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FINAL BIO EXAM
Chapters 18 and 20
| Question | Answer |
|---|---|
| If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then | the amino acid acts as a corepressor |
| Muscle cells differ from nerve cells mainly because they | express different genes |
| The functioning of enhancers is an example of | transcriptional control of gene expression |
| Cell differentiation always involves | the production of tissue-specific proteins, such as muscle actin |
| Which of the following is an example of post-transcriptional control of gene expression? | the removal of introns and alternative splicing of exons |
| What would occur if the repressor of an inducible operon were mutated so it could not bind the operator? | continuous transcription of the operon's genes |
| Absence of bicoid mRNA from a Drosophilia egg leads to the absence of anterior larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene | normally leads to formation of head structures |
| Which of the following statements about the DNA in one of your brain cells is true? | It is the same as the DNA in one of your heart cells |
| Within a cell, the amount of protein made using a given mRNA molecule depends partly on | the rate at which the mRNA is degraded |
| Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells? | Proto-oncogenes normally help regulate cell division. |
| Which of the following tools of recombinant DNA technology is incorrectly paired with its use? | DNA ligase-cutting DNA, creating sticky ends of restriction fragments |
| Plants are more readily manipulated by genetic engineering than are animals because | a somatic plant cell can often give rise to a complete plant |
| Paleontologist recovered bit of tissue frm 400yr old preserved skin of an extinct dodo To compare a specific region of DNA from sample with DNA from living birds which of following would be most useful for increasing amt of dodo DNA availble 4 testing? | polymerase chain reaction (PCR) |
| DNA technology has many medical applications. Which of the following is not done routinely at present? | introduction of genetically engineered genes into human gametes |
| In recombinant DNA methods, the term vector can refer to | a plasmid used to transfer DNA into a living cell |
| Which of the following would not be true of cDNA produced using human brain tissue as the starting material? | It could be used to create a complete genomic library |
| Expression of a cloned eukaryotic gene in a bacterial cell involves many challenges. The use of mRNA and reverse transcriptase is part of a strategy to solve the problem of | post-transcriptional processing |
| Which of the following sequences in double-stranded DNA is most likely to be recognized as a cutting site for a restriction enzyme? | GGCC CCGG |
| A bacterium may need to synthesize tryptophan, or its host may supply all the tryptophan it needs. Why do both bacteria and humans need tryptophan? | It is one of the 20 amino acids used by all organisms to synthesize proteins |
| Which statement about feedback inhibition is true? | All of the listed responses are correct |
| In prokaryotic genomes, groups of functionally related genes along with their promoters and operators are found together in _____. | an operon |
| A biochemist finds that glycine binds to a repressor protein and causes the repressor to bind to a bacterial chromosome, turning off an operon. If it is like other similar operons, the presence of glycine will result in the _____. | cessation of the synthesis of glycine |
| In general, operons that encode the enzymes of a biosynthetic (anabolic) pathway (such as the trp operon) are _____, and those encoding the enzymes of a catabolic pathway (such as the lac operon) are _____. | repressible...inducible |
| In an inducible operon, the inducer is often the _____ in the pathway being regulated; the inducer binds to the ____, thus rendering it _____. | substrate...repressor...inactive |
| You have inserted the gene for human growth factor into the E. coli lactose operon, replacing the structural genes with the gene for human growth factor. What substance must you add to your culture of bacteria to cause them to produce human growth factor? | allolactose |
| Both repressible and inducible operons control gene expression at the level of _____. | transcription |
| Gene expression in bacteria is regulated primarily by _____. | controlling the transcription of genes into mRNA |
| The control of gene expression is more complex in multicellular eukaryotes than in prokaryotes because ______. | in a multicellular eukaryote, different cells are specialized for different functions |
| In some cases DNA methylation and histone deacetylation combine to _____. | silence certain genes |
| In eukaryotes, DNA packing seems to affect gene expression primarily by _____. | controlling access to DNA |
| A scientist clones a regulatory gene that is involved in controlling the expression of other genes, and discovers that the regulatory gene encodes a histone deacetylase enzyme. It is likely that this enzyme regulates gene expression by _____. | causing tighter packing of the chromatin at the target gene, thereby inhibiting transcription |
| In a eukaryote, activating transcription factors may stimulate gene expression by binding to a DNA site called a(n) _____. | enhancer |
| Enhancers are _____. | All of the listed responses are correct. |
| Dioxin is suspected of causing cancer and birth defects in animals and humans. It apparently acts by entering cells & binding to specific proteins which then enter nucleus and alter pattern of gene expression. Therefore, dioxin acts by mimicking action of | steroid hormones |
| Post-transcriptional controls | All of the listed responses are correct. Post-transcriptional controls can occur at many steps, including mRNA stability, splicing, and translation. |
| Which of the following is a means of controlling eukaryotic gene expression? | All of the listed responses play a role in the regulation of gene expression. |
| What is the evolutionary significance of alternative RNA splicing? | It expands the number of proteins that can be coded for by one gene, increasing an organism's ability to produce novel proteins |
| What is the role of proteasomes? | They are giant protein complexes that recognize ubiquitin and degrade the tagged proteins |
| What determines how long a particular mRNA molecule will persist in a eukaryotic cell? | nucleotide sequences in the poly-A tail |
| The expression of a gene located in a tightly coiled region of DNA can be promoted by _____. | histone acetylation |
| Which of the following statements is NOT associated with epigenetic inheritance? | chemical mutagens |
| A high rate of gene transcription in eukaryotic cells is usually dependent on _____. | The third and fourth listed responses are correct. Specific binding of activator molecules to enhancers and the protein-protein interactions that are promoted by the activation domains of activator proteins equate to elevated rates of gene transcription. |
| Which of the following best depicts coordinate control of genes in eukaryotes? | The second and third listed responses are correct. |
| Although the number of genes in the human genome is surprisingly low compared to less complex organisms, the number of possible products from those genes is greatly amplified by _____. | alternate arrangements of exons from a primary transcript |
| Gene cloning is crucial to any application involving one gene because _____. | All of the listed responses are correct. |
| What is an advantage to using a bacterial artificial chromosome (BAC) for generating a genomic library compared to a plasmid or phage that has historically been used for this process? | The first and second responses listed are correct. |
| In which of the following would it be advantageous to create and work with a cDNA (complementary DNA) library rather than a genomic library? | a study of protein involved in eye development of a salamander and the regulation of the gene that expresses it |
| The expression of the PAX-6 gene when vertebrate and fruit fly versions of the gene are exchanged between these animal groups illustrates _____. | the common ancestry in the evolution of these animal groups |
| Which of the following enzymes is key to the automation of PCR (polymerase chain reactions)? | Taq polymerase |
| Bacteria use restriction enzymes to _____. | destroy foreign DNA |
| An enzyme that cuts DNA at a symmetrical sequence of bases is called _____. | a restriction enzyme |
| When a typical restriction enzyme cuts a DNA molecule, the cuts are staggered so that the DNA fragments have single-stranded ends. This is important in recombinant DNA work because _____. | the fragments will bond to other fragments with complementary single-stranded ends |
| In genetic engineering, "sticky end" refers to _____. | short bits of single-stranded DNA left at the end of DNA molecules cut by restriction enzymes |
| Which of the following enzymes could seal a nick in one strand of a double-stranded DNA molecule by creating a sugar-phosphate bond between the adjacent, unjoined nucleotides? | DNA ligase |
| To create recombinant DNA with long-term stability, it is necessary to have which of the following in the test tube? | DNA ligase |
| What two enzymes are needed to produce recombinant DNA? | a restriction enzyme and a ligase |
| In recombinant methods, the term "vector" refers to _____. | a plasmid or other agent used to transfer DNA into a living cell |
| Which arrangement of the following four enzymes represents the order in which they would be used in a typical gene-cloning experiment resulting in the insertion of a cDNA into a bacterial plasmid? Begin with the gene's mRNA transcript. | reverse transcriptase, DNA polymerase, restriction enzyme, DNA ligase |
| A scientist wishing to create an organism capable of breaking down several kinds of toxic waste combines genes from several species of bacteria to create a single "superbacterium." Which of the following would be needed to do this? | All of the listed responses are correct. |
| A nucleic acid probe is used to ______. | identify genes that have been inserted into bacterial plasmids or separated by electrophoresis |
| What is the source of the reverse transcriptase used in recombinant DNA technology? | retroviruses |
| B/c eukaryotic genes contain introns, they cannot be translated by bacteria, which lack RNA-splicing machinery. But if you want to engineer a bacterium to produce a eukaryotic protein you can synthesize a gene without introns. A good way to do this is to | work backward from mRNA to make a version of the gene without introns |
| DNA synthesized using an RNA template is called _____. | cDNA |
| In the polymerase chain reaction (PCR), the sequence of bases in the primers is important because it ______. | determines which segment of the genome will be amplified |
| A molecular biologist has isolated a short segment of DNA that she wants to replicate in vitro. First she heats the DNA, which separates the two strands, and then she adds _____. | nucleotides, primers, and polymerase |
| In the polymerase chain reaction (PCR) technique, a heating phase and a cooling phase alternate. An original sample of DNA would have to pass through how many total rounds of heating and cooling before a sample is increased eight times in quantity? | three |
| Single nucleotide polymorphisms (SNPs) _____. | All of the listed responses are correct. |
| Separating DNA fragments by gel electrophoresis is useful for which of the following? | All of the listed responses are correct. |
| Southern blotting is _____. | a technique used to study RFLPs |
| Which of the following is the first step of the Southern blotting procedure? | digesting the DNA with a restriction enzyme |
| The dideoxyribonucleotide chain-termination method _____. | produces a ladder of DNA fragments, with each individual band labeled with one of four different fluorescent tags |
| The term "RFLP" stands for _____. | restriction fragement length polymorphism |
| RFLPs have been tremendously useful for genomic mapping studies because _____. | they are not restricted to genes, and are abundantly scattered throughout the genome |
Created by:
lwelch4
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