Question

Match List - I with List - II. 

Choose the correct answer from the options given below : 
 

• A. A-IV, B-III, C-II, D-I
• B. A-III, B-II, C-I, D-IV
• C. A-II, B-I, C-IV, D-III
• D. A-II, B-IV, C-III, D-I

Hint:

Notice the evolutionary pattern!
Ciliates: TTGGGG
Vertebrates (Humans): TTAGGG (one G becomes an A)
Plants: TTTAGGG (adds an extra T). All are heavily 'G'-rich on the 3' overhanging strand to form G-quadruplex structures.

Answer 1

The Correct Option is A

Step 1: Concept:
The question tests knowledge of the specific, highly conserved DNA nucleotide sequences that make up the protective telomeres at the ends of linear chromosomes across different eukaryotic kingdoms.

Step 2: Step-by-step Explanation:

• Telomeres consist of tandem repeats of short, G-rich DNA sequences. While highly conserved, slight variations exist among major phylogenetic groups.

• A. Human (Vertebrates): The universal telomeric repeat sequence for humans and all other vertebrates is (TTAGGG)\(_n\).
Thus, A matches with IV.

• B. Yeast: In budding yeast like Saccharomyces cerevisiae, the telomere sequence is notably more irregular and heterogeneous compared to higher eukaryotes. It is characterized by variable repeats commonly denoted as ((TG)\(_{1-3}\)(TG)\(_{2-3}\))\(_n\) (often simplified as TG\(_{1-3}\) repeats).
Thus, B matches with III.

• C. Plant: The vast majority of higher plants, including the model organism Arabidopsis thaliana, possess a slightly longer telomeric repeat sequence consisting of seven nucleotides: (TTTAGGG)\(_n\).
Thus, C matches with II.

• D. Ciliated Protozoan: Telomeres were first discovered and sequenced by Elizabeth Blackburn (who won a Nobel Prize for it) in the ciliated protozoan Tetrahymena thermophila. Its characteristic telomere sequence is (TTGGGG)\(_n\).
Thus, D matches with I.

• Compiling the sequence gives: A-IV, B-III, C-II, D-I.

Step 3: Final Answer:
The matched sequence clearly aligns with Option (A).