what is one possible reason that mutation 2 leads to the production of normal blood cells rather than sickle- shaped blood cells ? The mRNA codon GAG acts as a stop signal rather than coding for an amino acid. The mRNA codon GAG corresponds to the tRNA molecule that can carry more than one amino acid. The mRNA codon GAG is unreadable and is therefore skipped over during protein synthesis. The mRNA codons GAA and GAG both code for the same amino acid.

Which of the following observation darwin shape his concept of descent with modification? a) species diversity declines farther from the equator. b) fewer species live on islands than on the nearest continents. c) birds live on islands located farther from the mainland than the bird's maximum nonstop flight distance. d) south american temperate plants are more similar to the tropical plants of south america than to the temperate plants of europe. e) earthquakes reshape life by causing mass extinctions.