydrocarbon chain HYDROPHOBIC.
What is the head of a Fatty Acid?
CARBOXYL group HYDROPHILIC.
Fatty Acids can be? (S.U.P)
Saturated Unsaturated Polyunsaturated
What does the Degree of unsaturation depend on?
the amount of hydrogen a compound can bind.
What is a saturated compound?
no double or triple bonds between carbons.
what is a unsaturated compound.
one or more double bonds between carbon atoms.
Saturated Fatty Acids?
Have long, straight chains that pack together well bc every carbon atom in the chain has the maximum number of hydrogen atoms attached to it.
Unsaturated Fatty Acids?
contain one or more double bonds, resulting in a bend or kink in the chain that prevents tight packing.
What are unsaturated Fatty Acids also known as and why?
Trans Fats • contain unsaturated fatty acids with a particular type of double bond that causes less of a bend in the fatty acid chain. • causes them to resemble saturated fatty acids both in their shape and in their ability to pack together more tightly than typical unsaturated fatty acids. • naturally present in small amounts of meat and dairy but trans fats are produced artificially during the commercial production of shortening and margarine. • Trans fats have been linked to changes in blood cholesterol that are associated with increased risk of heart disease.
Discuss the Double Bonds in Fatty Acids.
• Almost always in cis- config. • Trans bonds considered to be carcinogenic. • Usually separated by methylene group.
What are Triglycerides composed of?
a glycerol molecule linked three fatty acids
How are Fatty Acids linked to glycerol and how is this formed?
Fatty acids are linked to glycerol by ester bonds, which are formed by the removal of water (condensation reaction).
What is the main function of Triglycerides?
Energy Storage. Animals: Adipocytes (fat cells) -fat droplets fill the cell. Large quantity in many seeds (energy for germinating)
What are Triglycerides (triacylglycerol’s) containing mainly Saturated Fatty Acids structurally?
Are usually solid or semisolid at room temp and are called Fats.
How are triglycerides (triacylglycerol’s) in plants?
In plants, most triacylglycerol’s are liquid at room temperature e.g. vegetable oil.
How does the predominantly unsaturated fatty acid of oil effect it?
their hydrocarbon chains have kinks that prevent an orderly packing of the molecules
How are Fats more efficient?
• They liberate more energy upon oxidation per unit wt. - Fats are hydrophobic so don’t have associated water of hydration.
Fat Function in body?
Insulation, protect internal organs Adipocytes usually under skin -seals, penguins, etc.
What are Waxes? give examples
They are Esters of long chain Fatty acids with long chain alcohol. e.g. Triacontanylpalmitate
What is the function of Waxes? W.H.E.P
• Energy storage (plankton only) • H2O-repellant coatings • Wax layer on hair, feathers (esp. waterfowl) • Protective coating on fruit/berries/some leaves