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1 | |
What term is defined as a certain segment of DNA that contains the necessary code to make a protein or RNA molecule? |
| | A) | Genome |
| | B) | Chromosome |
| | C) | Gene |
| | D) | Nucleotide |
| | E) | Plasmid |
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2 | |
What statement regarding procaryotic and eucaryotic chromosomes is incorrect? |
| | A) | Most bacteria have a single, circular chromosome, while eucaryotic chromosomes can occur singly or in pairs. |
| | B) | Eucaryotic chromosomes are located in the nucleus, which the procaryotic chromosome is located in the Periplasm. |
| | C) | Histone proteins are wound around eucaryotic chromosomes, whereas histonelike proteins surround the bacterial chromosome. |
| | D) | Eucaryotic chromosomes can number from a few to several hundred, while procaryotes typically have one chromosome. |
| | E) | The chromosomes of both procaryotes and eucaryotes are subdivided into genes. |
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3 | |
Which statement regarding the structure of a DNA molecule is incorrect? |
| | A) | The general double helix structure of DNA is universal (with the exception of some viruses that contain ssDNA). |
| | B) | DNA is composed of the nitrogenous bases adenine, thymine, guanine, and cytosine. |
| | C) | DNA is antiparallel. |
| | D) | The nitrogenous bases of the two strands are linked by hydrogen bonds. |
| | E) | The sequence of base pairs along the DNA molecule is invariant. |
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4 | |
What enzyme is responsible for coiling the chromosome into a tight bundle by introducing a reversible series of twists into the DNA molecule? |
| | A) | DNA gyrase |
| | B) | Helicase |
| | C) | Ligase |
| | D) | Primase |
| | E) | DNA polymerase I |
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5 | |
Why is DNA replication said to be semiconservative? |
| | A) | A single copy of DNA is made from the (-) strand. |
| | B) | The products of replication are one double helix containing all parental DNA and one double helix containing all daughter DNA. |
| | C) | The enzyme DNA polymerase III copies the parent strands. |
| | D) | The products of replication are two double helices, each of which contains one parent and one daughter strand. |
| | E) | DNA replication is bidirectional on the bacterial replicon. |
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6 | |
Which statement concerning DNA polymerase III is incorrect? |
| | A) | It requires the double helix to be unwound and that the individual strands are separated. |
| | B) | It can only add nucleotides to the 3' end of an existing nucleotide. |
| | C) | It can only add nucleotides in the 5' to 3' direction. |
| | D) | It synthesizes the leading strand discontinuously and the lagging strand continuously. |
| | E) | It is a huge enzyme complex. |
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7 | |
What enzyme is responsible for detecting incorrect, unmatched bases, for excising them, and for replacing them with the correct base? |
| | A) | DNA gyrase |
| | B) | DNA polymerase III |
| | C) | Primase |
| | D) | Ligase |
| | E) | Helicase |
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8 | |
What determines the phenotype of a cell? |
| | A) | Its DNA |
| | B) | Its proteins |
| | C) | Its RNA |
| | D) | Its ribozymes |
| | E) | Its triplet code |
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9 | |
The transcription of what molecule is similar to leading strand synthesis in DNA replication? |
| | A) | mRNA |
| | B) | tRNA |
| | C) | rRNA |
| | D) | Primer |
| | E) | Ribozymes |
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10 | |
Although the nucleotide sequence of promoters can vary, what is similar about all promoter regions? |
| | A) | They are just distal to the beginning of the gene to be transcribed. |
| | B) | They are made up of four sequences of DNA. |
| | C) | They are rich in adenine and thymine nucleotides. |
| | D) | They are recognized by DNA polymerase III. |
| | E) | They are responsible for synthesizing the template strand of DNA. |
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11 | |
The enzymes required for the formation of a peptide bond between adjoining amino acids in a protein are supplied by what structure? |
| | A) | mRNA |
| | B) | Charged tRNAs |
| | C) | Small ribosomal subunit |
| | D) | Large ribosomal subunit |
| | E) | The E site on a ribosome |
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12 | |
Why can't the nucleotide sequence of DNA be derived by examining a protein's primary structure? |
| | A) | Because the genetic code is degenerate. |
| | B) | Because the genetic code is not universal. |
| | C) | Because each amino acid has a different codon in all organisms. |
| | D) | Because it is impossible to determine the anticodon of the tRNA. |
| | E) | Because posttranslational modification of a protein changes its original primary structure. |
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13 | |
The coding regions of eucaryotic mRNA molecules are known as what? |
| | A) | Spliceosomes |
| | B) | Split genes |
| | C) | Introns |
| | D) | Pre-mRNA |
| | E) | Exons |
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14 | |
The late phase of dsDNA viral replication includes which event? |
| | A) | Viral DNA enters the nucleus. |
| | B) | Viral DNA is replicated in the nucleus. |
| | C) | Viral mRNA is translated into proteins necessary for viral DNA replication. |
| | D) | Genes for the viral capsid and other structures are transcribed. |
| | E) | Genes coding for enzymes important in viral DNA replication are transcribed. |
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15 | |
Viruses containing what type of nucleic acid can become silently integrated into the host's genome? |
| | A) | ssRNA (+) |
| | B) | ssDNA |
| | C) | dsDNA |
| | D) | dsRNA |
| | E) | ssRNA (-) |
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16 | |
Following viral penetration and uncoating in RNA viruses, what possible form of genetic message is ready to be translated directly into proteins? |
| | A) | ss (+) sense genome |
| | B) | ss (-) sense genome |
| | C) | ds RNA |
| | D) | ssRNA → ssDNA → dsDNA |
| | E) | Close, circular RNA |
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17 | |
Along with the ssRNA nucleic acid, retroviruses also contain what enzyme within the viral capsid? |
| | A) | Helicase |
| | B) | RNA polymerase I |
| | C) | DNA polymerase III |
| | D) | Oncogenase |
| | E) | Reverse transcriptase |
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18 | |
Within an inducible operon, transcription is prevented by the presence of what? |
| | A) | The operator |
| | B) | The repressor |
| | C) | The activator |
| | D) | The promoter |
| | E) | The inducer |
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19 | |
In a repressible operon, transcription is halted when what event occurs? |
| | A) | The corepressor activates the repressor so that the repressor can bind to the operator. |
| | B) | The corepressor is in high demand by the cell. |
| | C) | The inducer attaches to the repressor so that the repressor can bind to the operator. |
| | D) | The repressor alone binds to the operator. |
| | E) | The corepressor binds to the inducer which activates the repressor so the repressor can bind to the operator. |
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20 | |
Why can antibiotics that selectively target bacterial ribosomes cause side-effects for patients? |
| | A) | Because both procaryotic and eucaryotic ribosomes contain the same rRNA sequences. |
| | B) | Because both procaryotic and eucaryotic ribosomes are 30S and 50S. |
| | C) | Because the proteins that make up all ribosomes are identical. |
| | D) | Because both procaryotic and eucaryotic ribosomes are 40S and 60S. |
| | E) | Because eucaryotic mitochondrial ribosomes are 30S and 50S. |
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21 | |
What mutational outcome leads to the placement of a different amino acid in a protein? |
| | A) | Back mutation |
| | B) | Silent mutation |
| | C) | Nonsense mutation |
| | D) | Missense mutation |
| | E) | Point mutation |
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22 | |
What accounts for the development of a silent mutation? |
| | A) | A back mutation |
| | B) | Excision repair |
| | C) | The degeneracy of the genetic code |
| | D) | Evolution |
| | E) | Photoreactivation |
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23 | |
What did Francis Griffith's experiments with Streptococcus pneumoniae and laboratory mice demonstrate? |
| | A) | Plasmids were present in bacteria. |
| | B) | Bacteria could be transformed by the DNA of other bacteria. |
| | C) | Bacteria could be infected with viruses. |
| | D) | Encapsulated bacteria are more virulent than nonencapsulated strains. |
| | E) | Eucaryotes could be transfected with bacterial DNA. |
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24 | |
What is the process of genetic recombination in which a highly specific portion of the host genome is regularly incorporated into a virus? |
| | A) | Transfection |
| | B) | Conjugation |
| | C) | Generalized transduction |
| | D) | Transformation |
| | E) | Specialized transduction |
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25 | |
Which of the following is not an outcome of the movement of transposons? |
| | A) | Replacement of damaged DNA |
| | B) | Changes in phenotypic traits |
| | C) | Creation of retroviruses |
| | D) | Intermicrobial transfer of drug resistance |
| | E) | Creation of different genetic combinations which are necessary for high levels of variation in some proteins |
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