Chapter all: How Cells Read the Genome
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BIO120H1 Full Course Notes
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How cells read the genome: from dna to protein. Transcription is the name given to the process of producing rna molecules using dna as guide. The enzymes that perform transcription are called rna polymerases. Rna polymerases make about one mistake for every 104 nucleotides compared with an error rate of about one in 107 nucleotides for dna polymerases. Rnas display some differences compared to dna: rnas have ribonucleotides in their composition instead of deoxyribonucleotides; Rnas contain the base uracil (u) instead of thymine (t); and rnas are single-strand molecules. There are different types of rnas: coding rnas and noncoding rnas. Example of coding rna is the messenger rna (mrna), which codes for proteins. Noncoding rnas comprise molecules that can perform enzymatic, structural and regulatory functions. Examples of these are: ribosomal rna (rrna), transfer rna (trna), small nuclear rna (snrna), small nucleolar rna (snorna), microrna (mirna), small interfering rna (sirna), piwi-interacting rna (pirna) and long noncoding rna (lncrna).
