1. There is no ____ that is specified by a stop codon on an mRNA molecule.
2. Why is it impostant for RNA polymerase to start at the right place and transcribe in the right direction?
I really had no ideas on these two.
Please help.
Any help is appreciated. Thank you.
1. The missing word in the first question is "protein". There is no protein that is specified by a stop codon on an mRNA molecule.
To understand why this is the case, we need to understand the process of protein synthesis. Proteins are built from amino acids, which are encoded in the DNA sequence of genes. During protein synthesis, the DNA sequence is transcribed into a messenger RNA (mRNA) molecule through a process called transcription. The mRNA then acts as a template for translation, where it is read by ribosomes to synthesize the corresponding protein.
Stop codons are specific sequences of nucleotides (UAA, UAG, and UGA) that signal the termination of protein synthesis. When the ribosome encounters a stop codon on the mRNA, it releases the newly synthesized protein and detaches from the mRNA.
However, it's important to note that a stop codon does not code for any particular amino acid. Instead, it serves as a termination signal, indicating that no further amino acids need to be added to the growing protein chain. Therefore, there is no specific protein that is specified by a stop codon on an mRNA molecule.
2. It is important for RNA polymerase to start at the right place and transcribe in the right direction because it ensures accurate transcription of the genetic information encoded in the DNA.
RNA polymerase is the enzyme responsible for synthesizing RNA. It binds to specific DNA sequences called promoters to initiate transcription. The promoter region contains crucial information, such as the location and orientation of the gene, and determines where RNA polymerase should start transcription.
If RNA polymerase starts transcription at the wrong place, it may result in the synthesis of an mRNA molecule that lacks essential genetic information. This could lead to the production of a non-functional or partially functional protein, disrupting normal cellular processes.
Similarly, transcribing in the wrong direction can result in an inverted or reversed sequence of the mRNA molecule. Consequently, this would alter the correct reading frame during translation, leading to the production of a completely different protein sequence.
Therefore, starting at the correct promoter sequence and transcribing in the proper direction are crucial for accurate gene expression and protein synthesis.