Chapter 9 Microbial Genetics

TRUE OR FALSE: The genomes of bacteria cells, eukaryotic cells, and viruses are all about the same size.

FALSE

Mismatch repair is activated by A-binding of DNA to the surface protein. B-any difference between the length of the donor and recipient DNAs. C-insertion of any DNA into the recipient. D-any difference between the nucleotide sequence in the donor and recipient DNAs.

any difference between the nucleotide sequence in the donor and recipient DNAs.

As a result of mismatch repair during transformation, A-all donor DNA will be excised. B-the donor DNA will become circularized and extrachromosomal. C-all cells will have donor DNA in them. D-cells may have either original DNA or donor DNA in them.

cells may have either original DNA or donor DNA in them.

Cells that are capable of bringing DNA from their environment in through their cell wall are called A-acceptant. B-competent. C-porous. D-endocytic.

competent.

3. In addition to transformation, the other two forms of horizontal gene transfer (or recombination) are A-conjugation and transduction. B-missense and nonsense. C-translation and transduction. D-insertion and deletion.

conjugation and transduction.

In the beginning of transformation, ______ binds to the target cell. A-hairpin loop RNA B-a plasmid C-double-stranded DNA D-single-stranded DNA

double-stranded DNA

The __________ is the sum total of genetic material in a cell. A- heredity B- phenotype C- genetics D- genome

genome

The classic transformation experiment done by Griffith used A-wild-type and mutant strains of E. coli. B-Bacillus anthracis. C-harmless and virulent strains of Streptococcus pneumoniae. D-smooth and rough strains of pea plants.

harmless and virulent strains of Streptococcus pneumoniae.

During the process of transformation in the lab setting, cells are plated on selective media to A-block the enzymes that might excise the inserted DNA. B-stimulate DNA repair enzymes. C-prevent the growth of contaminants that arise during the process. D-make sure that only transformants grow.

make sure that only transformants grow.

2. Transformation is a form of recombination. Recombination is A-a form of asexual reproduction for bacteria. B-a form of mutation that occurs in bacteria. C-DNA - protein binding. D-one bacterium donating DNA to another.

one bacterium donating DNA to another.

During the entry of the donor DNA into the recipient cell, A-it is converted into RNA, which passes through pores in the plasma membrane. B-it enters in double-stranded form. C-the DNA binds to fimbrae on the cell's surface. D-one strand is broken down by nucleases.

one strand is broken down by nucleases.

The donor DNA A-pairs with a homologous region of the recipient DNA. B-binds to the origin of replication in the recipient. C-binds to the F factor in the recipient DNA. D-pairs with a purine-rich region in the recipient DNA.

pairs with a homologous region of the recipient DNA

Extra pieces of DNA found in bacteria are called __________. A- chromosomes B- plasmids C- genomic fragments D- mitochondrial DNA E- gene fragments

plasmids

Transformation is facilitated by A-porins in the bacterial cell wall. B-chemicals such as acradine dyes. C-binding of the donor and recipient cells. D-proteins on the cell wall that bind DNA from the environment.

proteins on the cell wall that bind DNA from the environment.

DNA replication is said to be A-conservative B-semi-conservative C-dispersive D-liberal.

semi-conservative

Which of the following is NOT a nitrogen base found in DNA? A- uracil B- thymine C- guanine D- cytosine E- adenine

uracil

A 55-year-old woman being treated in intensive care for a lung transplant developed a case of pneumonia apparently acquired from a ventilator she needed for breathing. The bacteria isolated from her lungs turned out to be Acinetobacter baumannii, a widespread resident of soil and water that has found its way into hospitals and long-term care facilities as well. Tests showed that all of the drugs available to treat the infection except for one—colistin—were ineffective against the pathogen. Early in treatment with this drug, the lung infection appeared to be clearing up, but after a few days, it returned and the patient died of respiratory failure. Cultures taken late in the case detected a new strain of the infectious agent that had since developed resistance to all known drugs, even to the one to which it had originally been sensitive. During the same period, several other patients in the ICU developed drug-resistant A. baumannii infections. This outbreak of healthcare-associated infections spurred an investigation by the infection control nurse, and the bacteria were cultured and isolated from nearly every possible source. This "superbug" has received much attention in medical articles and the news media. This particular agent has become one of the most fearsome pathogens to infect soldiers with battle injuries in the Afghanistan and Iraq wars. For this reason, it has been given the nickname "Iraqnobacter." Some strains of A. baumannii are resistant to a broad range of antibiotics and are defined as multiple-drug resistant (MDR). One strain fits the category of extreme drug resistant (XDR), meaning it is resistant to all possible drugs. How did this agent go from being an uncommon infectious agent to one that accounts for 6% of healthcare-associated infections, and how did the number of resistant strains increase so dramatically since the pathogen's first reported cases in the 1970s? Medical specialists suggest that its rapid evolution can be explained by a combination of four factors: the widespread distribution of the bacteria in the environment, the drug-rich environment of hospitals and clinics, the increase in severely compromised patients, and the pathogen's extreme genetic adaptability to challenges from new drugs. 1. Where does Acinetobacter baumannii typically live? A-respiratory secretions B-soil and water C-fecal material D-the skin 2. Infections caused by A. baumannii have most frequently been seen in which group of people? A- soldiers returning from current battlefields B- cystic fibrosis patients on ventilators C- HIV/AIDS patients D- premature newborns 3. A "healthcare-associated" infection is an infection acquired through which means? A-indirect fecal-oral transmission B-food contaminated with endospores C-admission to a hospital for other reasons D-water 4. What was the most probable source of A. baumannii in this woman's infection? A-hospital visitors B-colistin treatment C-urinary catheter D-ventilator tube 5. The strain of A. baumanni cultured late in this woman's infection was most likely a(n) ______ strain. A-susceptible B- MDR C-XDR D-intermediate PART 2: . What does drug resistance mean from a genetic standpoint? A-The organism has lost genes from its chromosome and cannot be targeted by a drug. B-The organism contains genes that code for the ability to withstand the drug's effects. C-The organism has mutated into a form that cannot be destroyed by any means. D-An antibiotic has altered the genetic makeup of an organism. 2. Acinetobacter baumannii has the ability to acquire resistance to multiple antibiotics through A-transduction B-conjugation C-transformation D-All of these choices are correct. 3. Which of the following structures could assist A. baumannii in acquiring drug-resistance genes from another organism? A- pilus B-mesosome C-flagella D-fimbria 4. True or false: The colistin used to treat the pneumonia patient in this case likely transformed the genetic material in the pathogen, giving it the ability to resist destruction by the drug. 5. Based on the information in this particular case, what would be a good general practice to prevent the emergence of drug-resistant strains of bacteria in the future? A-Use antibiotics wisely and sparingly. B-Use higher doses of broad-spectrum antibiotics. C-Use penicillin as the first drug in treating any infection. D-Discontinue the use of antibiotics in ventilator patients.

PART 1: 1. soil and water 2. soldiers returning from current battlefields 3. admission to a hospital for other reasons 4. ventilator tube 5. XDR PART 2: 1. The organism contains genes that code for the ability to withstand the drug's effects 2. All of these choices are correct. 3. pilus 4. Use antibiotics wisely and sparingly

TRUE OR FALSE: A mutation that changes a single nucleotide can result in a different amino acid being added into a protein.

TRUE

Please match the types of mutations with the statements that most accurately describe them, to test your understanding of their causes. substitution mutation induced mutation frameshift mutation spontaneous mutation 1. random change in the DNA arising from errors in replication that occur without a known cause 2. result from exposure to known mutagens, which are primarily physical or chemical agents that damage DNA 3. changing of single base in the DNA code that may result in the placement of a different amino acid 4. addition or deletion of bases that changes the reading of mRNA codons

1. spontaneous mutation 2. induced mutation 3. substitution mutation 4. frameshift mutation