Lipids Flashcards
(17 cards)
Define Saturated Fatty Acids and explain their structure.
Saturated Fatty Acids are holding as many H atoms as possible, due to the lack of double bonds - hence the name saturated. This results in a relatively straight shape, so molecules can be tightly packed in parallel. This tight structure results in these lipids being solid, or fats.
Define the Ethanol Emulsion Test.
The Ethanol Emulsion Test is a method to check for the presence of lipids. A sample is added to ethanol and shaken to dissolve. Then, distilled water is added. If a cloudy white precipitate forms, then a lipid is present.
What is the role of the hydrophilic nature of the phosphate head in a phospholipid?
The hydrophilic nature of the phosphate head enables the surface of the plasma membrane to stay in place. It also allows carbohydrates to attach and form important receptors on the membrane.
Explain the formation of a phospholipid bilayer membrane structure.
When phospholipids are in water, they move to a position where the heads are exposed to water and the tails are not. This behavior results in the formation of a phospholipid bilayer membrane structure, which forms the plasma membrane around cells.
How does the structure of a phospholipid result in its properties?
The phosphate molecule, or the hydrophilic ‘head’ of a phospholipid, can interact with water as it is charged and repels other fats. The fatty acid chain, or the hydrophobic ‘tail’, is not charged and repels water but will mix with fats. These two regions make the phospholipid a polar molecule.
Describe the structure of a phospholipid.
A phospholipid is made up of a glycerol molecule, two fatty acid chains, and a phosphate group. The two fatty acids bond to the glycerol via two condensation reactions, resulting in two ester bonds.
What happens during a condensation reaction in the formation of a Triglyceride?
During a condensation reaction in the formation of a Triglyceride, a molecule is removed. This reaction occurs between the carboxyl group (COOH) of the fatty acid and the hydroxyl group (OH) of the glycerol. The bond that forms between the glycerol and carboxyl group of the fatty acids is an ester bond.
Explain the properties of Triglycerides.
Triglycerides are an energy storage. Due to the large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms, a lot of energy is stored in the molecule. Due to the high ratio of hydrogen to oxygen atoms, they can act as a metabolic water source. As lipids are large, hydrophobic molecules, they are insoluble in water. This means they will not affect water potentials and osmosis. Lipids are relatively low in mass.
How are Triglycerides formed?
Triglycerides are made up of one glycerol molecule and three (tri) fatty acids. These fatty acids are each bonded onto the glycerol by a condensation reaction. The condensation reaction occurs between the carboxyl group (COOH) of the fatty acid and the hydroxyl group (OH) of the glycerol. The bond that forms between the glycerol and carboxyl group of the fatty acids is an ester bond.
Describe the elements that make up lipids.
Lipids are biological molecules that contain the elements carbon, hydrogen, and oxygen. However, unlike carbohydrates, lipids have much less oxygen.
Describe the structure of Unsaturated Fatty Acids.
Unsaturated Fatty Acids have at least one double bond between carbon atoms. If they have one double bond, they are described as being monounsaturated. If there are many double bonds, it is polyunsaturated. Unsaturated fatty acid chains kink where the double bonds are, and are therefore far less straight. This means the lipid molecules can’t be as tightly packed and thus are in a liquid state, oils.
What is the structure of a fatty acid?
Fatty Acids are long chains of carbon and hydrogen atoms with a carboxyl group at one end (COOH).
What is the difference between saturated and unsaturated fatty acids?
Saturated Fatty Acids have no double bonds between the carbon atoms, while unsaturated fatty acids have one or more double bonds.
Define Saturated Fatty Acids.
Saturated Fatty Acids are long chains of carbon and hydrogen atoms with no double bonds between the carbon atoms.
What are the two molecules that make up lipids?
Lipids are made up of two molecules, fatty acids, and glycerol.
What are the two key types of lipids?
The two key types of lipids are triglycerides (fats and oils) and phospholipids (found in cell membranes).
How do lipids interact with water?
Lipids are non-polar molecules or uncharged and therefore are insoluble in water. They are described as being hydrophobic.
