BIOL1040 Lecture Notes - Lecture 10: Cod Liver Oil, Peanut Butter, Adipose Tissue
23 May 2018
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LIPIDS AND FATS
LIPIDS
• Lipids are a diverse group of hydrophobic molecules
• Unlike proteins and carbohydrates they are not true polymers
• The compounds called lipids are grouped together with one shared property - they mix poorly
if at all with water
• Although they may have polar bonds (e.g. covalent bonds to oxygen (electronegative)) they
consist mostly of hydrocarbon regions – i.e. hydrogens and carbon molecules
• Lipids are varied in form and function - contain various groups of compound e.g. waxes,
certain pigments, fats, phospholipids and steroids
FATS
• These are large molecules (but not polymers)
• Contain two kinds of smaller molecules
o Glycerol – this is an alcohol
o Fatty acids – long carbon chain (normally 16-18 carbons in length), they have a
carboxylic acid at one end – why they are called fatty acids
• Glycerol and fatty acids are joined by an ester bond – carboxyl group and a hydroxyl group
FATTY ACIDS
• There have been more than 100 fatty acids identified in living things
• By varying the types of Fatty Acids in the fat molecule different Fats are formed.
• The actual state of a fat, solid or liquid, is determined by the shape of the Fatty Acid Chain.
• They can be divided into two groups:
o Saturated Fatty Acids (saturated with respect to hydrogen - has as many hydrogen as it
can)
o Usaturated Fatty Aids doule od to aro so it does’t have as ay hydroges
as it could have)
STORAGE FATS
• The major form of energy storage is triacylglycerides (triglyceride),
• Can be simple (all fatty acids the same) or complex (different fatty acids)
• Saturated fats, saturated with hydrogens or unsaturated (double bonds, form kinks, cis
conformation)
• Most animal fats are saturated, this flexibility allows them to be packed tightly together
• Plant and fish fats are often unsaturated
• Fats liquid at room temperature are often called oils, cod liver oil, olive oil
• Hydrogenated vegetable oils, have been synthetically converted from unsaturated to
saturated fats, e.g. margarine and peanut butter)
• High dietary intake of saturated fats is a factor in cardiovascular disease – form plaques
• Hydrogenation of vegetable oils produces saturated fats but also trans- double bonds
WHY FATS FOR ENERGY STORAGE?
• a gram of fat stores more than twice as much energy as a gram of sugar
• Animals need to carry their energy reserves with them – advantage of fats
• I otrast plats predoiately use arohydrates starh as they do’t ove, ost
vegetable fats come from seeds
• Animal fats stored in adipose cells
• These cells swell and shrink with fat
• Cells cushions vital organs (e.g. kidneys) and insulation
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Document Summary
Lipids are varied in form and function - contain various groups of compound e. g. waxes, certain pigments, fats, phospholipids and steroids. Storage fats: the major form of energy storage is triacylglycerides (triglyceride), can be simple (all fatty acids the same) or complex (different fatty acids) Why fats for energy storage? a gram of fat stores more than twice as much energy as a gram of sugar: animals need to carry their energy reserves with them advantage of fats. I(cid:374) (cid:272)o(cid:374)trast pla(cid:374)ts predo(cid:373)i(cid:374)ately use (cid:272)ar(cid:271)ohydrates (cid:894)star(cid:272)h(cid:895) as they do(cid:374)"t (cid:373)ove, (cid:373)ost vegetable fats come from seeds: animal fats stored in adipose cells, these cells swell and shrink with fat, cells cushions vital organs (e. g. kidneys) and insulation. Why utilise fats: the carbon in fatty acids (mostly ch2) is highly reduced (so its oxidation yields the most energy possible). Phospholipids: major component of the cell membrane. Similar to triacylglyceride but only has two fatty acids, glyercol, phosophate (-ve charge)
