What is the nucleophile in the reaction catalyzed by DNA polymerase?
The chain-elongation reaction catalyzed by DNA polymerases is a nucleophilic attack by the 3′-hydroxyl group of the primer on the innermost phosphorus atom of the deoxynucleoside triphosphate (Figure 5.22). A phosphodiester bridge forms with the concomitant release of pyrophosphate.
What is the nucleophile in DNA synthesis?
The mechanism for the DNA polymerization reaction is shown in Figure 6. The terminal 3′ oxygen of the growing strand acts as a nucleophile and forms a covalent bond with the phosphorus atom of the α-phosphate group of the incoming dNTP.
What is the nucleophile in the reaction catalyzed by DNA polymerase What is the significance of this in terms of initiating DNA synthesis?
What is the nucleophile in the reaction catalyzed by DNA polymerase? pyrophosphate to inorganic phosphate ions makes the reaction essentially irreversible. Because a 3′-hydroxyl group is required for the reaction, DNA polymerase cannot simply bind to a single-stranded template DNA molecule and start synthesis.
What is the action of DNA polymerase?
DNA polymerase is an enzyme that synthesizes DNA molecules from deoxyribonucleotides, which are the building blocks of DNA. The enzymes play an essential role in DNA replication, usually working in pairs to produce two matching DNA stranges from a single DNA molecule.
How important is the DNA proofreading step?
Proofreading, which corrects errors during DNA replication. Mismatch repair, which fixes mispaired bases right after DNA replication. DNA damage repair pathways, which detect and correct damage throughout the cell cycle.
What is an example of a transcription error?
Human transcription errors are commonly the result of typographical mistakes; putting one’s fingers in the wrong place while touch typing is the easiest way to make this error. (The slang term “stubby fingers” is sometimes used for people who commonly make this mistake.)
What is the result of transcription?
The individual nucleotides that are read off of the DNA template strand are transcribed into the nucleotides of the corresponding RNA, so the final result is a single-stranded polymer, namely the mRNA, whose nucleotides correspond exactly to the complementary nucleotides on the DNA strand with the exception that …
What is the main goal of transcription?
The goal of transcription is to make a RNA copy of a gene’s DNA sequence. For a protein-coding gene, the RNA copy, or transcript, carries the information needed to build a polypeptide (protein or protein subunit). Eukaryotic transcripts need to go through some processing steps before translation into proteins.
Which is important for transcription?
CAAT is a promoter sequence that lies between -70 and -80 base pairs and is essential for transcription initiation. Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA (mRNA) by the enzyme RNA polymerase. Thus, the correct answer is option D.
Is the end result of transcription?
The outcome of Transcription is a complimentary strand of messengerRNA (mRNA).
How many codons are needed for 6 amino acids?
The “6 codons” could be interpreted as referring to a run of 6×3 = 18 nucleotides in the mRNA. Then, of course, the answer is trivially, 6 amino acids….How many codons are needed for each amino acids?
| Radioactive | Histidine |
|---|---|
| Observed | 4 |
How many codons are needed for 2 amino acids?
13 codon
How many codons are needed for each amino acids?
Because there are only 20 different amino acids but 64 possible codons, most amino acids are indicated by more than one codon. (Note, however, that each codon represents only one amino acid or stop codon.)