Microbiology - Chapter 7, Part 2

Ultraviolet light may induce a mutation by: binding together adjacent thymine molecules on the DNA molecule. restricting transcription of RNA molecules. dissolving the cell membrane of a bacterium. preventing synthesis of ATP during oxidative phosphorylation.

binding together adjacent thymine molecules on the DNA molecule.

Transposons are movable genetic elements that: form copies of themselves that move from the normal position into areas of gene activity. carry information such as antibiotic resistance from one gene location to another. are composed solely of protein. exist only in viruses.

carry information such as antibiotic resistance from one gene location to another.

Nitrous acid can cause a chemical mutation by: cross-linking adjacent thymine bases. eliminating transposons from a bacterium. binding two adjacent bacteria together in a syncytium. converting DNA's adenine to hypoxanthine.

converting DNA's adenine to hypoxanthine.

Which of the following is not part of an operon? Promoter Regulatory gene Operator Structural genes

regulatory gene.

The origin of the penicillin-resistant strain Neisseria gonorrhoeae probably is due to: infection by a virus. inadequate culture media. spontaneous mutation. nonsense mutation.

spontaneous mutation.

Mutations arising from chance events in the environment are known as: induced mutations. environmental mutations. point mutations. spontaneous mutations.

spontaneous mutations.

In the operon, genes that code for proteins are called: structural genes. operator genes. repressor genes. inducer genes.

structural genes.

One environmental mutagen is ultraviolet (UV) light. It exerts its mutagenic effect by forming a(n) __________ in the DNA. analog thymine dimer nucleotide mismatch plasmid

thymine dimer

Which one of the following is a base analog? 5-bromouracil DNA polymerase UV light Nitrous acid

5-bromouracil

All the following are true of a point mutation, except: it affects a base pair. it may be a change to a different base pair. it may be a substituted base pair. All of these are correct.

All of these are correct.

A mutagen is a nutritionally deficient mutant, requiring a nutrient in its medium for growth.

False

During transcription, both DNA strands in a gene are transcribed.

False

Okazaki fragments form on the continuous strand during DNA replication.

False

Smids contain over 50% of the total genetic information of a bacterial cell.

False

The codons for UGA, UAG, and UAA are called start codons because they initiate the addition of amino acids to a growing polypeptide chain.

False

There are two origins of replication in every bacterial DNA molecule.

False

Match each term with its correct characteristic. Plasmid Mutagen Nitrous acid DNA ligase Mutation Ames test Base pair insertion Bacteriocin

Plasmid - Closed circular DNA, with few genes, nonessential to the cell Mutagen - Substance that induces change in DNA bases Nitrous acid - Chemical mutagen DNA ligase - Enzyme that seals DNA fragments together Mutation - A change in DNA base sequence Ames test - Procedure to screen chemicals for mutagenic properties Base pair insertion - Type of mutation that produces a reading frameshift Bacteriocin - Chemical produced by bacteria that kill other bacteria

Which of the following enzymes would not be involved with excision repair of DNA? RNA polymerase Nucleases DNA ligase DNA polymerase

RNA polymerase

An insertion sequence (IS) is a small segment of DNA with about 1,000 base pairs. IS has no genetic information other than for the enzyme transposase, which is needed to move the IS to a new location in a DNA molecule.

True

In semiconservative DNA replication, a new strand of DNA with bases complementary to a parent strand combines with a parent strand to form the double helix.

True

Many antibiotics affect protein synthesis in bacterial cells and therefore are clinically useful in treating human infections and disease.

True

Messenger RNA contains start and stop codons.

True

Prokaryote genome studies have shown that genes involved with the same process are clustered. This makes genetic control more efficient because their activity can be coordinated within one cluster.

True

Resistance factors are known as R plasmids.

True

The genome of Escherichia coli has about 4,300 genes.

True

Transposable genetic elements may cause mutations by interrupting the coding sequence in genes, thereby often resulting in no protein being produced.

True

Watson and Crick worked out the structure of DNA using Rosalind Franklin's X-ray crystallography.

True

Which of the following is an example of a frameshift mutation when the original DNA molecule is ATA CGC GGG TAC GTA? (The responses are in mRNA language.) AUA CGC GGG UAC GUT UAU GCG CCA UGC AU AUA CGG CGG UAC GU UAU GCG CCC UAG CAU

UAU GCG CCA UGC AU

The deletion or insertion of nucleotides during chromosomal replication most likely would cause: a silent mutation. a missense mutation. plasmid replication. a "reading frameshift" mutation.

a "reading frameshift" mutation.