Biology: Lipids

Question 1

What is a lipid

Answer 1

Lipid is the term used to encompass fats and oils. They provide more energy than carbohydrates and so are a good energy store.

Question 2

Triglyceride

Answer 2

A lipid is commonly found in the form of a triglyceride, made up of one glycerol bonded to three fatty acids. Each fatty acid is joined onto the glycerol by an ester bond, formed during a condensation reaction.

Question 3

Saturated fats

Answer 3

Saturated fats are made up of long fatty acid chains, containing the maximum amount of hydrogen (no carbon-carbon double bonds. They are commonly found in meat and dairy products. They have strong inter molecular bonds between chains and so can be packed tightly together and require a lot of energy to break down, making them solid at room temperature.

Question 4

Unsaturated fats

Answer 4

Unsaturated fats contain carbon-carbon double bonds creating ‘kinks’. If only one double bond is present, the fat is monounsaturated and if multiple are present it is polyunsaturated. Due to the kinks in the chain, the fatty acids cannot pack closely together and so have weak inter molecular forces so can easily be broken down and are liquids at room temperature. They are most common in oils.

Question 5

Cholesterol

Answer 5

Cholesterol is a small lipid used to form many important structures such as the cell membrane, as well as produce hormones such as progesterone and testosterone.

Question 6

Phospholipids

Answer 6

Phospholipids are similar in structure to triglycerides, however they contain a negatively charged phosphate group in place of one of the fatty acids.

Question 7

Vitamins

Answer 7

Fats are also good sources of the fat soluble vitamins A, D, E and K as well as sources of essential fatty acids, which can lead to deficiency diseases if not enough are consumed in our diet through fats.