There are three tRNA binding sites -- A, P, and E (for Aminoacyl, Peptidyl, and Exit) -- but only one mRNA binding site. The enzyme which bonds amino acids carried by tRNAs at A and P is indeed called peptidyl transferase. tRNA is held at A and P when its anticodon matches the codon of the mRNA to be translated. Because each codon is three codons long, per amino acid, the mRNA is indeed shifted three nucleotides' length through the ribosome, each time an amino acid is added to the growing chain.

There are three tRNA binding sites -- A, P, and E (for Aminoacyl, Peptidyl, and Exit) -- but only one mRNA binding site. The enzyme which bonds amino acids carried by tRNAs at A and P is indeed called peptidyl transferase. tRNA is held at A and P when its anticodon matches the codon of the mRNA to be translated. Because each codon is three codons long, per amino acid, the mRNA is indeed shifted three nucleotides' length through the ribosome, each time an amino acid is added to the growing chain.

Protein translation begins by recognizing an initiation signal on the mRNA - the codon UAG. The amino acid that coded for by UAG is methionine.

For this question, we're asked to identify an answer choice that contains something that is not needed for transcription and translation.

To begin, let's define these two terms. Transcription is the production of mRNA from DNA. The subsequent coding of a polypeptide from this mRNA is known as translation. During translation, tRNA serves as the carriers of amino acids. In doing so, these tRNA's bring certain amino acids to the ribosome-mRNA complex, depending on the codon sequence of the mRNA. Furthermore, the ribosome itself is composed of rRNA as well as protein. So in total, DNA, mRNA, rRNA, and tRNA are needed for transcription and, subsequently, translation.

But what about miRNA? This type of RNA, together with another class of RNA called siRNA, are both involved in a process called RNA interference. In this process, either miRNA or siRNA acts to inhibit gene expression by inhibiting certain key steps at the level of transcription and translation. Therefore, miRNA is not required for proper transcription and translation to occur because it acts to inhibit these processes.

For this question, we're asked to identify an answer choice that contains something that is not needed for transcription and translation.

To begin, let's define these two terms. Transcription is the production of mRNA from DNA. The subsequent coding of a polypeptide from this mRNA is known as translation. During translation, tRNA serves as the carriers of amino acids. In doing so, these tRNA's bring certain amino acids to the ribosome-mRNA complex, depending on the codon sequence of the mRNA. Furthermore, the ribosome itself is composed of rRNA as well as protein. So in total, DNA, mRNA, rRNA, and tRNA are needed for transcription and, subsequently, translation.

But what about miRNA? This type of RNA, together with another class of RNA called siRNA, are both involved in a process called RNA interference. In this process, either miRNA or siRNA acts to inhibit gene expression by inhibiting certain key steps at the level of transcription and translation. Therefore, miRNA is not required for proper transcription and translation to occur because it acts to inhibit these processes.

Protein translation begins by recognizing an initiation signal on the mRNA - the codon UAG. The amino acid that coded for by UAG is methionine.

Aminoacyl-tRNA synthetases are important enzymes in translation. Their function is to match the specific amino acid to its tRNA. DNA polymerases, RNA polymerase, and DNA helicase are not involved in this process. DNA polymerases are enzymes involved in DNA replication; they create DNA molecules by assembling nucleotides. RNA polymerase produces RNA and has nothing to do with the translation process. Lastly, DNA helicase unwinds DNA during DNA replication, allowing the strands to be copied.

Aminoacyl-tRNA synthetases are important enzymes in translation. Their function is to match the specific amino acid to its tRNA. DNA polymerases, RNA polymerase, and DNA helicase are not involved in this process. DNA polymerases are enzymes involved in DNA replication; they create DNA molecules by assembling nucleotides. RNA polymerase produces RNA and has nothing to do with the translation process. Lastly, DNA helicase unwinds DNA during DNA replication, allowing the strands to be copied.

Scientists have indeed counted about 20,000 proteins coded for by the genome. Coding sequences are only about 2% or less of the genome. The definition of paralogs is genes related by duplication within a genome. Within the genome, not about 5%, but rather about 50%, of DNA sequences are repeated.

Scientists have indeed counted about 20,000 proteins coded for by the genome. Coding sequences are only about 2% or less of the genome. The definition of paralogs is genes related by duplication within a genome. Within the genome, not about 5%, but rather about 50%, of DNA sequences are repeated.