GENOMES AND THEIR EVOLUTION Chapter 21 Bioinformatics Scientists

GENOMES AND THEIR EVOLUTION Chapter 21

Bioinformatics Scientists have used the advances of genetics and computers to further understanding Gen. Bank BLAST Protein Data Bank

Bioinformatics � � No longer have to infer genotype from phenotype Goal now is to identify all protein coding regions – gene annotation � Software looks for certain short sequences that specify known m. RNA’s � Use of known proteins is used to predict new protein sequences

Bioinformatics � Project ENCODE � Researchers focused on 1% of human genome � Looked for protein coding genes, noncoding RNA’s, and regulatory sequences � 90% of the region was transcribed into RNA � BUT only 2% coded for proteins

Bioinformatics � Cancer Genome Atlas � Project of the National Cancer Institute and NIH Analyzed interacting genes and their role in cancer Three types: Lung, ovarian, and glioblastoma Glioblastoma research has shown the most promise

Genomes vary in size, density, and number of genes Size – Both bacteria are similar in size and much smaller than eukaryotes Density – Eukayotes have a smaller gene density that bacteria Genes – same as size

Noncoding DNA � � Previously called “junk DNA” Only 1. 5% of the human genome codes for proteins or RNA’s Gene regulatory sequences (5%) and introns (20%) Pseudogenes � Regions that have accumulated mutations over time

Transposable Elements Made up of repetitive DNA Account for 25 -50% of the genome Elements move from one spot in the DNA to another – transposition Can occur through the DNA bending Eukaryotic types: Transposons Retrotransposons

Alteration of DNA Meiosis errors can result in extra chromosomes – polyploidy If the organism survives one set of chromosomes can mutate and form new, novel genes

Alteration of DNA Humans and chimps diverged about 6 million years ago Humans 23 chromosomes Chimps 24 chromosomes Chimp chromosomes formed to make a human chromosome

Alteration of DNA Crossing over or replication errors can lead one chromosome with a deletion and one with a duplication Over time this can lead to STR’s or repeating units Can be used for analysis

Transposable elements and Evolution These elements can play an important role evolution Promote recombination Disrupt cellular genes or control elements Carry genes/exons to new locations

Comparing Genomes Comparing conserved genes in distantly related species can clarify evolutionary relationships – show lines of divergence Comparing closely related species serves many functions: Sequences can be used as a scaffold for another species Comparing different species allows for determination what makes a species FOXP 2 – involved in the vocalization in vertebrates Evolving faster in humans than mice