BIOL 2100 Lecture Notes - Lecture 32: Nuclear Membrane, Polyadenylation, Intron
Document Summary
Only some genes are being expressed at any moment. Dna replication and transcription are both nucleic acid synthesis. Synthesizing dna requires a dna polymerase and primers made by rna polymerases. Both strands of dna act as templates along the entire length. Synthesizing rna requires just an rna polymerase. Only certain regions of the chromosome are being copied. Only 1 of the 2 strands is being transcribed in these regions. Determine where polymerase will bind and start transcription. Some promoters have similar portions of sequences across species. Transcription and translation occur simultaneously in prokaryotes because there is no nuclear envelope separating the processes mrna processing. These additions: increase the stability of the rna. Assist in export from the nucleus to the cytoplasm. 5,000/250,000 are exons in the primary transcript. 98% of the primary transcript are introns that get cut out and thrown away. Introns are not reflected in the final rna or protein sequence. Significance: one gene can produce multiple polypeptides.