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How much DNA?

How much DNA?. Chromosomes. 46 Chromosomes = 23 homologous pairs. 44 autosomes 2 sex chromosomes. Average chromosome length = 4cm 120 base pairs long contains thousands of genes. Genes. Gene lengths vary from 8,000 - 2,000,000 base pairs. Genome = total set of genes in an organism.

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How much DNA?

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  1. How much DNA?

  2. Chromosomes 46 Chromosomes = 23 homologous pairs 44 autosomes 2 sex chromosomes Average chromosome length = 4cm 120 base pairs long contains thousands of genes

  3. Genes Gene lengths vary from 8,000 - 2,000,000 base pairs Genome = total set of genes in an organism Human genome = 30,000 - 40,000 genes

  4. Nucleus Chloroplast Mitochondrion Where do you find DNA? All mature cells contain DNA except the red blood cells DNA is found in the nucleus Small amounts of DNA are also present in the chloroplasts and mitochondria Source: http://www.tokyo-med.ac.jp/genet/picts/cell-e.jpg

  5. Mitochondrial DNA • Represented as mtDNA • Double-stranded circular molecule made up of 16,568 base pairs, coding for 37 genes • 13 genes code for proteins involved in cellular respiration • 2 genes code for ribosomal RNA (rRNA) • 22 genes code for transfer RNA (tRNA)

  6. Mitochondrial DNA

  7. Representing DNA 5’…A C G T T C G A A G C T A G G T T A T C G A…3’ If this represents the sequence of bases on one strand of DNA, what would the sequence of the other strand be? 3’…T G C _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ G C T…5’

  8. This is the principle used in gene-sequencing DNA sample is heated to separate strands forming a template 5’…A C G T T C G A A G C T A G G T T A T C G A…3’ Nucleotides are added to the mix with each of the 4 DNA bases. Additional fluorescent dye-labelled nucleotides are also added to the mix The mixture is cooled allowing the added nucleotides to attach to the template strand according to base-pair rules …A C G T T C G A A G C T A G G T T A T C G A… …T Varying lengths of complementary strands are produced. At the end of each strand, a nucleotide with the fluorescent dye attaches, causing the synthesis of the strand to stop …T G …T G C The dyes are detected by an electronic analyser which records the result …T G C A

  9. Human Genome Project • This technique of DNA sequencing has made it possible for scientists to collaboratively map the entire Human Genome • Began in 1990 and fully completed in 2003 • Aims: • Improve diagnosis of genetically inherited disorders • Improve treatments for a range of diseases • Prevent diseases that have a genetic predisposition

  10. Interesting facts about the Human Genome Two unrelated humans will share 99.9% of their total DNA The differences between individuals are called single nucleotide polymorphisms 95% of human DNA function is unknown and referred to as 'junk' 2,850,000,000 base pairs long Genes only make up 1.5% of total genome

  11. Flanking regions Coding Region Upstream Flanking Region Downstream Flanking Region

  12. Comparative Genomics • The sequences of many other genomes have been sequenced • This allows scientists to compare the genomes of a variety of species and determine degrees of relatedness between them

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