front 1 1) Which of the following is a protein produced by a regulatory gene? A) operon D) repressor | back 1 Answer: D |
front 2 2) A lack of which molecule would result in a cell's inability to "turn off" genes? A) operon D) corepressor | back 2 Answer: D |
front 3 3) Which of the following, when taken up by a cell, binds to a
repressor so that the repressor no longer binds to the operator? C) repressor | back 3 Answer: A |
front 4 4) Most repressor proteins are allosteric. Which of the following
binds with the repressor to alter its conformation? C) transcription factor | back 4 Answer: A |
front 5 5) A mutation that inactivates a regulatory gene of a repressible
operon in an E. coli cell would result in _____. C) irreversible binding of the repressor to the operator | back 5 Answer: A |
front 6 6) The lactose operon is likely to be transcribed when _____. D) the cAMP level is high and the lactose level is low | back 6 Answer: C |
front 7 7) Transcription of structural genes in an inducible operon _____. A) occurs continuously in the cell D) stops when the pathway's product is present | back 7 Answer: B |
front 8 8) For a repressible operon to be transcribed, which of the following
must occur? | back 8 Answer: C |
front 9 9) Altering patterns of gene expression in prokaryotes would most
likely serve an organism's survival by _____. C) allowing an organism to adjust to changes in environmental conditions D) allowing environmental changes to alter a prokaryote's genome | back 9 Answer: C |
front 10 10) In positive control of several sugar-metabolism-related operons,
the catabolite activator protein (CAP) binds to DNA to stimulate
transcription. What causes an increase in CAP activity in stimulating
transcription? | back 10 Answer: B |
front 11 11) There is a mutation in the repressor that results in a molecule
known as a super-repressor because it represses the lac operon
permanently. Which of these would characterize such a mutant? B) It cannot make a functional repressor. C) It cannot bind to the inducer. | back 11 Answer: C |
front 12 Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. 12) If she moves the promoter for the lac operon to the region
between the beta galactosidase (lacZ) gene and the permease (lacY)
gene, which of the following would be likely? C) The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be translated. D) Beta galactosidase will not be produced. | back 12 Answer: D |
front 13 Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. 13) If she moves the operator to the far end of the operon, past the
transacetylase (lacA) gene, which of the following would likely occur
when the cell is exposed to lactose? C) The operon will never be transcribed. | back 13 Answer: D |
front 14 Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. 14) If she moves the repressor gene (lacI), along with its promoter,
to a position at some several thousand base pairs away from its normal
position, we would expect the _____. C) lac operon will be expressed continuously D) lac operon will function normally | back 14 Answer: D |
front 15 Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. 15) What would occur if the repressor of an inducible operon were
mutated so that it could not bind the operator? C) continuous transcription of the operon's genes | back 15 Answer: C |
front 16 Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. 16) According to the lac operon model proposed by Jacob and Monod,
what is predicted to occur if the operator is removed from the
operon? C) Only lacY would be transcribed. | back 16 Answer: A |
front 17 7) The trp repressor blocks transcription of the trp operon when the repressor _____. A) binds to the inducer D) is not bound to the operator | back 17 Answer: B |
front 18 18) Extracellular glucose inhibits transcription of the lac operon by
_____. D) reducing the levels of intracellular cAMP | back 18 Answer: D |
front 19 19) CAP is said to be responsible for positive regulation of the lac operon because _____. A) CAP binds cAMP D) CAP bound to the CAP-binding site increases the frequency of transcription initiation | back 19 Answer: D |
front 20 20) Imagine that you've isolated a yeast mutant that contains
histones resistant to acetylation. What phenotype do you predict for
this mutant? C) The mutant will show low levels of gene expression. D) The mutant will show high levels of gene expression. | back 20 Answer: C |
front 21 21) The primary difference between enhancers and promoter-proximal
elements is that enhancers _____. C) are at considerable distances from the promoter;
promoter-proximal elements are close to the promoter | back 21 Answer: C |
front 22 22) The reason for differences in the sets of proteins expressed in a
nerve and a pancreatic cell of the same individual is that nerve and
pancreatic cells contain different _____. C) sets of regulatory proteins | back 22 Answer: C |
front 23 23) Gene expression is often assayed by measuring the level of mRNA
produced from a gene. If one is interested in knowing the amount of a
final active gene product, a potential problem of this method is that
it ignores the possibility of _____. B) transcriptional control C) alternative splicing D) translational control | back 23 Answer: D |
front 24 24) Not long ago, it was believed that a count of the number of
protein-coding genes would provide a count of the number of proteins
produced in any given eukaryotic species. This is incorrect, largely
due to the discovery of widespread _____. B) transcriptional control C) alternative splicing D) translational control | back 24 Answer: C |
front 25 25) One way to detect alternative splicing of transcripts from a
given gene is to _____. B) measure the relative rates of transcription of the given gene
compared to that of a gene known to be constitutively spliced | back 25 Answer: D |
front 26 26) Which of the following mechanisms is (are) used to coordinate the
expression of multiple, related genes in eukaryotic cells? C) The genes are organized into a large operon, allowing them to be
coordinately controlled as a single unit. | back 26 Answer: B |
front 27 27) DNA methylation and histone acetylation are examples of _____. A) genetic mutation D) translocation | back 27 Answer: C |
front 28 28) In eukaryotes, general transcription factors _____ | back 28 Answer: A |
front 29 29) Steroid hormones produce their effects in cells by _____. A) activating key enzymes in metabolic pathways D) binding to intracellular receptors and promoting transcription of specific genes | back 29 Answer: D |
front 30 30) Which of the following is most likely to have a small protein called ubiquitin attached to it? A) a cyclin protein, that usually acts in G1, in a cell that is in
G2 D) an mRNA produced by an egg cell that will be retained until after fertilization | back 30 Answer: A |
front 31 A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. 31) In one set of experiments she succeeded in increasing
acetlylation of histone tails. Which of the following results would
she most likely see? C) decreased binding of transcription factors D) inactivation of the selected genes | back 31 Answer: B |
front 32 A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. 32) One of her colleagues suggested she try increased methylation of C nucleotides in the DNA of promoters of a mammalian system. Which of the following results would she most likely see? A) decreased chromatin condensation C) higher levels of transcription of certain genes D) inactivation of the selected genes | back 32 Answer: D |
front 33 A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. 33) Which method is utilized by eukaryotes to control their gene
expression that is NOT used in bacteria? C) transcriptional control | back 33 Answer: D |
front 34 34) The phenomenon in which RNA molecules in a cell are destroyed if
they have a sequence complementary to an introduced double-stranded
RNA is called _____. C) RNA blocking | back 34 Answer: A |
front 35 35) At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. Many people were surprised that the number of protein-coding sequences was much smaller than they had expected. Which of the following could account for much of the DNA that is not coding for proteins? A) DNA that consists of histone coding sequences | back 35 Answer: C |
front 36 36) Among the newly discovered small noncoding RNAs, one type
reestablishes methylation patterns during gamete formation and blocks
expression of some transposons. These are known as _____. B) piRNA | back 36 Answer: B |
front 37 37) Which of the following best describes siRNA? | back 37 Answer: A |
front 38 A researcher introduces double-stranded RNA into a culture of mammalian cells and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. 38) Some time later, she finds that the introduced strand separates
into single-stranded RNAs, one of which is degraded. What does this
enable the remaining strand to do? C) activate other siRNAs in the cell | back 38 Answer: B |
front 39 A researcher introduces double-stranded RNA into a culture of mammalian cells and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. 39) When she finds that the introduced strand separates into
single-stranded RNAs, what other evidence of this single-stranded RNA
piece's activity can she find? C) The amount of miRNA is multiplied by its replication. D) The cell's translation ability is entirely shut down. | back 39 Answer: B |
front 40 40) The fact that plants can be cloned from somatic cells demonstrates that _____. A) differentiated cells retain all the genes of the zygote D) differentiation does not occur in plants | back 40 Answer: A |
front 41 41) Your brother has just purchased a new plastic model airplane. He
places all the parts on the table in approximately the positions in
which they will be located when the model is complete. His actions are
analogous to which process in development? B) determination | back 41 Answer: D |
front 42 42) The product of the bicoid gene in Drosophila provides essential information about _____. A) the dorsal-ventral axis D) the anterior-posterior axis | back 42 Answer: D |
front 43 43) If a Drosophila female has a homozygous mutation for a maternal effect gene, _____. A) she will not develop past the early embryonic stage D) only her female offspring will show the mutant phenotype | back 43 Answer: B |
front 44 44) Mutations in which of the following genes lead to transformations
in the identity of entire body parts? C) homeotic genes | back 44 Answer: C |
front 45 45) Which of the following are maternal effect genes that control the
orientation of the egg and thus the Drosophila embryo? C) egg-polarity genes | back 45 Answer: C |
front 46 46) The bicoid gene product is normally localized to the anterior end
of the embryo. If large amounts of the product were injected into the
posterior end as well, which of the following would occur? B) The embryo would probably show no anterior development and die. C) Anterior structures would form in both ends of the embryo. | back 46 Answer: C |
front 47 47) In colorectal cancer, several genes must be mutated for a cell to
develop into a cancer cell. Which of the following kinds of genes
would you expect to be mutated? C) genes that are especially susceptible to mutation | back 47 Answer: B |
front 48 48) A cell is considered to be differentiated when it _____. A) replicates by the process of mitosis D) appears to be different from the surrounding cells | back 48 Answer: C |
front 49 49) When the Bicoid protein is expressed in Drosophila, the embryo is
still syncytial (divisions between cells are not yet fully developed).
This information helps to explain which observation by
Nüsslein-Volhard and Wieschaus? B) Bicoid protein diffuses throughout the embryo in a concentration gradient. C) Bicoid protein serves as a transcription regulator. | back 49 Answer: B |
front 50 50) The protein of the bicoid gene in Drosophila determines the _____ of the embryo. A) anterior-posterior axis D) posterior-ventral axis | back 50 Answer: A |
front 51 51) Which of the following types of mutation would convert a proto-oncogene into an oncogene? A) a mutation that blocks transcription of the proto-oncogene D) a deletion of most of the proto-oncogene coding sequence | back 51 Answer: C |
front 52 52) Proto-oncogenes _____. C) stimulate normal cell growth and division | back 52 Answer: C |
front 53 53) The product of the p53 gene _____. | back 53 Answer: A |
front 54 54) Tumor-suppressor genes _____. C) encode proteins that help prevent uncontrolled cell growth D) often encode proteins that stimulate the cell cycle | back 54 Answer: C |
front 55 55) BRCA1 and BRCA2 are considered to be tumor-suppressor genes because _____. A) their normal products participate in repair of DNA damage D) they block penetration of breast cells by chemical carcinogens | back 55 Answer: A |
front 56 56) Forms of the Ras protein found in tumors usually cause which of the following? A) DNA replication to stop D) excessive cell division | back 56 Answer: D |
front 57 57) A genetic test to detect predisposition to cancer would likely
examine the APC gene for involvement in which type(s) of cancer? C) lung only | back 57 Answer: A |
front 58 58) In colorectal cancer, several genes must be mutated for a cell to
develop into a cancer cell. Which of the following kinds of genes
would you expect to be mutated? C) genes that are especially susceptible to mutation | back 58 Answer: B |