AP Bio Nucleic Acid Structure and Function

In a second experiment, the plasmid contained the gene for a viral protein as well as the ampr gene. Which of the following plates would have the highest percentage of bacteria that are expected to express the gene for this viral protein? a. III only b. I only c. I and III d. IV only

a. III only

In eukaryotes, general transcription factors a. are required for the expression of specific protein-encoding genes b. bind to other proteins or to a sequence element within the promoter called the TATA box c. inhibit RNA polymerase binding to the promoter and begin transcribing d. usually lead to a high level of transcription even without additional specific transcription factors

a. are required for the expression of specific protein-encoding genes

Bacterial cells that contain green fluorescent protein (GFP) will fluoresce under ultraviolet light. Which of the following is the most likely outcome of replacing the lacZ gene in the E. coli lac operon with the gene encoding GFP? a. bacteria growing in the presence of lactose will fluoresce under ultraviolet light b. beta-galactosidase will be made only when bacteria are cultured under ultraviolet light c. ultraviolet light will cause a bond to form between glucose and galactose monomers d. ultraviolet light will cause a duplication of the lac operon

a. bacteria growing in the presence of lactose will fluoresce under ultraviolet light

What would be the result of a mutation that deactivates the regulatory gene of a repressible operon in an Escherichia coli cell? a. continuous transcription of the structural gene controlled by that regulator b. complete inhibition of transcription of the structural gene controlled by that regulator c. irreversible binding of the repressor to the operator d. inactivation of RNA polymerase by alteration of its active site

a. continuous transcription of the structural gene controlled by that regulator

Which of the following is not true of RNA processing? a. exons are cut out before mRNA leaves the nucleus b. nucleotides may be added at both ends of the RNA c. ribozymes may function in RNA splicing d. RNA splicing can be catalyzed by spliceosomes

a. exons are cut out before mRNA leaves the nucleus

Based on the data in figure 1, the concentration of iron in the control diet used in the investigation is most likely within which of the following ranges? a. 20-25 mg/kg b. 35-40 mg/kg c. 70-75 mg/kg d. 100-125 mg/kg

b. 35-40 mg/kg

Which of the following statements best explains how protein X regulates gene expression? a. Protein X is responsible for processing pre-mRNA b. Protein X is responsible for activating transcription of some genes but not others c. Protein X is a member of some cytoplasmic protein complexes but not others d. Protein X causes specific base-pair changes to produce new alleles

b. Protein X is responsible for activating transcription of some genes but not others

In response to chemical signals, prokaryotes can carry out which of the following activities? a. turn of translation of their mRNA b. alter the level of production of various enzymes c. increase the number and responsiveness of their ribosomes d. inactivate their mRNA molecules

b. alter the level of production of various enzymes

Which of the following is the most likely consequence of a mutation at the operator locus that prevents binding of the repressor protein? a. Expression of the structural genes will be repressed, even in the presence of lactose b. beta-galactosidase will be produced, even in the absence of lactose c. RNA polymerase will attach to the pLAC locus, but transcription will be blocked d. the operator locus will code for a different protein and thereby prevent transcription of the structural gene

b. beta-galactosidase will be produced, even in the absence of lactose

After a search of nucleotide sequence databases, researchers identified an IRE in the 5' untranslated region of a gene encoding aconitase, an enzyme involved in the Krebs cycle. Which of the following pieces of experimental evidence best supports the claim that the synthesis of aconitase is controlled by a mechanism similar to ferritin regulation? a. IRP binds to the aconitase mRNA in the presence of iron b. the relative amount of aconitase protein increases in the presence of high levels of iron c. oxygen consumption by cells increases in the presence of high levels of iron d. the levels of reduced electron carriers, NADH FADH2 increase in the presence of high levels of iron

b. the relative amount of aconitase protein increases in the presence of high levels of iron

Which of the following is most likely to create genetic variation in a population? a. RNA polymerase errors during replication b. Helicase failure to unwind DNA during DNA replication c. DNA polymerase errors during replication d. Misincorporation of amino acids by tRNA during translation

c. DNA polymerase errors during replication

Which of the following describes the most likely consequence of a negative feedback pathway involving the lac operon? a. the breakdown products of lactose block cell division b. diffusion of lactose across the plasma membrane would stop in the presence of lactose c. expression of the lac operon diminishes as lactose is depleted d. binding of DNA by the repressor would increase in the presence of lactose

c. expression of the lac operon diminishes as lactose is depleted

a type of mutation in the repressor results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of these would characterize such a mutant? a. it cannot bind to the operator b. it cannot make a functional repressor c. it cannot bind to the inducer d. it makes molecules that bind to one another

c. it cannot bind to the inducer

Which of the following conclusions about dietary iron and ferritin synthesis is best supported by the data in figure 1? a. a dietary iron concentration of 25mg/kg has no effect on ferritin gene expression compared with the control diet b. at a dietary iron concentration of 50mg/kg, rats make twice as much ferritin as rats fed the control diet do c. maximum activation of ferritin synthesis occurs at dietary iron concentrations of 75mg/kg or greater d. the maximum rate of ferritin absorption from the gut occurs at dietary iron concentrations greater than 75mg/kg

c. maximum activation of ferritin synthesis occurs at dietary iron concentrations of 75mg/kg or greater

In the process of tyrptophan, the repressor is active and binds to the Trp operator, preventing RNA polymerase from transcribing the operon. The trpR regulatory gene responsible for producing the repressor protein is a. a significant component of the trp operon b. is only expressed in the presence of the trpR mRNA c. not considered to be a part of the trp operon d. according to the image, not being expressed

c. not considered to be a part of the trp operon

Retroviruses have an RNA genome. HTLV-1 is a lysogenic retrovirus that establishes a latent infection in human cells. By which of the following mechanisms does infection by a retrovirus such as HTLV-1 most likely cause long-lasting genetic changes to host cells? a. the host-cell ribosomes translate the viral RNA genome that enters the cell upon initial viral infection b. the viral RNA polymerase that transcribes host genes has a high error rate c. the RNA viral genome is reverse transcribed into DNA that integrates into the host genome d. the RNA viral genome integrates into the host genome

c. the RNA viral genome is reverse transcribed into DNA that integrates into the host genome

Based on the model of ferritin synthesis presented in figure 2, which of the following best describes the mechanism whereby iron most likely regulates ferritin production? a. translation occurs under low intracellular iron concentration when the IRP recruits ribosomes to the ferritin mRNA b. translation occurs under low intracellular iron concentration when the IRP stabilizes the stem-loop structure in the ferritin mRNA c. translation occurs under high intracellular iron concentrations when the IRP complex dissociates from ferritin mRNA, permitting ribosomes access to the ferritin coding region d. translation occurs under high intracellular iron concentration when the IRP complex brings the 5' end of the closer to the ferritin coding region

c. translation occurs under high intracellular iron concentrations when the IRP complex dissociates from ferritin mRNA, permitting ribosomes access to the ferritin coding region

Based on the model of ferritin synthesis presented in figure 2, which of the following describes the role of feedback on the control of intracellular iron levels? a. a decrease in iron levels activates the IRP. The IRP in turn activates iron transport proteins in the cell membrane, thereby returning free iron levels to normal b. a decrease in iron levels activates synthesis of the ferritin protein. Ferritin protein in turn releases bound iron, thereby returning free iron levels to normal c. an increase in iron levels activates the IRP. The IRP in turn binds iron, thereby decreasing both free iron levels and ferritin synthesis. d. an increase in iron levels activates synthesis of ferritin protein. Ferritin protein in turn binds iron, thereby decreasing both free iron levels and ferritin synthesis.

d. an increase in iron levels activates synthesis of ferritin protein. Ferritin protein in turn binds iron, thereby decreasing both free iron levels and ferritin synthesis

Plate IV shows bioluminescent bacteria but less overall growth than plate III. This is because a. bacteria on plate IV can only express genes for bioluminescense b. bacteria on the plate III were given additional nutrients and optimal growing conditions c. only the bacteria on plate III can express genes for antibiotic resistance d. bacteria on plate IV is expressing genes for both bioluminescence and antibiotic resistance

d. bacteria on plate IV is expressing genes for both bioluminescence and antibiotic resistance

Which of the following statements correctly describes the function of a signal peptide? a. it directs an mRNA molecule into the golgi apparatus b. it causes RNA polymerase to bind DNA and initiate transcription c. it terminates translation of the messenger RNA d. it assists in the translocation of polypeptides across the ER membrane

d. it assists in the translocation of polypeptides across the ER membrane

Which of the following best describes an event during step 2 in the simplified model above? a. a new RNA molecule is synthesized using a DNA template b. a new polypeptide is synthesized using an RNA template c. thymine nucleotides in an RNA molecule are replaced with uracil nucleotides d. noncoding sequences are removed from a newly synthesized RNA molecule

d. noncoding sequences are removed from a newly synthesized RNA molecule

Which of the following is a protein product of a regulatory gene? a. operon b. inducer c. promoter d. repressor

d. repressor

Plate II shows no bacterial growth because a. the bacteria added to this plate failed to express the genes for antibiotic resistance b. the bacteria added to this plate did not express genes for bioluminescence c. the bacteria added to this plate were resistant to the antibiotic d. the bacteria added to this plate were not transformed and therefore lack antibiotic resistance

d. the bacteria added to this plate were not transformed and therefore lack antibiotic resistance

Which of the following best explains the contribution of the lac operon to the metabolic efficiency of a bacterial cell? a. expression of the lac1 gene b. RNA polymerase is rapidly degraded by the product of the lacP locus c. the repressor binds to the DNA only when the cellular concentration of glucose is low d. the lacZ gene is highly expressed only when lactose is available

d. the lacZ gene is highly expressed only when lactose is available

The lac operon question

diagram with the enzyme floating with the lactose connected