Exam 3 MC
The critical step in the regulation of most bacterial genes occurs _____________.
A. during transcription.
B. at release of mRNA.
C. during ranslation.
What would be the phenotype of a nonsense mutation in the lac repressor function?
A. constitutive expression of the Lac operon.
B. inducible expression of the Lac operon.
C. permanently repressed expression of the Lac operon.
D. cannot predict what would happen to expression of the Pac operon
Transcription and translation can be coupled in bacteria but not eukaryotes since
A. there is no nuclear membrane in prokaryotes.
B. there is no nuclear membrane in eukaryotes.
C. the bacterial DNA is in the nucleoid
D. eukaryotic chromosomes are found in nucleoids.
Proteins that have their activity regulated by binding of another molecule at a site other than the active site are termed
B. allosteric proteins.
C. regulatory proteins.
D. activator proteins.
E. inhibitory proteins.
Catabolic pathways that break down complex substances into more usable units are usually regulated by the
A. end products of the pathway.
B. the levels of the molecule that is to be broken down.
C. other metabolites that are limiting.
D. other enzyme binding..
How is glucose involved in the catabolite repression of the lactose operon?
A. It has nothing to do with regulation of the lactose operon.
B. It results in decreased cAMP levels, which in turn leads to decreased CRP binding; thus the lac operon is repressed even if lactose is present along with the glucose.
C. It is also a substrate for β-galactosidase and thus competes with lactose for this enzyme.
D. Its presence in the cell increases the amount of lac repressor in the cell.
A common amino acid motif found in many of the polypeptides that function as repressors is
A. Leucine zipper motif.
B. Zinc finger motif.
C. Helix-turn-helix motif.
D. Helix-loop-helix motif.
- As a general principle of gene regulation through operons, regulatory genes encode
A. trans-acting proteins that interact with cis-acting DNA elements.
B. cis-acting proteins that interact with cis-acting DNA elements.
C. cis-acting proteins that interact with trans-acting DNA elements.
D. trans-acting proteins that interact with trans-acting DNA elements.
Transcription in prokaryotes and eukaryotes is similar in that
A. transcriptional machinery controls compaction and decompaction of chromatin.
B. the mRNA produced can undergo alternative splicing.
C. both prokaryotic and eukaryotic proteins have identical affinities for DNA.
D. both are contained within the cell nucleus.
E. both are regulated by attachment of proteins to DNA adjacent to the gene being transcribed.
The primary point of control for most genes for the amount of gene product synthesized is
A. termination of replication.
B. transport of mRNA to the cytoplasm.
C. initiation of transcription.
D. alternative splicing.
E. regulation of translation.
Zinc-finger peptide motifs are responsible for what aspect of protein function?
A. Kinase activity
B. DNA binding
C. mRNA splicing
D. DNA replication
DNA sequences that serve as binding sites for proteins regulating transcription and are often found adjacent to a gene are said to be
D. origins of transcription.
E. transcription factors.
What is the name of the cis-acting DNA sequence that serves as the binding site for the transcriptional initiation complex?
What is the term for the cis-acting DNA sequences that often function at a distance from the gene they are regulating?
A. Promoter elements
B. Terminator elements
C. Enhancer elements
D. Regulator elements
E. Initiator elements
In generating a reporter construct to study gene regulation, the reporter gene introduced replaces
B. a random region of DNA.
C. the cis-acting regulatory DNA sequence.
E. the coding region of the gene being studied.
The gene products encoded by trans-acting elements perform their function by
A. associating with regulatory sequences distant from the gene from which they were transcribed.
B. regulating the expression of the gene from which they were transcribed.
C. the association of nucleotides with the elongating RNA transcript.
D. physically associating with DNA polymerase.
E. regulating the activity of telomerase.
What is the term for the repeating structural unit of chromatin, consisting of approximately 200 base pairs of DNA and associated histone proteins?
To create transgenic mice DNA is injected into
A. a pronucleus of a zygote
B. the cytoplasm of a zygote
C. the nucleus after the pronuclei have fused.
D. a pronucleus of one cell from an embryo.
What is the purpose of the P element in the creation of transgenic Drosophila?
A. Efficiently transfer DNA into Drosophila chromosomes
B. Transfer DNA into a specific site in the host chromosome.
C. Transfer DNA only into the nuclei of somatic cells.
D. Transfer DNA only into primitive eye cells.
The Ti plasmid allows:
A. the transfer of the plasmid from Agrobacterium to a plant cell.
B. transfer of plant DNA to Agrobacterium.
C. the transfer of DNA between two Agrobacterium cells.
D. the transfer of the plasmid from Agrobacterium to E. coli.
Transgenic organisms can help clarify which gene may be responsible for a particular phenotype since
A. individuals with the phenotype frequently carry other mutations as well.
B. the genes that cause disease are always dominant.
C. the genes that cause diseases are always recessive.
D. strains used to create transgenic organisms carry no mutations and all of their genes are wild-type.
What is a possible disadvantage of using genetically modified crops?
A. The transgene may make its way into non-transgenic plants.
B. Transgenic strains are typically less competitive than the usual strains used for farming.
C. The ability of transgenic plants to use nutrients is reduced so more fertilizer has to be applied.
D. The ability of transgenic strains to use water is poor so these strains are not drought tolerant.
Which of the following is not one of the three characteristics of value to geneticists for model organisms?
A. ease of cultivation
B. rapid reproduction
C. small size
D. small genome
Evolution has had what effect on development in various organisms?
B. conservation of many genes and genetic pathways
C. removal of all mutations.
Which model organism would be best suited for studying cellular lineage, ?
A. . E. coli
B. S. cerevisiae
C. C. C. elegans
D. M. musculus
The Aniridia gene in humans is involved in eye formation. Although eye development is very different in flies, this gene is highly conserved. What is its homolog in Drosophila?
A. eyeless (ey)
A partial loss-of-function mutation is
What is the most significant advantage of using RNAi to study development?
A. Geneticists have only been able to identify a subset of the genes involved in development.
B. Genetic studies on a single gene can be completed without the creation or isolation of new mutant organisms.
C. RNA is easy to isolate.
D. RNAi causes phenotypes not typical of in vivo development.
What is the most common cause of rare spontaneous ectopic gene expression?
A. insertion mutation
B. deletion mutation
C. a mutation that moves the gene next to a new regulatory element
D. None of the choices is correct.
The presence of a homeodomain in a protein suggests what about its function?
A. It has kinase activity.
B. It is a membrane bound receptor.
C. It is a secreted protein.
D. It is a transcription factor.
How would you best follow the developmental timing of a given protein in vivo?
A. in situ hybridization
B. Western blotting
C. using a GFP-fusion protein transgenic organism
D. microarray analysis
The enzymatic activity of CDKs are regulated by their forming a complex with which proteins?
C. Growth factors
Which statement best describes the action of polypeptide growth factors?
A. They bind to intracellular receptors and trigger intracellular signal transduction pathways.
B. They bind to cell surface receptors and trigger intracellular signal transduction pathways.
C. They bind to cell surface receptors which phosphorylate cyclins.
D. They make a complex with an intracellular receptor which then acts as a transcription factor.
The retinoblastoma (Rb) protein regulates progression into S phase by regulating ___________ activity.
A. cyclin D
The activity of Rb is regulated by
A. its phosphorylation state.
B. cyclin A.
D. its polyA tail.
E. its level of methylation.
A programmed cell change that results in cell death is referred to as
B. contact inhibition.
C. post-translational control.
What is a characteristic that is typical of a cancer cell but not of a normal cell?
A. Cell division is inhibited when they contact neighboring cells
B. Lack of an S phase in the cell cycle.
C. Ability to invade surrounding tissue.
D. Limited number of divisions before the cell dies.
The ability of a cell to move to other parts of the body is known as
B. contact inhibition
What is the term for a mutated gene that can act dominantly to predispose a cell to a cancerous phenotype?
D. Tumor suppressors
Why are some individuals are predisposed to getting cancer?
A. They have chromosomal deletions so that they carry fewer copies of proto-oncogenes
B. They have chromosomal duplications so that they carry more copies of proto-oncogenes
C. The individuals mutate their genes to create a cancer.
D. They inherit mutant alleles of genes that are involved in cancer development.
The sum total of all alleles carried in all members of a population is called its
A. gene pool.
D. polygenic sum.
The proportion of individuals in a population that are of a particular phenotype is the
A. phenotype frequency.
B. genotype frequency.
C. allele frequency.
D. None of the choices is correct.
E. None of the choices is correct.
Which of the following is not one of the assumptions of the Hardy-Weinberg law?
A. The population is very large.
B. Non-random mating occurs within the population.
C. Mutations in the alleles do not occur.
D. No migration occurs into or out of the population.
E. The ability of all genotypes for survival and reproduction is the same.
The Hardy-Weinberg equation is best at predicting short term genotypic frequencies since
A. the equation does not take into consideration epistatic effects.
B. it is based on inheritance based on Mendel's second law.
C. the equation is based on Mendelian principles of single gene inheritance.
D. over the long term some of the assumptions of the equation will not be true.
What evidence supports the hypothesis that humans originated in Africa?
A. H. spaiens genomes contain some Neaderthal DNA sequences.
B. A Y chromosomal mutation is common in 1 in 1,000 males in Asia.
C. Mt sequence variation is least in African populations.
D. Mt sequence variation is highest in African populations.
A. are affected by both genetic and environmental factors.
B. usually do not result in continuous phenotypes.
C. are not usually affected by environmental conditions.
D. usually result in one or two phenotypic values such as red/white eye color in Drosophila.
Broad sense heritability is defined as
A number of interacting genes produce quantitative inheritance. The transmission of these genes can be seen in the phenotypical pattern of
A. discontinuous distribution of discrete phenotypes.
B. continuous variation in phenotypic expression.
C. strict dominance and recessiveness.
D. All of the choices are correct.
E. only discontinuous distribution of discrete phenotypes and continuous variation in phenotypic expression.
Multifactorial inheritance is observed in phenotypes that show typically
A. only one discrete type.
B. two extremes.
C. a bell-shaped distribution.
D. a higher mutation rate.
E. All of the choices are correct.
QTL refers to
A. Quantitative Train Localization
B. Quantitative Trait Loci
C. Quantitative Training Loci
D. All of the choices are correct