The resulting mRNA is a single-stranded complementary copy of the gene (with uracil instead of thymine), which is translated by the ribosome, into a protein molecule. As with DNA polymerase, RNA polymerase can only add nucleotides to the 3′ end of the growing strand, so transcription is from only one side of the DNA strand. The DNA needs to be unwound for transcription to occur, and is rewound after transcription. Transcription is halted when the RNA ploymerase enzyme encounters a terminator sequence in the DNA, again a short sequence of bases. This is a short sequence which the RNA ploymerase binds to. Transcription is initiated at a region of the DNA called the promtoer.
DNA TRANSCRIPTION AND TRANSLATION STEPS FREE
The DNA of the gene serves as a template for complementary base-pairing, and RNA polymerase enzyme forms a pre-mRNA molecule using free RNA nucleotides. Transcription (the details of the spliceosome are outside the scope of the Higher course)ĭuring this stage, the information in DNA is first transferred to a messenger RNA (mRNA) molecule. As a result of differentiation in cells, not all genes are expressed at all times.Ģ. The term gene expression means the cell manufacturing the protein encoded by that gene. The genes in DNA encode protein molecules, which carry out all the functions necessary for life including enzymes and structural proteins. (Write Science Right) © 2008 Nature Education) © 2008 Nature Education and Translation: DNA to mRNA to Protein By: Suzanne Clancy, Ph.D. © 2008 Nature Education, RNA Splicing: Introns, Exons and Spliceosome By: Suzanne Clancy, Ph.D. Homework Sheets 1_4/ 1_4A (Sources: DNA Transcription By: Suzanne Clancy, Ph.D. Codon recognition of incoming tRNA, peptide bond formation and exit of tRNA from the ribosome as polypeptide is formed.
DNA TRANSCRIPTION AND TRANSLATION STEPS CODE
Triplet codons on mRNA and anticodons translate the genetic code into a sequence of amino acids.
TRNA folds due to base pairing to form a triplet anticodon site and an attachment site for a specific amino acid. (d) Translation of mRNA into a polypeptide by tRNA at the ribosome. The exons are coding regions and are joined together to form mature transcript. The introns of the primary transcript of mRNA are non-coding and are removed in RNA splicing. (c) Transcription of DNA into primary and mature RNA transcripts to include the role of RNA polymerase and complementary base pairing.
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