each strand is used as a template by ___________ to synthesize two new strands of DNA
the enzyme RNA polymerase synthesizes a strand of RNA from one strand of double-stranded DNA, which serves as a template during what process
Which of the following about bacteriocins are TRUE
a) the genes coding for them are on plasmids
b) Nisin is a bacteriocin used as food preservative
c) they can be used to identify certain bacteria
d) bacteriocins kill bacteria
When glucose is high, cAMP is _______: CAP ________bind the lac operator, and RNA polymerase _____ bind the lac promoter
cAMP is low
CAP does not
RNA polymerase does not
Transformation is the transfer fo DNA from a donor to a recipient cell
as naked DNA in solution
Genetic change in bacteria can be brought about by
Which of the following regarding a bacterium that is R+ is True
a) It possesses a plasmid
b) R+ can be transferred to a cell of the same species
c) it is resistant to certain drugs and heavy metal
d) R+ can be transferred to a different species
Depending on the gene, transcription makes one of three possible kinds of RNA:
1. messenger RNA (or mRNA)
2. ribosomal RNA (or rRNA)
3. transfer RNA (or tRNA)
Messenger RNA carries the coded information blueprint (the message)
from the DNA to the ribosome for the making of proteins.
The source of information.
Ribosomal RNA forms ribosomes, the site of protein synthesis
Makes sure that we start in the right spot and catalyzes the reactions
Transfer RNA bring amino acids (specific amino acids dictated by the
sequence of codons) to the ribosome where they are incorporated into
functions as an interpreter between the language of nucleic acids and the language of protein
RNA that has been folded up into a U shape
lines everyone up
the genes are in the "off" mode until an inducer is present which acts to induce transcription
the genes are transcribed until they are turned off, or repressed
3 ways genetic information is shared between two bacterial cells or between a virus and a bacterial cell
so-called naked DNA in solution is taken up by a bacterial cell
taking up free floating DNA from environment.
bacteria can transform and change themselves.
example was the mice with the rough and smooth cells. there was something in the bacteria that the bacteria were taking from the dead cells and giving them the information to turn themselves into smooth cells that would kill the mice.
requires direct contact between two living cells. A sex pilus connects two cells allowing the transfer of DNA
direct contact between two living cells.
bacterial sex. Some bacteria have genes for a structure called a pili. Uses this to connect into another cell and can send copies of DNA that way.
Is mediated by a plasmid
Only form of gene exchange in which donor survives
bacterial DNA is transferred from a donor cell to a bacteriophage
recipient cell inside a virus that infects bacteria
Polymerase Chain Reaction (PCR)
is used to make multiple copies of a desired piece of DNA enzymatically
The Ames Test
Based on observation that most carcinogens are also mutagens
Microbes used to test potential carcinogenic activity
Tests are based on mutagenic effect chemical has on microbial DNA
Ames test common chemical carcinogen test
Tests rate of reversion of Salmonella auxotroph
Also tests potential lethality
They do it backwards. We start with a strain of salmonella bacteria that has a mutation in it. And that salmonella has a mutation in one of the genes that is required for this bacteria to be able to synthesize the amino acid. Mutation in histidine synthesis. We then add our mutation causing probable chemical (mutagen) to this and mix it together and then we plate them out on plates without the histidine. And we want to know how many colonies grow. The only way they colonies grow is if a reversion mutation occurs. And that happens in the mutated gene that was mutated already. So the bacteria that are mutated can grow and synthesizes histidine. The more of these you have, then your chemical component that you added to it is probably the reason why.
vertical gene transfer
Clonal process of vertical reproduction. When we go from one parent cell to two daughter cells, those two daughter cells are directly identical. No shuffling of genes. No swapping parts. One copy of everything and we are not interacting with another cell in reproduction they divide themselves in half.
horizontal gene transfer
Bacteria can transfer genes between each other as adults. If you could go and swap genes with other people in a room that would be horizontal gene transfer.
establishes a physical bridge in between two cells through which we can transfer genetic information
F plasmid transfer
We start with a cell that makes a pili and one that does not. The one that has the pili and has F plasmid as an F + cell. That is our donor cell and the recipient one is F- cell. Pili forms a physical bridge in between these two cells that penetrates the cell wall. We transfer DNA from along pili from cytoplasm of one cell into the other cytoplasm of other cell. We make copy of F plasmid and transfer copy to other end and at the end of the day when the pili breaks apart we end up with donor cell and recipient cell that now has extra genetic F plasmid info and can make a pili itself so it can go and contact another cell and transfer itself. A copying method
high frequency recombination
Conjugation between Hfr and F- cell
Bacterial chromosome is being transferred
Breakage of pilus usually occurs before transfer complete
only a portion of the F factor replicated and transferred.
However, portion of donor chromosome is also transferred
F- has new information but may not have the complete F factor
F- remains F-
13) Salts and sugars work to preserve foods by creating a
A) depletion of nutrients.
B) hypotonic environment.
C) lower osmotic pressure.
D) hypertonic environment.
E) lower pH.
The term aerotolerant anaerobe refers to an organism that
A) does not use oxygen but tolerates it.
B) is killed by oxygen.
C) tolerates normal atmospheric nitrogen gas levels.
D) requires less oxygen than is present in air.
E) requires more oxygen than is present in air.
Which of the following is an advantage of the standard plate count?
A) can readily count cells that form aggregates
B) determines the number of viable cells
C) can be performed on very dilute samples, such as lake water
D) provides immediate results
E) can be used to count heat-sensitive bacteria
Bacterial growth refers to an increase in the numbers of cells in a bacterial culture.
Pure cultures can easily be obtained on streak plates, even if the desired bacteria are present in very low concentrations in the initial culture broth.
Most pathogenic bacteria are thermophiles.
Which of the following pairs is mismatched? A) DNA polymerase makes a molecule of DNA from a DNA template
B) RNA polymerase makes a molecule of RNA from an RNA template
C) DNA ligase joins segments of DNA
D) transposase insertion of DNA segments into DNA
E) DNA gyrase coils and twists DNA
DNA is constructed of
A) a single strand of nucleotides with internal hydrogen bonding.
B) two complementary strands of nucleotides bonded AC and GT.
C) two strands of nucleotides running in an antiparallel configuration.
D) two strands of identical nucleotides in a parallel configuration with hydrogen bonds between them.
E) None of the answers is correct.
Culture 1: F+, leucine+, histidine+
Culture 2: F, leucine, histidine
In Table 8.1, what will be the result of conjugation between cultures 1 and 2 (reminder: F+ has a different meaning than Hfr)?
A) 1 will remain the same; 2 will become F+, leucine, histidine
B) 1 will become F, leu+, his+; 2 will become F+, leu, his
C) 1 will become F, leu, his; 2 will remain the same
D) 1 will remain the same; 2 will become F+, leu+, his+
E) 1 will remain the same; 2 will become F+ and recombination may occur
An enzyme produced in response to the presence of a substrate is called a(n)
A) inducible enzyme.
B) repressible enzyme.
C) restriction enzyme.
Transformation is the transfer of DNA from a donor to a recipient cell
A) by a bacteriophage.
B) as naked DNA in solution.
C) by cell-to-cell contact.
D) by crossing over.
E) by sexual reproduction.
Genetic change in bacteria can be brought about by A) mutation. B) conjugation. C) transduction. D) transformation. E) All of the answers are correct.
Which of the following statements regarding a bacterium that is R+ is FALSE?
A) It possesses a plasmid.
B) R+ can be transferred to a cell of the same species.
C) It is resistant to certain drugs and heavy metals.
D) It is F+.
E) R+ can be transferred to a different species.
The initial effect of ionizing radiation on a cell is that it causes A) DNA to break. B) bonding between adjacent thymines. C) base substitutions. D) the formation of highly reactive ions. E) the cells to get hot.
According to the operon model, for the synthesis of an inducible enzyme to occur, the
A) end-product must not be in excess. B) substrate must bind to the enzyme. C) substrate must bind to the repressor.
D) repressor must bind to the operator.
E) repressor must not be synthesized
Synthesis of a repressible enzyme is stopped by the A) allosteric transition. B) substrate binding to the repressor. C) corepressor binding to the operator. D) corepressor-repressor complex binding to the operator. E) end product binding to the promoter.
In Figure 8.3, if compound C reacts with the allosteric site of enzyme A, this would exemplify A) a mutation. B) repression. C) feedback inhibition. D) competitive inhibition. E) transcription.
In Figure 8.3, if enzyme A is an inducible enzyme, A) compound C would bind to the repressor for Gene a. B) compound A would bind to the repressor for Gene a. C) compound B would bind to enzyme A directly. D) compound A would react with enzyme B directly. E) compound C would react with gene a directly.
Conjugation differs from reproduction because conjugation A) replicates DNA. B) transfers DNA vertically, to new cells. C) transfers DNA horizontally, to nearby cells without those cells undergoing replication. D) transcribes DNA to RNA. E) copies RNA to make DNA.
The necessary ingredients for DNA synthesis can be mixed together in a test tube. The DNA polymerase is from Thermus aquaticus, and the template is from a human cell. The DNA synthesized would be most similar to A) human DNA. B) T. aquaticus DNA. C) a mixture of human and T. aquaticus DNA. D) human RNA. E) T. aquaticus RNA.
In Figure 8.4, the antibiotic chloramphenicol binds the 50S large subunit of a ribosome as shown (the light gray area is the large subunit, while the black shape is the drug). From this information you can conclude that chloramphenicol A) prevents transcription in eukaryotes. B) prevents translation in eukaryotes. C) prevents transcription in prokaryotes. D) prevents translation in prokaryotes. E) prevents mRNA-ribosome binding.
The mechanism by which the presence of glucose inhibits the lac operon is A) catabolite repression. B) translation. C) DNA polymerase. D) repression. E) induction.
If you knew the sequence of nucleotides within a gene, which one of the following could you determine with the most accuracy? A) the primary structure of the protein B) the secondary structure of the protein C) the tertiary structure of the protein D) the quaternary structure of the protein E) The answer cannot be determined based on the information provided.
An enzyme that makes covalent bonds between the sugar of one nucleotide and the phosphate groups in another nucleotide in DNA is
An enzyme that copies DNA to make a molecule of RNA is A) RNA polymerase. B) DNA ligase. C) DNA helicase. D) transposase. E) DNA polymerase.
An enzyme that catalyzes the cutting and resealing of DNA, and is translated from insertion sequences, is A) RNA polymerase. B) DNA ligase. C) DNA helicase. D) transposase. E) DNA polymerase.
Repair of damaged DNA, in some instances and mechanisms, might be viewed as a race between an endonuclease and A) DNA ligase. B) DNA polymerase. C) helicase. D) methylase. E) primase.
The cancer gene ras produces mRNA containing an extra exon that includes a number of UAA codons. Cancer cells produce ras mRNA missing this exon. This mistake most likely is due to a mistake by A) a chemical mutagen. B) DNA polymerase. C) photolyases. D) snRNPs. E) UV radiation.
The miRNAs in a cell A) are found in prokaryotic cells. B) are a part of the prokaryotic ribosome. C) are a part of the eukaryotic ribosome. D) allow different cells to produce different proteins. E) are responsible for inducing operons.
Assume the two E.coli strains shown below are allowed to conjugate. Hfr: pro+, arg+, his+, lys+, met+, ampicillin-sensitive F-: pro, arg, his, lys, met, ampicillin-resistant What supplements would you add to glucose minimal salts agar to select for a recombinant cell that is lys+, arg+, amp-resistant? A) ampicillin, lysine, arginine B) lysine, arginine C) ampicillin, proline, histidine, methionine D) proline, histidine, methionine E) ampicillin, proline, histidine, lysine
Recombination will always alter a cells genotype.
Open-reading frames are segments of DNA in which both start and stop codons are found.
Bacteria typically contain multiple chromosomes.
Mutations that are harmful to cells occur more frequently than those that benefit cells.
The miRNAs in a cell inhibit protein synthesis by forming complementary bonds with rRNA.
Some cells may contain multiple genomes.
Both base substitution and frameshift mutations can result in the formation of premature stop codons
In the Ames test, any colonies that form on the control should be the result of spontaneous mutations.
Transposition (insertion of a transposon into a DNA sequence) results in the formation of base substitution mutations in a cells DNA.
Cell-to-cell contact is required for transduction to occur
A red pigment produced by a bacterial species is an example of a(n)?
- Inducible enzyme
In Figure 6.1, which line best depicts a facultative anaerobe in the absence of O2? A) a B) b C) c
In Figure 6.1, which line best illustrates a mesophile at 5°C above its optimum temperature? A) a B) b C) c
In Figure 6.1, which line best depicts a mesophile with an optimum temperature of 35°C incubated at 40°C? A) a B) b C) c
In Figure 6.1, which line shows the growth of an obligate aerobe incubated anaerobically? A) a B) b C) c
In Figure 6.1, which line best illustrates the growth of a facultative anaerobe incubated aerobically? A) a B) b C) c
) Micrococci are facultative halophiles. In Figure 6.1, which line best depicts the growth of Micrococcus luteus in a nutrient medium containing 7.5% NaCl? A) a B) b C) c
In Figure 6.1, which line best depicts a psychrophile incubated at room temperature? A) a B) b C) c
In Figure 6.1, which line best depicts Neisseria gonorrhoeae when growing inside the human body? A) a B) b C) c
The term facultative anaerobe refers to an organism that A) Doesn't use oxygen but tolerates it. B) Is killed by oxygen. C) Uses oxygen or grows without oxygen. D) Requires less oxygen than is present in air. E) Prefers to grow without oxygen.
Figure 6.3 shows three containers of water connected by tubes. A selectively permeable membrane divides each tube. Solutes are added to each container to give final concentrations of 5% NaCl in
(a); 10% NaCl in
(b); and 5% sucrose in
c). When the experiment is first set up, the initial movement of water will be
A) a to b; b to c; c to a.
B) a to b; c to b; c to a.
C) a to c; b to c; c to a.
D) a to c; c to b; c to a.
E) b to a; b to c; c to a.
A culture medium on which only gram-positive organisms grow and a yellow halo surrounds Staphylococcus aureus colonies is called a(n) A) Selective medium. B) Differential medium. C) Enrichment culture. D) A and B E) B and C
Which enzyme catalyzes the reaction: O2- + O2- + 2H+ → H2O2 + O2? A) Catalase B) Oxidase C) Peroxidase D) Superoxide dismutase
Which enzyme catalyzes the reaction: 2H2O2 → 2H2O + O2? A) Catalase B) Oxidase C) Peroxidase D) Superoxide dismutase
Which enzyme catalyzes the reaction: H2O2 + 2H+ → 2H2O? A) Catalase B) Oxidase C) Peroxidase D) Superoxide dismutase
Which of the following is the best method to sterilize heat-labile solutions? A) Dry heat B) Autoclave C) Membrane filtration D) Pasteurization E) Freezing
Which of the following best describes the pattern of microbial death? A) The cells in a population die at a constant rate. B) All the cells in a culture die at once. C) Not all of the cells in a culture are killed. D) The pattern varies depending on the antimicrobial agent. E) The pattern varies depending on the species.
Which of the following substances is used for surgical hand scrubs? A) Phenol B) Chlorine bleach C) Chlorhexidine D) Soap E) Glutaraldehyde
Which of the following substances can sterilize? A) Alcohol B) Phenolics C) Ethylene oxide D) Chlorine E) Soap
Place the following surfactants in order from the most effective to the least effective antimicrobial activity: 1-Soap; 2-Acid-anionic detergent; 3-Quats.
A) 1, 2, 3
B) 1, 3, 2
C) 2, 1, 3
D) 3, 2, 1
E) 3, 1, 2
The initial effect of ionizing radiation on a cell is that it causes A) DNA to break. B) Bonding between adjacent thymines. C) Base substitutions. D) The formation of highly reactive ions. E) The cells to get hot.
According to the operon model, for the synthesis of an inducible enzyme to occur, the A) End-product must not be in excess. B) Substrate must bind to the enzyme. C) Substrate must bind to the repressor. D) Repressor must bind to the operator. E) Repressor must not be synthesized.
The mechanism by which the presence of arabinose controls the arabinose operon is A) Catabolite repression. B) Translation. C) DNA polymerase. D) Repression. E) Induction.
In transcription, A) DNA is changed to RNA. B) DNA is copied to RNA. C) DNA is replicated. D) RNA is copied to DNA. E) Proteins are made.
In a DNA double-helix, nucleotides on complementary strands are held together by
- covalent bonds
- salt bridges
- hydrogen bonds
- phosphodiester bonds
- none of the above
Which of the following is found at the 5 end of a DNA strand?
A) a phosphate group
B) a hydrogen bond
C) a hydroxyl group
E) a methyl group
The bacterial chromosome is A) usually circular. B) found in a nucleoid. C) found in a nucleus. D) both circular and found in a nucleoid. E) both circular and found in a nucleus.
) Which of the following types of plasmids allows a bacterial cell to kill its competitors? A) virulence factors B) fertility factors C) bacteriocin factors D) resistance factors E) cryptic plasmids
Which of the following statements is true of bacterial plasmids? A) They are found in the nucleoid. B) They can replicate autonomously. C) They carry genes for essential metabolic functions. D) They are small circular DNA molecules. E) They are small circular DNA molecules that can replicate autonomously.
Which of the following statements concerning transcription in bacteria is FALSE? A) It occurs in the nucleoid region. B) Sigma factors are parts of RNA polymerase that recognize promoter regions. C) The same RNA polymerase transcribes primer RNA, mRNA, tRNA, and rRNA. D) Termination is either self-induced or due to the presence of Rho protein. E) There are a variety of sigma factors that affect transcription.
A charged tRNA first enters the ribosomal ________ site and then moves into the ________ site.
A) A, E
B) P, A
C) P, E
D) A, P
E) E, A
Semiconservative DNA replication means that
A) each daughter DNA molecule is composed of one original strand and one new strand.
B) nucleotides are constantly being recycled as cells make DNA.
C) the cell can proofread its newly synthesized DNA only part of the time.
D) the sequence of a DNA molecule is preserved as it is being replicated.
E) each strand of a double-stranded DNA molecule is replicated differently.
A) are active in the presence of a repressor.
B) are generally anabolic pathways.
C) are normally active.
D) usually require an activator to be transcribed.
E) usually require a repressor to be transcribed.
If the codon AAA is changed to AAG, it still codes for the amino acid lysine; this is an example of a
A) silent mutation.
B) nonsense mutation.
C) frameshift mutation.
D) gross mutation.
E) missense mutation.
The Ames test proves that a chemical is A) carcinogenic. B) carcinogenic in Salmonella. C) mutagenic in Salmonella. D) carcinogenic in humans. E) mutagenic in humans.
The horizontal transfer process known as transduction A) involves a virus. B) requires a pilus. C) requires a cell to be "competent." D) requires a plasmid. E) involves a mutagen.
Frederick Griffith discovered A) transformation. B) transposons. C) the lac operon. D) DNA. E) conjugation.
In conjugation, F+ cells A) serve as recipient cells. B) contain an F plasmid. C) do not have conjugation pili. D) can transfer DNA only to other F+ cells. E) contain "jumping genes."
The energy required for DNA replication comes from A) DNA polymerase. B) triphosphate deoxyribonucleotides. C) DNA ligase. D) RNA primer. E) the leading strand.
Prokaryotic cells are diploid.
The most common type of mutation is a point mutation.
Bidirectional replication means that each strand of a DNA molecule is replicated in the opposite direction from the other.
the repressor for the lac operon is active when lactose is present
- Which of the following statements is false?A) DNA polymerase joins nucleotides in one direction only. B) The leading strand of DNA is made continuously.C) The lagging strand of DNA is started by an RNA primer.D) DNA replication proceeds in one direction around the bacterial chromosome. E) Multiple replication forks are possible on a bacterial chromosome.
Codon on mRNA and corresponding amino acid
UCG, UCU serine
- (Use Table 8.2.) If the sequence of amino acids encoded by a strand of DNA is serine-alanine-lysine-leucine, what is the order of bases in the sense strand of DNA? A) 3′ UGUGCAAAGUUA B) 3′ AGACGTTTCAAT C) 3′ TCTCGTTTGTTA D) 5′ TGTGCTTTCTTA E) 5′ AGAGCTTTGAAT
Codon on mRNA and corresponding amino acid
UCG, UCU serine
- If the sequence of amino acids encoded by a strand of DNA is serine-alanine-lysine-leucine, the coding for the antisense strand of DNA is
A) 5′ ACAGTTTCAAT
B) 5′ TCTGCAAAGTTA
C) 3′ UGUGCAAAGUUA
D) 3′ UCUCGAAAGUUA
E) 3′ TCACGUUUCAAU
Codon on mRNA and corresponding amino acid
UCG, UCU serine
What is the sequence of amino acids encoded by the following sequence of bases in a strand of DNA?
B) Asparagine-arginine-lysine-alanine C) Asparagine-cysteine-valine-serine
D) Transcription would stop at the first codon E) Can't tell
Codon on mRNA and corresponding amino acid
UCG, UCU serine
- If a frameshift mutation occurred in the sequence of bases shown below, what would be the sequence of amino acids coded for? 3′ ATTACGCTTTGC A) Leucine-arginine-lysine-alanineB) Asparagine-arginine-lysine-alanine C) Asparagine-cysteine-valine-serine D) Translation would stop at the first codon E) Can't tell
- In Figure 8.3, if enzyme A is a repressible enzyme, compound C would A) Always be in excess. B) Bind to the enzyme.C) Bind to the corepressor. D) Bind to RNA polymerase
E) Bind to gene a.
In Figure 8.3, if enzyme A is an inducible enzyme,
A) Compound C would bind to the repressor.
B) Compound A would bind to the repressor.
C) Compound B would bind to enzyme A.
D) Compound A would react with enzyme B.
E) Compound C would react with gene a.
An enzyme that cuts double-stranded DNA at specific nucleotide sequences.
A) RNA polymerase
B) DNA ligase
C) Restriction enzyme
E) DNA polymerase
Which mutation would most severely affect the protein coded for by a gene?
A frameshift deletion at the beginning of the gene
A frameshift mutation at the beginning of a gene would affect every codon after the point where the mutation occurred. During protein synthesis, incorrect amino acids would be inserted from the point where the frameshift mutation occurred on; the resulting protein would most probably be nonfunctional. For this reason, a frameshift mutation at the beginning of a gene is generally the most severe type of mutation.
True or False? When treating an organism with a mutagen, although it is possible that homozygous mutations will occur, it is more likely that most new mutations will be heterozygous or hemizygous.
True or False?
A missense mutation causes premature chain (protein) termination.
True or false? All compounds that have been found to be mutagenic in the Ames test are also carcinogenic
Which bacteria grow on the Agar plate if the Ames test is positive?
The bacteria used in the Ames test to evaluate mutagenicity are his− auxotrophs. If the Ames test is positive, these bacteria have reverted back to wild type and are his+ prototrophs
Genetic change in bacteria can be brought about by?
e. all of the answers are correct
In E. coli, the lactose operon is?
a. under positive control
b. under negative control
d. all of the above
e. two of the above
In E. coli, the tryptophan operon is?
a. under positive control
b. under negative control
d. all of the above
e. two of the above
The region of DNA at which RNA polymerase binds to start
transcription is the?
c. start codon
d. activator binding site
Which of the following is not true of RNA molecules?
a. the molecules are singe stranded
b. nucleotides include adenine, guanine, cytosine, and uracil
c. the enzyme that makes them proofreads very carefully
d. compared with DNA, they don't last very long in a cell
e. actually all of these are true
Conjugation differs from reproduction because conjugation?
a. transfers DNA horizontally
b. copies RNA to make DNA
c. transfers DNA vertically, to new cells
d. replicates DNA
e. transcribes DNA to RNA
The purpose of the Southern blotting techniques is to?
a. amplify fragments of DNA
b. cleave DNA into small fragments
c. construct a plasmid vector
d. remove introns prior to cloning
e. detect specific DNA fragments from a mixture of DNA molecules
A small molecule that combines with a specific allosteric protein so
that both prevent RNA
polymerase activity is called a(n):
Hfr strains of bacteria:
A. do not have an "F" (fertility) factor.
B. have an "F" factor plasmid.
C. have an "F" factor integrated in the bacterial chromosome.
D. transfer the genetic information to other bacteria with high frequency