BIOL 3450 Chapter 8: Chapter 8 – Genes, Genomics, and Chromosomes
Document Summary
8. 1 eukaryotic gene structure: enhancers ~ transcription control regions. Isoform ~ various proteins encoded by alternatively spliced mrnas expressed from one gene. In molecular terms, gene is entire dna sequence required for synthesis of functional protein or rna molecule. 8. 2 chromosomal organization of genes and noncoding dna. In genomes of prokaryotes and most lower eukaryotes, which contain few nonfunctional sequences, coding regions are densely arrayed along genomic dna. In contrast, genomes of multicellular animals and plants contain many sequences that do not apparently code for dunctional rnas or have any regulatory function: much of this nonfunctional dna is composed of repeated sequences. In humans, only about 2. 9% of total dna (exons) actually encodes proteins or functional. Variation in amount of nonfunctional dna in genomes of different species is largely responsible for lack of consistent relationship between amount of dna in haploid chromosomes of animal or plant and its phylogenetic complexity.
