Distinguish between sense and nonsense mutations and describe the characteristics of a protein affected by each type
of mutation. What will be an ideal response?
ANSWER: Sense mutations produce longer-than-normal proteins by changing a termination codon into
one that codes for an amino acid. For example, an extended polypeptide chain would be
produced by a single nucleotide substitution in the normal termination codon, allowing for
the insertion of many additional amino acids before another stop codon is reached. Nonsense
mutations change codons for amino acids into one of the three stop codons. This shortens the
protein product. For example, this mutation could result in a protein that is 100 amino acids
long instead of 105, and may have little or no effect on the function of the molecule.
However, other nucleotide substitutions could have more serious phenotypic effects. In some
cases, a single nucleotide substitution can cause a serious genetic disorder.
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Keratins are considered to be obligate heterodimers in that the dimers forming their filaments must contain one __________ and one __________ subunit?
Fill in the blank(s) with the appropriate word(s).
Which type of molecular movement is a passive process
A) sodium-potassium pump B) endocytosis C) exocytosis D) diffusion E) active transport
Which of the following is not true of tropical communities?
a. they occur at the equator b. they receive more intense sunlight c. they have a longer growing season d. they receive less rainfall than temperate communities e. they have been established for a longer period of time
A difference between a grassland and a savanna is
A. the pattern of rainfall. B. fire. C. carnivores. D. decomposers.