CH. 7 Mastering Microbiology

Which of the following enzymes is responsible for "unzipping" a DNA molecule in preparation for its replication? a. DNA polymerase b. DNA ligase c. DNA helicase d. primase

Which of the following statements is NOT accurate about microbial DNA? a. Archaea and eukaryotes have histone proteins associated with their DNA, while bacteria do not have histones. b. The chromosomes and plasmids in bacteria, archaea, and eukaryotes contain double-stranded DNA. c. All of the DNA in eukaryotic cells is contained within a nucleus. d. Most bacteria and archaea have circular DNA in the cytoplasm, while most eukaryotes have linear DNA in the nucleus.

Okazaki fragments are formed because DNA replication ____. a. is performed by different versions of DNA polymerase in different cells b. is discontinuous on the lagging strand c. involves proofreading d. is semiconservative

Plasmids have been found in all of the following types of cells EXCEPT _____. a. animal cells b. fungal cells c. protozoan cells d. prokaryotic cells

Which of the following characteristics of a chromosome would identify it as a prokaryotic chromosome rather than a eukaryotic chromosome? a. it contains histones b. it contains A, C, G, and T c. it is a circular molecule d. it contains double-stranded DNA

Which of the following must occur to enable the transcription of genes in the lactose operon? a. the inducer must bind the operator b. the inducer must bind to the repressor c. the repressor must bind to the operator d. the inducer must bind RNA polymerase

Which of these is NOT a difference between eukaryotic and bacterial gene expression? a. Eukaryotic RNA is modified prior to translation, whereas bacterial RNA is not. b. Initiation of translation in bacteria occurs when the ribosomal subunit binds to the 5' guanine cap, while in eukaryotes it binds to a specific nucleotide sequence c. bateria must have genes organized and regulated within operons, while eukaryotes lack operons d. bacteria have 70S ribosomes, while eukaryotes have 80S ribosomes in their cytoplasm

In a repressible operon, which of the following must occur to enable gene expression? a. the corepressor must be absent b. the repressor must bind to the operator c. the inducer must bind to the repressor d. the corepressor must bind to the repressor

The process of making a complementary copy of DNA into the form of RNA is called ____. a. transformation b. transcription c. translation d. transduction

Which of the following types of mutations creates a stop codon where one did not exist before? a. missense mutation b. frameshift mutation c. nonsense mutation d. silent mutation

Insertions and deletions usually lead to which of the following types of mutations? a. pyrimidine dimers b. silent mutations c. frameshift mutations d. base-substitution mutations

Base-excision repair is a DNA repair mechanism designed to cope with which of the following types of problems in a cell? a. chromosome breaks b. damage from UV light c. damage from mutagenic chemicals d. incorrect nucleotide incorporation

Which of the following is capable of conjugation? a. F+ and Hfr cells b. F+ cells c. bacteriophages d. F-cells

Bacteriophages are important for which of the following processes? a. transformation b. transduction c. transcription d. translation

Which of the following events occurs during transcription? a. mRNA binds to a ribosome in the cytoplasm b. A cap is added to the RNA molecule c. A molecule of RNA is formed based on the sequence of nucleotides in DNA d. The message in mRNA is translated into a protein e. Those segments of the RNA strand that do not actually code for the protein are removed

Which of the following is a correct statement about mRNA? a. mRNA includes a cap that consists of extra adenine nucleotides b. mRNA binds directly to amino acids during translation c. mRNA moves from nucleus to the cytoplasm following RNA processing d. mRNA is transcribed from DNA in the cytoplasm e. Segments of mRNA that code for protein are removed before translation

The site of translation is a. the Golgi apparatus b. ribosomes in the cell nucleus c. the cell nucleus d. the plasma membrane e. ribosomes in the cell cytoplasm

Which one of the following does not play a role in translation? a. anticodon b. ribosomes c. amino acids d. DNA e. tRNA

Which of the following does not occur during RNA processing? a. Adenine nucleotides are added to the end of the RNA strand, forming a tail b. mRNA attaches to the small subunit of a ribosome c. Segments of RNA that do code for the protein are reconnected d. a modified guanine nucleotide is added to the beginning of the RNA strand as a cap e. segments of the RNA strand that do not actually code for the protein are removed

Which of the following regions of a ribosome holds the growing polypeptide? a. the E site b. the P site c. the A site d. the Z site

A mutation that causes production of a defective pilus in a bacterium will prevent _____. a. translation b. transformation c. transduction d. conjugation