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RNA polymerase stops transcribing mRNA when it encounters a termination signal in the DNA sequence, typically a specific sequence of nucleotides that signals the end of a gene. This signal can be formed by specific sequences that lead to the formation of a hairpin loop in the RNA, causing RNA polymerase to dissociate from the DNA template. Additionally, termination factors may assist in this process, ensuring that transcription is completed accurately.
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What is the terminator in mRNA synthesis?
The terminator in mRNA synthesis is a specific DNA sequence that signals the end of transcription. When the RNA polymerase reaches the terminator sequence, it stops transcribing the mRNA molecule, releasing it from the DNA template.
What is the stop codon in most molecules of mRNA?
stop codon on mRNA
How does transcription end?
Transcription ends when RNA polymerase reaches a terminator sequence on the DNA template strand. This signals the enzyme to stop synthesizing the RNA transcript and release it. The RNA transcript is then further processed and can be translated into a protein.
What is the DNA sequence responsible for mRNA codon?
The DNA sequence responsible for an mRNA codon is found in the coding region of a gene, specifically in the form of triplet base pairs. During transcription, RNA polymerase synthesizes mRNA by complementary pairing with the DNA template strand, where each group of three nucleotides (codon) in the mRNA corresponds to a specific amino acid or stop signal in protein synthesis. For example, if the DNA sequence is A-T-G, the corresponding mRNA codon would be U-A-C. Thus, the sequence of nucleotides in DNA directly determines the sequence of codons in mRNA.
What determines where on the DNA molecule transcription begins and ends?
Transcription begins at a specific DNA sequence called the promoter region, which signals the RNA polymerase enzyme where to start transcribing. Transcription ends at a specific DNA sequence called the terminator region, which signals the RNA polymerase to stop transcribing. These regions, along with other regulatory elements, help determine the initiation and termination points of transcription.
What is the terminator in mRNA synthesis?
The terminator in mRNA synthesis is a specific DNA sequence that signals the end of transcription. When the RNA polymerase reaches the terminator sequence, it stops transcribing the mRNA molecule, releasing it from the DNA template.
How does RNA polymerase know where to start transcribing a gene into mRNA?
The enzyme that synthesizes RNA (RNA polymerase) binds specific DNA sequencesthat typically lie before the gene being transcribed. When everything it needs to start synthesis is properly assembled (any cofactors, etc.), only then can it begin transcribing DNA into RNA.
What are the steps taken to translate a 9-base DNA strand into an amino acid sequence?
There are a huge number of steps involved in this process, but briefly it goes like this: # Transcription factors bind to DNA and promote binding of RNA polymerase # RNA polymerase binds in complex with transcription factors # Transcription is initiated and RNA polymerase uses free NTPs, complementary to the antisense strand of DNA to create an RNA copy of the DNA. # The mRNA leaves the nucleus - some modification may take place # Translation factors bind mRNA # Ribosome binds to mRNA # tRNA brings amino acids to ribosome # Ribosome begins translation at methionine start codon - matching anticodon on tRNA to triplet codons on mRNA to pair correct amino acid to the mRNA code # Ribosome stops translation at stop codon # Ribosome/mRNA/tripeptide complex will dissociate
What is the stop codon in most molecules of mRNA?
stop codon on mRNA
How does transcription end?
Transcription ends when RNA polymerase reaches a terminator sequence on the DNA template strand. This signals the enzyme to stop synthesizing the RNA transcript and release it. The RNA transcript is then further processed and can be translated into a protein.
Describe the process of transcription in biology?
This process occurs in the nucleus of a cell. Firstly DNA helicase, will break the hydrogen bonds holding together the two strands of DNA. This exposes the bases on the two strands. RNA polymerase then anneals free nuleotides via phosphodiester bonds, via complementary base pairing to one strand of DNA, known as the template strand. Thus a strand of pre-messenger RNA is built, as the RNA polymerase moves along the DNA strand, the two DNA strands join up behind it. RNA polymerase stops the process of transcription when it reaches stop codons, which tell the enzyme to stop annealing nucleotides. The product is a length of pre-mRNA, which can then leave the nucleus throguh the nuclear pores and undergo splicing to remove introns and then translation.
Synthesis of a protein stops when?
Synthesis of a protein stops when a stop codon is reached on the mRNA during translation. This signals the ribosome to release the newly synthesized protein so it can fold into its functional structure.
What is the DNA sequence responsible for mRNA codon?
The DNA sequence responsible for an mRNA codon is found in the coding region of a gene, specifically in the form of triplet base pairs. During transcription, RNA polymerase synthesizes mRNA by complementary pairing with the DNA template strand, where each group of three nucleotides (codon) in the mRNA corresponds to a specific amino acid or stop signal in protein synthesis. For example, if the DNA sequence is A-T-G, the corresponding mRNA codon would be U-A-C. Thus, the sequence of nucleotides in DNA directly determines the sequence of codons in mRNA.
What determines where on the DNA molecule transcription begins and ends?
Transcription begins at a specific DNA sequence called the promoter region, which signals the RNA polymerase enzyme where to start transcribing. Transcription ends at a specific DNA sequence called the terminator region, which signals the RNA polymerase to stop transcribing. These regions, along with other regulatory elements, help determine the initiation and termination points of transcription.
What can stop gene expression?
Gene expression can be stopped by transcription factors binding to the promoter region of a gene, thus preventing RNA polymerase from transcribing the gene. Additionally, epigenetic modifications like DNA methylation and histone deacetylation can inhibit gene expression by altering chromatin structure and making the gene inaccessible for transcription. Other factors such as microRNAs can also interfere with gene expression by degrading mRNA molecules or blocking their translation into proteins.
What tells the cell it is time to stop translating?
Stop codons in the mRNA
What signals the termination of translation?
Translation terminates when a stop codon (UAA, UAG, or UGA) is reached in the mRNA. This stop codon is recognized by release factors, which promote the release of the completed polypeptide chain from the ribosome.
