Chromosome Structure, Karyotype & Banding Techniques

Question No. 1 Marks +1 -0 Time

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Which of the following statements correctly describes the primary function of a centromere in chromosome structure?

A. It protects the ends of chromosomes from degradation and fusion.
B. It is the site of active gene transcription and protein synthesis.
C. It serves as the attachment point for spindle fibers during cell division.
D. It contains the nucleolar organizer regions responsible for rRNA synthesis.

Question No. 2 Marks +1 -0 Time

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A typical human somatic cell karyotype is represented as 46,XX or 46,XY. What does the number '46' specifically indicate?

A. The number of autosomes present in the cell.
B. The total number of chromosome pairs.
C. The total number of individual chromosomes.
D. The number of sex chromosomes.

Question No. 3 Marks +1 -0 Time

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G-banding is the most common cytogenetic technique. What characteristic feature of chromosomes does it primarily highlight?

A. Regions rich in Guanine-Cytosine (GC) base pairs.
B. Telomeric regions and their repetitive sequences.
C. Heterochromatic, AT-rich regions that stain darkly.
D. Euchromatic, gene-rich regions that stain darkly.

Question No. 4 Marks +1 -0 Time

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Consider the following types of chromosomes based on centromere position:

1. Metacentric
2. Submetacentric
3. Acrocentric
4. Telocentric

Which of these types describes a chromosome where the centromere is located near one end, resulting in one very short arm and one long arm, and is commonly found in humans?

A. Only 1
B. Only 2
C. Only 3
D. Only 4

Question No. 5 Marks +1 -0 Time

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The hierarchical packaging of DNA into chromosomes involves several levels of compaction. Which of the following sequences correctly represents these levels from the least to the most condensed state?

A. DNA double helix → 30-nm fiber → Nucleosome → Metaphase chromosome
B. Nucleosome → DNA double helix → 30-nm fiber → Metaphase chromosome
C. DNA double helix → Nucleosome → 30-nm fiber → Metaphase chromosome
D. 30-nm fiber → Nucleosome → DNA double helix → Metaphase chromosome

Question No. 6 Marks +1 -0 Time

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What is the primary function of telomeres in eukaryotic chromosomes?

A. To initiate DNA replication at multiple origins along the chromosome.
B. To serve as the binding site for the kinetochore during mitosis.
C. To protect chromosome ends from degradation and prevent fusion with other chromosomes.
D. To facilitate homologous recombination and genetic diversity.

Question No. 7 Marks +1 -0 Time

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Differentiate between euchromatin and heterochromatin based on their typical characteristics:

A. Euchromatin is highly condensed and transcriptionally inactive, while heterochromatin is less condensed and transcriptionally active.
B. Euchromatin is less condensed and transcriptionally active, while heterochromatin is highly condensed and transcriptionally inactive.
C. Both euchromatin and heterochromatin are highly condensed but differ in their DNA sequence composition.
D. Euchromatin is found only in centromeric regions, while heterochromatin is found only in telomeric regions.

Question No. 8 Marks +1 -0 Time

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A patient's karyotype analysis reveals 47,XX,+18. What does this notation signify?

A. The patient is male with a deletion on chromosome 18.
B. The patient is female with an extra copy of chromosome 18.
C. The patient is male with an extra sex chromosome and a normal chromosome 18 complement.
D. The patient is female with a translocation involving chromosome 18.

Question No. 9 Marks +1 -0 Time

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Which banding technique is known for producing a staining pattern that is the reverse of G-banding, highlighting GC-rich regions brightly?

A. C-banding
B. Q-banding
C. R-banding
D. NOR-banding

Question No. 10 Marks +1 -0 Time

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Match the following banding techniques with the chromosomal regions they primarily highlight:

Banding Technique	Primary Highlighted Region
1. G-banding	a. Constitutive heterochromatin (centromeres)
2. C-banding	b. AT-rich, gene-poor regions
3. NOR-banding	c. Nucleolar Organizer Regions (rDNA)

A. 1-b, 2-a, 3-c
B. 1-a, 2-b, 3-c
C. 1-c, 2-a, 3-b
D. 1-b, 2-c, 3-a

Question No. 11 Marks +1 -0 Time

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The use of banding techniques in karyotyping significantly advanced cytogenetics. What is the main advantage of using banding techniques over simply observing unstained metaphase chromosomes?

A. Banding increases the total number of chromosomes visible in a cell.
B. Banding allows for the precise identification of individual chromosomes and detection of subtle structural rearrangements.
C. Banding makes all chromosomes appear uniformly dark, simplifying counting.
D. Banding prevents chromosome condensation, making them easier to measure.

Question No. 12 Marks +1 -0 Time

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Consider the following pairs regarding chromosome components and their associated features:

1. Kinetochore: Site of spindle microtubule attachment
2. P-arm: The shorter arm of a chromosome
3. Histones: Non-histone proteins involved in scaffolding

How many of the above pairs are correctly matched?

A. Only one
B. Only two
C. All three
D. None

Question No. 13 Marks +1 -0 Time

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High-resolution banding techniques are employed when standard banding methods are insufficient. What is the key principle behind achieving 'high resolution' in these techniques?

A. Using stronger dyes to make the bands darker and more distinct.
B. Analyzing chromosomes at a more condensed metaphase stage.
C. Synchronizing cells and analyzing chromosomes at an earlier, less condensed prophase or prometaphase stage.
D. Employing electron microscopy instead of light microscopy.

Question No. 14 Marks +1 -0 Time

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Fluorescence In Situ Hybridization (FISH) is a molecular cytogenetic technique often used in conjunction with karyotyping. What is the fundamental principle of FISH?

A. It stains entire chromosomes with a fluorescent dye to visualize banding patterns.
B. It uses fluorescently labeled DNA probes that bind to specific complementary sequences on chromosomes.
C. It detects protein expression levels on the surface of chromosomes.
D. It measures the size and shape of chromosomes using laser diffraction.

Question No. 15 Marks +1 -0 Time

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An idiogram is a diagrammatic representation of a karyotype. What information does an idiogram typically convey?

A. A photographic image of all chromosomes from a single cell.
B. The evolutionary relationship between different species based on their chromosome numbers.
C. A schematic drawing of a set of chromosomes, showing their relative sizes, centromere positions, and banding patterns.
D. A graph plotting the frequency of chromosome abnormalities in a population.

Question No. 16 Marks +1 -0 Time

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In the standard nomenclature for chromosome arms, what do 'p' and 'q' refer to, respectively?

A. Paternal and maternal arms.
B. Proximal and distal arms.
C. Primary and quiescent arms.
D. Petit (short) and queue (long) arms.

Question No. 17 Marks +1 -0 Time

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The kinetochore is a protein structure that forms on the centromere during cell division. Its crucial role is to:

A. Replicate the DNA content of the chromosome.
B. Synthesize ribosomal RNA for protein production.
C. Mediate the attachment of spindle microtubules to chromosomes.
D. Protect the ends of chromosomes from degradation.

Question No. 18 Marks +1 -0 Time

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Which type of DNA is primarily responsible for the dark staining observed with C-banding, and where is it typically located?

A. Euchromatic DNA; in gene-rich regions.
B. Repetitive satellite DNA; primarily at centromeres and secondary constrictions.
C. Telomeric DNA; at the ends of chromosomes.
D. Mitochondrial DNA; within the cytoplasm.

Question No. 19 Marks +1 -0 Time

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What are the core components that constitute a nucleosome, the fundamental unit of chromatin packaging?

A. DNA wrapped around a complex of non-histone proteins.
B. RNA wrapped around a single histone protein.
C. DNA wrapped around an octamer of histone proteins.
D. Only DNA double helix with no associated proteins.

Question No. 20 Marks +1 -0 Time

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How many pairs of autosomes are typically found in a normal human somatic cell?

A. 1 pair
B. 22 pairs
C. 23 pairs
D. 46 pairs

Question No. 21 Marks +1 -0 Time

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Consider a chromosome with its centromere positioned exactly in the middle. If a deletion occurred on one of its arms, how would its classification (e.g., metacentric, submetacentric) likely change when viewed in metaphase?

A. It would remain metacentric, as the centromere position is fixed.
B. It would become acrocentric due to the significant arm length difference.
C. It would become submetacentric, as the arms would no longer be equal in length.
D. It would become telocentric, as one arm would be completely lost.

Question No. 22 Marks +1 -0 Time

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Which of the following statements accurately describes a characteristic of Q-banding?

A. It requires pretreatment with barium hydroxide and stains centromeres.
B. It produces bright fluorescent bands that correspond to G-bands.
C. It stains GC-rich regions darkly and is the reverse of G-banding.
D. It specifically stains nucleolar organizer regions.

Question No. 23 Marks +1 -0 Time

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Consider the following chromosomal abnormalities and their typical karyotype presentations:

1. Down Syndrome: 47,XY,+21
2. Turner Syndrome: 45,X
3. Klinefelter Syndrome: 47,XXY
4. Cri-du-chat Syndrome: 46,XX,del(5p)

How many of the above pairs are correctly matched?

A. Only one
B. Only two
C. Only three
D. All four

Question No. 24 Marks +1 -0 Time

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Why are banding techniques considered essential for comprehensive cytogenetic analysis, beyond simply counting chromosomes and observing their overall size and shape?

A. They allow for the visualization of individual genes, which is not possible otherwise.
B. They provide unique, reproducible patterns on each chromosome, enabling identification of homologous pairs and subtle structural rearrangements.
C. They are the only way to determine the total chromosome number in a cell.
D. They increase the overall size of chromosomes, making them easier to handle.

Question No. 25 Marks +1 -0 Time

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Which specialized banding technique is used to identify the nucleolar organizer regions (NORs), which are sites of ribosomal RNA gene clusters?

A. G-banding
B. C-banding
C. R-banding
D. Ag-NOR banding

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