Sterols

Question 1

What are sterols?

Answer 1

Also known as sterol alcohols and have little in common with fats and oils

Question 2

What is the structure of a sterol?

Answer 2

It is based on a common 4 carbon ring structure with OH attached at one end and a hydrophilic end and a hydrophobic end

Question 3

Where is cholesterol made?

Answer 3

In liver cells and intestines and is then transported in the blood

Question 4

Where is cholesterol vital?

Answer 4

In the blood

Question 5

What are steroid hormones?

Answer 5

Testosterone, oestrogen and progesterone

Question 6

What are steroid hormones made of?

Answer 6

Cholesterol

Question 7

Why can steroid hormones pass through membranes (including the nuclear envelope)?

Answer 7

Because they are lipids so they can reach their receptor in the nucleus to trigger a response

Question 8

What are vitamin D and bile made of?

Answer 8

Also cholesterol

Question 9

What part of cholesterol is hydrophilic?

Answer 9

The alcohol group

Question 10

What part of cholesterol is hydrophobic?

Answer 10

The methyl group at the other end

Question 11

What is the structure of cholesterol?

Answer 11

Small and narrow so it can sit between phospholipid tails in membranes (OH group between the head)

Question 12

What does cholesterol binding to the phospholipids do?

Answer 12

It binds to the membrane which prevents it from becoming too fluid or from fatty acids getting too close together and crystallising so is fluid enough to function well

Question 13

What else do sterols make?

Answer 13

Waxes ,e.g, waxy cuticle leaves