Lipids Flashcards
Describe the structure of a triglyceride.
1 molecule of glycerol and 3 fatty acids.
What bond exists between a glycerol and fatty acid?
Ester bond.
Are triglycerides polar or non polar
Non polar.
Are triglycerides hydrophilic or hydrophobic?
Hydrophobic.
What functional group does glycerol have?
Hydroxyl
What functional group do fatty acid tails have?
Carboxylic acid.
How many carbon atoms could be found in a fatty acid group?
4-24
Describe how an ester bond is created when forming triglycerides.
The methyl group of the fatty acid undergoes a condensation reaction with the hydroxyl group of the glycerol, eliminating a water molecule, forming an ester functional group.
How are triglycerides able to store lots of energy?
How does this compare to carbohydrates?
High ratio of C-H bonds to C atoms in the hydrocarbon tail.
This means they can release more energy than the same mass of carbohydrates.
Why do triglycerides have no effect on the water potential of cells?
Triglycerides are insoluble in water so there is no effect on water potential.
How do triglycerides behave in water?
They clump together to form droplets.
What is a saturated fatty acid?
A fatty acid with a hydrocarbon chain containing single C-C bonds only.
What is an unsaturated fatty acid?
A fatty acid with a hydrocarbon chain consisting of C=C bonds as well as C-C bods
Where do saturated fats come from?
Animal sources.
Where do unsaturated fats come from?
Plant sources.
Describe the breakdown of triglycerides.
The triglyceride will undergo 3 hydrolysis reactions for each ester bond. This means 3 water molecules are required.
Why are trans fatty acids more unhealthy than cis fatty acids?
Trans fatty acids can’t be metabolised by enzymes as the functional groups lie on opposite sides of the C=C bond. This means they can’t be broken down by the body, leading to coronary heart disease.
Give 4 roles of fats.
Insulation
Organ protection
Energy source
Waterproofing
Why are saturated fats bad for you?
What state are they at room temperature?
How do they affect cholesterols?
The straight hydrocarbon chain means fats can easily stack on top of each other.
They are solid at room temperature.
They cause LDL cholesterols to raise.
Why are unsaturated fats more healthier than saturated fats?
What state are they at room temperature?
How do they affect cholesterols?
Unsaturated fats have a bent hydrocarbon chain. This means molecules cannot pack as tightly together.
This means they are liquid at room temperature.
They cause LDL cholesterols to lower and raise HDL cholesterols.
Describe the structure of phospholipids.
1 glycerol molecule bonded to 2 fatty acids and 1 phosphate head.
Why are phospholipids polar?
A dipole is present in the phosphate group, leading the phosphate head to be negatively charged, while the rest of the molecule is more positively charged.
Why phospholipids hydrophillic or hydrophobic?
Why?
They are both.
This is because the phosphate head is polar, and therefore hydrophilic. The fatty acid tails are non polar and therefore are hydrophobic.
Why do phospholipids form a bilayer?
The hydrophilic heads face outwards as they are attracted to water.
The hydrophobic tails point inwards towards each other so they can avoid water.
