Micro exam 3

In the figure, what are the correct terms for the regions labeled "A" and "B"?

A: Promoter; B: Terminator

Which pairing is incorrect?

A:G

On which of the following DNA strands would UV radiation have the most effect?

AATTAGTTC

If the transcript shown here is translated, what is the codon that corresponds to the second amino acid in the resulting protein?

AUC

GCCCAAAG is a molecule of

Cannot tell as written.

What structure is indicated by: 10A, 15T, 3G, 7C?

Single-stranded DNA

Which pair is INCORRECT?

Splicing—removal of introns from prokaryote mRNA following transcription.

The sequence of cDNA synthesized from an mRNA template with the sequence AUGGUA would be ______. This cDNA probe would hybridize to gene chip DNA with the sequence ______.

TACCAT; ATGGTA

If a DNA triplet is AGT, the mRNA codon would be ______ and the tRNA anticodon would be ______.

UCA; AGU

The formation of a covalent bond between two adjacent thymines is caused by

UV radiation.

Why would it be beneficial for cells to wait until a critical population density is reached before expressing certain genes?

Without a certain density, it would be highly unlikely that the molecules produced by a cell in the group could find and bind to other cells of the population effectively.

A mutation in E. coli results in the loss of both restriction endonucleases and modification enzymes. Would you expect any difference in the frequency of gene transfer via transduction FROM Salmonella INTO this E. coli strain?

Yes—the loss of the restriction endonucleases would leave the recipient E. coli unable to break down "invading" viral DNA from the transducing phage, AND the loss of the modification enzymes would leave the recipient E. coli unable to tag its own DNA as "self," leaving the viral DNA untagged and recognizable as "foreign," and targeted for destruction. Together, these would lead to higher rates of successful transduction.

In a FISH experiment, what would happen if unbound probe was not washed off?

You would get false-positive results in different areas where the probe hadn't actually bound, but it was still sitting there and lighting up.

For synthesis of an inducible enzyme to occur,

a compound must bind to the repressor.

Taq polymerase is

a heat-stable DNA polymerase from Thermus aquaticus.

Goal(s) of gene cloning may be to produce

a protein, many copies of the gene to be used as a probe, AND many copies of the gene for sequencing.

An open reading frame or a possible protein-encoding region of prokaryotic DNA is

a region of DNA that begins with a start codon (ATG) and ends with a stop codon.

A regulatory protein binds to the operator in a strand of DNA, blocking transcription. The protein is

a repressor.

Intercalating agents

act during DNA synthesis AND often result in frameshift mutations.

Genetic engineering

allows the use of bacteria as production factories for a number of molecules AND relies on recombinant DNA technology.

Phase variation is a phenomenon used by some bacteria (such as E. coli) to evade host immune mechanisms. In this process, the cells

alternately turn genes on/off to adjust bacterial behavior.

The polymerase chain reaction is used to

amplify certain sections of DNA.

In conjugation the donor cell is recognized by the presence of

an F plasmid.

The energy to separate fragments during agarose gel electrophoresis is supplied by

electricity.

RNA interference (RNAi) is a mechanism by which

eukaryotic cells destroy RNA transcripts in a selective and specific manner to control gene expression.

Post-translational modification may include

folding of the protein, often with the aid of chaperones, AND removal of the signal sequence.

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.

In conjugation, transformation, or transduction, the recipient bacteria is most likely to accept donor DNA

from the same species of bacteria.

In order to get around the lack of ability of prokaryotes to remove introns from precursor RNA, it may be necessary to

generate cDNA from mRNA.

Bacteria that have properties of both the donor and recipient cells are the result of

genetic recombination.

The simultaneous regulation of many bacterial genes is

global control.

To increase the chance of detecting carcinogens in the Ames test, the test substance is treated with

ground-up rat liver.

The 3' end of DNA

has a hydroxyl group attached to the number 3 carbon of deoxyribose.

Double-stranded DNA will separate into two strands when exposed to

high temperature AND high pH.

Cells that are His-, StrR could be isolated from a mixed sample by using a medium containing

histidine AND streptomycin

Chemical mutagens often act by altering the

hydrogen bonding properties of the nucleobase.

The two strands of DNA are bonded to one another by

hydrogen bonds.

Knowing the sequence of a genome is useful in

identifying genetic alterations associated with disease, studying evolutionary relationships, AND determining protein sequences.

Selecting for transformants involves

identifying organisms that have taken up recombinant DNA.

DNA repair mechanisms occur

in both eukaryotes and prokaryotes.

The molecules that bind to a repressor and cause it to no longer bind to the operator are called

inducers.

The lac operon is ______.

inducible

A fundamental aspect of gene regulation lies in the ______ of mRNA molecules. Because of this trait, these molecules won't remain in the cell long after transcription has been turned off by the cell, regulating gene expression.

instability

The clustered, regularly interspaced short palindromic repeats (CRISPR) system in bacterial cells has been called the "immune" system of bacteria. CRISPR protect bacteria from a repeat infection from the same phage because bacterial cells

integrate fragments from the phage DNA in their own chromosomes and target for destruction any DNA that contains the same fragments in the future.

Planar molecules used as chemical mutagens are called

intercalating agents.

Some segments of the precursor mRNA in eukaryotes are non-coding and are called

introns.

Among the easiest of the mutations to isolate are those which

involve haploid chromosomes AND involve antibiotic resistance.

Quorum sensing

involves the production and monitoring of signaling molecules AND is used by bacteria to sense the density of cells within their population.

The lagging strand

is formed during DNA replication because of the antiparallel nature of DNA.

CAP

is involved in positive control AND works in conjunction with cAMP.

In the lac operon, glucose

is preferentially used over lactose in E. coli as a result of catabolite repression AND glucose levels are the inverse of cAMP levels.

The P-site

is the peptidyl site on the ribosome.

Signal transduction

is the relay of information about conditions outside a cell to inside the cell.

Replica plating

is useful for identifying auxotrophs AND uses media on which the mutant will not grow but the parental cell type will.

Is it as effective to take two antibiotics sequentially for an infection as it is to take them simultaneously, as long as the total length of time of the treatment is the same?

No. If the antibiotics are given sequentially, there is a chance that resistance to either one may arise through mutation. When antibiotics are given simultaneously, the chance of resistance to two different antibiotics occurring is extremely low.

Which of the following pairs about mutation is NOT correctly matched?

Nonsense mutation—incorrect amino acid

DNA in cells can encode for thousands of different proteins. Why do cells require mechanisms to regulate expression of the genes that code for these proteins?

Not all proteins are needed at all times, or in equal amounts. Regulating their expression saves energy and time.

Antibiotics

provide an environment in which preexisting mutants survive.

DNA molecules that contain pieces of DNA from two different sources are defined as

recombinant DNA.

The genetic code has more than one codon for some amino acids. This is an example of

redundancy.

Operon(s) in bacteria

refers to a group of genes that are controlled in a coordinated manner AND involve polycistronic mRNA.

The term antiparallel

refers to the opposite orientation of the two strands in DNA.

Consider the figure of two plasmids below. Bacteria containing the plasmid shown in panel A would generate ______ colonies on medium containing x-gal, while those in panel B would generate ______ colonies.

blue; white

Negative control means a regulator molecule is

bound, and transcription is inhibited OR removed, and transcription starts.

A clever technique that streamlines the identification of auxotrophic mutants is

replica plating.

Transcription is often controlled by DNA-binding proteins. A(n) ______ is a regulatory protein that blocks transcription, while a(n) ______ is a regulatory protein that facilitates transcription.

repressor; activator

The molecules used to cut target DNA in genetic engineering are

restriction enzymes.

The transcription terminator

results in a hairpin loop structure in RNA, AND results in the polymerase falling off the DNA template.

DNA replication is

semiconservative.

The agarose used in electrophoresis

separates DNA fragments by size.

Bacteria use ______ attached to the polymerase to direct RNA polymerase to promoters; eukaryotic cells use ______ that attach directly to the DNA first instead.

sigma factors; transcription factors

All of the following are true about DNA sequence analysis EXCEPT

the (−) strand of DNA is used.

When E. coli is grown in medium containing both glucose and lactose,

the cells grow fastest initially when glucose is available.

The designation his- refers to

the genotype of bacteria that lack a functional gene for histidine synthesis AND bacteria that are auxotrophic for histidine.

The size of the amplified DNA fragment generated during PCR is determined by

the location to which the primers anneal.

The diploid character of eukaryotic cells may mask the appearance of a mutation since

the matching chromosome may carry the correct version of the gene.

Genetically modified food has raised some concerns because

the modified DNA may transfer to other organisms.

Direct selection involves inoculating cells onto growth media on/in which

the mutant but not the parental cell type will grow.

A danger in using E. coli in cloning is that

the outer membrane is toxic to humans.

RNAi

uses short pieces of single-stranded RNA to direct the degradation of specific RNA transcripts

Host cells containing recombinant DNA can be selected on the basis of the properties of the

vector.

When a vector that uses the lacZ gene as a second marker is used in a cloning experiment, bacteria that contain the recombinant DNA will give rise to

white colonies.

Transposons can cause mutations by

"jumping" into a gene and disrupting its function.

Vectors must have at least one restriction enzyme recognition site.

True

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.

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

1: synonymous; 2: nonsense; 3: missense

Without changing the sequence or the orientation of the sequence(s), which is/are complementary to the sequence 5' AGGCUAAC 3'?

3' TCCGATTG 5'

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'.

Identify the correct sequence in which the steps below occur during a single PCR cycle. 1. Complementary base pairing between primers and target DNA. 2. Addition of DNA nucleotides by Taq DNA polymerase. 3. Heat separation of strands of target DNA.

3;1;2

Consider the figure below. Which statement is TRUE?

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

Starting with a single piece of dsDNA, after 3 PCR cycles there are

8 additional pieces of dsDNA.

Scientists have cloned the human insulin gene into E. coli. Which of the following would NOT have been used in the procedure?

A bacteriophage

Please select the INCORRECT statement regarding mutation.

A missense mutation is also called a synonymous mutation, meaning no change in the amino acid encoded.

Which regions of the gene (or segment of DNA) shown here encodes the amino acid sequence of a protein?

A, C, E

The restriction-modification system always has two genes involved, the cutting enzyme and the methylating enzyme.

True

A graduate student is trying to isolate bacterial mRNA for an enzyme that will degrade trinitrotoluene (TNT). She's frustrated to find that the enzyme isn't produced when the bacterium in question is grown on nutrient agar. What might she do to solve the problem and obtain the mRNA?

Add TNT to the agar—this will drive synthesis of the enzyme to degrade it, leading to production of the mRNA the student is looking for.

Which change in a gene's DNA sequence would have the least effect on the eventual amino acid sequence produced from it?

Addition or deletion of three consecutive nucleotides

If you did a cloning experiment but you accidentally left X-gal out of the medium you use to grow your transformants, what would be the result (assuming you remembered all other important ingredients in your culture medium, including ampicillin)?

All cells that grow would produce white colones.

Plasmids work well for insertion of foreign DNA into a cell. Which statement is FALSE?

All known bacteria contain plasmids of some kind.

Gene regulation may entail

All of the answer choices are correct.

Genetic engineering of plants has so far produced

All of the answer choices are correct.

PCR is particularly useful in

All of the answer choices are correct.

Which is true about DNA replication?

All of the choices are correct.

The scientists responsible for the idea that RNA can act as a catalyst were

Altman and Cech.

A quick microbiological test for potential carcinogens was developed by

Ames.

The material responsible for transformation was shown to be DNA by

Avery, MacLeod, and McCarty.

If you want to use PCR to generate the target sequence indicated by the gray box in the figure below, DNA primers that have the complementary sequence for which sections are required?

B and C

Transposons can potentially inactivate bacterial genes by "jumping" into them.

True

A graduate student wants to clone a particular gene into a plasmid. The sequence includes AluI and BamHI sites on both sides of the desired fragment. AluI cuts symmetrically directly between the G and C nucleotides in a palindromic 5' AGCT 3' sequence. BamHI cuts asymmetrically directly between the G and G nucleotides in a palindromic 5' GGATCC 3' sequence. Which of the two restriction endonucleases should the graduate student choose, and why?

BamHI to cut both sides—since this enzyme cuts asymmetrically, it'll leave the sticky, cohesive single-strand DNA ends that will make it easier to ligate into a BamHI-cut plasmid DNA sequence.

The report that genes direct the synthesis of proteins was first made by

Beadle and Tatum.

During PCR, which primer anneals to template DNA at its 3' end?

Both the forward primer and the reverse primer.

Which tasks must a bacterial cell accomplish in order to multiply?

DNA duplication, RNA synthesis, protein synthesis

PCR produces

DNA fragments of a particular size.

The entire set of cloned fragments of the complete human genome is termed a

DNA library.

The molecule(s) that act as molecular glue to bind DNA fragments together is/are

DNA ligase.

Please choose the statement that describes the purpose of DNA microarray analysis.

DNA microarray analysis is used to determine which genes are being transcribed.

The polymerase chain reaction is used to duplicate small sections of

DNA.

DNA is characterized by which of the following feature(s)?

Deoxyribose AND thymine

How can some bacteria sense the density of cells in an environment?

Detecting the concentration of a signaling molecule.

DNA transfer by conjugation is more efficient in a liquid medium setting, subjected to very mild agitation (stirring), rather than on an agar plate format. Why?

Direct cell-to-cell contact is required for this process, and this is more likely to be achieved in the fluid liquid format than on an agar plate (especially for relatively non-motile types of bacteria).

Possessing the entire sequence of a particular human genome may not be as useful as we think. Why not?

Due to the presence of introns/exons, and splicing of RNA after transcription, the DNA sequence doesn't necessarily tell us the exact number/type of proteins that will eventually be made from it.

Which of the following is NOT true about laboratory strains of E. coli being desirable hosts for genetic engineering?

E. coli is fastidious but can usually be grown in the lab.

Which of the following is an example of phase variation?

E. coli producing pili for attachment to epithelial cells.

A missense mutation has a greater impact on a cell than does a frameshift mutation.

False

Adenine binds to thymine via three hydrogen bonds.

False

Bacteria are the only microorganisms that can be used for genetic engineering.

False

Bacteria use CRISPR for gene editing.

False

DNA replication is usually unidirectional.

False

Double-stranded DNA enters the recipient cell during transformation.

False

Organisms termed his- are considered prototrophic for histidine.

False

Scientists have always worked to advance genetic engineering technologies further, even in direct opposition and without thought of the general public's concerns.

False

The Ames test determines antibiotic sensitivity of a bacterium.

False

The most difficult aspect of the new field of metagenomics is generating sequence data reliably and cost-effectively.

False

The plus (+) strand of DNA acts as a template during transcription.

False

When using lacZ containing vectors, colonies containing intact vector turn white.

False

What is the number of tRNA molecules that may be associated with translation?

Fewer than 64

Which may be or is an RNA molecule?

GGGCCCA and GCCCUUA

Please select the statement that best describes the purpose of gel electrophoresis.

Gel electrophoresis separates DNA fragments based on size.

Which of the following statements regarding bacterial gene control is FALSE?

Genes for constitutive enzymes can be turned on and off as necessary.

Why is it beneficial for a bacterial cell to be able to use glucose FIRST as an energy source (until it is depleted), THEN switch to lactose?

Glucose is an easier compound to break down and obtain energy from than lactose AND for conservation of energy: why use the energy to make the enzymes for breaking down lactose when glucose doesn't need any extra enzymes for breakdown?

Which of the following statements about spontaneous mutation is TRUE?

If the mutation rate to antibiotic A is 10-9 per cell division, and to antibiotic B is 10-6 per cell division, the probability of the cell being resistant to both medications is 10-15.

Please choose the statement that best describes the role of a cloning vector.

Introduce DNA into a cloning host.

Why must an agarose gel be placed in a buffer solution for DNA gel electrophoresis?

Ions in the buffer conduct the electric current needed to move the DNA fragments in the gel matrix.

Which is not true of RNA?

It contains both uracil and thymine.

Does the presence of introns/exons in eukaryotic cells provide more potential diversity in gene products (proteins) than is possible in prokaryotic cells?

It does. Exons/introns can be spliced together in different ways post-transcription to yield different mRNAs (and therefore, different proteins). Bacteria lack this system.

To maximize the number of thymine dimer mutations following UV exposure, should you keep human cells in tissue culture in the dark, in the light, or does it matter at all?

It doesn't matter—human cells don't have the enzymes needed for photorepair of thymine dimers.

Why is the position of the first AUG after the ribosome binding site critical?

It establishes the reading frame.

Which is FALSE about the RNA transcript?

It is made in short fragments that are then stitched together.

Which is true about prokaryotic (bacterial) RNA polymerase?

It is used during transcription.

Which of the following about DNA microarray technology is NOT true?

It relies on visual detection of the labeled probes after hybridization.

Which is not true about mismatch repair?

It removes both strands in the mismatch area.

Which is TRUE about a crown gall tumor?

It results from the incorporation of bacterial plasmid DNA into the plant chromosome.

Two bacterial genes are transduced simultaneously. What does this suggest about their proximity to each other within the original host genome?

It's highly likely that the two genes are located next to each other in the host cell chromosome. Since transduction results from a packaging error or an excision error that occurs during the infection cycle of the bacteriophage, the genes must lie close to each other to be transduced into a new cell simultaneously.

Using the genetic code (below), determine what type of mutation would occur if the last nucleotide in the codon AGA was converted to a U.

Missense

The amino acid that is placed first during translation in bacteria, mitochondria, and chloroplasts is

N-formyl-methionine.

Polymerase chain reaction (PCR) can be used to perform DNA sequencing reactions. In this case, are two primers (a forward and a reverse) necessary?

No—dideoxynucleotide sequencing depends on different length fragments being formed and then separated based on size. This can take place with only a specific forward OR a specific reverse primer.

Which of the following is/are true of DNA replication?

Nucleotides are added to the 3' end.

When E. coli is placed in a medium containing both glucose and lactose, why does cell growth stop temporarily when the glucose is used up?

Once glucose is depleted, the cell must use the lactose; before it can do this, it must express the lac operon and synthesize the enzymes needed to use lactose, which takes time.

Every 24 hours, every genome in every cell of the human body is damaged 10,000 times or more. Given the possible DNA repair mechanisms, which order listed below would be most effective at repairing these as quickly as possible in order to prevent mutations from being carried forward in DNA replication?

Proofreading by DNA polymerase, glycosylase enzyme activities, excision repair, SOS repair

If you were carrying out a penicillin enrichment culture and you forgot to add penicillinase before plating the sample onto nutrient agar, what would happen?

Prototrophs and auxotrophs would both be killed by the penicillin; only PenR mutants would grow and you would not enrich for auxotrophs.

What phenomenon is being illustrated in the figure below?

Quorum sensing

Please choose the statement that best describes the role of restriction enzymes in genetic engineering.

Restriction enzymes are used to cut DNA at specific locations.

RNA is characterized by which one of the following features?

Ribose

Which of the following types of repair does not require the standard DNA polymerase with proofreading capability?

SOS repair

Thymine dimers are removed by

SOS repair, photoreactivation repair, AND excision repair.

You mix two bacterial stains in a tube of glucose-salts agar. One strain is His−, Val−, while the other strain is Trp−, Leu−. You previously showed that neither strain grows on glucose-salts agar. After incubating the tube, you plate a sample onto a new glucose-salts agar plate. Several colonies grow. What do you know is TRUE about these colonies?

The bacteria in the colonies are His+, Val+, Trp+, Leu+.

A bacterial strain is resistant to infection by a bacteriophage. Which statement is FALSE?

The bacterial host DNA is protected from restriction enzyme degradation by phosphorylation.

What would be the consequence of a transposon inserting into the site shown by the red arrow?

The bacterium would likely become sensitive to tetracycline.

In direct selection methods used to identify possible carcinogens (example: Ames testing), what does it mean when a chemical can cause a bacterium to develop resistance to some environmental condition?

The chemical is a mutagen.

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.

Some bacteria have a higher incidence rate of thymine dimer mutations following exposure to UV light than others. What might be going on here to lead to this outcome?

They may simply have a higher proportion of T nucleotides next to each other in their DNA than other bacteria, leading to more possible dimers being formed AND they may have a weaker expression of photoreactivation enzymes, leading to formation of more thymine dimers.

True of False: The encoded protein of the DNA sequence 3' TAC CGC TTA CAT GAG 5' (assume it is the minus strand) has the amino acid sequence met-ala-asn-val-leu. Use the genetic code below.

True

Cells are often ground up with abrasive to get to their internal enzymes/molecules, followed by removal of the abrasives. Here are two situations and two outcomes. What is the correct interpretation of the results? In situation #1, radioactive amino acids are mixed with ground-up cell material. Radioactive proteins are produced. In situation #2, radioactive amino acids AND the enzyme RNAse (an enzyme that degrades RNA) are mixed with ground-up cell material. No radioactive proteins are produced.

The mRNA from the cell can be used to make proteins with the radioactive amino acids in the first situation. In the second situation, the mRNA is destroyed by the RNAse before it can be translated into protein containing the radioactive amino acids.

You are examining the DNA profile of an unknown pathogen. The pathogen's DNA has been digested with EcoRI restriction enzyme. There are 7 bands on DNA on the gel. Which of the following is NOT true?

The original piece of DNA has seven EcoRI restriction sites.

You make two agar plates: one is a nutrient agar plate (plate A) that contains histidine and penicillin. The other is a glucose salts agar (plate B) that also contains penicillin. You inoculate a sample onto both plates using replica plating technique, incubate the plates, and compare the growth after 48 hours. There are 12 colonies on the nutrient agar plate and 11 colonies on the glucose salts medium. Which of the following statements is INCORRECT?

The prototrophs are resistant to penicillin but the auxotrophs are sensitive to this antibiotic.

How is dCas9 different from cas9?

They do not have a nuclease function so don't cut target DNA.

Which of the following about transposons is not true?

They were first recognized in fungi.

Which of the following is INCORRECT?

Transcription is the conversion of DNA into RNA.

Which of the following statements concerning transcription and translation in eukaryotes is TRUE?

Transcription occurs in the nucleus and translation occurs in the cytoplasm.

A DNA microarray contains oligonucleotides that contain a label.

True

A very common vector is a plasmid.

True

Antisense RNA is the complement of the plus strand and may be useful in inhibiting translation.

True

Crown gall is caused by a prokaryote plasmid that can be expressed in plant cells.

True

DNA polymerase is able to proofread the DNA sequence.

True

DNA probes are used to find regions of complementary DNA.

True

Each gene mutates at a characteristic frequency.

True

F plasmids and oftentimes R plasmids are both able to code for production of a pilus.

True

FISH uses labeled probes to detect specific whole cells.

True

It is useful to have a reference sequence when assembling DNA sequence data in high through-put methods because assembly will be quicker if two sequences can be compared.

True

One end of a strand of DNA is different from the other end.

True

PCR is useful for amplifying a particular section of DNA.

True

Ribozymes are non-protein molecules with catalytic activity.

True

The Human Microbiome Project is an application of DNA sequencing where the genomic information of the normal microbiota of the human body (the microbes in us/on us) is sequenced and analyzed.

True

The anticodon determines which amino acid is linked to its tRNA.

True

The genetic code is nearly universal.

True

The minus strand of DNA serves as the template for RNA production.

True

Activators

are allosteric proteins AND are involved in positive control.

The Ames test is useful as a rapid screening test to identify those compounds that

are mutagens.

Ribozymes

are self-catalytic RNA AND suggest that nucleic acids evolved before proteins.

Insertion sequences

are the simplest type of transposon, code for a transposase enzyme, AND are characterized by an inverted repeat.

Short tandem repeats (STRs)

are useful in identifying specific individuals.

All of the following are true about DNA probes EXCEPT they

are usually tagged dsRNA.

Human DNA cut with restriction enzyme A can be joined to

bacterial DNA cut with restriction enzyme A.

Chemical mutagens that mimic the naturally occurring bases are called

base analogs.

Antigenic variation is a phenomenon used by some bacteria (such as Neisseria gonorrhoeae) to evade host immune mechanisms. In this process, the cells

can change the characteristics of certain surface proteins on the bacteria, forcing immune response to constantly adapt.

AUG

codes for methionine AND determines the reading frame.

A stop codon

codes for no amino acid.

Not all bacteria can take up DNA from the environment. Those that can are referred to as

competent.

The placement of the amino acid during translation is determined by the

complementarity of the codon-anticodon.

Gene transfer that requires cell-to-cell contact is

conjugation

The regulatory protein

may inhibit or enhance transcription.

Use the genetic code below to translate the mRNA sequence 5' AUGCACUCAAGAGCAGUA 3'

methionine - histidine - serine - arginine - alanine - valine

DNA is protected from restriction enzymes by being

methylated.

Consider the figure of replica plating. 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

DNA polymerases

move in a 3' to 5' direction on the template DNA.

The source of variation among microorganisms that were once identical is

mutation

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

no longer be able to conjugate.

When cloning eukaryotic genes into bacteria for protein production, a copy of DNA that lacks introns must first be obtained. Introns are removed from primary RNA transcripts by the cell's own machinery, but the copy of the DNA lacking introns must be generated by a biotechnology method. This intron-free copy DNA (or cDNA) is generated by

obtaining mRNA from the cell, then using reverse transcriptase enzyme to convert it into a stable cDNA (or copy of DNA) molecule for insertion into the bacterial cell.

The DNA site to which the repressor protein binds is the

operator.

The set of genes in bacteria that are linked together and transcribed as a single unit is referred to as a(n)

operon.

To increase the proportion of auxotrophic mutants in a population of bacteria, one may use

penicillin enrichment.

The characteristics displayed by an organism in any given environment is its

phenotype

The properties of a cell that are determined by its DNA composition are its

phenotype.

Colonies of the bacterium Serratia marcescens are red when incubated at 22°C but white when incubated at 37°C. This is an example of

phenotypic change.

A culture of E. coli is irradiated with UV light. The highest frequency of mutations would be obtained if after the irradiation, the cells were immediately

placed in the dark.

The lac operon

positively regulated by the presence of lactose

Transcription begins at the ______ and ends at the ______, while translation begins at the ______ and ends at the ______.

promoter; terminator; start codon; stop codon

In transformation, genes from a donor chromosome are transferred as

single-stranded DNA.

Agarose gel electrophoresis separates nucleic acid fragments according to

size.

Which molecule carries an anticodon?

tRNA

The F plasmid carries the information for

the sex pilus.

Restriction enzymes have proved so useful in manipulating DNA because

they cut at defined sites AND the sticky ends make it very easy to allow recombination of any type of DNA.

The codon ACA encodes ______.

threonine

Metagenomics is the analysis of

total microbial genomes in an environment.

The mechanism by which genes are transferred into bacteria via viruses is called

transduction.

Segments of DNA capable of moving from one area in the DNA to another are called

transposons.