Genes and Chromosomes Lecture Notes PDF

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1 2 3 4 5 6 7 8 9 10 11 12 24/10/2024 A G Lecture Many types of RNA MIRNA , siRNA , piRNA , for cellular proteins , CicRNA INCRNA · mRNA (messenger) : codes ,... tRNA (transfer) bring a to ribosome · : · rRNA (ribosomal) : structural RNAs that contribute to ribosome enRNA /mall nuclear) involved in mRNA splicing in nucleus · : SUMMARY GENES AND CUROMOSOMES E Slides LEARNING OUTCOMES DNA packaging in Eukaryotic cells 1. Explain how DNA is compacted into chromatin within eukaryotic cells, with reference to the structure of nucleosomes and the 30nm/solenoid fibre Euchromatin and Heterochromatin 2. Outline the differences between euchromatin and heterochromatin Chromosomes and Genes 3. Describe the major features of eukaryotic chromosomes and give brief functions for these. 4. Describe the major features of eukaryotic genes and give brief functions for these. Measurements · 1 basepair (bp) = single nucleotide (A , T, C G , , 4) Human genome : 3 x 105 bp 1000bp = 1kb 106 bp = 1 Mb 105 bp = 1 Gb Chromati Functions : · Package and condense CNA = complex of DNA and proteins · Prevent DNA damage DNA Control gene expression ~2 metres long · is  1 2 3 4 5 6 7 8 9 10 11 12 24/10/2024 A G Lecture Nucleosome "beads on a string"Composed of : 146 bp of DNA (wrapped-1. 7x around a 'core' & octamer o histore proteins 2xHIA , 2x HIB , 2x H3 , 2x HY Nucleosome are particles separated by 10-50 bp of linker DNA · are DNA H1 brings muchosomes together into ↑ I ringe I x-helix histone proteins (colour coded Multiple stacked sings = 30 nm fibre (or solenoid fibre Morcoiling - Euchromati Heterochromati dark · sene-rich areas of genome · gene poor · I transcribed light · Nucleosomes loosely packed · Nucleosomes tightly packed accessible DNA for DNA- binding proteins · stains lightly with G-stain stairs darkly on G-stain hoser packing 4 %G C C types of heterochromatin · -. : , · constitutive · facultative  1 2 3 4 5 6 7 8 9 10 11 12 24/10/2024 A G Lecture CONSTITUTIVE HE TEROCHROMATIN FACULTATIVE HETEROCHROMATIN came resion of genome in all cells areas of facultative hetewchromatin differs between · · centromeres telomeres repetitive elemente cell types · , , · stably inherited between celle · mere fluid · can change within a cell as it transits between States (differentiation) Nucleosome histore proteins Histone tails are important for determining Euchromation and Heterochromatin DNA · Modification of Histone rails is important in regulating chromatin structure Modifications include methylation phosphorylation, , acetylation , citullination,... histore tails Eukaryotic chromosome Basic features : - protecte Centromere : region of chromosome that links sister chromatide relomere repetitive DNA sequences at ends of chromosome (preserve integrity · : · replication origins : initiating DNA sequence for DNA replication · senes : basic unit of heredity (found on both strands and crientation) = species # number of chromosome E Senes · sequence of DNA nucleotides (order encodes sequence of a a in polypeptide · stretch of DNA transcribed and encodes a functional product (usually protein but can be functional RNA)  1 2 3 4 5 6 7 8 9 10 11 12 24/10/2024 A G Lecture DNA sequences in sene included in matur messenger (MRNA) DNA sequences transcribed but not N included in mature mRNA M Eukaryotic gene DNA sequences indicating which machinery , of transcription ' DNA sequences at point of end for transcription assembles L find nucleotide in sone transcribed into RNA during transcription Sene nomenclature Name of sence car : · reflect function · reflect family of related seves · reflect disease associated with when referring to a gene (c RNA) always italicise the gene name a symbol : e. g : Cystic Fibrosis Transmembrane , Regulator CFTR when referring to a protein , use normal type : e. : g Cystic Fibrosis Transmembrane Regulator , CFTR SUMMARY