Which of the following characteristics with respect to bacterial DNA polymerase III are TRUE? P. Initiation of chain synthesis Q. 5'-3' polymerization R. 3'-5' exonuclease activity S. 5'-3' exonuclease activity
The question asks to identify the true characteristics of bacterial DNA polymerase III.
DNA Polymerase III Functions
Let's analyze each characteristic:
- P. Initiation of chain synthesis: Bacterial DNA polymerase III is the primary enzyme for DNA synthesis but does not initiate it. Initiation requires an RNA primer synthesized by primase. Thus, P is FALSE.
- Q. 5'-3' polymerization: DNA polymerase III adds nucleotides to the 3' end of the growing DNA strand, synthesizing the new strand in the 5' to 3' direction. Thus, Q is TRUE.
- R. 3'-5' exonuclease activity: DNA polymerase III possesses proofreading capability. It can remove incorrectly incorporated nucleotides from the 3' end using its 3'-5' exonuclease activity to ensure replication fidelity. Thus, R is TRUE.
- S. 5'-3' exonuclease activity: This activity is typically associated with removing RNA primers or DNA segments ahead of the replication fork, a function usually performed by other enzymes like DNA polymerase I in bacteria, not DNA polymerase III. Thus, S is FALSE.
Conclusion on Characteristics
Based on the analysis, the true characteristics of bacterial DNA polymerase III are 5'-3' polymerization (Q) and 3'-5' exonuclease activity (R).
- Therefore, the correct option includes Q and R only.
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`
