The document provides an overview of steroids and cholesterol, detailing their structures, functions, and the biosynthesis pathways. It highlights the role of steroids in various body functions, diseases caused by hormonal imbalances, and the synthesis and regulation of cholesterol. Additionally, it lists relevant enzymes and the energy requirements for cholesterol synthesis, along with associated health issues from fluctuations in cholesterol levels.

1. Success begins with bismillah

2. Metabolism of cholesterol
and steroids

3. Group members
• Hafiza minahil 0112
• Wajeeha baryar 0089
• Samiullah 0110
• Ummehani 0124
• Saman shehzadi 0126
• Zakia akram 0115

4. What are Steroids ?
• Lipophilic, low molecular weight, derived from
cholesterol
• contains four rings of carbon atoms
• Acts as hormones in body estradiol,
testosterone, progesterone
• includes drugs such as prednisone, cortisone,
dexamethasone.
• Classes of steroids
1. Glucocorticoids
2. Mineralocorticoids
3. Sex hormones

5. Functions of steroids
• Stress response
• Immune response
• Regulation of inflammation
• Carbohydrate metabolism
• Protein catabolism
• Blood electrolyte level maintenance
Regulation
Done by Coactivators and Corepessors

6. Diseases caused by fluctuations in steroid
hormone levels
• Osteoporosis
• Adrenal cortex suppression
• Growth retardation
• Hypertension
• Development of secondary sex characteristics
in male and female
• Cushing's syndrome

7. Major pathways involved in biosynthesis of
steroid hormones
• All the three classes of steroid hormones can
be produced in the outer portion of adrenal
gland ,called adrenal cortex.

8. Steps for steroid hormone synthesis
• From cholesterol to aldosterone
• Occurs in Zona Glomerulosa

9. Steps for steroid hormone synthesis
• From cholesterol to cortisol
• Occurs in Zona Fasiculata

10. Steps for steroid hormone synthesis
• From cholesterol to sex hormones
(testosterone and estradiol)
• Occurs in Zona Reticularis

11. What is cholesterol ?
• Cholesterol is a waxy fat (lipid) carried through blood
by lipoproteins
• the most decorated small molecule in biology
• First isolated from gall stones in 1784
• two main types of cholesterol are
i. Good cholesterol (HDLs)
ii. Bad cholesterol (LDLs)
• Also known as sterol because it is made of alcohol
and steroid
• amphipathic molecule ,contains both hydrophobic
and hydrophilic part

12. Structure of cholesterol
• cyclopentanoperhydrophenanthrene(CPPP)
• 4 non aromatic rings
• 1 carbon double bond
• 1 side chain
• 1 hydroxyl group

13. Cholesterol synthesis
• 1gm/day synthesized in adults
• Enzymes are present in cytosol
• Acetyl CoA is the source of carbon
• NADPH is source of hydrogen
• Cholesterol is 27C compound
• Contribution
1. Liver (50%)
2. Intestine(15%)
3. Skin
4. Adrenal cortex
5. Reproductive tissue

14. Biosynthesis of cholesterol

15. Enzymes involved are as follows
• Thiolase
• HMG reductase
• HMG synthase
• HMG reductase
• Squalene synthase
• Cyclase
Energy required
• 58 ATP equivalents are required to make a
cholesterol molecule.
• Hence, it is an energy expensive process requiring a
lot of ATP and must be carefully regulated

16. Regulation of cholesterol synthesis
• Controlled by HMG CoA reductase
Degradation of cholesterol
• Synthesis of bile acids
• Synthesis of steroid hormones
• Synthesis of Vitamin D
Diseases caused by fluctuation in levels
• Atherosclerosis
• Obesity
• Kidney diseases
• Cushing syndrome
• Diabetes mellitus
• Obstructive jaundice
• Nephrotic syndrome
• Hypothyroidism

18. References
• https://en.wikibooks.org/wiki/Structural_Bioc
hemistry/Lipids/Cholesterol
• https://www.slideshare.net/ashokktt/metabol
ism-of-cholesterol
• https://www.gfmer.ch/Books/Reproductive_h
ealth/Steroid_hormone_metabolism.html
• https://www.youtube.com/watch?v=37EZp-
LD2kU
• https://www.youtube.com/watch?v=SWOwdP
NzMrQ