AP Bio Select Review Questions Chapters 13-14

Which enzymes are needed to create recombinant DNA?

restriction endonuclease and ligase Restriction endonucleases cut the DNA at the appropriate segment, and the ligase seals it

Place the following steps in the correct order to make transgenic organisms. 1—use vector to deliver new rDNA to bacterial or other cells 2—use restriction enzymes to cut a plasmid and add the desired gene 3—isolate and cut out a desired gene using restriction enzymes 4—use DNA ligase to seal the new gene 5—allow bacterial cells to replicate and produce desired product

3, 2, 4, 1, 5

Microarray

Silicon or glass sheet with thousands of DNA probes that can be used to identify which genes in a tissue are expressed/being transcribed

What has occurred in the DNA (pictured above) to make it active? a) The DNA has been unlooped to form a cursive B and is called a Barr body. b) The heterochromatin has been exposed to an alkaline solution which results in the loss of H+ from the methyl groups. c) The DNA has become unpacked and is called a chromosome. d) The DNA is no longer attached to the histones and now is now called lampbrush chromosomes.

The DNA is no longer attached to the histones and now is now called lampbrush chromosomes. Histone proteins with acetylated tails do not attract the DNA as tightly as methyl groups. The DNA separates from the histones to allow accessibility for transcription. The euchromatin is often referred to as lampbrush chromosomes.

If this diagram represented the lac operon, then this operon is a) a repressible operon. b) an inducible operon. c) turned on. d) mutated.

The lac operon is normally switched off by the active repressor that is attached to section d. When lactose is present in the environment, lactose will bind to the active repressor, e, resulting in inducing the action of the operon.

Which of the following is true about prokaryotic gene regulation? a) A regulator gene codes for a repressor protein that controls the operon. b) An operator is the sequence of DNA where RNA polymerase attaches. c) Promoters code for enzymes and are transcribed as a unit. d) Structural genes are located outside the operon and code for enzymes.

a) A regulator gene codes for a repressor protein that controls the operon. Regulators are located outside the operon and code for repressor proteins. Promoters are where RNA polymerases attach, operators are where the repressors bind, and structural genes are located within the operon and code for enzymes.

Cells prefer to use glucose over other energy sources. Therefore, in prokaryotes a) high levels of glucose will prevent expression from other operons that metabolize lactose. b) low levels of glucose will cause the lactose mechanism to be turned off. c) cAMP binds to activators to slow down transcription of the lac operon. d) lactose will be synthesized only when there is ample glucose in the cell.

a) High levels of glucose will prevent expression from other operons that metabolize lactose Glucose is the preferential energy source for prokaryotic cells. Therefore, lactose will be broken down only if glucose isn't present. cAMP assists in activating the lac operons.

As a new medical doctor specializing in preventative medicine, you draw only one drop of blood from your patient instead of several vials as other doctors might need for a battery of tests. The only test you will run is a microarray. Why? a) The microarray can identify the mutations that predispose a person to illnesses such as diabetes, Alzheimer's, and high cholesterol. b) The microarray tests for antibodies that indicate infections both past and present. c) The microarray determines the level of hormones, vitamins, and toxins in the blood. d) The microarray tests for viruses that are present within the body.

a) The microarray can identify the mutations that predispose a person to illnesses such as diabetes, Alzheimer's, and high cholesterol. Preventative medicine will attempt to prevent the disease instead of treating the symptoms. The microarray will tell doctors about a person's predisposition to certain diseases. Preventative treatment might include a proper diet to prevent the onset of diabetes.

Which statement is correct about the trp operon? a) The structural genes make products that act in a metabolic pathway to produce tryptophan. b) It is normally turned off when tryptophan is present. c) Tryptophan acts as the repressor in a positive feedback loop. d) Tryptophan binds to the repressor protein and inactivates it.

a) The structural genes make products that act in a metabolic pathway to produce tryptophan. Tryptophan is a necessary amino acid for prokaryotic cells and is normally produced at all times. If tryptophan is present in the environment, it will act as a corepressor and bind to the inactive repressor to switch off the operon.

What is the correct order of events in eukaryotic gene control? a) acetylation, transcription activation, alternative splicing, translational control, posttranslational control b) methylation, transcription activation, removal of exons, addition of microRNA, cleaving of polypeptide chain c) replication, unpacking of DNA, phosphorylation, addition of methylated cap, folding of protein d) transcription activation, acetylation, alternative splicing, translational control, posttranslational control

a) acetylation, transcription activation, alternative splicing, translational control, posttranslational control Acetylation allows the DNA strands to unpack and allow access to the gene, transcriptional factors will activate transcription, the alternative splicing of the transcript produces the variety, translation is often controlled by the presence of the 5' cap, and finally, posttranslational control involves the folding of the protein.

A DNA sequence that has had methyl groups added to it will likely a) be silenced or weakened. b) be transcribed faster and more efficiently. c) attract large amounts of small RNAs. d) attract additional acetyl groups to bind to the methyl groups.

a) be silenced or weakened The presence of methyl groups interferes with transcription.

Which of the following events occurs first while transforming bacteria with a recombinant DNA molecule? a) extract plasmid DNA from cell b) cut the plasmid DNA using restriction enzymes c) seal the plasmid with ligase d) bond the plasmid region into the linear chromosome

a) extract plasmid DNA from cell

In order to distinguish the DNA of one person from another, scientists often rely on the presence of short tandem repeats (STRs). These consist of short DNA sequences that are repeated many times in a row. Why are STRs useful for identification? a) the presence of these repeats make genes longer; restriction enzymes cut them into different-sized fragments b) the presence of these repeats makes DNA heavier; it show up better in gel electrophoresis studies c) STRs are abundant in the DNA for those crucial proteins likely to be found in close relatives d) STRs will be identical in close relatives.

a) the presence of these repeats make genes longer; restriction enzymes cut them into different-sized fragments STRs used for identification are in non-coding DNA. Because the repeats result in different-sized fragments, the DNA fingerprint will look different from person to person.

Point mutations a) are changes in codons that can cause a defective enzyme. b) can cause a genetic disease such as sickle-cell disease. c) can result in a sexual change. are changes in multiple nucleotides. d) A point mutation is a change in one nucleotide.

b) can cause a genetic disease such as sickle-cell disease. Sickle-cell disease results from a point mutation.

While identical twins often appear truly "identical" at first glance, their friends and family can easily tell them apart. Which most likely explains the differences people use to distinguish one identical twin from the other? a) differential operon control b) epigenetics c) X chromosome accumulation d) base substitution

b) epigenetics Epigenetics refers to heritable changes in gene expression that are not due to a change in DNA sequence, but instead to subtle differences in environmental effects.

What technique should he use to determine the relationships of the bones? a) STR profiling b) gel electrophoresis c) cloning d) produce complementary DNA

b) gel electrophoresis The researcher should extract and amplify the DNA from the bone marrow. By using gel electrophoresis of the PCR products, the same or different fragment lengths would indicate the relationship between the bones.

Which gene in an operon is incorrectly matched with its function? a) promoter—section where enhancers bind to DNA to start transcription b) regulator—binds to the repressor protein c) structural—contains section of DNA that will be transcribed into enzymes d) operator—RNA polymerase attaches and binds with DNA

b) regulator—binds to the repressor protein The regulator gene produces a repressor that can bind to the operator. If the repressor is bound to the operator, RNA polymerase cannot attach to the promoter. The structural genes immediately after the operator are the genes that are transcribed and translated into the enzymes

Future expectations for genetic engineering include the production of plants that have a) a requirement for more fertilizer. b) the ability to produce human proteins. c) increased susceptibility to herbicides. d) decreased resistance to disease.

b) the ability to produce human proteins Genetically engineered plants have the potential to produce products such as human hormones, antibodies, and enzymes in their cells.

An example of gene therapy in humans is a) the insertion of the gene for bovine growth hormone. b) the alteration of bone-marrow stem cells with the normal gene for the enzyme involved in the maturation of T and B cells. c) the use of genetically engineered skin to treat severe burns. d) the cloning of humans.

b) the alteration of bone-marrow stem cells with the normal gene for the enzyme involved in the maturation of T and B cells. Gene therapy manipulates the genes often by replacing a set of faulty DNA instructions.

When a trp operon is in the "off" condition, a) the repressor will code for an operator and change shape. b) tryptophan will bind to the repressor. c) the binding site for tryptophan will change shape. d) RNA polymerase will attach to the promoter, and tryptophan is produced.

b) tryptophan will bind to the repressor Some operons in E. coli usually exist in the "on" rather than the "off" condition. E. coli produces five enzymes as part of the anabolic pathway to synthesize the amino acid tryptophan. If tryptophan is already present in medium, these enzymes are not needed, and the operon is turned off. The regulator codes for a repressor that usually is unable to attach to the operator. The repressor has a binding site for tryptophan (if tryptophan is present, it binds to the repressor). This changes the shape of the repressor that now binds to the operator.

Under what conditions are repressible products made in prokaryotes? a) when the substrate is in the environment and needs to be metabolized b) when a signal molecule is scarce c) when a metabolite activates the repressor d) when a repressor is in its active form

b) when a signal molecule is scarce Operons can be inducible or repressible. Inducible products are made when the substrate is in the environment (lactose) and needs to be metabolized. Repressible products are made when a signal molecule is scarce.

operator site of operon

binding site for repressor protein

Regarding the lac operon, if lactose is present which of the following occurs? a) Lactose binds to the operator, preventing the promoter from attracting RNA polymerase and preventing transcription. b) Lactose binds to RNA polymerase, which then binds to the promoter and transcribes the needed genes. c) Lactose binds to the repressor, which prevents the binding to the operator, and RNA polymerase transcribes the needed genes. d) Lactose binds to the operon, which attracts RNA polymerase, and then transcription of the needed genes occurs.

c) Lactose binds to the repressor, which prevents the binding to the operator, and RNA polymerase transcribes the needed genes. The lac operon is normally turned off by the repressor that is bound to the operator. Lactose will bind to the repressor, the repressor will change shape and no longer attach to the operator. Now RNA polymerase can transcribe the genes.

When the tumor suppressor gene p16 mutates, the production of a growth factor is not regulated and too much is produced. How could a drug control the production of the protein product? a) Enhance the transcription of antisense RNA from ordinarily inactive DNA; this will bind with sense mRNA and prevent the ribosome from further translating it. b) Use the drug to induce regulator genes to produce repressor proteins that physically bind to mRNA and stop its activity in ribosomes. c) Provide a repressor that will be activated by the growth factor to prevent transcription of more. d) Activate other genes to produce enzymes that digest the mRNA.

c) Provide a repressor that will be activated by the growth factor to prevent transcription of more. The protein products normally inhibit translation, but if the regulator gene has mutated and cannot produce the correct repressor, the amount of growth factor will not inhibit translation. If the drug supplied the correct repressor, the inactivation of the gene would occur, and the tumor would be suppressed.

What is the function of restriction enzymes that naturally occur in bacterial cells? a) used during DNA replication in the bacterial cell b) used to degrade the bacterial cell's DNA c) intended to destroy foreign DNA that enters the cell d) used to attach pieces of DNA together

c) intended to destroy foreign DNA that enters the cell Scientists have harnessed the natural ability of prokaryotes to defend against invading viral DNA. Restriction enzymes are used to lyse foreign DNA to prevent takeover by viral DNA.

A species' proteome (all of its proteins) is larger than that species' genome (all of its genes). Which statement explains how this is possible? a) each gene codes for several different proteins b) the number of proteins differs from one species to another c) mechanisms such as differential RNA processing result in different protein products d) smaller proteins will join together to make larger non-functional proteins

c) mechanisms such as differential RNA processing result in different protein products Differential RNA processing can remove different introns, therefore creating different RNA transcripts and different final products

A cancer researcher has requested a certain species of a knockout mouse. What will the researcher receive? a) mice that are especially sensitive to anesthesia b) mice with specific genes that reduce the time from conception to sexual maturity c) mice with a p53 gene that is not functional d) mice without pain receptors to reduce any suffering during research

c) mice with a p53 gene that is not functional A knockout mouse has a set of alleles rendered dysfunctional. A cancer researcher would want mice that develop cancers at a high rate. Since the normal p53 gene monitors for DNA damage and will prevent tumors from forming, this gene would need to be dysfunctional, or knocked out.

Cyclic AMP (cAMP) plays a role in catabolic activity in prokaryotes. cAMP enhances the lac operon's transcription by binding to a catabolic activator protein. Based on this, cAMP is an example of a) negative feedback. b) phosphorylation. c) positive feedback. d) translational control.

c) positive feedback The enhancement of lactose catabolism as the result of an increase of cAMP is an example of positive feedback.

Recombinant DNA can

contain DNA from a human gene and a bacterial plasmid. Recombinant DNA can contain DNA from a human gene and a bacterial plasmid, thus the term recombinant. Restriction enzymes are used to cleave plasmid and foreign DNA. Vectors carry foreign DNA into host cells.

Genetic control differs between prokaryotes and eukaryotes. Which statement below describes a difference? a) RNA polymerase must bind to a promoter on the DNA to begin DNA synthesis in prokaryotes. b) Eukaryotic gene expression is regulated at the level of translation. c) An active repressor protein keeps RNA polymerase from binding to DNA in prokaryotic cells. d) Multiple genes are controlled by one promoter in prokaryotic cells.

d) Multiple genes are controlled by one promoter in prokaryotic cells. Eukaryotic genes have a promoter for each gene rather than one promoter for several genes.

Which of the following is a characteristic unique to prokaryotic gene expression? a) promoters b) mRNA caps c) exon processing and intron excision d) coupled transcription and translation

d) coupled transcription and translation Due to the lack of a nucleus, prokaryotes are capable of transcription and translation at the same time

Which of the following is a method of posttranscriptional control? a) transcription factors and the life span of an mRNA molecule b) the life span of an mRNA molecule c) microRNA d) differential RNA processing and how fast mRNA leaves the nucleus

d) differential RNA processing and how fast mRNA leaves the nucleus In post-transcriptional control, the primary mRNA has been produced and the editing process is occurring. The alternative splicing determines both the final mRNA and how fast the mRNA is able to leave the nucleus.

Which type of mutation is most likely to be the least deleterious? a) frameshift b) substitution in the first base c) deletion d) point

d) point In a point mutation, especially in the third position, there is a chance that there will be no change in the amino acid coded for. In the deletion and substitution mutations, there will be a shift in codons that will most likely shift all of the amino acids after that point.

Cells in the lining of the stomach produce a protein called pepsinogen. When this protein is released into the chamber of the stomach, the stomach acid cleaves off a section of the protein, which now becomes an enzyme called pepsin. In this form, pepsin will actively begin the breakdown of proteins in food. This is an example of which type of eukaryotic gene regulation? a) transcriptional control b) posttranscriptional control c) translational control d) posttranslational control

d) post translational control Post Translational control occurs in the cytoplasm. A polypeptide will have been produced through protein synthesis, but is not considered functional until some activation process occurs.

Eukaryotic protein synthesis differs from that of prokaryotes because a) transcription and translation occur simultaneously in eukaryotes. b) ribosomal subunits are larger in prokaryotes. c) operons regulate gene expression in eukaryotes. d) related prokaryotic genes are organized into groups called operons.

d) related prokaryotic genes are organized into groups called operons. Transcription and translation occur simultaneously in prokaryotes, not eukaryotes. Ribosomal subunits are larger in eukaryotes than in prokaryotes, and operons regulate prokaryotes. Transcription factors (DNA binding factors) are proteins that bind to specific sequences of DNA. Without transcription factors, the creation of RNA from DNA cannot occur. Prokaryotic operons feature clusters of genes that are physically close and are turned on or off together.