General Pathology Practice Questions

Q: In-situ DNA nick end labeling can quantitate what fraction of cells?

Cells in apoptotic pathways. **Explanation:** **TUNEL (Terminal deoxynucleotidyl transferase dUTP Nick End Labeling)** is a specialized laboratory technique used to detect and quantitate cells undergoing **apoptosis**. **Why Option A is Correct:** A hallmark of apoptosis is the activation of endogenous endonucleases (caspase-activated DNase), which cleave genomic DNA into fragments of 180–200 base pairs (creating the characteristic "DNA laddering" on electrophoresis). These breaks result in numerous exposed **3'-hydroxyl (3'-OH) ends** or "nicks." The TUNEL assay uses the enzyme **Terminal deoxynucleotidyl transferase (TdT)** to attach labeled nucleotides (like dUTP) to these 3'-OH ends. The intensity of the labeling is proportional to the degree of DNA fragmentation, allowing for the quantification of apoptotic cells. **Why Other Options are Incorrect:** * **Option B (Cells in S phase):** These are typically identified using **BrdU (Bromodeoxyuridine)** labeling or Ki-67 protein expression, which mark DNA synthesis and active proliferation. * **Option C (p53 gene product):** p53 is a tumor suppressor protein detected via **Immunohistochemistry (IHC)**. While p53 can trigger apoptosis, TUNEL measures the resulting DNA damage, not the protein itself. * **Option D (bcr/abl gene):** This fusion gene (Philadelphia chromosome) is detected using **FISH (Fluorescence In Situ Hybridization)** or **RT-PCR**, not by end-labeling DNA nicks. **High-Yield Clinical Pearls for NEET-PG:** * **DNA Laddering:** A specific feature of apoptosis (not necrosis) seen on agar gel electrophoresis. * **Annexin V:** Another marker for apoptosis; it binds to **Phosphatidylserine**, which flips from the inner to the outer leaflet of the plasma membrane during early apoptosis. * **Caspase-3:** The most common "executioner" caspase involved in both intrinsic and extrinsic pathways.

Question 1

Zenker's degeneration of the abdominal musculature is seen in which of the following conditions?

Accepted Answer

Typhoid

Answer

Cholera

Answer

Myotonia congenita

Answer

Amyloidosis

Question 2

Increased amounts of calcium in the cytosol of an injured cell reflect a release of calcium from which intracellular organelle?

Accepted Answer

Mitochondria

Answer

Peroxisomes

Answer

Smooth Endoplasmic Reticulum

Answer

Lysosomes

Question 3

Which of the following is a characteristic light microscopic feature of apoptosis?

Accepted Answer

Condensation of the nucleus

Answer

Intact cell membrane

Answer

Eosinophilic cytoplasm

Answer

Nuclear moulding

Question 4

Which of the following is NOT true for Cystic fibrosis?

Accepted Answer

Ultimately lead to bronchogenic carcinoma

Answer

Abnormal sweat gland function

Answer

Exocrine pancreatic insufficiency

Answer

Intestinal dysfunction

Question 5

Apoptosis activating factor 1 (Apaf-1) is known to perform which of the following functions?

Accepted Answer

Activates caspase 9

Answer

Activates caspase 8

Answer

Activates Bcl-1 and Mcl-1

Answer

Binds with mitochondrial cytochrome C

Question 6

Which of the following is NOT a predisposing factor for thrombosis and embolism?

Accepted Answer

Huntington disease

Answer

Atrial fibrillation

Answer

Prolonged immobilization

Answer

Prosthetic cardiac valve

Question 7

Ladder pattern of DNA electrophoresis is seen in which of the following cellular processes?

Accepted Answer

Apoptosis

Answer

Necrosis

Answer

Cytolysis

Answer

Karyorrhexis

Question 8

What does not occur in lysosomal storage disorders?

Accepted Answer

Lysis of the cell

Answer

Increased number and size of lysosomes

Answer

Apoptosis of the cell

Answer

Accumulation of polyubiquitinated proteins

Question 9

In-situ DNA nick end labeling can quantitate what fraction of cells?

Accepted Answer

Cells in apoptotic pathways

Answer

Cells in S phase

Answer

p53 gene product

Answer

bcr/abl gene

Question 10

Which of the following statements is NOT true about cutaneous calciphylaxis?

Accepted Answer

It exemplifies dystrophic calcification.

Answer

It is a potentially lethal condition.

Answer

It is characterized by progressive cutaneous vascular calcification.

Answer

It is seen in patients with chronic renal failure who have increased calcium, phosphate, and parathormone levels.

General Pathology — MCQs

General Pathology — MCQs

On this page

Practice by Chapter

Want unlimited practice?