Test 3 Questions

Question 1

What TWO regulatory systems determine when the lactose utilization genes are expressed in E. coli? What environmental conditions are required to produce HIGH level expression of these genes, and how do these conditions affect the regulatory systems?

Answer 1

The Lac repressor and the catabolite repression system (cAMP and CRP) regulate the Lac genes. Glucose must be absent, so that cAMP is produced, and Lactose must be present, so that the Lac repressor does not bind DNA, for high level expression.

Question 2

Describe how an Hfr strain is produced. Then describe how this leads to high frequency recombination among cells in a population.

Answer 2

An Hfr strain is produced when the F plasmid is inserted into the host cell chromosome. When conjugation is initiated from the inserted F plasmid, donor chromosomal DNA os transferred to a recipient cell, allowing for homologous recombination with the recipient chromosome.

Question 3

Tetracycline inhibits bacterial growth by blocking____.

Answer 3

Translation

Question 4

DNA transfer during cell-to-cell contract is called_____.

Answer 4

conjugation

Question 5

During regulation of the E. coli lactose utilization genes, the small molecule lactose functions as an_____.

Answer 5

inducer

Question 6

_____ recognizes the origin and recruits other proteins during DNA replication.

Answer 6

DnaA

Question 7

The enzyme responsible for moving a transposon is called ___.

Answer 7

transposase

Question 8

____ is a regulatory mechanism used by bacterial cells to determine their population density and respond accordingly.

Answer 8

Quorum sensing

Question 9

A protein that assists other proteins in folding properly is called a ____

Answer 9

chaperone

Question 10

A ribosome-binding site is NOT required in which domain of life?

Answer 10

Eukarya

Question 11

The summed collection of all the genes found among all the strains of bacterial species is called the ____

Answer 11

pangenome

Question 12

A chemical compound that causes bacterial cells to break open would be described as____

Answer 12

bacteriolytic

Question 13

Proteins that bind DNA and increase transcription are called ____

Answer 13

activators

Question 14

The genetically-encoded process of picking up DNA from the environment is called____

Answer 14

Natural transformation

Question 15

Two similar genes that have similar functions in one species are called___

Answer 15

paralogs

Question 16

A compound that killed all life forms, including endospores within an environment is called a ____

Answer 16

Sterilant

Question 17

UAA is a commonly used _____ codon.

Answer 17

stop

Question 18

An OPERON is:
1)Multiple genes transfered to a new strain via conjugation
2)Multiple genes transcribed from a single promoter
3)Multiple genes translated from a single
4)Multiple genes replicated together on a plasmid
5)Multiple proteins in a single metabolic pathway.

Answer 18

Multiple genes transcribed from a single promoter.

Question 19

If a bacterial genome contains 1,000,000 base pairs, then approximately how many genes would you predict it would contain?
1)100
2)1000
3)10000
4)100000
5)1000000

Answer 19

1000

Question 20

The tra genes are involved in:
1)Formation of mating pairs
2)Binding and uptake of DNA from the medium
3)Assembly of bacteriophage particles
4)Homologous recombination

Answer 20

Formation of mating pairs

Question 21

Orthologs arise via what process?
1)One species differentiating to produce two species
2)One gene duplicating and then one copy changing over time
3)Transduction
4)Homologous recombination
5)Transposon insertion

Answer 21

One species differentiating to produce two species

Question 22

Which of the following is not true about plasmids?
1)They are much smaller than chromosomes
2)They always replicate at the same time as the chromosome
3)They are non-essential
4)They are dsDNA

Answer 22

They always replicate at the same time as the chromosome

Question 23

A tRNA is considered charged when it is:
1)Covalently linked to an amino acid
2)Properly folded
3)Covalently linked to an mRNA
4)Held within a ribosome
5)Based-paired with an mRNA

Answer 23

Covalently linked to an amino acid

Question 24

Signal transmission by the 2-Component Regulatory Systems discussed in class is carried out via:
1)Protein degradation
2)Adenosine methylation
3)Protein phosphorylation
4)Transcription antitermination

Answer 24

Protein phosphorylation

Question 25

The processes of transcription and translation are coupled processes in: 1)eukaryotic cells 2)prokaryotic cells 3)both eukaryotic and prokaryotic cells 4)neither eukaryotic nor prokaryotic

Answer 25

prokaryotic cells

Question 26

Which subunit of bacterial RNA polymerase is responsible for recognizing the conserved promoter elements? 1)The alpha subunit 2)The beta subunit 3)The epsilon subunit 4)The sigma subunit 5)The TATA-binding protein

Answer 26

The sigma subunit

Question 27

The site in the DNA that is bound by a repressor is called an: 1)Operator 2)Inducer 3)Terminator 4)BRE element 5)-35 sequence 6)None of the above

Answer 27

Operator

Question 28

Which of the following enzymes is NOT required for lagging strand synthesis or completion? 1)DNA Polymerase I 2)DNA Polymerase III 3)Primase 4)DNA Lipase 5)RNA Polymerase

Answer 28

RNA Polymerase

Question 29

If we find that an organism has linear chromosomes we can assume that it is likely in which domain of life? 1)Bacteria 2)Archea 3)Eukarya 4)Bacteria or Archaea 5)Archaea or Eukarya

Answer 29

Eukarya

Question 30

The end result of chromosome mobilization between an Hfr cell and an F- cell is: 1)Conversion of the F- cell to an Hfr cell 2)Conversion of the F- cell to an F+ 3)Conversion of the Hfr cell to an F- cell and the F- cell to an Hfr cell 4)Conversion of both cells to F+ 5)No change occurs; the Hfr cell remains Hfr and the F- cell remains F-

Answer 30

No change occurs; the Hfr cell remains Hfr and the F- cell remains F-

Question 31

The entire complement of RNA produced in a cell under a given set of conditions is called an: 1)Array 2)Genome 3)Proteome 4)Regulon 5)Transcriptome

Answer 31

Transcriptome

Question 32

Which is NOT a reason why a bacterial species may have resistance to an antibiotic? 1)The organism may be impermeable to the antibiotic 2)The organism may be protected from the drug by its nuclear membrane 3)The organism may be able to pump out an antibiotic that enters the cell 4)The organism may be able to alter the antibiotic to an inactive form

Answer 32

The organism may be protected from the drug by its nuclear membrane

Question 33

The portion of an exported protein that directs it to the bacterial protein export apparatus is called the: 1)Signal sequence 2)Signal Recognition particle 3)Sec system 4)Amino terminus 5)Carboxy terminus

Answer 33

Signal sequence

Question 34

The MIC of an antibiotic is the concentration at which: 1)Growth of a specific microorganism is decreased 10% 2)Growth of a specific microorganism is decreased 50% 3)Growth of a specific microorganism is completely blocked 4)Growth of all microorganisms is blocked 5)The antibiotic is no longer effective

Answer 34

Growth of a specific microorganism is completely blocked

Question 35

If bacterial cells are said to be "competent", it means they are in a state capable of undergoing what process? 1)Conjugation 2)Cell division 3)Replication 4)Transduction 5)Transformation

Answer 35

Transformation

Question 36

DNA polymerase is responsible for all of the following except: 1)New DNA strand synthesis 2)Insuring replication fidelity through proofreading 3)Recognition of -10 and -35 sequences in bacteria 4)Some steps in DNA repair 5)Formation of Okazaki fragments

Answer 36

Recognition of -10 and -35 sequences in bacteria

Question 37

The term "Catabolite repression" refers to the fact that: 1)In E.coli, most catabolic systems are regulated by repressors. 2)In E. coli, use of glucose is regulated by a repressor 3)When Glucose is present, E. coli will use no other carbon sources 4)When Lactose is present is present , E. coli will use no other carbon sources 5)When Glucose and Lactose are both present, E. coli will use both at the same time

Answer 37

When Glucose is present, E. coli will use no other carbon sources

Question 38

Bacteriocidal agents cause: 1)Total cell count and viable cell count to remain constant 2)Total cell count and viable cell count to decrease 3)Total cell count to decrease while viable cell count remains constant 4)Total cell count to remain constant while viable cell count decrease 5)Bacteriocidal agents do not affect cell count

Answer 38

Total cell count to remain constant while viable cell count decrease

Question 39

Which of the following is true about parasitic organism s that live ONLY within the host environment? 1)A greater percentage of their genome is involved in translation, relative to free-living organisms 2)A smaller percentage of their genome is involved in translation, relative to free-living organisms 3)The small percentage of their genome is involved in translation, relative to free-living organisms 4)Essentially all of their genome is involved in translation 5)Almost none of their genome is involved in translation

Answer 39

A greater percentage of their genome is involved in translation, relative to free-living organisms

Question 40

A "Corepressor" is: 1)A protein that binds a small molecule and then binds DNA 2)A small molecule that binds a protein, causing it to bind DNA 3)A protein that binds RNA polymerase and blocks it activity 4)A protein that binds ribosomes and blocks translation 5)None of the above

Answer 40

A small molecule that binds a protein, causing it to bind DNA

Question 41

Transduction is not sensitive to DNase activity because: 1)The DNA is never outside of a cell 2)The process does not involve DNA 3)The donor and recipient cells are in direct contact 4)The DNA is protected by the phage structure 5)The phage inactivates DNase function

Answer 41

The DNA is protected by the phage structure

Question 42

During Conservative Transposition: 1)A new copy of the transposon is created 2)A single copy of the transposon moves to a new site 3)A transposon hops, but stays in the same species 4)The transposon remains in its original position AND is replicated at a new site 5)A transposon hops from a plasmid into the chromosome

Answer 42

A single copy of the transposon moves to a new site

Question 43

Transduction differs from other mechanisms of genetic exchange in what way? 1)Transduction requires the activity of a virus while other mechanisms do not 2)Transduction requires direct cell-cell contact while other mechanisms do not 3)Transduction can transfer plasmid DNA while other mechanisms cannot 4)transduction can transfer chromosomal DNA while other mechanisms cannot

Answer 43

Transduction requires the activity of a virus while other mechanisms do not

Question 44

How many origins of replication are present in a bacterial chromosome? 1)Zero 2)One 3)Three to five 4)Ten to twenty 5)More than 100

Answer 44

One

Question 45

During artificial transformation of a plasmid into E. coli cells, what form of DNA enters the cell? 1)Linear ssDNA 2)Circular ssDNA 3)Linear dsDNA 4)Circular dsDNA

Answer 45

Circular dsDNA

Question 46

Hydrogen peroxide poured on an injury like a scraped knee acts as an: 1)antiseptic 2)sanitizer 3)disinfectant 4)sterilant 5)antibiotic

Answer 46

antiseptic

Question 47

The two cells involved in producing a bacterial spore coordinate the timing of changes in their gene expression by: 1)Activating alternate sigma factors in the two cell types 2)Recombining genes in and out of the chromosomes in the two cells 3)Transferring DNA between the two cells 4)Detecting quorum sensing signals excreted by the two cell types 5)Alternately translation in the opposite cell

Answer 47

Activating alternate sigma factors in the two cell types