lipids Flashcards
(27 cards)
what are the four types of biological molecules?
proteins, lipids, carbohydrates, nucleic acid
what is the structural formula of glycerol?
structure (C3H8O3):
H
|
H — C — OH
|
H — C — OH
|
H — C — OH
|
H
what is a triglyceride?
one molecule of glycerol and three fatty acid tails
what is the general formula of a saturated fatty acid?
Cn H2n O2
what is the structural formula of a fatty acid tail?
structure
O
||
HO — C — (CH2)n — CH3
what type of reaction joins glycerol and fatty acid tails together?
condensation reaction
what is produced as a byproduct after the formation of a triglyceride?
3H2O
name some functions of lipids
phospholipids- in biological membranes and myelin sheaths (electrical insulation)
triglycerides- buoyancy, energy storage, thermal/electrical insulation, protection of internal organs
what is the structural formula of a phospholipid?
structure
H
|
H — C — fatty acid tail
|
H — C — fatty acid tail
|
H — C — PH4
|
H
what does the phosphate head contain?
glycerol + phosphate group (PH4), joined by an ester bond
describe the properties of the phosphate head
hydrophilic (polar), meaning it will interact with H2O
describe the properties of the fatty acid tails
hydrophobic (non-polar), meaning they will not interact with H2O
how are phospholipids arranged in the cell membrane?
phospholipids are arranged in a bilayer. the phosphate heads are arranged at the edges of the membrane, as they interact with the extracellular fluid on the outside and cytoplasm on the inside (containing H2O). the fatty acid tails point into the middle of the membrane as they do not interact with H2O
explain the differences between a triglyceride and a phospholipid
a phospholipid only contains 2 fatty acid tails, whereas a triglyceride contains 3
triglycerides do not contain a phosphate group
describe a saturated fatty acid
-only single carbon-carbon bonds (‘saturated’ in hydrogens- max. no)
-chains pack closely together as the tails are straight, so saturated fats are liquid at room temperature
- e.g. animal fats such as butter
describe an unsaturated fatty acid
-contains one or more carbon-carbon double bonds (‘unsaturated’ in hydrogen- doesn’t contain max. no.)
-chains do not align as the tails are kinked, so unsaturated fats are liquid at room temperature
-e.g. plant fats such as olive oil
what is the difference between a polyunsaturated fatty acid and a monounsaturated fatty acid?
poly- two or more double C-C bonds
mono- only one C-C double bond
what type of reaction breaks down a triglyceride into glycerol + fatty acids?
hydrolysis
describe the test for lipids
the emulsion test- ethanol and water are added to the sample. if lipids are present a white emulsion will form
what is meant by a polar compound?
has an uneven distribution of electrons:
§+ (slightly positive, less pull on electrons)
§- (slightly negative, more pull on electrons)
polar compounds interact with other polar compounds
what is meant by a non-polar compound?
even distribution of electrons
interacts with other non polar compounds
what is an LDL?
low-density lipoprotein
“bad cholesterol”
what does an LDL do?
deposits cholesterol in the coronary arteries -> increases risk of atheroma forming -> narrows arteries -> blood flow to heart decreased -> increases risk of coronary heart disease
what kind of diet promotes LDLs?
a diet high in saturated fats
