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tRNA molecules deliver amino acids to ribosomes where the amino acid next [cite: 7]
A. forms an ionic bond with another amino acid [cite: 8]
B. is deaminated and catabolized. [cite: 9]
C. becomes an anticodon [cite: 10]
D. is covalently bonded to a growing polypeptide [cite: 11]
E. forms hydrogen bonds with esters [cite: 12]
The CFTR protein is made up of 1,480 amino acids linked together in a chain. [cite: 13] Some humans produce a version of the CFTR protein in which phenylalanine (an amino acid) has been deleted from position 508 of the amino acid chain. [cite: 14]
Which of the following best predicts how the amino acid deletion will affect the structure of the CFTR protein? [cite: 15]
A. It will have no observable effect on the structure of the CFTR protein. [cite: 16]
B. It will affect the primary structure of the CFTR protein, but the other levels of protein structure will not be affected. [cite: 17]
C. It will affect the secondary and tertiary structures of the CFTR protein, but the primary structure will not be affected. [cite: 18]
D. It will affect the primary, secondary, and tertiary structures of the CFTR protein. [cite: 19]
Which of the following describes a key difference among the 20 amino acids that are used to make proteins? [cite: 20]
A. Only some amino acids have an R-group. [cite: 21]
B. Only some amino acids have a carboxyl group (COOH). [cite: 22]
C. Some amino acids are hydrophobic. [cite: 23]
D. Some amino acids contain the element phosphorus. [cite: 24]
Scientists examined the folded structure of a purified protein resuspended in water and found that amino acids with nonpolar R groups were primarily buried in the middle of the protein, [cite: 25] whereas amino acids with polar R groups were primarily on the surface of the protein. [cite: 26]
Which of the following best explains the location of the amino acids in the folded protein? [cite: 27]
A. Polar R groups on the surface of the protein can form ionic bonds with the charged ends of the water molecules. [cite: 28]
B. Polar R groups are too bulky to fit in the middle of the protein and are pushed toward the protein's surface. [cite: 29]
C. Nonpolar R groups that cannot form hydrogen bonds with water are pushed into the middle of the protein. [cite: 30]
D. Nonpolar R groups from different parts of the protein form covalent bonds with each other to maintain the protein's structure. [cite: 31]
How might this change affect the structure and function of the protein? [cite: 57]
A. The R-group of the new amino acid, valine, has different chemical properties than the R-group of cysteine. [cite: 58] This will cause the protein to misfold and not function properly in the cell. [cite: 59]
B. The new amino acid, valine, has replaced cysteine in the new protein. [cite: 60] Since the number of amino acids has remained the same, there will be no change in the three-dimensional folding, or function, of the protein. [cite: 61]
C. Since this is a linear section, it does not influence protein folding. [cite: 62] Thus, there will be no change in protein structure or function. [cite: 63]
D. Since the new amino acid is bounded on one side by an amino acid with a negatively charged R-group and by an amino acid on the other side with a positively charged R-group, the charges will balance and the protein will fold as usual. [cite: 64]