RNA Primer Removal in Bacterial DNA Replication
During bacterial DNA replication, RNA primers are synthesized to initiate DNA synthesis. These RNA primers must be removed and replaced with DNA.
Enzyme Responsible for Primer Removal
The enzyme responsible for removing RNA primers in bacteria is DNA Polymerase I. This is due to its specific enzymatic activities:
- 5' to 3' Exonuclease Activity: This allows DNA Polymerase I to remove the RNA nucleotides from the 5' end of the primer.
- 5' to 3' Polymerase Activity: After removing the RNA, DNA Polymerase I fills the resulting gap with DNA nucleotides.
Analysis of Options
- DNA gyrase: This enzyme (a topoisomerase) relieves torsional stress during replication but does not remove primers.
- DNA Polymerase I: Correctly identified as the enzyme with the necessary exonuclease and polymerase activity for primer removal and replacement.
- Primase: Synthesizes the RNA primer, it does not remove it.
- DNA Polymerase III: This is the main replicative polymerase responsible for synthesizing the bulk of the new DNA strand, but it lacks the specific exonuclease activity to remove RNA primers.
Therefore, DNA Polymerase I is the enzyme that removes the RNA primer synthesized during bacterial DNA replication.
Important Questions from Replication Transcription Splicing and Translation
Messenger RNAs (mRNAs) translate to generate polypeptides and the translation terminates at the UGA, UAG or UAA stop codons. The AGA codon acts as additional stop codon in the mitochondria. The longest possible polypeptide(s) that can be hypothetically translated in the cytosol and/or mitochondria, from the given full length mRNA sequence (36 nucleotides) is/are
5'-AACACCAUGACCCAUGUGGCGAGACGGUAGUUAAAA- 3'
- Which of the following statements about initiation of DNA replication in eukaryotes is/are true?
Match the drugs in Group I with their mechanism of action in Group II.
Group I Group II P) Paclitaxel 1) Inhibits protein translation Q) Colchicine 2) Inhibits microtubule depolymerization R) Etoposide 3) Inhibits DNA replication S) Methotrexate 4) Alkylates DNA 5) Inhibits dihydrofolate reductase 6) Inhibits microtubule polymerization Match the enzyme (Column I) with its corresponding function (Column II).
Column I Column II P. Primase 1. RNA dependent RNA synthesis Q. Reverse transcriptase 2. DNA dependent DNA synthesis R. RNA Replicase 3. RNA dependent DNA synthesis S. DNA Polymerase III 4. DNA dependent RNA synthesis Which of the following statements regarding the below mentioned mRNA sequence is/are TRUE?
5`-UGAUGAGCCUUAACCGGGAACGAAUUUAAG-3`
