Exam 12: Evolution of the Nervous System

Which of the following issues could lead to erroneous estimates of phylogenetic distance based on molecular clock analysis?

State whether each of the following is true for r-opsin, c-opsin, both, or neither. A. Believed to detect light for circadian rhythm regulation B. Hyperpolarizes neurons when activated by light C. Opens an ion channel when activated by light D. Works with a G protein and second messenger to regulate ion channels E. Only found in chordates F. Only found in invertebrates

The conserved function of GPCRs in unicellular organisms is:

In bacterial chemotaxis, diagrammed in Figure , the CheZ phosphatase rapidly reverses the phosphorylation of CheY by histidine kinase CheA. Figure This activity by CheZ:

Which of the following is not true of human FoxP2?

Which of the following are true of color vision in New World monkeys?

Bacteria do not respond directly to a concentration gradient by curving their trajectory toward an attractant; instead, they tumble (randomly switch directions) unless inhibited from doing so. How do larger organisms navigate toward the source of a chemoattractant? With which other sensory system might we expect to see parallels in circuitry organization?

Which of the following is not a likely outcome of gene duplication?

Mice that are homozygous mutant for Small eyes/Pax6 completely lack eyes. If you were to express the fly Eyeless gene in the eye primordia of a mouse embryo during development, you would expect to see mice with:

Which mechanism(s) could contribute to larger brains with more cortical neurons?

Many synapse components, neural fate and patterning genes, and neurotransmitters are found in both cnidarians and ctenophores, which have nerve nets, but not in sponges, which do not. Ctenophores are currently believed to be the outgroup to cnidarians, bilaterians, and sponges, casting doubt on the origins of nervous systems. What are two plausible scenarios consistent with these observations, and how could one experimentally distinguish between them?

What are some of the parallels between the yeast mating signal transduction pathway and neuronal signaling?

In both insects and mammals, most ORNs express only one specific odorant receptor, and the axons of ORNs that express the same odorant receptor project to the same glomerulus. Is this similarity in organization likely to be due to shared ancestry or to convergent evolution? Briefly explain your reasoning.

Put the following events in the evolution of human color vision in chronological order. A) Duplication of one cone opsin gene to generate the rod opsin B) Duplication of one red/green cone opsin gene on the X chromosome C) Divergence of humans from other Old World monkeys and apes D) Loss of two cone opsin genes E) Two genome duplication events in the chordate lineage F) Appearance of red/green cone opsin variants with distinct spectral sensitivities in an ancestral Old World primate population (still hypothetical)

A significant increase in the number of cortical neurons is sufficient for the formation of gyri and sulci in previously lissencephalic brains.

Which of the following are NOT conserved between vertebrates and invertebrates?

Delivery of newly synthesized proteins from the ER to the Golgi apparatus and neurotransmitter release at the synaptic cleft both require:

The complex organization of the human eye has often been used as an argument for intelligent design. What evidence would you cite to respond to someone who believes that it would have been impossible for the eye to evolve by natural selection?

Ionotropic receptors:

Put the following events of the yeast mating pathway in chronological order. A. Replacement of GDP by GTP in CDC42 B. Polarized growth (shmoo formation) C. Dissociation of G protein βγ subunits (STE4/STE18) from α subunit D. Regulation of actin cytoskeleton E. Cell fusion F. Binding of mating factor to G-protein-coupled receptor