Lipids

Question 1

What is the structure of a triglyceride?

Answer 1

Glycerol with three fatty acid chains

Question 2

What are the roles of triglycerides?

Answer 2

1. Store energy in adipose tissue
2. Adipose tissue provides thermal insulation to maintain core temperature.
3. Adipose tissue provides shock absorption due to its flexibility.

Question 3

What happens if people don’t have enough adipose tissue?

Answer 3

They can become susceptible to hypothermia and bruising/damage from of a protective layer provided by adipose tissue.

Question 4

Compare triglyceride to glycogen?

Answer 4

Once free glucose has been catobolised, glycogen can be hydrolised quickly.

Fatty acids are for long-term energy storage. The process to access them for energy use is more complicated and difficult.

Question 5

How are stored triglycerides used for energy?

Answer 5

1. Adrenaline or glucagon is released which mobilises LIPASE which liberates triglycerides from ADIPOSE tissue and in a series of hydrolysis reactions cleaves ester bond of GLYCEROL and FATTY CHAIN.
2. Protein ALBUMIN binds to fatty acids and TRANSPORTS to required location where the KREBS CYCLE transforms the fatty acid into GLUCOSE within the MITOCHONDRIAL MATRIX.
3. GLYCEROL is absorbed into the LIVER where it is turned into GLUCOSE.

Question 6

What is a phospholipid and its structure?

Answer 6

A sub-class of lipid with a phosphate group in the hydrophilic head region.

Question 7

What is the structure of a phospholipid?

Answer 7

A glycerol is a bridge between two fatty tails and the phosphate.

Question 8

What is a MICELLE?

Answer 8

Head is hydrophilic and hydrocarbon tail is hydrophobic. The tail faces away from the water, and the head faces the water, making a single layer phospholipid sphere called a MICELLE.

Question 9

What is a PHOSPHOLIPID BILAYER?

Answer 9

If there are enough phospholipids, they create bilayer which is the major constituent of cell membrane where the hydrophobic tails face into each other with the hydrophilic polar heads facing outwards, protecting the cell.

Question 10

What is a steroid and its structure?

Answer 10

A type of lipid, such as cholesterol.

Structure is FOUR FUSED CARBON RINGS.

Question 11

What is the role of steroids in the human body?

Answer 11

1. Component of the cell membrane imparting flexibility to the membrane, to maintain desired fluidity of the phospholipid bilayer.
2. Cholesterol is a precursor molecule to Vitamin D and sex hormones.
3. In digestion, the LIVER secrets steroids in the form of bile acids which emulsify fats to allow lipase to digest them.