AP BIO CH. 18 – Flashcards
Unlock all answers in this set
Unlock answersquestion
The role of a metabolite that controls a repressible operon is to bind to the ___ protein and ___ it.
answer
Repressor, activate
question
The tryptophan operon is a repressible operon that is turned ___ whenever ___ is added to the growth medium.
answer
Off, tryptophan
question
Which of the following is a protein produced by a regulatory gene?
answer
repressor
question
A lack of which molecule would result in the cell's inability to "turn off" genes?
answer
Corepressor
question
Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator?
answer
Inducer
question
Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?
answer
Inducer
question
A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in ___ ___ of the structural gene controlled by that ___.
answer
continuous transcription, regulator
question
The lactose operon is likely to be transcribed when the ___ ___ and ___ ___ are both ___ within the cell.
answer
cyclic AMP, lactose levels, high
question
Transcription of the structural genes in an inducible operon ___ when the pathway's ___ is present.
answer
Starts, substrate
question
For a repressible operon to be transcribed, what must occur is that ___ ___ must bind to the ___, and the repressor must be ___.
answer
RNA polymerase, promoter, inactive
question
Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. What occurs when the lactose enters the cell is that Allolactose binds to the ___ ___.
answer
repressor protein
question
Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in allowing the organism to ___ to changes in ___ conditions
answer
Adjust, environmental
question
In response to chemical signals, prokaryotes can alter the level of production of various ___.
answer
Enzymes
question
If glucose is available in the environment of E. coli, the cell responds with a very low concentration of cAMP. When the cAMP increases in concentration, it binds to CAP. An expected measurable effect would be ___ concentrations of ___ such as arabinose in the cell
answer
Increased, sugars
question
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 is a ___ in glucose and increase in ___.
answer
Decrease, cAMP
question
There is a mutation in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. What would characterize such a mutant is that It cannot ___ to the ___.
answer
Bind, inducer
question
The mechanism that is used to coordinate the expression of multiple, related genes in eukaryotic cells is that Genes are organized into ___, with local ___ structures influencing the __ of all the genes at once.
answer
Clusters, chromatin, expression
question
If you were to observe the activity of methylated DNA, you would expect it to have ___ ___ or ___ ___ the process of ___.
answer
Turned off, slowed down, transcription
question
Genomic imprinting, DNA methylation, and histone acetylation are all examples of
answer
epigenetic phenomena
question
When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. The processes contributing to this dynamic activity are ___ and ___ of ___ tails
answer
Methylation, phosphorylation, histone
question
Two potential devices that eukaryotic cells use to regulate transcription are DNA ___ and histone ___.
answer
methylation, modification
question
During DNA replication, methylation of the DNA is maintained because methylation ___ act at DNA sites where one strand is already methylated and thus correctly methylates ___ strands after replication.
answer
Enzymes, daughter
question
In eukaryotes, general transcription factors bind to other ___ or to a sequence element within the promoter called the ___ ___.
answer
proteins, TATA box
question
Steroid hormones produce their effects in cells by ___ to intracellular receptors and promoting ___ of specific genes.
answer
binding, transcription
question
Transcription factors in eukaryotes usually have DNA binding domains as well as other domains that are also specific for binding. In general, which of the following would you expect many of them to be able to bind?
answer
other transcription factors
question
Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because Eukaryotic ___ may be ___ in alternative patterns.
answer
Exons, spliced
question
The following experimental procedures most likely to hasten mRNA degradation in a eukaryotic cell is the ___ of the 5' ___.
answer
Removal, cap
question
Of the following, the most likely to have a small protein called ubiquitin attached to it is a ___ that usually acts in G₁, now that the cell is in G₂
answer
Cyclin
question
In prophase I of meiosis in female Drosophila, studies have shown that there is phosphorylation of an amino acid in the tails of histones of gametes. A mutation in flies that interferes with this process results in sterility. The most likely hypothesis is that Histone tail ___ prohibits chromosome __.
answer
phosphorylation, condensation
question
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
answer
RNA interference
question
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. There was surprise expressed by many that the number of protein-coding sequences was much smaller than they had expected. What could account for most of the rest is non-___-coding DNA that is transcribed into several kinds of small RNAs ___ biological function
answer
Protein, with
question
Among the newly discovered small noncoding RNAs, one type reestablishes methylation patterns during gamete formation and block expression of some transposons. These are known as
answer
piRNA
question
What best describes siRNA is a short ___-stranded RNA, one of whose strands can complement and ___ a sequence of mRNA
answer
Double, inactivate
question
One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, what you would expect to gain most from RNAs is ___ siRNAs to disable the expression of an allele associated with autosomal ___ disease
answer
targeting, dominant
question
What describes the function of an enzyme known as Dicer is that It ___ small double-stranded RNAs into molecules that can block __.
answer
trims, translation
question
In a series of experiments, the enzyme Dicer has been inactivated in cells from various vertebrates so that the centromere is abnormally formed from chromatin. What is most likely to occur is that __ will be euchromatic rather than heterochromatic and the cells will soon ___ in culture.
answer
Centromeres, die
question
Since Watson and Crick described DNA in 1953, what might best explain why the function of small RNAs is still being explained is that Changes in ___ as well as our ability to determine how much of the DNA is expressed have now made this possible.
answer
Technology
question
You are given an experimental problem involving control of a gene's expression in the embryo of a particular species. One of your first questions is whether the gene's expression is controlled at the level of transcription or translation. What might best give you an answer is that You ___ the quantity of the appropriate pre-mRNA in various cell types and find they are all the ___.
answer
measure, same
question
In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to ___ genes that produce different ___ of globins during development.
answer
nonidentical, versions
question
The fact that plants can be cloned from somatic cells demonstrates that ___ cells retain all the genes of the ___.
answer
differentiated, zygote
question
In animals, embryonic stem cells differ from adult stem cells in that embryonic stem cells are ___, and adult stem cells are ___.
answer
totipotent, pluripotent
question
What is considered to be the first evidence of differentiation in the cells of an embryo is the occurrence of ___s for the production of ___-specific proteins
answer
mRNA, tissue
question
Embryonic lethal mutations result in Phenotypes that are never ___/hatched.
answer
Born
question
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?
answer
Pattern formation
question
The product of the bicoid gene in Drosophila provides essential information about the
answer
anterior posterior axis
question
If a Drosophila female has a homozygous mutation for a maternal effect gene, ___ of her offspring will show the mutant phenotype, regardless of their ___.
answer
All, genotype
question
Mutations in which of the following genes lead to transformations in the identity of entire body parts?
answer
Homeotic genes
question
Which of the following genes map out the basic subdivisions along the anterior-posterior axis of the Drosophila embryo?
answer
Segmentation genes
question
Gap genes and pair-rule genes fall into which of the following categories?
answer
Segmentation genes
question
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, what would occur is that ___ structures would form in both sides of the embryo.
answer
Anterior
question
What gap genes, pair-rule genes, segment polarity genes, and homeotic genes all have in common is that Their products act as ___ ___.
answer
transcription factors
question
The statement that describes proto-oncogenes is that They can code for ___ associated with cell ___.
answer
Proteins, growth
question
A characteristic of the product of the p53 gene is that It is an __ for other genes.
answer
activator
question
Tumor-suppressor genes can encode proteins that promote DNA ___ or cell-cell ___.
answer
repair, adhesion
question
BRCA1 and BRCA2 are considered to be tumor-suppressor genes because their ___ products participate in ___ of DNA damage.
answer
Normal, repair
question
The cancer-causing forms of the Ras protein are involved in the following process of ___ a signal from a growth factor ___.
answer
relaying, receptor
question
Forms of the Ras protein found in tumors usually cause a ___ factor signaling to be ___.
answer
Growth, hyperactive
question
A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?
answer
Colorectal only
question
In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. At this point, the embryo is characterized as nuclei in the ___ that has not undergone ___.
answer
cortex, cytokinesis
question
In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. The four sequestered cells at one end are most probably destined to become the ___ cells of the adult.
answer
Germ
question
In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. Formation of the pole cells (the four sequestered cells) demonstrates the role of ___ effect genes.
answer
Maternal
question
In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. The next step after the embryo is formed would be ___ of the nuclei in ___, forming a single layer over the surface.
answer
Enclosure, membranes
question
In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end. The developmental stages described for Drosophila illustrate
answer
A hierarchy of gene expression
question
Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome If she moves the promoter for the lac operon to the region between the beta galactosidase gene and the permease gene, what's likely is that ___ galactosidase will be produced.
answer
Beta
question
Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome If she moves the operator to the far end of the operon (past the transacetylase gene), what would likely occur when the cell is exposed to lactose is that The ___ genes will be ___ continuously.
answer
Structural, transcribed
question
Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome If she moves the repressor gene (lac I), along with its promoter, to a position at some several thousand base pairs away from its normal position, you would expect to occur that The ___ operon will function ___.
answer
Lac, normally
question
Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome If she moves the operator to a position upstream from the promoter, what would occur is that The ___ operon will be expressed ___.
answer
Lac, continuously
question
A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. What is a likely explanation for the lack of transgene expression in the fifth cell line is that A __ integrated into a ___ region of the genome.
answer
Transgene, heterochromatic
question
A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Of the lines that express the transgene, one is transcribed but not translated. What is a likely explanation is that there is no ___ in any frame.
answer
AUG
question
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 using this procedure in Drosophila, she was readily successful in increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. The result she would most likely see is ___ chromatin condensation
answer
Decreased
question
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 decreasing methylation of histone tails. The result she would most likely see is ___ chromatin condensation
answer
Increased
question
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 a mammalian system. The result she would most likely see is ___ of the selected genes
answer
Inactivation
question
A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. She tried decreasing the amount of methylation enzymes in the embryonic stem cells and then allowed the cells to further differentiate. The result she would most likely see is ___ of mouse embryos
answer
Absnormalities
question
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. Within the first quarter hour, the researcher sees that the intact RNA is found in the cells. After 3 hours, she is not surprised to find that ___ enzyme has reduced it to smaller ___-stranded pieces.
answer
Dicer, double
question
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. This enables the remaining strand to ___ to ___ regions of target mRNAs
answer
Bind, complementary
question
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. In addition, she finds the other evidence of this single-stranded RNA piece's activity is that the rate of ___ of the ___ to be translated from the target mRNA is reduced.
answer
Accumulation, polypeptide
question
A researcher has arrived at a method to prevent gene expression from Drosophila embryonic genes. The following questions assume that he is using this method. The researcher in question measures the amount of new polypeptide production in embryos from 2—8 hours following fertilization and the results show a steady and significant rise in polypeptide concentration over that time. The researcher concludes that the ___ new polypeptides are due to ___ of maternal mRNAs.
answer
Resulting, translation
question
A researcher has arrived at a method to prevent gene expression from Drosophila embryonic genes. The following questions assume that he is using this method. The researcher continues to study the reactions of the embryo to these new proteins and you hypothesize that he is most likely to see (while embryonic genes are still not being expressed) ___ ___ (anterior → posterior, etc.) begin to be determined.
answer
Spatial axes
question
The researcher measures the concentration of the polypeptides from different regions in the early embryo and finds the following pattern (darker shading = greater concentration): SEE IMAGE His most logical assumption would be that The substance is produced in region _ and diffuses toward region _.
answer
1,5
question
One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure, patients soon succumb to numerous skin cancers. What best describes this phenomenon is an __ inability to repair __-induced mutation
answer
Inherited, UV
question
One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure, patients soon succumb to numerous skin cancers. Given the damage caused by UV, the kind of gene affected in those with XP is one whose product is involved with the ability to ___ single-strand damage and ___ it.
answer
Excise, replace
question
A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. Two children are born from the same parents. Child one inherits a predisposition to retinoblastoma (one of the mutations) and child two does not. However, both children develop the retinoblastoma. You would expect an ___ age of onset in child __.
answer
Earlier, one
question
A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. In colorectal cancer, several genes must be mutated in order to make a cell a cancer cell, supporting Knudsen's hypothesis. The kinds of genes you would expect to be mutated would be genes involved in control of the ___ ___.
answer
Cell cycle
question
A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. Knudsen and colleagues also noted that persons with hereditary retinoblastoma that had been treated successfully lived on but then had a higher frequency of developing osteosarcomas (bone cancers) later in life. This provided further evidence of their theory because ___ of the mutations involved in retinoblastoma is also one of the ___ involved in osteosarcoma.
answer
One, changes
question
A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye. One of the human leukemias, called CML (chronic myelogenous leukemia), is associated with a chromosomal translocation between chromosomes 9 and 22 in somatic cells of bone marrow. What allows CML to provide further evidence of this multistep nature of cancer is that The translocation requires ___ in both chromosomes 9 and 22, followed by ___ between the reciprocal pieces.
answer
Breaks, fusion
question
Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. In areas of the world in which malaria is endemic, notably in sub-Saharan Africa, EBV can cause Burkitt's lymphoma in children, which is usually associated with large tumors of the jaw. What is consistent with these findings is that Malarial ___ of the immune system prevents an individual from making EBV ___.
answer
Response, antibodies
question
Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. In a different part of the world, namely in parts of southeast Asia, the same virus is associated with a different kind of cancer of the throat. The most probable is that viral infection is correlated with a different ___ reaction.
answer
immunological
question
Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. A very rare human allele of a gene called XLP, or X-linked lymphoproliferative syndrome, causes a small number of people from many different parts of the world to get cancer following even childhood exposure to EBV. Given the previous information, what might be going on is that They must be unable to mount an ___ ___ to EBV.
answer
Immune response
question
Epstein Bar Virus (EBV) causes most of us to have an episode of sore throat and swollen glands during early childhood. If we first become exposed to the virus during our teen years, however, EBV causes the syndrome we know as mononucleosis. However, in special circumstances, the same virus can be carcinogenic. What must characterize the XLP population is that They must all be _ with affected ___ relatives.
answer
Males, female
question
If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then the ___ ___ acts as a ___.
answer
Amino acid, corepressor
question
Muscle cells differ from nerve cells mainly because they ___ different genes.
answer
Express
question
The functioning of enhancers is an example of ___ control of gene ___.
answer
transcriptional, expression
question
Cell differentiation always involves the production of ___-specific proteins, such as muscle __.
answer
Tissue, actin
question
An example of post-transcriptional control of gene expression is the __ of introns and alternative __ of exons
answer
Removal, splicing
question
What would occur if the repressor of an inducible operon were mutated so it could not bind the operator is ___ transcription of the ___'s genes
answer
continuous, operon
question
Absence of bicoid mRNA from a Drosophila 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 ___ leads to formation of ___ structures.
answer
Normally, head
question
A statements about the DNA in one of your brain cells that is true is that It is the ___ as the DNA in one of your ___ cells.
answer
Same, heart
question
Within a cell, the amount of protein made using a given mRNA molecule depends partly on the ___ at which the mRNA is ___.
answer
Rate, degraded
question
Proto-oncogenes can change into oncogenes that cause cancer. What best explains the presence of these potential time bombs in eukaryotic cells is that Proto-oncogenes normally help regulate ___ __.
answer
Cell division