1. Define carbohydrate. Write in detail about aerobic glycolysis pathway and its energetics.
Answer: Carbohydrates are polyhydroxy aldehydes or ketones, or substances that yield these upon hydrolysis.
- Aerobic glycolysis is the metabolic pathway that converts glucose into pyruvate, which is then converted to acetyl-CoA and enters the citric acid cycle in the presence of oxygen.
- The net energy yield from aerobic glycolysis alone is 2 ATP and 2 NADH molecules per glucose molecule.
- The overall process (glycolysis, citric acid cycle, and oxidative phosphorylation) yields significantly more ATP (around 30-32 ATP).
2. Define disaccharide. Discuss the steps involved in citric acid cycle and its energetics.
Answer: A disaccharide is a carbohydrate formed by two monosaccharide units joined by a glycosidic bond.
- The citric acid cycle (Krebs cycle) involves a series of reactions that oxidize acetyl-CoA, producing , NADH,, and ATP.
- Key steps include the formation of citrate, its conversion to isocitrate, oxidative decarboxylation to alpha-ketoglutarate, further oxidation to succinyl-CoA, conversion to succinate, fumarate, malate, and regeneration of oxaloacetate.
- Each turn of the cycle produces 3 NADH, 1 , and 1 ATP (or GTP) molecule.
3. Define fatty acid. Explain the pathway of beta oxidation of fatty acids and its energetics.
Answer: Fatty acids are carboxylic acids with a long aliphatic chain, which is either saturated or unsaturated.
- Beta-oxidation is the catabolic process by which fatty acid molecules are broken down in the mitochondria to generate acetyl-CoA, NADH, and .
- The pathway involves four recurring steps: oxidation by FAD, hydration, oxidation by , and thiolysis.
- The energetics depend on the fatty acid length; for a 16-carbon fatty acid (palmitate), the full oxidation yields approximately 106 ATP molecules.
4. Define isoenzymes with examples. Explain one isoenzyme.
Answer: Isoenzymes (or isozymes) are different forms of an enzyme that catalyze the same reaction but differ in amino acid sequence, kinetic properties, and/or regulatory controls.
- An example is lactate dehydrogenase (LDH), which exists as five different isoenzymes (to).
- is found primarily in the heart and red blood cells, whileis predominant in the liver and skeletal muscle.
- Their different compositions allow them to function optimally in different tissue environments.
5. Describe the classification of fatty acids.
Answer: Fatty acids are classified based on the length of their carbon chain and the presence and number of double bonds.
- Chain Length: Short-chain (less than 6 carbons), medium-chain (6-12 carbons), long-chain (13-21 carbons), and very long-chain (22+ carbons).
- Saturation: Saturated (no double bonds), monounsaturated (one double bond), and polyunsaturated (two or more double bonds).
- Essentiality: Essential fatty acids (e.g., omega-3 and omega-6) cannot be synthesized by the body and must be obtained from diet.
6. Define enzymes. Also classify enzymes with suitable examples.
Answer: Enzymes are biological catalysts that accelerate the rate of specific biochemical reactions without being consumed in the process.
- Enzymes are classified into six major categories by the International Union of Biochemistry and Molecular Biology (IUBMB):
- Oxidoreductases: Catalyze oxidation-reduction reactions (e.g., lactate dehydrogenase).
- Transferases: Transfer a functional group (e.g., hexokinase).
- Hydrolases: Catalyze hydrolysis reactions (e.g., amylase).
- Lyases: Catalyze the cleavage of bonds by means other than hydrolysis or oxidation (e.g., aldolase).
- Isomerases: Catalyze isomerization reactions (e.g., phosphoglucose isomerase).
- Ligases: Join two molecules with covalent bonds (e.g., DNA ligase).
7. Write short note of liver function test.
Answer: Liver function tests (LFTs) are blood tests used to help diagnose and monitor liver disease or damage.
- Common LFTs measure the levels of liver enzymes (like ALT and AST) and proteins (like albumin and total protein) in the blood.
- High levels of enzymes can indicate liver cell damage, while low levels of proteins may suggest impaired liver function.
- Other tests include bilirubin levels (indicating jaundice or bile duct issues) and prothrombin time (assessing clotting factor production).
8. Difference between innate and acquired immunity.
Answer: Innate immunity is the body's non-specific, first line of defense present from birth, while acquired (adaptive) immunity is a specific, long-term defense that develops throughout life upon exposure to specific pathogens.
- Innate immunity provides immediate protection and does not have a memory component.
- Acquired immunity is slower to develop but provides a targeted response and immunological memory, leading to a faster and stronger response upon subsequent exposure to the same pathogen.
- Components of innate immunity include physical barriers (skin), phagocytic cells (macrophages), and inflammation, while acquired immunity involves B and T lymphocytes and antibodies.
9. Define CBC and its components.
Answer: CBC stands for Complete Blood Count, a common blood test that evaluates the overall health and detects conditions such as anemia, infection, and leukemia.
- Key components measured in a CBC include:
- Red Blood Cells (RBCs): Transport oxygen.
- White Blood Cells (WBCs): Part of the immune system.
- Platelets: Involved in blood clotting.
- Hemoglobin and Hematocrit: Measures of oxygen-carrying capacity.
10. Give normal value of: a) Urea b) Creatinine c) Glucose d) Thyroid stimulating hormone
Answer: Normal values for these blood components can vary slightly depending on the lab, but general ranges are as follows:
- a) Urea: Approximately 7 to 20 mg/dL (milligrams per deciliter) in adults.
- b) Creatinine: Approximately 0.6 to 1.2 mg/dL in adult males and 0.5 to 1.1 mg/dL in adult females.
- c) Glucose (fasting): Approximately 70 to 99 mg/dL.
- d) Thyroid stimulating hormone (TSH): Approximately 0.4 to 4.0 mIU/L (milli-international units per liter).
11. Define vaccine. Write its types with suitable examples.
Answer: A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease.
- Vaccines work by introducing an agent that resembles a disease-causing microorganism, stimulating the body's immune system to recognize and destroy it in the future.
- Types include:
- Live-attenuated: Use a weakened form of the germ (e.g., Measles, Mumps, Rubella (MMR) vaccine).
- Inactivated: Use a killed version of the germ (e.g., Polio vaccine).
- Subunit, recombinant, polysaccharide, and conjugate: Use specific pieces of the germ (e.g., Hepatitis B vaccine).
- Toxoid: Use a toxin made by the germ (e.g., Tetanus vaccine).
- mRNA: Use mRNA to teach cells how to make a protein piece that triggers an immune response (e.g., Pfizer-BioNTech COVID-19 vaccine).
12. Define antigen and antibody.
Answer: An antigen is any substance that causes the body's immune system to produce antibodies against it, while an antibody is a Y-shaped protein produced by B-cells that specifically recognizes and binds to an antigen to help eliminate it.
- Antigens can be foreign substances from the environment (e.g., bacteria, viruses, pollen) or formed within the body.
- Antibodies are a key component of the adaptive immune system and are also known as immunoglobulins (Ig).
13. Define and classify protein.
Answer: Proteins are large, complex molecules essential for life, made up of chains of amino acids, that perform a vast array of functions within organisms.
- Proteins can be classified in several ways, including by their function and structure:
- By Function: Enzymes, structural proteins, hormones, antibodies, transport proteins, and storage proteins.
- By Structure: Fibrous (e.g., collagen, keratin) are long and insoluble, while globular (e.g., hemoglobin, enzymes) are compact and soluble.
- By Composition: Simple proteins contain only amino acids, while conjugated proteins have a non-protein part (prosthetic group) such as a metal ion or carbohydrate attached.
