3.5 Lipids Flashcards
What state are fats, normally? (1 mark)
Solid
What state are oils, normally? (1 mark)
Liquid
Are lipids polar? (1 mark)
No.
Why are lipids non-polar, what does this mean for its interaction with water? (2 marks)
The electrons in the outer orbitals are more evenly distributed.
This means lipids are not soluble in water.
What is a macromolecule? (1 mark)
Large, complex molecules built from repeating units (monomers).
What is a triglyceride made up of? (1 mark)
One glycerol molecule bonded to three fatty acids.
What type of molecule is glycerol, what does this mean? (1 mark)
An alcohol, it has an OH group(s) (in this case 3)
What type of molecule is a fatty acid, what does this mean? (1 mark)
Carboxylic acid, contains a COOH group
How do the bonds between fatty acids and glycerol form? (1 mark)
Condensation reaction (or esterification), interaction between the hydroxyl groups.
What are the bonds between fatty acids and glycerol called? (1 mark)
Ester bonds
What is a fatty acid with double bonds between the carbons called? (1 mark)
Unsaturated
What is a saturated fatty acid? (1 mark)
A fatty acid with only single bonds between the carbons.
What is a fatty acid with one double bond linking two carbons called? (1 mark)
Monounsaturated
What is a fatty acid with two or more double bonds linking carbons called? (1 mark)
Polyunsaturated
Why are unsaturated fatty acids oils? (3 marks)
The double bonds cause the molecule to bend, so they do cannot pack as closely together, making them liquid at room temperature.
What elements do phospholipids contain? (2 marks)
Carbon, oxygen, hydrogen, phosphorus
What components does a phospholipid contain? (2 marks)
A glycerol, two fatty acids, and a phosphate group.
Are fatty acids polar? (1 mark)
No, they are non-polar
Where are inorganic phosphate ions found? (1 mark)
In the cytoplasm of every cell.
Is a phosphate group hydrophobic or hydrophilic? (1 mark)
Hydrophilic
Phospholipids either form a layer on the surface of water or form bilayer structures in water, explain why this happens. (4 marks)
The ‘heads’ of the phospholipids are hydrophilic.
The ‘tails’ of the phospholipids are hydrophobic.
This means on the surface of water, the ‘heads’ are pointing downward into the water and the tails avoid it.
It also means, they form bilayers when in water, where there are two layers of phospholipids, so the tails can point inwards away from the water.
Why is the dual hydrophobic/hydrophilic structure of phospholipids so important? (1 mark)
They form cell membranes, separating environments.
What type of molecule is a sterol? (1 mark)
An alcohol
Describe the structure of a sterol. (2 marks)
They are a four carbon ring structure, with an OH group at one end and a hydrocarbon chain at the other end.
