Cell communication 1

Question 1

What is special about cholesterol?

Answer 1

Has an OH group attached but is a lipid and is therefore hydrophilic and hydrophobic

Question 2

2. What are the 2 types of steroids?

Answer 2

Corticosteroids and sex hormones

Question 3

3. What does the DNA binding domain of a steroidal nuclear receptor encode?

Answer 3

Zinc fingers that contain 4x cystine residues which coordinate with a zinc atom to access the major groove of DNA

Question 4

1. What is the receptor for dexamethasone/cortisol?

Answer 4

Glucocorticoid receptor

Question 5

5. What is the hypothalamic-pituitary-adrenal axis for cortisol

Answer 5

Hypothalamus  Corticotropin releasing hormone (CRH)  pituitary  Adrenocorticotropic releasing hormone (ACTH)  Adrenal glands  cortisol

Question 6

6. What causes Addison’s disease?

Answer 6

Primary or secondary adrenal insufficiency

Primary – damage to adrenal glands
Secondary – Lack of ACTH

• Flu like symptoms
• Depression etc

Question 7

8. What is the insulin receptor? (structure)

Answer 7

Hetero-tetramer linked by di-sulphide bonds

- Has 2 intracellular tyrosine kinase domains

Question 8

10. Steps in intracellular insulin signalling:

Answer 8

1. Tyrosine phosphorylation of receptor and substrate IRS1
2. Activation of lipid kinase P13K
3. P13K synthesis PIP3
4. PIP3 recruits PDK (phosphoinositide dependent kinase)
5. Phosphorylation of (serine/threosine kinases) AKT

Question 9

1. What does good control of glucose levels depend on? (diabetic)

Answer 9

Slow acting insulin

Fast acting insulin (right after certain meals

Question 10

13. What is the drug used to treat type 2 diabetes?

Answer 10

Metformin ***
Positively charged
Inhibits MC complex 1
Prevents mitochondrial ATP production