IMPORTANT QUESTIONS - MECHANISM OF HORMONE ACTION

LAQ:

1. Describe the role of hormones in regulation of blood sugar levels.

SAQ


1. Describe the action of peptide hormones / epinephrine.
2. Describe the action of steroid hormones / estrogen.
3. Describe the action of thyroid hormone.
4. Describe the factors affecting Ca and P levels in the body.
5. Describe the role of secondary messengers in hormone signalling.
6. Explain the metabolic role of cAMP.

IMPORTANT QUESTIONS - AMINO ACID METABOLISM

LAQ:

1. Describe urea cycle. Also mention energetics and its regulation.
2. Describe the catabolism of  amino acids.

SAQ:

1. Explain transamination reaction giving example. Also give it's clinical significance.
2. Explain deamination (oxidative and non oxidative) reaction giving example. 
3. Explain transdeamination reaction giving example.
4. What are the various methods of disposal of ammonia.
5. Explain the role of glutamine in disposal of ammonia.
6. Describe some of the disorders related to urea cycle.

OTHER IMPORTANT QUESTIONS FOR MBBS STUDENTS
1. Describe glycine metabolism.(SAQ)
2. What is the metabolic fate of glycine. (SAQ)
3. Explain hyperoxaluria.(SAQ)
4. Describe the activation of methionine.(SAQ)
5. Explain the significance of transmethylation reaction.(SAQ)
6. Describe homocystinuria.(SAQ)
7. Describe synthesis of NO. Also mention the physiological role of NO.(SAQ)
8. Describe maple syrup urine disease.(SAQ)
9. Describe catabolism of phenylalanine.(SAQ)
10. Which are the important products formed from tyrosine.(SAQ)
11. Describe phenylketonuria.(SAQ)
12. Describe alkaptonuria. (SAQ)
13. Describe albinism.(SAQ)
14. Describe the formation of serotonin. (SAQ)

IMPORTANT QUESTIONS - MINERALS.

LAQ

1.Describe Ca under following headings- biochemical functions, sources, RDA and hyper and hypocalcemia.
2.Describe iron under following headings- biochemical functions, sources, RDA and iron balance disorders.

SAQ

1. What are the factors affecting Ca absorption.
2. How is blood calcium level regulated in the body.
3. Describe the biochemical functions of phosphorous.
4. Explain digestion and absorption of iron.
5. What is mucosal block theory.
6. Briefly describe anemia.
7.  Briefly describe hemosiderosis.
8. Briefly describe fluorosis.
9. Name some trace elements and list their functions.

OTHER IMPORTANT QUESTIONS FOR MBBS STUDENTS
1. Explain the process of bone mineralization.
2. Biochemical functions of copper.
3. Briefly describe Wilson's disease.
4. biochemical functions of Zinc.
5.. Biochemical functions of selenium.
6. Explain the role of lithium in treatment of manic depressive disorder.
7. Biochemical functions of sodium.
8. Explain hyper and hypokalemia. 

IMPORTANT QUESTIONS - VITAMINS

LAQ

1. Discuss vitamin A under the following headings - biochemical functions, sources, RDA and hyper & hypovitaminosis. 
2. Discuss vitamin D under the following headings - biochemical functions, sources, RDA and hyper & hypovitaminosis. 
3. Discuss vitamin C under the following headings - biochemical functions, sources, RDA and hyper & hypovitaminosis. 
4. Which are the different vitamins in  B complexes and mention their respective coenzymes. in detail.

SAQ

1. Describe Wald's visual cycle with diagram.
2. Describe the activation of vitamin D.
3. Justify vitamin D is also a hormone.
4. Explain rickets.
5. explain the role of vitamin K in blood clotting.
6. What are provitamins.
7. Explain scurvy.
8. Which are the different vitamins in  B complexes and mention their respective coenzymes.
9. Write about Beri-Beri.
10. Write about ariboflavinosis.
11. Write about pellagra.
12. Mention the vitamins whose coenzymes act as reducing equivalents.
13. Biochemical functions of pyridoxine.
14. Explain the role of folic acid in one carbon metabolism.
15. What is methyl folate trap.
16. Explain the digestion and absorption of vitamin B12.

IMPORTANT QUESTIONS - FREE RADICALS

SAQ:

1.What are the different type of free radicals. Also mention their sources.
2. Explain the clinical significance of free radicals. 
3. What are the various free radical scavenging mechanisms.
4. Explain the various enzymatic antioxidants. 
5. Explain the various non - enzymatic antioxidants. 
6. What is lipid peroxidation.

IMPORTANT QUESTIONS - BIOLOGICAL OXIDATION

SAQ:

1. Describe briefly the energy rich compounds.
2. Explain the organization of ETC.
3. Schematically represent ETC. Also mention the site of ATP synthesis.
4. Schematically represent ETC. Also mention the site various inhibitors of ETC.
5. What are uncouplers. Also give examples.
6. What is oxidative phosphorylation.
7. Explain the role of cytochromes in ETC.
8. Explain the chemiosmotic theory.

OTHER IMPORTANT QUESTIONS FOR MBBS STUDENTS:
1. Which are the enzymes and coenzymes which play a role in biological oxidation. (SAQ)
2. Explain malate aspartate shuttle. (SAQ)
3. Describe ATP Synthase complex. (SAQ)

IMPORTANT QUESTIONS - ACID BASE BALANCE

LAQ:

1.What is the normal pH of blood. Explain the role of plasma buffers and renal mechanisms in maintenance of acid base balance.
2. Define metabolic acidosis. What causes it and describe the mechanisms needed to counteract this imbalance. 

SAQ:

1.Explain the role of blood buffers in acid base balance.
2.Explain the role of renal regulation in acid base balance.
3.What do you mean by acidosis. Also mention the compensatory responses.
4. What do you mean by alkalosis. Also mention the compensatory responses.

OTHER IMPORTANT QUESTIONS FOR MBBS STUDENTS:
1. What do you mean by alkali reserve. (SAQ)
2. Explain anion gap. (SAQ)

IMPORTANT QUESTIONS - NUTRITION

LAQ

1. Define BMR. State the factors affecting BMR.
2. Define protein energy malnutrition. Differentiate between Kwashiorkar and Marasmus.

SAQ

1. What is balanced diet. Explain properties of a good balance diet.
2. Explain specific dynamic action of food.
3. Explain the dietary importance of carbohydrates.
4. Explain the dietary importance of lipids.
5. Explain the dietary importance of proteins.
6. Explain the role of dietary fibers in human nutrition. 
7. What are essential fatty acids. Also give examples.
8. Explain nitrogen balance or schematic representation of nitrogen balance.
9. Explain the role of essential fatty acids. Also give examples.
10. Explain the term protein sparers.

OTHER IMPORTANT QUESTIONS FOR MBBS STUDENTS:
1. What is biological value of proteins. (SAQ)
2. What is protein efficacy ratio. (SAQ)
3. What is net protein utilization. (SAQ)
4. Define limiting amino acids. Also give examples. (SAQ)
5. What do you mean by mutual supplementation of proteins. (SAQ)

IMPORTANT QUESTIONS - DIGESTION AND ABSORPTION

LAQ:

1. Describe the process of digestion and absorption of proteins.
2. Describe the process of digestion and absorption of lipids.
3. Describe the process of digestion and absorption of carbohydrates.

SAQ:

1. What is lactose intolerance.
2. Explain the role of bile in lipid digestion. Also add a note on obstructive jaundice.
3. What is enterohepatic circulation.
4. What are the different types of abnormalities in digestion / different types of malabsorption diseases.
5. Describe the role of pancreatic enzymes in digestion.
6. Explain the process of digestion and absorption of milk.

OTHER QUESTIONS FOR MBBS STUDENTS;
1. Which are the different type of glucose transporters. (SAQ)

IMPORTANT QUESTIONS - METABOLISM OF XENOBIOTICS

LAQ:

1.Explain in detail the different phases of detoxification.

SAQ:

1. Explain the metabolic role of glucuronic acid.
2. Describe detoxification by conjugation.
3. Describe detoxification by oxidation.
4. Describe detoxification by hydrolysis.
5. How is hippuric acid formed. 
6. Explain the role of glutathione in conjugation.
7. Explain the role of cytochrome P450 in detoxification.

IMPORTANT QUESTIONS - LIPID METABOLISM


LAQ:


1. Explain the steps of beta oxidation of palmitic acid, giving energetics and regulation.
2. Describe the reactions of de novo synthesis of fatty acids and how is it regulated.
3. Enumerate the major steps of synthesis of cholesterol. Name the rate limiting step.
4. What are ketone bodies? Explain the reactions leading to their formation. how are they utilized in the body.
5. Describe the pathway for synthesis of TAG.
6. Describe the role of liver in fat metabolism.


SAQ:


1. Explain the role of carnitine in fatty acid transport.
2. Regulation of hormone sensitive lipase.
3. What are the different types of ketone bodies? also mention the diseases in which ketone bodies increase in the body.
4. Important functions of cholesterol.
5. Briefly explain atherosclerosis.
6. What is fatty liver ? Mention the factors leading to fatty liver and the lipotropic factors.
7. Explain lipoproteins. Also mention the role of different type of lipoproteins and their clinical significance. 


Other questions for MBBS students:
1. Oxidation of odd chain fatty acids (SAQ).
2. What is alpha oxidation. (SAQ) 
3. What is omega oxidation. (SAQ)
4. Explain what is methyl malonic aciduria. (SAQ)
5. Explain what is Refsum's disease. (SAQ)
6. Explain the metabolism of adipose tissue in well fed condition and during fasting. (LAQ)
7. What is brown adipose tissue. (SAQ)
8. Mention and explain the different types of hyperlipidemia. Also mention the therapeutic interventions. (LAQ)

IMPORTANT QUESTIONS - LIPIDS


LAQ:


1.Classify lipids giving examples.
2. What are phospholipids and explain about their functions.


SAQ:


1. What are essential fatty acids. Also give examples.
2. Functions of lipids.
3. Function of phospholipids. 

IMPORTANT QUESTIONS - CARBOHYDRATE METABOLISM

LAQ:

1.Which are the various  oxidative pathways of glucose.
2. Explain glycolysis aerobic and anaerobic (EMP pathway) in detail. Also mention energetic's and regulation involved in it .
3. Explain TCA (Krebs cycle) in detail. Also mention energetic's and regulation involved in it .
4. Explain gluconeogenesis in detail. Also mention energetic's and regulation involved in it .
5. Importance of HMP (pentose phosphate) pathway. Mention the tissues were this pathway is active.
6. Explain glycogenesis in detail. Also mention regulation involved in it . (rare question)
7. Explain glycogenolysis in detail. Also mention regulation involved in it . (rare question)

SAQ:

1. Importance of Fructose 2,6 - bisphosphate in regulation of glycolysis.
2. Explain the Rapaport Leubering cycle and significance of 2,3 BPG (Sometimes it might be asked as - the supplementary cycle in glycolysis which takes place in erythrocytes).
3. Important of Pyruvate dehydrogenase enzyme and which are the cofactors required by it.
4. Metabolic fate of pyruvate.
5. Metabolic fate of acetyl CoA.
6. What are the different precursors for gluconeogenesis.
7. Diagrammatic representation of Cori's cycle and mention its importance. 
8. Importance of uronic acid pathway.
9. Key enzymes of glycolysis.
10. Substrate level phosphorylation.
11. Drug induced hemolytic anemia.
12. Lactose intolerance.
13. Metabolic fate of glucose 6 phosphate.

Other important questions for MBBS students:
1. Glycogen storage diseases. (LAQ)
2. Explain HMP shunt in detail. (LAQ)
3. Essential pentosuria. (SAQ)
4. Hereditary fructose intolerance. (SAQ)
5. Galactosemia (SAQ).
6. Metabolism of alcohol. (SAQ) 
7. Why is TCA called as amphibolic pathway. (SAQ)
8. What are anaplerotic reactions. (SAQ)

IMPORTANT QUESTIONS - CARBOHYDRATES.

LAQ:

1. General classification of carbohydrates with examples (in this answer always mention in monosaccharides - classification based on number of carbon and functional group, in polysaccharides mention - Homo and hetero).
2. Describe in detail about polysaccharides.
3. Explain in detail  homopolysaccharides .
4. Explain in detail  heteropolysaccharides .

SAQ:

1. Explain stereoisomerism in carbohydrates.
2. Explain anomers.
3. Explain epimers.
4. Explain mutarotation.
5. Explain about the reducing property of sugars (in this answer always mention the examples and importance of  Benedict's test).
6. What is inversion in context to sucrose.
7. Short note on starch.
8. Short note on glycogen.
9. Short note on sucrose.
10. Functions of carbohydrates.

Other Important questions for MBBS students:
1. What are glycosides and mention some of the important glycosides.(SAQ)
2. Which are the physiologically important sugar derivatives (SAQ)

VIAGRA

I am sure after reading the label all of you must have got those naughty smirks on your face, specially the guys. To be honest even my inquisitiveness about viagra started for all the mischievous reasons, like any other regular college dude. As I read along about the "Blue pill", it made me realize that there is more to this pill than the adult overtones associated with it. My whole concept changed after I read an article which stated that it was a work which was awarded the Nobel prize for Medicine in 1998 that lead to the discovery of the drug. And I wondered was so great about the drug.

To begin its an exemplary example of how a signalling cycle which I read in biochem books was manipulated to give many men the wonder medicine for erectile dysfunction. Before that lets look at the process of erection. An erection begins with arousal. The brain detects the body becoming sexually aroused and transmits a message along the NANC (nonadrenergic, noncholinergic and uses nitric oxide to transmit the message) neuron to tell the body to begin creating an erection.  Once the nitric oxide reaches the neurovascular bundles near the prostate , an enzyme called guanylyl (soluble NO activated) cyclase is released. This enzyme converts GTP to cGMP. This causes the the relaxation of the smooth muscles lining the arteries of penis. The arteries dilate, filling the corpora spongiosum and cavernosa with blood.Then comes the part which most guys don't like- cGMP, however, is broken down by a second enzyme called phosphodiesterase type 5 or PDE 5. PDE 5 turns cGMP back into guanosine triphosphate or GTP to cause the arterial walls to not relax and decreasing the blood flow into the penis.

Discovery of viagra is serendipity at its best. Initially the drug was being tested on patients with cardiovascular diseases. But it did not work out that well, however one of the other effects of the drug was that it improved the erections in men. The whole focus of the clinical trial shifted in this direction now. The drug worked by inhibiting the enzyme PDE. It was originally developed by British scientists and then brought to market by the US-based pharmaceutical company Pfizer. It acts by inhibiting cGMP-specific phosphodiesterase type 5, an enzyme that promotes degradation of cGMP, which regulates blood flow in the penis. Since becoming available in 1998, sildenafil has been the prime treatment for erectile dysfunction. Never thought that studying Biochemistry could be so uplifting (pun unintended). 

PREBIOTICS AND PROBIOTICS

Prebiotic are non digestible food substances that promote the growth of good bacteria like - bifidobacteria and lactic acid bacteria. Most of the prebiotics comprise of carbohydrates, specially oligosaccharides and soluble fibers. However there are certain non carbohydrate prebiotics also. There are short chain prebiotics (eg: oligofructose) and long chain prebiotics (eg: inulin). These prebiotics are fermented in the colon and this acts as an energy source for the bacteria to thrive. Dietary source of prebiotics are soyabeans, raw oats, raw chicory root, raw atrichoke etc. Prebiotics have potential effects on mineral absorption, immune effectiveness (breast milk contains oligosaccharides that helps development of proper immunity in infants), reduce risk of colon cancer, hypertension. Only caution to be exercised is that you should not be fooled by commercials proving that the food is prebiotic. Always remember -- Prebiotic are a component of the food and not the food itself.

Probiotics are live microorganisms like bifidobacteria and lactic acid bacteria. It is usually consumed in the form of fermented food like yogurt. Probiotics are available as dietary supplements (including capsules, tablets, and powders) and in dairy foods (such as yogurts with live active cultures). Although the FDA has not approved any health claims for probiotics, they are used for a variety of gastrointestinal conditions such as infectious diarrhea, diarrhea associated with using antibiotics, irritable bowel syndrome, and inflammatory bowel disease (e.g., ulcerative colitis and Crohn’s disease). Probiotics are also being used for preventing tooth decay and for preventing or treating other oral health problems such as gingivitis and periodontitis.

LABORATORY FINDINGS FOR JAUNDICE




SERUM ENZYMES              Prehepatic                        Hepatic                               Post-hepatic
1. Alkaline Phosphatase            Normal                   Increased slightly                   Increased significantly


2. Alanine Transaminase           Normal                  Increased significantly                Increased slightly

3. Aspartate Transaminase        Normal                  Increased significantly                Increased slightly

4. Gamma Glutamyl                  Normal                   Increased slightly                           Increased
    Transferase

HORMONE SIGNALLING


See the videos for better understanding of hormone signalling and then read your books.

Peptide hormone signalling:

Steroid hormone signalling:

Note: The videos are downloaded from youtube. You may also see the videos by clicking the links
Peptide hormone & Steroid hormone

INDIA AND BIOCHEMISTRY - FACT 1

What better way to start this series than giving the scientific explanation of our age old tradition of giving yogurt mixed with sugar before the beginning of any work. This is considered to be auspicious. Is it just another superstition or is there any scientific relevance to it?

There is a strong scientific base to it. Yogurt contains Lactobacillus which is considered as beneficial bacteria for our gut microenviroment (colon). Basically, the bacteria in yogurt seems to deactivate harmful substances (such as nitrates and nitrites before they are converted to nitrosamines) before they can become carcinogenic.The sugar is mixed to provide energy source for the bacteria to grow. This was the best form of probiotics are ancestors formulated. A splendid mixture of biochemistry, microbiology and fermentation. 

So basically that teaspoon of yogurt is not just for auspicious reasons but to keep your gut healthy all day so that you are able to do your work without any ailments. All medical professionals will agree with the saying "You're only as healthy as your colon." 

So go ahead and lap that teaspoon of "Dahi shakkar" for all the scientific reasons and more importantly for the fact that is filled with motherly love and prayers that her child succeed in all that they do. "Cho Sweet" 

INDIA AND BIOCHEMISTRY

Before your minds set trotting or you start to scratch your head in wonderment about the connection of India and biochemistry. Let me tell you our traditions and biochemistry share an ancient relation, which are hidden because we were ignorant of our ancient science and ran after modernized format of science.

A few examples will illustrate this to you more clearly. Long before the discovery of nine planets, we have worshipped them as “Navagrahas”. We had discovered the “Nakshatras” or the constellations long before the others realized it existed. Our astronomy, medical sciences, physics, chemistry or biology is highly advanced in all senses, and yet, to our dismay we are tagged as a developing nation.

Sadly we are to busy labeling our tradition as superstition, to appear modern on the global platform. It’s high time we stop neglecting our scriptures and ancient science. I will keep trying to give you the scientific reasons of our beliefs. Keep following my series “India and Biochem” and even you say in exhilaration that you are proud to be an INDIAN.

FACTORS AFFECTING CALCIUM ABSORPTION:

Factors increasing absorption :
1. Vitamin D - induces the synthesis of calbindin (carrier protein for Ca) in the intestinal epithelial cells, thus increasing Ca absorption.
2. Parathyroid hormone - it increases Ca transport across the membrane of intestinal cells.
3 Acidity - Ca is more soluble and absorbed in acidic medium.
4. Lactose - it favors absorption in infants. Lactose is acted upon by intestinal microbial flora to form acid which causes lowering of pH which makes calcium more soluble.
5. Need for calcium - efficiency of calcium absorption increases according to body demands.During pregnancy, lactation and adolescence calcium absorption efficiency increases by 50%.
6. Amino acids - Lysine and arginine increases Ca absorption.

Factors decreasing absorption: 
1. Oxalic acid - It is present in vegetables. It combines with Ca to form insoluble complex calcium oxalate which cannot be absorbed.
2. Phytic acid - It is a hexaphosphate of inositol which is present in cereals. Fermentation and cooking reduces the phytate content. It is primarily found in the outer coat of cereals.
3. Malabsorption - eg: steatorrhoea. The fatty acids are not absorbed. This forms insoluble calcium salts of fatty acids.
4. Phosphate - When present in high amount it causes precipitation of calcium in the form of calcium phosphate.
Ideal ratio of Ca: P is 1:2 to 2:1.
5. Laxatives- they decrease the transit time for passage of food through intestinal tract. Thus reducing time for absorption.
6. Caffeine , drugs like anticoagulants, cortisone and thyroxine reduce calcium absorption.

CRITERIA FOR THE DIAGNOSIS OF DIABETES


In a patient accompanied with classic symptoms of hyperglycemia:

1. Random plasma glucose >= 200 mg/dl (11.1mmol/l)
                                  OR
2. Fasting blood glucose >= 126 mg/dl (7.0 mmol/l)
                                  OR
3. 2-hour plasma glucose >= 200 mg/dl (11.1mmol/l)
                                 OR
4. Hb A1C >= 6.5%.