Genome Sequencing & App. of DNA Technologies

• Genomics is a branch of science that focuses on the interactions of sets of genes with the environment. – Identification of Genes• computer software scans for the existence of certain

known features associated with genes – start and stop sequences – intron splicing sites – ESTs - expressed sequence tags

» known gene sequences expressed in functioning genes

• Identification of Genes

– computer software scans for the existence of certain known features associated with genes • start and stop sequences • intron splicing sites • ESTs - expressed sequence tags

– known gene sequences expressed in functioning genes

Genomic Patterns

organism haploid genome size (Mb) # of genes genes per Mb

E. coli 4.6 4,400 940

nematode 97 19,000 200

drosophila 180 13,700 76

zebra fish 1,700 22,000 13

human 2,900 25,000 10

• As the complexity of the organism increases so does the amount of non-coding DNA, the amount of genes per Mb decreases • may be due to the role of non-coding regions in the regulation of gene

expression • larger intron regions lead to alternative splicing and increased complexity

of protein products

Determining Gene Function

• in vitro mutagenesis – introducing a mutation to a gene and seeing the consequences – can use cloned genes in yeast or in mouse embryos

• the use of embryos helps see the role of the gene in early development

Determining Gene Function

• RNA interference – probes (complimentary to the mRNA sequence) are

introduced to block the translation of a particular gene

Determining Gene Function• Interactions of groups of genes

– accomplished through the use of micro arrays (DNA chips) • all known genes are attached to a class slide • mRNA are harvested and copies made using cDNA, reverse transcriptase, and

fluorescent labeled nucleotides • cDNA mixture is added to the slide displaying the genes active at that particular

time

Applications of DNA technology• Medicine

– diagnosis of disease – gene therapy – development of pharmaceuticals

• Forensics • Environmental cleanup • Agriculture Applications • Safety & ethical questions

– GM organisms & food – privacy issues – cloning