1、Transcription and TranslationFrom DNA to RNA to proteinOverview Genes in DNA contain information to make proteins. The cell makes mRNA copies of genes that are needed. The mRNA is read at the ribosomes in the rough ER. Protein is produced.Key Players mRNA carries the information from a gene in DNA.
2、Ribosomes, made of rRNA, consist of subunits and carry out an enzyme-like role. tRNA carries specific amino acids to the ribosome.TranscriptionRNA polymerase is the enzyme responsible for making mRNA copies of genes. DNA unzips at the site of the gene that is needed. TranscriptionRNA polymerase matc
3、hes bases in the sense strand with RNA bases, building a strand of mRNA that carries the information encoded in the DNA.TranscriptionEncoded in DNA is a signal telling RNA polymerase where to stop. Transcription ends at that point.TranscriptionThe completed mRNA molecule then moves from the nucleus
4、to the rough ER for translation.Translation Initiation begins with a tRNA bearing methionine (met) attaching to one of the ribosomal units. The codon for methionine is a universal “start” codon for “reading” the mRNA strand.Translation The ribosomal unit binds to mRNA where the code for met is located (AUG). The anticodon (UAC) of the tRNA matches the “start” codon on mRNA (AUG). Translation The larger ribosomal subunit now binds to the smaller unit, forming a ribosomal complex. The tRNA binds to the first active site on the ribosome. Translation may now begin.
