Evolution, 4th Edition

The people around you differ in the color of their hair, the shape of their noses, the length of their fingers, and in countless ...

80 CHAPTER 4 is neither exceptionally big or small. Some bacteria have genomes that are thou- sands of times smaller, with less ...

mUTATIon AnD VARIATIon 81 Proteins are synthesized in three steps (FIGURE 4.4). A cell first transcribes the DNA from a gene int ...

82 CHAPTER 4 Like the genetic code, the cellular machinery for transcribing DNA and trans- lating mRNA is almost universal acros ...

mUTATIon AnD VARIATIon 83 occurs at a locus or a DNA base in a population (FIGURE 4.5). Some alleles are very rare. For example, ...

84 CHAPTER 4 the probability that a sperm carries the A 2 allele times the probability that an egg also carries the A 2 allele, ...

mUTATIon AnD VARIATIon 85 No real population meets all of these conditions. Thus no real population is expected to be exactly in ...

86 CHAPTER 4 Hardy-Weinberg equilibrium, linkage equilibrium takes more than one generation to reach. How long it takes depends ...

mUTATIon AnD VARIATIon 87 that a gamete carries allele A 2 tells us that it is more likely to carry allele B 2 than expected by ...

88 CHAPTER 4 locus to evolve if the two loci are in linkage disequilibrium. A second reason that linkage disequilibrium is impor ...

mUTATIon AnD VARIATIon 89 Point mutations The simplest type of mutations are point mutations, which occur when a single DNA base ...

90 CHAPTER 4 of three DNA bases (CAG) into the huntingtin gene. Other insertions have played important roles in adaptation. A du ...

mUTATIon AnD VARIATIon 91 into two. Fissions and fusions are responsible for changes in the number of chromo- somes in the genom ...

92 CHAPTER 4 Effects of mutations Mutations affect virtually all aspects of an organism, ranging from the ability of a bacterium ...

mUTATIon AnD VARIATIon 93 A second general feature of mutations involves their effects on an organism’s fitness, that is, the nu ...

94 CHAPTER 4 selection is not efficient enough to drive mutation rates to zero. Were that to hap- pen, life on Earth would be de ...

mUTATIon AnD VARIATIon 95 There is substantial variation between the mutation rates of different regions of the genome, and betw ...

96 CHAPTER 4 environment because natural selection picks out the favorable mutations and causes them to spread. How that happens ...

mUTATIon AnD VARIATIon 97 change to their structure (FIGURE 4.20). Likewise, the histones that bind to DNA to form eukaryotic ch ...

98 CHAPTER 4 provided depends on the mother’s physiological condition as well as her genotype. Maternal effects like these are t ...