Biochemistry
3 questionsUnfolded protein metabolism is associated with
Which of the following is the most reactive free radical?
Which of the following is a positive acute phase protein that enhances the acute phase response?
NEET-PG 2015 - Biochemistry NEET-PG Practice Questions and MCQs
Question 281: Unfolded protein metabolism is associated with
- A. Endoplasmic reticulum (Correct Answer)
- B. Golgi apparatus
- C. Mitochondria
Explanation: ***Endoplasmic reticulum*** - The **endoplasmic reticulum (ER)** is the primary site for protein folding, modification, and assembly, especially for secreted and transmembrane proteins. - When misfolded proteins accumulate, the ER triggers the **unfolded protein response (UPR)** to restore homeostasis or induce apoptosis. *Golgi apparatus* - The Golgi apparatus is primarily involved in **further processing**, sorting, and packaging of proteins and lipids synthesized in the ER. - It does not directly manage the initial folding of proteins or the response to widespread protein misfolding. *Mitochondria* - **Mitochondria** are known for their role in **energy production** (ATP synthesis) through cellular respiration. - While they possess their own protein synthesis machinery for some essential mitochondrial proteins, they are not involved in the overall cellular management of unfolded protein metabolism from the ER.
Question 282: Which of the following is the most reactive free radical?
- A. Alkyl radical
- B. Superoxide radical
- C. Peroxide radical
- D. Hydroxyl radical (Correct Answer)
Explanation: ***Hydroxyl radical*** - The **hydroxyl radical (•OH)** is the most reactive free radical in biological systems due to its extremely high oxidation potential and short half-life. - It readily reacts with virtually all cellular macromolecules, including **DNA, proteins, and lipids**, causing widespread damage. *Peroxide radical* - The **peroxide radical (ROO•)**, or more specifically the peroxyl radical, is less reactive than the hydroxyl radical, but still significant in lipid peroxidation. - It plays a role in propagating chain reactions of **lipid damage** in cell membranes. *Alkyl radical* - **Alkyl radicals (R•)** are generally formed as intermediates during the abstraction of hydrogen atoms from saturated compounds. - While reactive, they are typically less reactive and less frequently encountered in biological systems compared to oxygen-centered radicals like the hydroxyl radical. *Superoxide radical* - The **superoxide radical (O₂•−)** is a relatively less reactive free radical compared to the hydroxyl radical, but it is the precursor to many other reactive oxygen species (ROS). - It is primarily involved in **initiation of oxidative stress** and can lead to the formation of more damaging species through reactions like the Haber-Weiss reaction.
Question 283: Which of the following is a positive acute phase protein that enhances the acute phase response?
- A. Fibrinogen (Correct Answer)
- B. Transferrin
- C. Albumin
- D. Prealbumin
Explanation: ***Fibrinogen*** - **Fibrinogen** is a key **positive acute phase protein** whose concentration increases significantly during inflammation - Its elevation contributes to the acute phase response by promoting **blood clotting** and influencing **erythrocyte sedimentation rate (ESR)** - Along with C-reactive protein (CRP), haptoglobin, and serum amyloid A, fibrinogen is among the major positive acute phase reactants *Transferrin* - **Transferrin** is a **negative acute phase protein**, meaning its concentration decreases during inflammation - This reduction is part of the body's iron-sequestration strategy to limit iron availability for invading pathogens - The decrease in transferrin helps restrict bacterial growth by reducing available iron *Albumin* - **Albumin** is a prominent **negative acute phase protein**, with its concentration decreasing during acute inflammation due to redistribution and reduced synthesis - It plays a vital role in maintaining **oncotic pressure** and transporting various substances - Its decline reflects the severity of inflammation and is used as a marker of the acute phase response *Prealbumin* - **Prealbumin** (also known as transthyretin) is a **negative acute phase protein** and a sensitive marker of nutritional status - Its rapid decline during inflammation makes it a useful indicator, as its synthesis is quickly reduced - It has a short half-life (2-3 days), making it more sensitive to acute changes than albumin
Pathology
5 questionsWhich of the following is not considered an example of excess tissue growth?
First mediator of inflammation to be released is
Rolling of leucocytes on endothelial cells is mediated by which of the following?
Which substance plays a significant role in the tumor metastasis cascade?
Which of the following is derived from fibroblast cells?
NEET-PG 2015 - Pathology NEET-PG Practice Questions and MCQs
Question 281: Which of the following is not considered an example of excess tissue growth?
- A. Granulation tissue (Correct Answer)
- B. Neoplasia
- C. Hyperplasia
- D. Fibrosis
Explanation: ***Granulation tissue*** - Granulation tissue is a normal part of the healing process and does not represent an **excessive growth** of tissue [3]. - It consists mainly of **new connective tissue** and blood vessels formed during healing, rather than a pathological proliferation [3]. *Hyperplasia* - Hyperplasia is characterized by an **increase in the number** of cells in a tissue, leading to tissue enlargement [1][2]. - This process is often a response to a stimulus, such as hormonal changes or injury, indicating **excess tissue growth** [2]. *Neoplasia* - Neoplasia refers to the **abnormal proliferation** of cells, forming a neoplasm or tumor, which can be benign or malignant. - This is a clear example of **excess tissue growth**, as it involves uncontrolled cell division. *Fibrosis* - Fibrosis implies the formation of excess **fibrous connective tissue**, leading to a stiff or thickened tissue, signifying abnormal tissue growth [4]. - It often results from chronic inflammation or injury, again reflecting **excessive tissue** formation [4]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 87-88. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 85-87. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 105-106. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 111-112.
Question 282: First mediator of inflammation to be released is
- A. Nitric oxide
- B. PAF
- C. Histamine (Correct Answer)
- D. IL-1
Explanation: ***Histamine*** - Histamine is the **first mediator of inflammation released** by mast cells and basophils during an allergic or inflammatory response [1][3]. - It promotes **vasodilation** and increased vascular permeability, leading to typical symptoms of inflammation [1][2]. *PAF* - Platelet-activating factor (PAF) is released later in the inflammatory process and is primarily involved in **amplifying** the response rather than initiating it. - It plays a role in **platelet aggregation** and acting on vascular smooth muscle but is not the first released mediator. *Nitric oxide* - Nitric oxide is produced by endothelial cells and plays a role in **vascular relaxation and inflammation**, but it is not among the first mediators released. - It is involved in more **regulatory functions** in the inflammatory response rather than the initial trigger. *IL-1* - Interleukin-1 (IL-1) is a cytokine that is important for the **inflammatory response**, but it is produced after the initial release of mediators like histamine [2]. - It is primarily secreted by **activated macrophages** and contributes to the **amplification** of the immune response [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 84-85. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 101. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 93-94.
Question 283: Rolling of leucocytes on endothelial cells is mediated by which of the following?
- A. ICAM-1
- B. Integrin
- C. IL-8
- D. P-selectin (Correct Answer)
Explanation: ***P- selectin*** - P-selectin is a **cell adhesion molecule** crucial for the **rolling** of leukocytes on endothelial cells during the inflammatory response [1]. - It is expressed on activated endothelial cells and binds to **sialylated carbohydrates** on leukocytes, facilitating their transient adhesion [1]. *IL-8* - IL-8 is a **chemokine** that primarily acts as a chemotactic factor for neutrophils rather than mediating rolling on endothelium. - While it attracts leukocytes to sites of inflammation, it does not play a role in the initial contact or rolling process. *ICAM-1* - ICAM-1 is an **intercellular adhesion molecule** that facilitates **firm adhesion** rather than rolling of leukocytes. - It primarily interacts with **integrins** on leukocytes to stabilize their adhesion after rolling has occurred. *(3, integrin* - Integrins play a significant role in **firm adhesion** and not the rolling phase, interacting with receptors like ICAM-1. - The binding of integrins to their ligands occurs after leukocytes have initially rolled on the endothelium. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 87.
Question 284: Which substance plays a significant role in the tumor metastasis cascade?
- A. TNF-alpha
- B. CD99
- C. NM23
- D. MMP-2 (Matrix Metalloproteinase-2) (Correct Answer)
Explanation: ***Collagenase IV*** - Collagenase IV is involved in the **degradation of extracellular matrix**, facilitating tumor invasion and metastasis [1,2]. - It plays a crucial role in breaking down **type IV collagen**, a major component of the **basement membrane**, allowing cancer cells to migrate [2]. *TNF-alpha* - While TNF-alpha is a cytokine that can promote **tumor growth**, it is not directly involved in the **metastatic cascade** like collagenase IV [3,4]. - It primarily functions in **inflammation** and immune response, affecting tumor microenvironment rather than directly facilitating invasion. *NM23* - NM23 is noted for its potential role as a **tumor suppressor**, and lower levels are associated with metastasis. - However, it does not play a direct role in the *metastatic cascade* itself [3,4], as it primarily influences **tumor progression** rather than matrix degradation. *CD99* - CD99 is a cell adhesion molecule implicated in **cell migration**, but it is not a significant factor in the **enzymatic breakdown** of tissue during metastasis [1,2]. - Its expression has more to do with **cell adhesion characteristics**, rather than directly promoting invasive capabilities. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 315-316. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 232-233. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 314-315. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 233-234.
Question 285: Which of the following is derived from fibroblast cells?
- A. MMP2
- B. Collagen (Correct Answer)
- C. Angiopoietin
- D. TGF-β
Explanation: ***Collagen*** - Collagen is a structural protein that is predominantly produced by **fibroblast cells** in the extracellular matrix [1][2]. - It provides tensile strength and structural support to various tissues, playing a crucial role in wound healing and tissue repair [2]. *TGF-13* - Transforming Growth Factor-beta 1 (TGF-β1) is primarily produced by **immune cells** and is involved in cell growth and differentiation, not primarily by fibroblasts. - It plays a role in **fibrosis** and inflammation, but is not directly synthesized by fibroblast cells themselves. *MMP2* - Matrix Metalloproteinase-2 (MMP-2) is produced by various cell types, including **endothelial and epithelial cells**, but not predominantly by fibroblasts. - It is involved in the degradation of **extracellular matrix** components rather than being a product of fibroblast synthesis. *Angiopoietin* - Angiopoietin is primarily secreted by **endothelial cells** and plays a significant role in blood vessel formation and maturation. - It is not derived from fibroblast cells and is unrelated to their primary function of producing the extracellular matrix. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 31-32. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 34-35.
Physiology
2 questionsChemotaxis is mediated by-
Interleukin responsible for Pyrexia is:
NEET-PG 2015 - Physiology NEET-PG Practice Questions and MCQs
Question 281: Chemotaxis is mediated by-
- A. Histamine
- B. Leukotriene C4 and C3a
- C. Bradykinin
- D. Leukotriene B4 and C5a (Correct Answer)
Explanation: ***Leukotriene B4 and C5a*** - Both **Leukotriene B4** [2] and **C5a** [1] are potent **chemoattractants** that guide the migration of neutrophils and other immune cells to sites of inflammation. - They are crucial in amplifying the **immune response**, particularly during acute inflammatory reactions. *Histamine* - Primarily involved in **vasodilation** and increased **vascular permeability**, rather than mediating chemotaxis. - Does not specifically attract immune cells to sites of injury or infection like leukotrienes do. *Bradykinin* - Mainly functions in **pain sensation** and promoting **vascular permeability**, not as a direct chemotactic agent. - It influences inflammation but does not effectively recruit immune cells to tissues. *Leukotriene C4 and C3a* - **Leukotriene C4** is involved in bronchoconstriction, while **C3a** [1] has roles in the complement system but is less potent than C5a in chemotaxis. - These mediators have different primary roles in inflammation, lacking the specificity of B4 and C5a for leukocyte attraction. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 99-100. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 95-96.
Question 282: Interleukin responsible for Pyrexia is:
- A. IL1 (Correct Answer)
- B. IL4
- C. IL3
- D. IL8
Explanation: ***IL1*** - **Interleukin-1 (IL-1)** is a primary **endogenous pyrogen**, directly acting on the thermoregulatory center in the hypothalamus to induce fever. - It stimulates the production of **prostaglandin E2 (PGE2)**, which then alters the hypothalamic set point, leading to increased body temperature. *IL3* - **Interleukin-3 (IL-3)** is a **hematopoietic growth factor** that primarily stimulates the proliferation and differentiation of hematopoietic stem cells. - Its main role is in the development of various blood cell lineages, not directly in inducing fever. *IL4* - **Interleukin-4 (IL-4)** is a key cytokine in **allergic reactions** and **Th2 immune responses**, promoting B cell activation and IgE production. - It does not directly cause pyrexia; its primary functions are related to humoral immunity and immune regulation. *IL8* - **Interleukin-8 (IL-8)**, also known as **CXCL8**, is a potent **chemotactic factor** for neutrophils and other immune cells. - Its main function is to recruit inflammatory cells to sites of infection or injury, not to induce fever directly.