BIOL 2131 Lecture Notes - Lecture 10: Audiology, Meiosis, Transferase

• School: University of Windsor
• Department: Biological Sciences
• Course: BIOL 2131
• Professor: Hubberstey

Document Summary

Introduction:(where(do(our(genes(come(from: we!all!have!common!ancestors!that!go!way!back!!!genes!also!have!ancestors, exons!are!thought!to!be!the!building!blocks!of!genes, exons!make!a!particular!string!of!amino!acids, exons!are!separated!by!introns, when!you!look!at!gene!structure!of!every!species! (mammals,!frogs,!birds),!the, this!implies!that!when!the!gene!evolved!in!the!ancestral!organisms,!the, the!gene!went!along!with!the!species!as!it!evolved( introns!occur!in!the!exact!same!positions! evolution!worked!really!well! !all!it!does!is!change: however,!there!are!some!mutations!within!introns!that!can!have!very!serious! effects. !these!are!found!in!the!splicing!sequences! (shown!in!green,!between! introns/exons), mutations!that!affect!splicing!can!affect!protein!function, very!dramatic!effect, frameshift!mutations!can!result, frameshift!mutations!are!usually!very!bad!for!a!cell!and!a!gene, genes!involved!in!human!disease!were!thought!to!be!disturbed!by!splicing, 15%!of!human!diseases!are!caused!by!mutations!in!introns!that!affect! Intron structure: (cid:0)mutations within introns may be silent (cid:0)mutations that affect splicing can affect protein function: our!introns!are!sometimes!huge!compared!to!exons. !if!you!look!at!our!genome,!the: some!eukaryotes!have!very!few!introns!(e. g. !yeast), summary!picture:! (cid:0)frameshift mutations can result (cid:0)15% of human disease are caused by majority!of!it!codes!for!introns,!while!a!minority!is!for!exons! (surprisingly)! In!eukaryotes,!introns!are!generally!longer!than!exons! mutations in introns that affect splicing: 90%!of!yeast!genes!have!no!introns!whatsoever! (cid:0)in eukaryotes, introns are generally longer than exons. If!you!get!a!mutation!at!red!*! (in!splicing!sequences),!it!will!have!a!much! (cid:0)some eukaryotes have very few introns (e. g. yeast) more!deleterious!effect! splicing! Progeria(disease:( exon1 intron: only!140!cases!recorded!in!all!of!medical!literature, thus,!incredibly!rare!disease, 1!in!8!million!births, causes!premature!and!rapid!ageing!of!cells, death!usually!by!age!15, mostly!die!of!arteriosclerosis,!hardening!of!arteries,!stroke,!etc, dominant!defective!gene!for!progeria!was!discovered!in!2003! !you!get!the!disease: dinovel!mutation, usually!not!hereditary!because!the!kids!don"t!live, single!nucleotide!mutation, lamin!a, lines!the!inner!nuclear!membrane!of!the!nucleus, nuclear!protein!which!causes!proper!nuclear, nucleus!shape!is!messed!up!because!the!lamin!is, non!circular!shape!of!nucleus!! Progeria exon2 (cid:0) 1 in 8 million births (cid:0)causes premature and rapid ageing of cells (cid:0)death usually by age 15. Dominant defective gene for progeria was discovered in 2003. Lamin a mutation: gly608gly which is a c (cid:0)t transition: cg!base!pair!changed!to!an!at!base!pair , ggc!codon!changed!to!ggu!codon, specific!rna!sequences!determine!splice!sites, these!2!codons!code!for!glycine!! !this!is!why!it!took!such!a!long!time!to!find: how!does!it!change!the!function!of!the!protein!without!changing!the!amino! this!gene! changes ggc codon to a ggu.