Study Questions - Evo-Devo
Readings - chapter 10
1) It seems both remarkable and logical that some genes have been conserved across 2 billion years of divergence between eukaryotes and prokaryotes. What types of genes are these, and why is their conservation logical? Give a few examples.
2) Development of a tissue requires co-ordinated action of different genes. At a simplistic genetic level, how does this co-ordination occur?
3) Similarly, how can two genes that code for proteins involved in different metabolic pathways become synchronized in their expression?
4) How is it that mutations in regulatory genes cause different activity in different tissues, while mutations in the structural genes affect expression in all tissues? Remember, all genes--structural and regulatory-- are present in all cells. Use the metallothionein gene as an example.
5) Describe the difference between cis and trans regulation. What would a mutation in a transcription factor be, to the genes it activates?
6) Structural novelty in multicellular organisms usually involves gene duplication and subsequent changes in its regulation. Explain the evolutionof citrate metabolism by E. coli in this light.
7) What is the putative steps in the duplication and differential regulation of hox genes?
8) What determines the ventral-dorsal axis in animals, and how does this differ in protostomes and deuterostomes?
9) How about limb development in protostomes and deuterostomes?
10) What role do hox genes play in the evolution of walking linbs from fish fins?
11) Homolous structures differ mainly in the relative sizes of parts (allometry). Describe how bat wings, beetle horns, and finch beaks vary as a consequence of difference in gene regulation.
12) There are some developmental reversal that occur embryologically, like the loss of legs in snakes and dolphins. How does this occur?
13) The evolution of the camera eye in molluscs and vertebrates proceeds through similar steps. What are they?
14) Many novelties in evolution arise by using an existing protein or structure in a new way. Explain the evolution of vertebrate lenses in this light.
15) One of the most remarkable examples of the homology of hox genes invovles pax6 and 'eyeless'. Explain the experiments that demonstrated the functional homology between these genes.