General Pathology Practice Questions

Q: In-situ DNA nick end labeling can quantitate:

Fraction of cells in apoptotic pathways. **Explanation:** **In-situ DNA nick end labeling**, commonly known as the **TUNEL assay** (Terminal deoxynucleotidyl transferase dUTP Nick End Labeling), is a specialized technique used to detect and quantitate cells undergoing **apoptosis**. **Why Option A is correct:** A hallmark of apoptosis is the activation of endogenous endonucleases, which cleave genomic DNA into fragments (internucleosomal cleavage). This process creates numerous "nicks" or free 3'-hydroxyl (3'-OH) ends. The TUNEL assay uses the enzyme **Terminal deoxynucleotidyl transferase (TdT)** to attach labeled nucleotides (like dUTP) to these 3'-OH ends. Because necrotic cells have random, irregular DNA breakdown and healthy cells have intact DNA, the concentration of labeled ends specifically identifies the fraction of cells in the apoptotic pathway. **Why other options are incorrect:** * **Option B:** The fraction of cells in the S phase is typically measured using **flow cytometry** (DNA content analysis) or **BrdU labeling**. * **Option C:** p53 gene products (proteins) are usually detected via **Immunohistochemistry (IHC)** or Western Blotting. * **Option D:** The *bcr/abl* fusion gene (associated with CML) is detected using **FISH** (Fluorescence In Situ Hybridization) or **RT-PCR**. **High-Yield Clinical Pearls for NEET-PG:** * **DNA Laddering:** On agar gel electrophoresis, apoptotic DNA appears as a "ladder" (multiples of 180-200 bp), whereas necrotic DNA appears as a diffuse "smear." * **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:** Known as the "Executioner Caspase," its activation is a definitive marker for the commitment to apoptosis.

Question 1

Which of the following is NOT an autosomal dominant disorder?

Accepted Answer

Alkaptonuria

Answer

Polycystic kidney disease

Answer

Ehlers-Danlos syndrome

Answer

Osteogenesis imperfecta

Question 2

In-situ DNA nick end labeling can quantitate:

Accepted Answer

Fraction of cells in apoptotic pathways

Answer

Fraction of cells in S phase

Answer

p53 gene product

Answer

bcr/abl gene

Question 3

Which anticoagulant is the choice for anticoagulation testing?

Accepted Answer

3.2% trisodium citrate

Answer

Heparin

Answer

EDTA

Answer

Sodium oxalate

Question 4

Which of the following is an example of a gain-of-function mutation?

Accepted Answer

Huntington's disease

Answer

Osteogenesis imperfecta

Answer

Ehlers-Danlos syndrome

Answer

Marfan syndrome

Question 5

All the following occur in hemostasis except?

Accepted Answer

None of the above

Answer

Vasospasm of blood vessel

Answer

Platelet plug formation

Answer

Dissolution of clot by plasmin

Question 6

Which of the following is an apoptosis inhibitor gene?

Accepted Answer

BCL-2

Answer

p53

Answer

Rb

Answer

c-myc

Question 7

The Hess test is performed to assess which of the following?

Accepted Answer

Capillary fragility

Answer

Bleeding time

Answer

Clotting time

Answer

Prothrombin time

Question 8

Partial or complete obstruction of some part of the cardiovascular system by a foreign body transported by the bloodstream is termed as:

Accepted Answer

Embolism

Answer

Thrombosis

Answer

Coagulation

Answer

Ischaemia

Question 9

Necrosis of cells is due to which of the following processes?

Accepted Answer

Enzymatic digestion

Answer

Calcium efflux from the cell

Answer

Fat deposition in cells

Answer

Water imbibition in cells

Question 10

Satellite sequences are observed during which phase of the cell cycle?

Accepted Answer

G0 phase

Answer

M phase

Answer

S phase

Answer

G1 phase

General Pathology — MCQs

General Pathology — MCQs

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