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Medical Biochemistry — MCQ ও উত্তর

মেডিকেল ভর্তি · । এই অধ্যায়ে মোট 69টি প্রশ্ন আছে। নিচে প্রথম 10টি প্রশ্ন ও সঠিক উত্তর দেওয়া হলো।

এই অধ্যায়ে সব প্রশ্নে অনুশীলন করুন

  1. Which lipid is a major component of myelin sheaths?

    1. Sphingomyelin
    2. Cholesterol
    3. Triglyceride
    4. Phosphatidylcholine

    সঠিক উত্তর: Sphingomyelin

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A Sphingomyelin is a major lipid component of the myelin sheath, which insulates nerve fibers and enhances rapid nerve impulse conduction. It is abundant in the membranes of myelinating cells such as Schwann cells and oligodendrocytes. Unlike triglycerides, which are energy storage lipids, sphingomyelin contributes structurally and functionally to the compact, multilamellar myelin sheath. Cholesterol is also present but sphingomyelin is more specific to myelin. Phosphatidylcholine is common in cell membranes but less specific to myelin sheaths. Understanding this is crucial in diagnosing and managing demyelinating diseases like multiple sclerosis.Reference: Gray’s Anatomy, Standring S, 42nd Edition.

  2. Which mineral is a major structural component of bones and teeth?

    1. Calcium
    2. Iron
    3. Potassium
    4. Magnesium

    সঠিক উত্তর: Calcium

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A Calcium is the primary mineral responsible for the structural integrity of bones and teeth. It combines with phosphate to form hydroxyapatite crystals, which provide rigidity and strength to the bone matrix. Adequate calcium levels are critical for maintaining bone density and preventing conditions like osteoporosis. In teeth, calcium contributes to enamel hardness, which is essential for resisting mechanical forces and decay. Deficiency in calcium directly impacts bone remodeling and repair, making it a vital element in skeletal health.Reference: Gray's Anatomy, Susan Standring, 42nd Edition.

  3. Which vitamin is essential for fatty acid oxidation?

    1. Vitamin B2
    2. Vitamin C
    3. Vitamin D
    4. Vitamin K

    সঠিক উত্তর: Vitamin B2

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A Vitamin B2, also known as riboflavin, is essential for fatty acid oxidation because it is a precursor for the cofactors flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). These cofactors serve as electron carriers in the mitochondrial fatty acid β-oxidation pathway. Specifically, FAD is required for the activity of acyl-CoA dehydrogenase, the enzyme that catalyzes the initial step of fatty acid oxidation. Without adequate vitamin B2, this step is impaired, leading to deficient energy production from fatty acids. This makes vitamin B2 crucial for metabolic processes involving energy extraction from fats.Reference: Harper's Illustrated Biochemistry, Rodwell, 31st Edition.

  4. What is considered the currency of energy in cells?

    1. ATP
    2. Glucose
    3. NADH
    4. GTP

    সঠিক উত্তর: ATP

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A ATP is considered the universal currency of energy in cells because it directly provides the energy required for most cellular functions. Its high-energy phosphate bonds release energy upon hydrolysis, fueling processes such as muscle contraction, active transport, and biochemical synthesis. Unlike glucose or NADH, ATP is immediately usable without further metabolic conversion. This rapid energy transfer is critical in surgical contexts, where cellular metabolism and tissue repair depend on efficient ATP availability. Understanding ATP's role aids in managing conditions involving energy deficits or ischemia during surgery. Reference: Principles of Physiology, Guyton and Hall, 14th Edition.

  5. The primary product of fatty acid beta-oxidation is:

    1. Acetyl-CoA
    2. Pyruvate
    3. Lactate
    4. Glycerol

    সঠিক উত্তর: Acetyl-CoA

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A The primary product of fatty acid beta-oxidation is Acetyl-CoA, which enters the citric acid cycle to generate ATP. During beta-oxidation, fatty acids are broken down in the mitochondria by sequential removal of two-carbon units in the form of Acetyl-CoA. This process is crucial for energy production, especially during fasting or increased energy demand. Pyruvate and lactate are products of carbohydrate metabolism, while glycerol originates from triglyceride breakdown but is not a direct product of beta-oxidation. Understanding this pathway is essential for managing metabolic and energy-related surgical conditions.Reference: Harper's Illustrated Biochemistry, Murray et al., 31st Edition.

  6. What is the main role of carnitine in fatty acid metabolism?

    1. Transports fatty acids into mitochondria
    2. Synthesizes fatty acids
    3. Breaks down triglycerides
    4. Converts glucose to glycogen

    সঠিক উত্তর: Transports fatty acids into mitochondria

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A Carnitine plays a crucial role in transporting long-chain fatty acids into the mitochondria for β-oxidation. Fatty acids cannot cross the mitochondrial membrane freely; they require conversion to acyl-carnitine by carnitine palmitoyltransferase I (CPT I). This complex is shuttled across the inner mitochondrial membrane, where carnitine palmitoyltransferase II (CPT II) regenerates acyl-CoA for energy production. Without carnitine, fatty acid breakdown and subsequent ATP generation are severely impaired, affecting energy homeostasis especially during fasting or increased energy demand. This function is essential for sustaining muscle and hepatic metabolism. Reference: Principles of Biochemistry, Lehninger, 7th Edition.

  7. What is the primary source of energy for the brain under normal physiological conditions?

    1. Glucose
    2. Fatty acids
    3. Ketone bodies
    4. Amino acids

    সঠিক উত্তর: Glucose

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A The brain primarily relies on glucose as its main energy source under normal physiological conditions due to its high metabolic demand and limited capacity to store energy. Unlike other tissues, the brain's ability to metabolize fatty acids is minimal because of the blood-brain barrier and low levels of enzymes required for fatty acid oxidation. While ketone bodies can serve as an alternative during prolonged fasting or starvation, glucose remains the essential fuel for maintaining neuronal function and synaptic activity. Efficient glucose uptake and metabolism are critical for sustaining cognitive processes and overall brain health.Reference: Principles of Neural Science, Kandel et al., 5th Edition.

  8. Which type of mutation does NOT alter the amino acid sequence of a protein?

    1. Silent
    2. Missense
    3. Nonsense
    4. Frameshift

    সঠিক উত্তর: Silent

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A A silent mutation involves a nucleotide change that does not alter the amino acid sequence due to the redundancy of the genetic code. This means the protein's primary structure remains unchanged, typically preserving its function. In contrast, missense, nonsense, and frameshift mutations change the amino acid sequence, often leading to altered or truncated proteins. Understanding silent mutations is crucial in genetic analysis, as they may not have direct clinical effects despite DNA sequence changes.Reference: Robbins Basic Pathology, Kumar V et al., 10th Edition.

  9. Which laboratory technique is used to amplify specific DNA sequences?

    1. Polymerase chain reaction
    2. Gel electrophoresis
    3. Western blot
    4. ELISA

    সঠিক উত্তর: Polymerase chain reaction

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A The Polymerase Chain Reaction (PCR) is a laboratory technique specifically designed to amplify targeted DNA sequences exponentially. It uses a cyclic process of denaturation, annealing of primers, and extension by DNA polymerase to create millions of copies of a specific DNA region. This amplification allows for detection and analysis of tiny amounts of DNA, which is crucial in diagnostics, forensic science, and genetic research. Unlike gel electrophoresis, Western blot, or ELISA, PCR uniquely increases DNA quantity rather than just separating or detecting molecules.Reference: Molecular Biology of the Cell, Alberts et al., 6th Edition.

  10. The lac operon in E. coli is responsible for:

    1. Controlling lactose metabolism
    2. DNA replication
    3. Protein synthesis
    4. Cell division

    সঠিক উত্তর: Controlling lactose metabolism

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A The lac operon in *E. coli* is a genetic regulatory system that controls the utilization of lactose as an energy source. It consists of genes encoding enzymes necessary for lactose uptake and metabolism, such as β-galactosidase. When lactose is absent, the operon is repressed to conserve energy. In the presence of lactose, it induces the expression of these genes, enabling the bacteria to metabolize lactose efficiently. This precise regulation exemplifies gene expression control in prokaryotes. Reference: Molecular Biology of the Cell, Bruce Alberts, 6th Edition.

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