Chapter 25: Problem 25
What genetic changes take place during speciation?
Chapter 25: Problem 25
What genetic changes take place during speciation?
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Get started for freeShown below are two homologous lengths of the alpha and beta chains of human hemoglobin. Consult a genetic code dictionary (Figure 13.7 ) and determine how many amino acid substitutions may have occurred as a result of a single nucleotide substitution. For any that cannot occur as a result of a single change, determine the minimal mutational distance.
Some critics have warned that the use of gene therapy to correct genetic disorders will affect the course of human evolution. Evaluate this criticism in light of what you know about population genetics and evolution, distinguishing between somatic gene therapy and germ-line gene therapy.
Recent reconstructions of evolutionary history are often dependent on assigning divergence in terms of changes in amino acid or nucleotide sequences. For example, a comparison of cytochrome c shows 10 amino acid differences between humans and dogs, 24 differences between humans and moths, and 38 differences between humans and yeast. Such data provide no information as to the absolute times of divergence for humans, dogs, moths, and yeast. How might one calibrate the molecular clock to an absolute time clock? What problems might one encounter in such a calibration?
Population geneticists study changes in the nature and amount of genetic variation in populations, the distribution of different genotypes, and how forces such as selection and drift act on genetic variation to bring about evolutionary change in populations and the formation of new species. From the explanation given in the chapter, what answers would you propose to the following fundamental questions? (a) How do we know how much genetic variation is in a population? (b) How do geneticists detect the presence of genetic variation as different alleles in a population? (c) How do we know whether the genetic structure of a population is static or dynamic? (d) How do we know when populations have diverged to the point that they form two different species? (e) How do we know the age of the last common ancestor shared by two species?
A certain form of albinism in humans is recessive and autosomal. Assume that \(1 \%\) of the individuals in a given population are albino. Assuming that the population is in HardyWeinberg equilibrium, what percentage of the individuals in this population is expected to be heterozygous?
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