Final Pt 2 of 3 - Pt 5

83. A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is a. 3' UCA 5'. b. 3' UGA 5'. c. 5' TCA 3'. d. 3'ACU 5'. e. either UCA or TCA, depending on wobble in the first base.

a. 3' UCA 5'.

85. RNA polymerase moves in which direction along the DNA? a. 3' → 5' along the template strand b. 3' → 5' along the coding (sense) strand c. 5' → 3' along the template strand d. 3' → 5' along the coding strand e. 5' → 3' along the double-stranded DNA

a. 3' → 5' along the template strand

89. A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that a. many noncoding stretches of nucleotides are present in mRNA. b. there is redundancy and ambiguity in the genetic code. c. many nucleotides are needed to code for each amino acid. d. nucleotides break off and are lost during the transcription process. e. there are termination exons near the beginning of mRNA.

a. many noncoding stretches of nucleotides are present in mRNA.

96. Sickle-cell disease is probably the result of which kind of mutation? a. point b. frameshift c. nonsense d. nondisjunction e. both B and D

a. point

82. If proteins were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides? a. 1 b. 2 c. 3 d. 4 e. 12

b. 2

81. Using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because a. RNA is much more stable than DNA. b. RNA acts as an expendable copy of the genetic material. c. only one mRNA molecule can be transcribed from a single gene, lowering the potential rate of gene expression. d. tRNA, rRNA and others are not transcribed. e. mRNA molecules are subject to mutation but DNA is not.

b. RNA acts as an expendable copy of the genetic material.

87. What is a ribozyme? a. an enzyme that uses RNA as a substrate b. an RNA with enzymatic activity c. an enzyme that catalyzes the association between the large and small ribosomal subunits d. an enzyme that synthesizes RNA as part of the transcription process e. an enzyme that synthesizes RNA primers during DNA replication

b. an RNA with enzymatic activity

91. A mutation in which of the following parts of a gene is likely to be most damaging to a cell? a. intron b. exon c. 5' UTR d. 3' UTR e. All would be equally damaging.

b. exon

88. What are the coding segments of a stretch of eukaryotic DNA called? a. introns b. exons c. codons d. replicons e. transposons

b. exons

80. The nitrogenous base adenine is found in all members of which group? a. proteins, triglycerides, and testosterone b. proteins, ATP, and DNA c. ATP, RNA, and DNA d. alpha glucose, ATP, and DNA e. proteins, carbohydrates, and ATP

c. ATP, RNA, and DNA

86. A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which might this illustrate? a. The sequence evolves very rapidly. b. The sequence does not mutate. c. Any mutation in the sequence is selected against. d. The sequence is found in many but not all promoters. e. The sequence is transcribed at the start of every gene.

c. Any mutation in the sequence is selected against.

84. The genetic code is essentially the same for all organisms. From this, one can logically assume all of the following except a. a gene from an organism could theoretically be expressed by any other organism. b. all organisms have a common ancestor. c. DNA was the first genetic material. d. the same codons in different organisms usually translate into the same amino acids. e. different organisms have the same number of different types of amino acids.

c. DNA was the first genetic material.

95. What is the effect of a nonsense mutation in a gene? a. It changes an amino acid in the encoded protein. b. It has no effect on the amino acid sequence of the encoded protein. c. It introduces a premature stop codon into the mRNA. d. It alters the reading frame of the mRNA. e. It prevents introns from being excised.

c. It introduces a premature stop codon into the mRNA.

97. Of the following, which is the most current description of a gene? a. a unit of heredity that causes formation of a phenotypic characteristic b. a DNA subunit that codes for a single complete protein c. a DNA sequence that is expressed to form a functional product: either RNA or polypeptide d. a DNA---RNA sequence combination that results in an enzymatic product e. a discrete unit of hereditary information that consists of a sequence of amino acids

c. a DNA sequence that is expressed to form a functional product: either RNA or polypeptide

93. What is the most abundant type of RNA? a. mRNA b. tRNA c. rRNA d. pre-mRNA e. hnRNA

c. rRNA

94. Why might a point mutation in DNA make a difference in the level of protein's activity? a. It might result in a chromosomal translocation. b. It might exchange one stop codon for another stop codon. c. It might exchange one serine codon for a different serine codon. d. It might substitute an amino acid in the active site. e. It might substitute the N terminus of the polypeptide for the C terminus.

d. It might substitute an amino acid in the active site.

79. The elongation of the leading strand during DNA synthesis a. progresses away from the replication fork. b. occurs in the 3' → 5' direction. c. produces Okazaki fragments. d. depends on the action of DNA polymerase. e. does not require a template strand.

d. depends on the action of DNA polymerase.

90. Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes a. union with ribosomes. b. fusion into circular forms known as plasmids. c. linkage to histone molecules. d. excision of introns. e. fusion with other newly transcribed mRNA.

d. excision of introns.

92. Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the a. binding of ribosomes to mRNA. b. shape of the A and P sites of ribosomes. c. bonding of the anticodon to the codon. d. attachment of amino acids to tRNAs. e. both C and D

e. both C and D