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How many of the following is/are correct...

How many of the following is/are correct statement?
(A)In capping an unusual nucleotides is added to the 3' end of hn RNA
(B)In tailing adenylated residues are added at 3' end in a template independent manner.
(C)The untranslated regions (UTR) are required for efficient DNA replication process.
(D)The DNA-dependent DNA polymerases catalyse polymerisation only in one direction that is 5' ` to ` 3'.

A

Four

B

Three

C

Two

D

One

Text Solution

AI Generated Solution

The correct Answer is:
To determine how many of the given statements are correct, let's analyze each statement one by one. ### Step 1: Analyze Statement A **Statement A:** In capping, an unusual nucleotide is added to the 3' end of hnRNA. - **Analysis:** Capping refers to the addition of a 7-methylguanylate (m7G) cap to the 5' end of the hnRNA (heterogeneous nuclear RNA), not the 3' end. Therefore, this statement is incorrect. ### Step 2: Analyze Statement B **Statement B:** In tailing, adenylated residues are added at the 3' end in a template-independent manner. - **Analysis:** This statement is correct. During the process of polyadenylation (tailing), adenine nucleotides (A) are added to the 3' end of the RNA molecule without the need for a template. ### Step 3: Analyze Statement C **Statement C:** The untranslated regions (UTR) are required for efficient DNA replication process. - **Analysis:** This statement is incorrect. Untranslated regions (UTRs) are parts of mRNA that do not code for proteins and are involved in the regulation of translation, not in DNA replication. Therefore, this statement is false. ### Step 4: Analyze Statement D **Statement D:** The DNA-dependent DNA polymerases catalyze polymerization only in one direction that is 5' to 3'. - **Analysis:** This statement is correct. DNA polymerases can only synthesize new DNA strands in the 5' to 3' direction, meaning they add nucleotides to the 3' end of the growing strand. ### Conclusion Now, let's summarize the correctness of each statement: - **Statement A:** Incorrect - **Statement B:** Correct - **Statement C:** Incorrect - **Statement D:** Correct Thus, the number of correct statements is **2** (B and D). ### Final Answer The number of correct statements is **2**.
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