A lack of which molecule would result in a cell's inability to "turn off" genes?
Corepressor
Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator?
inducer
A mutation that inactivates a regulatory gene of a repressible operon in an E. coli cell would result in _____.
continuous transcription of the structural gene controlled by that regulator
Transcription of structural genes in an inducible operon _____.
starts when the pathway's substrate is present
Altering patterns of gene expression in prokaryotes would most likely serve an organism's survival by _____.
allowing the organism to adjust to changes in environmental conditions
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?
It cannot bind to the inducer
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?
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?
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 _____.
According to the lac operon model proposed by Jacob and Monod, what is predicted to occur if the operator is removed from the operon?
Extracellular glucose inhibits transcription of the lac operon by _____.
CAP is said to be responsible for positive regulation of the lac operon because _____.
Imagine that you've isolated a yeast mutant that contains histones resistant to acetylation. What phenotype do you predict for this mutant?
The primary difference between enhancers and promoter-proximal elements is that enhancers _____.
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 _____.
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 _____.
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 _____.
One way to detect alternative splicing of transcripts from a given gene is to _____.
Which of the following mechanisms is (are) used to coordinate the expression of multiple, related genes in eukaryotic cells?
DNA methylation and histone acetylation are examples of _____.
In eukaryotes, general transcription factors _____
Steroid hormones produce their effects in cells by _____.
Which of the following is most likely to have a small protein called ubiquitin attached to it?
A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture.
In one set of experiments she succeeded in increasing acetlylation of histone tails. Which of the following results would she most likely see?
A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture.
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?
Which method is utilized by eukaryotes to control their gene expression that is NOT used in bacteria?
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 _____.
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?
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 _____.
Which of the following best describes siRNA?
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.
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?
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.
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?
The fact that plants can be cloned from somatic cells demonstrates that _____.
A) embryonic stem cells are totipotent, and adult stem cells are
pluripotent. *
B) embryonic stem cells are pluripotent, and adult
stem cells are totipotent.
C) embryonic stem cells have more
genes than adult stem cells.
D) embryonic stem cells have fewer
genes than adult stem cells.
E) embryonic stem cells are
localized to specific sites within the embryo, whereas adult stem
cells are spread throughout the body.
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?
A) morphogenesis
B) determination
C) induction
D)
differentiation
E) pattern formation *
The product of the bicoid gene in Drosophila provides essential information about _____.
A) lethal genes.
B) the dorsal-ventral axis.
C) the
left-right axis.
D) segmentation.
E) the
anterior-posterior axis. *
If a Drosophila female has a homozygous mutation for a maternal effect gene, _____.
A) she will not develop past the early embryonic stage.
B)
all of her offspring will show the mutant phenotype, regardless of
their genotype. *
C) only her male offspring will show the
mutant phenotype.
D) her offspring will show the mutant
phenotype only if they are also homozygous for the mutation.
E)
only her female offspring will show the mutant phenotype.
Mutations in which of the following genes lead to transformations in the identity of entire body parts?
A) morphogens
B) segmentation genes
C) egg-polarity
genes
D) homeotic genes *
E) inducers
Which of the following are maternal effect genes that control the orientation of the egg and thus the Drosophila embryo?
A) homeotic genes
B) segmentation genes
C) egg-polarity
genes *
D) morphogens
E) inducers
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?
A) The embryo would grow to an unusually large size.
B) The
embryo would grow extra wings and legs.
C) The embryo would
probably show no anterior development and die.
D) Anterior
structures would form in both sides of the embryo. *
E) The
embryo would develop normally.
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?
A) genes coding for enzymes that act in the colon
B) genes
involved in control of the cell cycle *
C) genes that are
especially susceptible to mutation
D) genes of the bacteria,
which are abundant in the colon
A cell is considered to be differentiated when it _____.
A) replicates by the process of mitosis
B) loses connections
to the surrounding cells
C) produces proteins specific to a
particular cell type *
D) appears to be different from the
surrounding cells
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?
A) mRNA from the egg is translated into the Bicoid protein.
B)
Bicoid protein diffuses throughout the embryo in a concentration
gradient. *
C) Bicoid protein serves as a transcription
regulator.
D) Bicoid protein determines the dorsoventral axis of
the embryo.
The protein of the bicoid gene in Drosophila determines the _____ of the embryo.
A) anterior-posterior axis *
B) anterior-lateral axis
C)
posterior-dorsal axis
D) posterior-ventral axis
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
B) a mutation that creates an unstable
proto-oncogene mRNA
C) a mutation that greatly increases the
amount of the proto-oncogene protein *
D) a deletion of most of
the proto-oncogene coding sequence
Proto-oncogenes _____.
A) normally suppress tumor growth
B) were initially introduced
into eukaryotic cells by retroviruses
C) are produced by somatic
mutations induced by carcinogenic substances
D) stimulate normal
cell growth and division *
E) are underexpressed in cancer cells
The product of the p53 gene _____.
A) inhibits the cell cycle *
B) slows down the rate of DNA
replication by interfering with the binding of DNA polymerase
C)
causes cells to reduce expression of genes involved in DNA
repair
D) allows cells to pass on mutations due to DNA damage
Tumor-suppressor genes _____.
A) are frequently overexpressed in cancerous cells
B) are
cancer-causing genes introduced into cells by viruses
C) encode
proteins that help prevent uncontrolled cell growth *
D) often
encode proteins that stimulate the cell cycle
BRCA1 and BRCA2 are considered to be tumor-suppressor genes because _____.
A) they prevent infection by tumor viruses that cause
cancer
B) their normal products participate in repair of DNA
damage *
C) the mutant forms of either one of these prevent
breast cancer
D) the normal genes make estrogen
receptors
E) they block penetration of breast cells by chemical carcinogens
Forms of the Ras protein found in tumors usually cause which of the following?
A) DNA replication to stop
B) DNA replication to be
hyperactive
C) cell-to-cell adhesion to be nonfunctional
D)
cell division to cease
E) excessive cell division *
A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?
A) colorectal only *
B) lung and breast
C) lung
only
D) lung and prostate
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?
A) genes coding for enzymes that act in the colon
B) genes
involved in control of the cell cycle *
C) genes that are
especially susceptible to mutation
D) genes of the bacteria,
which are abundant in the colo
...