38) There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of these would characterize such a mutant?
A) It cannot make a functional repressor.
B) It makes a repressor that binds CAP.
C) It cannot bind to the inducer.
D) It cannot bind to the operator.
It cannot bind to the inducer.
43) The reason for differences in the sets of proteins expressed in a nerve and a pancreatic cell of the same individual is that nerve and pancreatic cells contain different _____.
B) sets of regulatory proteins
D) regulatory sequences
sets of regulatory proteins
1) After mixing a heat-killed, phosphorescent (light-emitting) strain of bacteria with a living, nonphosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observation(s) would provide the best evidence that the ability to phosphoresce is a heritable trait?
A) phosphorescence in descendants of the living cells
B) especially bright phosphorescence in the living strain
C) evidence that protein passed from the heat-killed strain to the living strain
D) evidence that DNA was passed from the heat-killed strain to the living strain
phosphorescence in descendants of the living cells
2) Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
3) Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells cannot_____.
A) undergo mitosis
B) replicate DNA
C) exchange DNA with other cells
D) repair thymine dimers
repair thymine dimers
4) The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that _____.
A) the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups
B) ATP contains three high-energy bonds; the nucleoside triphosphates have two
C) ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells
D) the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose
the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose
5) Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
A) All four bases of the DNA would be radioactive.
B) One of the daughter cells, but not the other, would have radioactive DNA.
C) Neither of the two daughter cells would be radioactive.
D) DNA in both daughter cells would be radioactive.
DNA in both daughter cells would be radioactive.
6) In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in the figure above would be expected after one round of DNA replication in the presence of 14N?
- A) A B) B C) C D) D
8) The DNA of telomeres has been highly conserved throughout the evolution of eukaryotes. This most likely reflects
A) a critical function of telomeres
B) the low frequency of mutations occurring in this DNA
C) that new mutations in telomeres have been advantageous
D) continued evolution of telomeres
a critical function of telomeres
9) You briefly expose bacteria undergoing DNA replication to radioactively labeled deoxynucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent _____.
A) lagging strands and Okazaki fragments
B) leading strands and Okazaki fragments
C) leading strands and RNA primers
D) Okazaki fragments and RNA primers
leading strands and Okazaki fragments
10) DNA contains the template needed to copy itself, but it has no catalytic activity in cells. What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in the DNA polymer being formed
B) deoxyribonucleotide triphosphates
C) DNA polymerase
11) What provides the energy for the polymerization reactions in DNA synthesis?
A) DNA polymerase
B) the deoxyribonucleotide triphosphate substrates
D) breaking the hydrogen bonds between complementary DNA strands
the deoxyribonucleotide triphosphate substrates
12) Which of the following cells have reduced or very little active telomerase activity?
A) most normal germ cells
B) most cancer cells
C) most normal somatic cells
most normal somatic cells
13) Researchers found E. coli that had mutation rates one hundred times higher than normal. Which of the following is the most likely cause of these results?
A) The single-stranded binding proteins were malfunctioning.
B) The proofreading mechanism of DNA polymerase was not working properly.
C) There were one or more mismatches in the RNA primer.
D) The DNA polymerase was unable to add bases to the 3’ end of the growing nucleic acid chain.
The proofreading mechanism of DNA polymerase was not working properly.
14) In E. coli replication the enzyme primase is used to attach a 5 to 10 base ribonucleotide strand complementary to the parental DNA strand. The RNA strand serves as a starting point for the DNA polymerase that replicates the DNA. If a mutation occurred in the primase gene, which of the following would you expect?
A) Replication would only occur on the lagging strand.
B) Replication would not occur on either the leading or lagging strand.
C) Replication would only occur on the leading strand.
D) Replication would not be affected as the enzyme primase in involved with RNA synthesis.
Replication would not occur on either the leading or lagging strand.
15) Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because _____.
A) certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors
B) genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes
C) metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies
D) enzymes are made of DNA, and affected individuals lack DNA polymerase
genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes
16) The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
A) Different organisms have different types of amino acids.
B) A gene from an organism can theoretically be expressed by any other organism.
C) DNA was the first genetic material.
D) The same codons in different organisms translate into different amino acids.
A gene from an organism can theoretically be expressed by any other organism.
17) Which of the following occurs in prokaryotes but not in eukaryotes?
A) concurrent transcription and translation
B) post-transcriptional splicing
C) translation in the absence of a ribosome
D) gene regulation
concurrent transcription and translation
18) Refer to the metabolic pathway illustrated above. If A, B, and C are all required for growth, a strain that is mutant for the gene-encoding enzyme A would be able to grow on medium supplemented with _____.
A) nutrient A only
B) nutrient B only
C) nutrient C only
D) nutrients A and C
nutrient B only
19) A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be _____.
A) 3’AAA-AAT-ATA-ACA 5’
B) 5’AUG-CTG-CAG-TAT 3’
C) 3’AAA-GAA-TAA-CAA 5’
D) 5’TTG-CTA-CAG-TAG 3’
C) 3’AAA-GAA-TAA-CAA 5’
20) Refer to the figure above. What would the anticodon be for a tRNA that transports phenylalanine to a ribosome?
- A) UUU B) TTT C) CCC D) AAA
D) 5’TTG-CTA-CAG-TAG 3’