chapter 8 review

Transposons can cause mutations by

"jumping" into a gene and disrupting its function.

After the transfer of the F plasmid is complete

F- cell becomes F+

Mismatch repair is activated by

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

A virus that infects bacterial cells is called a ______.

bacteriophage

Match the chemical mutagens with their descriptions.

base analogs- used in place of normal nucelobases transposons- randomly insert into DNA alkylating agents- add CH3 and others to nucleobases intercalating agents- insert between base pairs

After entry of the bacteriophage into the host cell, a phage enzyme

breaks the host DNA into fragments

When the bacteriophage transfers bacterial DNA into a recipient bacterial cell, that DNA

can integrate into the chromosome

Consider the figure below and check all the TRUE statements.

- A vancomycin-resistant S. aureus mutant is created. - In order for S. aureus to become vancomycin-resistant, conjugation must have occurred between the E. faecalis and the S. aureus. - Either the S. aureus or the E. faecalis must have a conjugative plasmid.

Which of the following genes are likely to be found on a plasmid rather than on the bacterial chromosome?

- BT toxin gene - chloramphenicol-resistance gene - oil degradation enzyme genes

Which of the following is/are true about CRISPR? (NOTE: Please change all question marks to checkmarks for correct

- CRISPR loci can reveal a historical record of phage infections of a bacterial cell. - CRISPR systems act as a barrier to horizontal gene transfer.

consider the figure below. which statement is true

5- bromouracil may be incorporated into a newly synthesized DNA strand in place of thymine nuclease

On which of the following DNA strands will UV light have the most effect?

ACTTGCTTAC

Which of the following is FALSE about transposons?

They are capable of moving independently from one cell to another cell.

Generalized transduction occurs when

a bacteriophage packages a piece of bacterial DNA during replication

During maturation or formation of phage particles

a few phage heads may surround fragments of host bacterial DNA

A "nosocomial" infection is an infection acquired through

a hospital stay

which of the following statements regarding mutations is TRUE

a phototroph can grow on glucose-salts media

the F pilus is

a protein appendage that attaches the two cells

Based upon information in Chapter 8 and the case study, it appears that multidrug resistant strains of bacteria such as A. baumannii:

acquired their resistance genes from other bacteria in healthcare facilities.

cinetobacter baumannii may have acquired resistance to multiple antibiotics through

all of these (transformation, conjunction, transduction)

The plasmid is mobilized for transfer when

an endonuclease cleaves it at the origin of transfer

The basic parts of a bacteriophage are

an icosohedral head, central tube, tail pins, and fibers

A. baumannii is easily removed from hospital surfaces by disinfectants.

false

Nosocomial infections caused by A. baumannii in civilian hospitals are not a major concern.

false

A culture of E. coli is irradiated with UV light. The UV light affects the cell's DNA by

forming covalent bonds between thymine bases on the same strand of DNA.

During the process of transformation in the lab setting, cells are plated on selective media to

make sure that only transform ants grow

Genes from the donor chromosome are transferred as

single stranded DNA

In transformation, genes from a donor chromosome are transferred as

single-stranded DNA

During conjugation, the donor chromosome is transferred as

single=stranded DNA

Acinetobacter baumannii is a common resident of ____

soil and water

Infections caused by A. baumannii have most frequently been seen in

soldiers at military hospitals

the F pilus binds to

specific receptors on the cell wall of the recipient

the F plasmid encodes for

the F pilus

After the conjugation of an Hfr cell with an F- cell,

the recipient remains f-

Two bacterial genes are transduced simultaneously. What does this suggest about the location of the two genes relative to each other?

the two genes must be close together on the bacterial chromosome.

The main advantage for bacteria that have the ability to carry out conjugation and other forms of genetic exchange is that

they become genetically diverse

Preventing the function of light repair (photoreactivation) interferes with the repair of which of the following?

thymine dimers

The donor cell DNA is integrated into the recipient cell's DNA by homologous recombination.

true

plasmids are

able to replicate independently of the chromosome

Transformation is facilitated by

proteins on the cell wall that bind DNA

if you find that a particular plasmid has an R factor, the bacteria that has it will be

resistant to certain antibiotics

Match each mechanism of resisting phage infection with its description.

restriction-modification systems- modifying self-DNA shortly after it's produced, followed by using restrictions endonuclease to digest DNA that lacks modification CRISPR system- insertion of small fragments of phage genome into host chromosomes, giving the cell a "memory" of previous attempted infection and a way to recognize and destroy that foreign DNA in the future preventing phage attachment- changing or covering up molecules on the surface of the bacterium to which the phage particle binds

DNA polymerases use their ______ activity to remove a mismatched base pair.

3'-> 5' exonuclease

The researcher inoculates the test population of bacteria onto glucose salts agar containing penicillin and also on nutrient agar containing penicillin. She counts 25 colonies on the glucose salts plate lacking histidine and 32 colonies on the nutrient agar. Which of the following statements is TRUE?

- The colonies on both plates contain penicillin-resistant mutants. - The glucose salts plate contains some mutants.

Place the following events in the process of virus replication and the generation of a transducing particle in the correct order.

- a bacteriophage attaches to a specific receptor on a host cell - phage DNA enters the bacterial cell. the empty phage coat remains outside the host cell - enzymes coded for by the phage cut the bacterial DNA into small pieces - phage nucleic acid is replicated and coat proteins are synthesized - during virus assembly, bacterial DNA can sometimes mistakenly be packaged in the protein coat, creating a transduction particle

which of the following statements regarding bacterial genetics is/are TRUE

- a change in genotype can change the phenotype -an auxotroph has different genotype than a phototroph - an auxotroph has a different phenotype than a photo trough

Place the correct sequence of experiments in order to better understand the Griffith Experiment for Transformation.

- living encapsulated cells - living non-encapsulated cells/ heat-killed encapsulated cells - heat killed encapsulated cells/ living non-encapsulated cells

Examples of advantageous genes that can be transferred by transduction are genes for

- sugar fermentation. - toxin production. - drug resistance. - only drug resistance and toxin production. - All of these.

Consider the figure and check the CORRECT statements. (NOTE: Please change all question marks to checkmarks for correct answers or empty boxes for incorrect answers.)

- the nucelobase shown in yellow should be a C - The CH3 groups alert the mismatch repair system to which DNA strand is the template strand. - Without the CH3 groups, it is possible that the mismatch repair system would replace the G nucleobase (purple arrow) with an A.

Consider the figure. If methylguanine replaces guanine in a DNA strand with the sequence 5'CGA3', the resulting change in the complementary strand after DNA replication would be

3'GTT5'

Repair mechanisms that occur during DNA synthesis are 1. mismatch repair 2. proofreading by DNA polymerase 3. light repair 4. excision repair 5. SOS repair

1 and 2

Match the mutation with the correct name. Not all labels are used.

1. Wild type 2. silent mutation 3. missense mutation 4. nonsense mutation 5. outcome

Place the following events in the process of transduction in the correct order. Not all labels are used.

1. a transfusing particle attaches to a specific receptor on a host cell 2. bacterial DNA is injected into a cell 3. foreign bacterial DNA integrates into the host genome by homologous recombination 4. bacteria multiply with new genetic material

Which is the correct labeling of the mutations in the figure?

1: silent; 2. nonsense; 3. missense

Which of the following statements about the Ames test is FALSE?

Liver extract is added to provide nutrients.

Please match each type of mutation with its appropriate description.

Nonsense mutation- a mutation that changes a codon that specifies an amino acid to a stop codon, resulting in premature termination of polypeptide synthesis minssense mutation- a mutation that results in changing a codon such that a different amino acid is specified - silent mutation- a mutation that changes a codon into a different codon, but both codons specify the same amino acid; this causes no change in resulting polypeptide frameshift mutation- a mutation resulting from an insertion or deletion of bases that cause a change in the reading frame of the mRNA

which of the following types of repair does not require the strand DNA polymerase with proofreading capability

SOS repair

Consider the figure below, showing repair of DNA. Which statement about the process is TRUE?

The enzymes involved in the process are DNA degrading enzyme, DNA polymerase and DNA ligase.

As a result of mismatch repair during transformation:

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

Cells that are capable of bringing DNA from their environment into the cell through their cell wall are ______.

competent

horizontal gene transfer can occur via

conjugation

In addition to transformation, the other two forms of horizontal gene transfer are

conjugation and transduction

Because all of the genes coding for antibiotic resistance have been found to come from other organisms, A. baumannii most likely acquired them through

conjugation or a similar process of genetic exchange.

the 1st step in conjugation is

contact between the donor and recipient.

acterial cells that have been genetically modified to carry an antibiotic resistance gene can be separated from susceptible (non-resistant) microbes by using a ______ selection method using agar plates with antibiotic.

direct

In the beginning of transformation, ______ binds to the target cell.

double-stranded DNA

Transformation is a form of horizontal gene transfer that involves homologous recombination. Homologous recombination is

genetic recombination between similar or identical nucleotide sequences

The classic transformation experiment done by Griffith used

harmless and virulent strains of Streptococcus pneumoniae.

f+ cells

have a plasmid and are donors in conjugation.

plasmid DNA is transferred

in single-stranded form

In transduction, bacterial DNA is transferred to a new cell when

it is injected by the virus carrying bacterial DNA

Consider the figure. If the purple liquid was distilled water, the researcher would expect the number of colonies on plate A to be _____ as the number on plate B.

more or less the same

If Gene X codes for an F pilus and transposition occurs, then the bacterium containing the plasmid would

no longer be able to conjugate

During the entry of the donor DNA into the recipient cell

one strand is broken down by nucleases

a recombinant organism is

one that contains genes from another organism

Bacteriophages adsorb or attach

only to members of the same bacterial species

the donor DNA

pairs with a homologous region of the recipient DNA.

If a Gram-positive competent cell takes up DNA containing a penicillin resistance gene, what would be added to a selective medium to isolate the transformants?

penicillin

To isolate penicillin-resistant mutants, the scientist must inoculate the parent population on plates containing ______; this approach is ______ selection.

penicillin; direct

After host cell DNA is broken down by a viral enzyme,

phage DNA is replicated and phage coat proteins are produced

A difference between transferring plasmids and DNA fragments between bacterial cells is

plasmids can replicate independently