and telomeres(the end of chromosomes, some is simply intergenic regions(non coding regions between genes) but much of it is present as introns What does it mean Genes have introns". this represents one of the fundamental organizational differences between prokaryotic and eukaryotic genes. Eukaryotic genes turn out to be interrupted with long DNA sequences that do not encode for protein. these exons introns intervening sequences are called introns transcription The DNa segments that are ultimately expressed primary transcript (ss RNA)1[2 as protein i e the dna addition of 5 cap triplet codon informatic are called Is. The RNA (ssRNA) MeG 3 intronic sequences are AUG d from the transcript by splicing. cids)1 2 A major consequence of this arrangement is the potential for alternative splicing to produce different proteins species from the same gene and primary transcript. This gives the potential for tremendous amplification of the complexity of mammals(and other eukaryotes) through many more thousands of possible proteins Note that lower eukaryotes such as the yeast s. cerevisiae only have N 5% of their genes interrupted by introns but for multicellular organisms, like humans >90% of all genes are interrupted by anywhere between 2 and 60 introns, but most genes have between 5 and 12 introns Saccharomyces cerevisiae YFLO40W YFLO30W TUB2 RP041 YFLO34W STE2 CAK BST1 EPLl RPL22B CAF16 Drosophila melal CG3131 uman Loc139168 Figure by MIT OCW.and telomeres (the end of chromosomes, some is simply intergenic regions (non￾coding regions between genes) but much of it is present as introns. What does it mean “Genes Have Introns”. This represents one of the fundamental organizational differences between prokaryotic and eukaryotic genes. Eukaryotic genes turn out to be interrupted with long DNA sequences that do not encode for protein…these “intervening sequences” chromosome (ds DNA) are called introns. 1 2 3 gene exons introns transcription primary transcript (ss RNA) 1 2 3 mRNA (ssRNA) translation protein (amino acids) 1 2 3 MeG 1 2 3 cap AAAAA addition of 5’ cap 3’ polyadenylation splicing out of introns AUG stop chromosome (ds DNA) 1 2 3 gene exons introns transcription primary transcript (ss RNA) 1 2 3 mRNA (ssRNA) translation protein (amino acids) 1 2 3 MeG 1 2 3 cap AAAAA addition of 5’ cap 3’ polyadenylation splicing out of introns MeG 1 2 3 cap AAAAA addition of 5’ cap 3’ polyadenylation splicing out of introns AUG stop The DNA segments that are ultimately expressed as protein, i.e., the DNA sequence that contains triplet codon information, are called exons. The intronic sequences are removed from the primary transcript by splicing. A major consequence of this arrangement is the potential for alternative splicing to produce different proteins species from the same gene and primary transcript. This gives the potential for tremendous amplification of the complexity of mammals (and other eukaryotes) through many more thousands of possible proteins. Note that lower eukaryotes such as the yeast S. cerevisiae only have ~ 5% of their genes interrupted by introns, but for multicellular organisms, like humans, >90% of all genes are interrupted by anywhere between 2 and 60 introns, but most genes have between 5 and 12 introns. Drosophila melanogaster syt CG16987 CG2964 CG3123 CG15400 CG3131 0 50 Human GATA1 HDAC6 LOC139168 PCSK1N 0 50 Saccharomyces cerevisiae RGD2 SEC53 ACT1 FET5 TUB2 RP041 YFL034W HAC1 STE2 YFL046W YFL044C YPT1 MOB2 RPL22B RIM15 CAK1 BST1 EPL1 CAF16 YFL042C 0 50 GYP8 YFL040W YFL030W Figure by MIT OCW