9.5 Genomics and Bioinformatics Updates: Unit 5 quiz 2 Molecular clocks: cytochrome C due Homework: –Read 5.1 –Unit 5 test Wednesday –Last call for unit 5 work is Tuesday! Keystone Biology Exam: 5/15, 5/18

9.5 Genomics and Bioinformatics Keystone Question of the Day (review 3.3): Which of the following structures in the plasma membrane forms a selective barrier to the passage of hydrophilic chemicals? –transport proteins –carbohydrates –polar heads of phospholipids –nonpolar tails of phospholipids

9.5 Genomics and Bioinformatics Northern Rough Greensnake Opheodrys aestivus Size: inches in length Status: Endangered Species Habitat: Moist habitat, waterways in woodlands, lake & river borders, moist meadows. Mostly found in trees or shrubs near water, and seldom seen on the ground.

9.5 Genomics and Bioinformatics What is a molecular clock? Activator: Next slide Key terms: molecular clock, mitochondrial DNA (mtDNA),

9.5 Genomics and Bioinformatics GULO (L-gulonolactone oxidase) is the enzyme that produces vitamin C from glucose. Pigs and cows have a high number of conserved bases in this gene when compared to each other, while the human gene has a very low number of conserved bases when compared to pigs or cows. Which is potentially more alike/closely related? –pigs and cows? –cows and humans? –Humans and pigs? Humans historically have a diet rich in fruit and also no longer produce GULO from this gene. What might have happened?

9.5 Genomics and Bioinformatics Mutations Revisited Mutations alter the sequence of a gene: –random “typos” –heritable –natural variation Effects: –neutral –beneficial –harmful (deleterious)

9.5 Genomics and Bioinformatics Scientists attempt to link molecular data and real time. –an event known to separate species –the first appearance of a species in fossil record

9.5 Genomics and Bioinformatics Molecular clocks use mutations to estimate evolutionary time. Mutations add up at a constant rate in related species. –This rate is the “ticking” of the molecular clock. –As more time passes, there will be more mutations. DNA sequence from a hypothetical ancestor The DNA sequences from two descendant species show mutations that have accumulated (black). The mutation rate of this sequence equals one mutation per ten million years. Mutations add up at a fairly constant rate in the DNA of species that evolved from a common ancestor. Ten million years later— one mutation in each lineage Another ten million years later— one more mutation in each lineage

9.5 Genomics and Bioinformatics Discussion: What did lice teach us about human evolution?

9.5 Genomics and Bioinformatics Mitochondrial DNA is used to study closely related organisms. –mutation rate ten times faster than nuclear DNA –passed down unshuffled* from mother to offspring grandparents parents child Nuclear DNA is inherited from both parents, making it more difficult to trace back through generations. Mitochondrial DNA is passed down only from the mother of each generation,so it is not subject to recombination. mitochondrial DNA nuclear DNA

9.5 Genomics and Bioinformatics Ribosomal RNA is used to study distantly related species. –many conserved regions –lower mutation rate (slow ticker)

9.5 Genomics and Bioinformatics Summary: What can studying bird brains and bird genes tell us about the evolution of the nervous system? What can making comparisons between humans and birds tell us about language and speech disorders?