Life 120 Exam 4
many noncoding stretches of nucleotides are present in eukaryotic DNA
A eukaryotic transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that
either an insertion or a deletion of a base
A frameshift mutation could result from
colorectal only
A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?
corepressor
A lack of which molecule would result in the cell's inability to "turn off" genes?
data that could alert patients to what kind of cancer they were likely to acquire
A microarray known as a GeneChip, with most of the human protein-coding genetic sequences, has been developed to aid in the study of human cancer by fire comparing two-three subsets of cancer subtypes. What kind of information might be gleaned from this GeneChip to aid in cancer prevention?
genes whose sequences are very similar and that probably arose by duplication
A multigene family is composed of
proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU
A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that
continuous transcription of the structural gene controlled by that regulator
A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in
any mutation in the sequence is selected against
A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate?
UUU
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
3' UCA 5'
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is
a number of modern H. sapiens with Neanderthal sequences
A recent study compared the H. sapiens genome with that of Neanderthals. The results of the study indicated that there was a mixing of the two genomes at some period in evolutionary history. The data that suggested this were
the cells from the two sources exhibit different patterns of DNA methylation
A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following is a likely finding?
the plants would develop the typical symptoms of TMV infection
A researcher lyses a cell that contains nucleic acid moleculues and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?
bonding of the anticodon to the codon and the attachment of amino acids to tRNAs
Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the
allolactose binds to the repressor protein
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. Which of the following occurs when the lactose enters the cell?
allowing the organism to adjust to changes in environmental conditions
Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways?
can allow the production of proteins of different sizes and functions from a single mRNA
Alternative RNA splicing
piRNA
Among the newly discovered small noncoding RNAs, one type reestablished methylation patterns during gamete formation and blocks expression of some transposons. These are known as
the amino acid methionine will not become covalently bound
An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following hypotheses describes the most likely result?
interference with viral replication
Antiviral drugs that have become useful are usually associated with which of the following properties?
non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function
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. Which of the following could account for most of the rest?
their normal products participate in repair of DNA damage
BRCA1 and BRCA2 are considered to be tumor-suppressor genes because
allow the expression of many or even all of the genes in a genome to be compared at once
DNA microarrays have had a huge impact on genomic studies because they
methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication
During DNA replication,
RNA
During splicing, which molecular component of the spliceosomes catalyzes the excision reaction?
phenotypes that are never born/hatched
Embryonic lethal mutations result in
RNA polymerase must bind to the promoter, and the repressor must be inactive
For a repressible operon to be transcribed, which of the following must occur?
growth factor signaling to be hyperactive
Forms of the Ras protein found in tumors usually cause which of the following?
understand the evolutionary relationships among members of related taxa
Fragments of DNA have been extracted from the remnants of extinct woolly mammoths, amplified, and sequenced. These can now be used to
genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes
Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because
it would have no effect, because tyrosin is also available from the diet
Garrod's information about the enzyme alteration resulting in alkaptonuria led to further elucidation of the same pathway in humans. Phenylketonuria (PKU) occurs when another enzyme in the pathway is altered or missing, resulting in a failture of phenylalanine (phe) to be metabolized to another amino acid: tyrosine. Tyrosine is an earlier substrate in the pathway altered in alkaptonuria. How might PKU affect the presence or absence of alkaptonuria?
Domain Archaea has numerous transcription factors.
Gene expression in the domain Archaea in part resembles that of bacteria and in part that of the domain Eukarya. In which way is it most like the domain Eukarya?
eukaryotic exons may be spliced in alternative patterns
Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?
epigenetic phenomena
Genomic imprinting, DNA methylation, and histone acetylation are all examples of
that homeotic genes are selectively expressed over developmental time
Homeotic genes contain a homeobox sequence that is highly conserved among very diverse species. The homeobox is the code for that domain of a protein that binds to DNA in a regulatory developmental process. Which of the following would you then expect?
the common ancestor of humans and chimpanzees had 24 pairs of chromosomes, and at some point in the human lineage, two chromosomes fused end to end, providing some selective advantage
Humans have 23 pairs of chromosomes. In contrast, chimpanzees have 24 pairs of chromosomes and lack any pair resembling the long human chromosome 2 pair; instead, chimpanzees have two pairs of medium-sized chromosomes. What is the most likely explanation for these differences in the human and chimpanzee genomes?
all of her offspring will show the mutant phenotype, regardless of their genotype
If a Drosophilia female has a homozygous mutation for a maternal effect gene,
its signal sequence must target it to the ER, after which it goes to the Golgi
If a newly made polypeptide is to be secreted from a cell, what must occur before it is secreted?
have turned off or slowed down the process of transcription
If you were to observe the activity of methylated DNA, you would expect it to
fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate
In 1997, Dolly the sheep was cloned. Which of the following processes was used?
expression of a specific gene by a cell
In a genome-wide expression study using a DNA microarray assay, each well is used to detect the
the molecule is digested by exonucleases because it is no longer protected at the 5' end
In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5' cap and poly-A tail. Which of the following would you expect him to find?
embryonic stem cells can differentiate into more cell types than adult stem cells
In animals, embryonic stem cells different from adult stem cells in that
therapeutic cloning supplies cells for repair of diseased or injured organs
In animals, what is the difference between reproductive cloning and therapeutic cloning?
genes involved in control of the cell cycle
In colorectal cancer, several genes must be mutated in order to contribute to a cell developing into a cancer cell, supporting Knudsen's hypothesis. Which of the following kind of genes would you expect to be mutated?
The entire template molecule is represented in the product.
In comparing DNA replication with RNA transcription in the same cell, which of the following is true only of replication?
RNA polymerase II
In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?
bind to other proteins or to a sequence element within the promoter called the TATA box
In eukaryotes, general transcription factors
nonidentical genes that produce difference versions of globins during development
In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to
control of more than one gene in an operon
In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage?
a bacterial promoter sequence
In order for a eukaryotic gene to be engineered into a bacterial colony to be expressed, what must be included in addition to the coding exons of the gene?
look for a reasonably identical sequence in another species, prepare a knockout of this sequence in that species, and look for the consequences
In order to determine the probable function of a particular sequence of DNA in humans, what might be the most reasonable approach?
decrease in glucose and increase in cAMP
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?
a retrovirus is used to introduce four specific regulatory genes
In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). In order to make this conversion, what has been done to the adult cells?
alter the level of production of various enzymes
In response to chemical signals, prokaryotes can do which of the following?
We want to prevent any increase in mutation freqeuncy
In the 1920s, Muller discovered that X-rays caused mutation in Drosophila. In a related series of experiments in the 1940s, Charlotte Auerbach discovered that chemicals—she used nitrogen mustards—have a similar effect. A new chemical food additive is developed by a cereal manufacturer. Why do we test for its ability to induce mutation?
all of them
Let us suppose the someone is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the following could still be problematic
viral genomes are usually similar to the genome of the host cell
Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observation supports this theory?
inducer
Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?
homeotic genes
Mutations in which of the following genes lead to transformations in the identity of entire body parts?
a DNA sequence that is expressed to form a functional product: either RNA or polypeptide
Of the following, which is the most current description of a gene?
targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease
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, which would you expect to gain most from RNAs?
Pax-6 is highly conserved and shows shared evolutionary ancestry
Pax-6 is a gene that is involved in eye formation in many invertebrates, such as Drosophilia. Pax-6 is found as well in vertebrates. A Pax-6 gene from a mouse can be expressed in a fly and the protein (PAX-6) leads to a compound fly eye. This information suggests which of the following?
it might allow the polymerase to recognize different promoters under certain environmental conditions
RNA polymerase in a prokaryote is composed of several subunits. Most of these subunits are the same for the transcription of any gene, but one, known as sigma, varies considerably. Which of the following is the most probably advantage for the organism of such variability in RNA polymerase?
3' to 5' along the template strand
RNA polymerase moves in which direction along the DNA?
cloning to produce embryonic stem cells may lead to great medical benefits for many
Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation?
pattern shared among some or all of the samples that indicates gene expression differing from control samples
Researchers are looking for better treatments for breast cancer. For a particular DNA microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. The researchers will be looking for a
changed in technology as well as our ability to determine how much of the DNA is expressed have now made this possible
Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs is still being explained?
binding to intracellular receptors and promoting transcription of specific genes
Steroid hormones produce their effects in cells by
one altered tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones
Suppose than an error in transcription alters the formation of a single tRNA molecule in a cell. The altered tRNA still attaches to the same amino acid (Phe), but its anticodon loop has the sequence AAU, which binds to the mRNA codon UUA (usually specifying leucine, Leu). What will be the effect on the translation of this cell?
If UGA, usually a stop codon, is found to code for an amino acid such as tryptophan (usually coded for by UGG only)
The "universal" genetic code is now known to have exceptions. Evidence for this can be found if which of the following is true?
anterior structures would form in both sides of the embryo
The bicoid gene product is normally localized to the anterior end of the embryo. If large amount of the product were injected into the posterior end as well, which of the following would occur?
relaying a signal from a growth factor receptor
The cancer-causing forms of the Ras protein are involved in which of the following processes?
the number of proteins expressed by the human genome is far more than the number of its genes
The comparison between the number of human genes and those of other animal species has led to many conclusions, including that
vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant
The difference between vertical and horizontal transmission of plant viruses is that
differentiated cells retain all the genes of the zygote
The fact that plants can be cloned from somatic cells demonstrated that
X inactivation the embryo is random and produced different patterns
The first cloned cat, called Corbon Copy, was a calico, but she looked significantly different from her female parent. Why?
a gene from an organism can theoretically be expressed by any other organism
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
the proteins on its surface and that of the host
The host range of a virus is determined by
the cyclic AMP and lactose levels are both high within the cell
The lactose operon is likely to be transcribed when
a polypeptide missing an amino acid.
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in
ATP, RNA, and DNA
The nitrogenous base adenine is found in all members of which group?
RNA interference
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
polypeptide factors plus GTP
The process of translation, whether in prokaryotes or eukaryotes, requires tRNAs, amino acids, ribosomal subunits, and which of the following?
the anterior-posterior axis
The product of the bicoid gene in Drosophilia provides essential information about
bind to the repressor protein and activate it
The role of a metabolite that controls a repressible operon is to
turned off whenever tryptophan is added to the growth medium
The tryptophan operon is a repressible operon that is
the rules for base pairing between the third base of a codon and tRNA are flexible
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that
it cannot bind to the inducer
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?
other transcription factors
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?
several transcription factors
Transcription in eukaryotes requires which of the following in addition to RNA polymerase?
starts when the pathway's substrate is present
Transcription of the structural genes in an inducible operon
can encode proteins that promote DNA repair or cell-cell adhesion
Tumor-suppressor genes
DNA methylation and histone modifiction
Two potential devices that eukaryotic cells use to regulate transcription are
there should also be persons whose hemoglobin contains two copies of the series of amino acids that is deleted in hemoglobin Lepore
Unequal crossing over during prophase I can result in one sister chromosome with a deletion and another with a duplication. A mutated form of hemoglobin, so called hemoglobin Lepore, exists in the human population. Hemoglobin Lepore has a deleted series of animo acids. If this mutated form was caused by unequal crossing over, what would be an expected consequence?
Removal of the 5' UTR also removes the 5' cap, and the mRNA will quickly degrade.
Use: 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'
at certain sites along an intron
Use: 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3'
inclusion of I1 in the mRNA
Use: 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Suppose that exposure to a chemical mutagen results in a change in the sequence that alters the 5' end of intron 1 (I1). What might occur?
to the end of an intron
Use: 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' When the spliceosome binds to elements of this structure, where can it attach?
5' UTR E1 E2 E3 E4 UTR 3'
Use: 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Which components of the previous molecule will also be found in mRNA in the cytosol?
antibodies against specific proteins not found in the host membranes
Viral enveloped can best be analyzed with which of the following techniques?
the number of repeats varies widely from person to person or animal to animal
What characteristic of short tandem repeat DNA makes it useful for DNA fingerprinting?
an RNA with enzymatic activity
What is a ribozyme?
the application of computational methods to the storage and analysis of biological data
What is bioinformatics?
the occurence of mRNAs for the production of tissue-specific proteins
What is considered to be the first evidence of differentiation in the cells of an embryo?
sequencing DNA from a group of species from the same ecosystem
What is metagenomics?
the study of the full protein set encoded by a genome
What is proteomics?
it introduces a premature stop codon into the mRNA
What is the effect of a nonsense mutation in a gene?
GTP energizes the formation of the initiation complex, using initiation factors
What is the function of GTP in translation?
it uses viral RNA as a template for DNA synthesis
What is the function of reverse transcriptase in retroviruses?
it binds to the stop codon in the A site in place of a tRNA
What is the function of the release factor (RF)?
methylation and phosphorylation of histone tails
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. Which processes contribute to this dynamic activity?
during meiotic recombination
When does exon shuffling occur?
There are also genes for RNAs other than mRNA.
When the genome of a particular species is said to include 20,000 protein-coding regions, what does this imply?
an assembled ribosome with a polypeptide, and free tRNA
When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If the translation reaction were to be experimentally stopped at this point, which of the following would you be able to isolate?
a signal-recognition particles that brings ribosomes to a receptor protein in the ER membrane
When translating secretory membrane proteins, ribosomes are direction to the ER membrane by
A base-pair deletion
Which of the following DNA mutation is the most likely to be damaging to the protein in specifies?
copies of the herpesvirus genome permanently maintained in host nuclei
Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of his or her life?
a short double-stranded RNA< one of whose strands can complement and inactivate a sequence of mRNA
Which of the following best describes siRNA?
it is the recognition site for a specific transcription factor
Which of the following best describes the significance of the TATA box in eukaryotic promoters?
sequences, chromosomes, or sets of chromosomes
Which of the following can be duplicated in a genome?
getting vaccinated
Which of the following can be effective in preventing the onset of viral infection in humans?
they are spread via the the plasmodesmata
Which of the following describes plant virus infections?
A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end
Which of the following does not occur in prokaryotic gene expression, but does occur in eukaryotic gene expression?
removal of the 5' cap
Which of the following experimental procedures is most likely to hasten mRNA degradation in a eukaryotic cell?
segmentation genes
Which of the following genes map out the basic subdivisions along the anterior-posterior axis of the Drosophilia embryo?
to translocate polypeptides across the ER membrane
Which of the following is a function of a signal peptide?
it codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage~10-35 nucleotides away
Which of the following is a function of the poly-A signal sequence
repressor
Which of the following is a protein produced by a regulatory gene?
a large number of phages are released at a time
Which of the following is characteristic of the lytic cycle?
it is an activation of other genes
Which of the following is characteristic of the product of the p53 gene?
organismal cloning
Which of the following is most closely identical to the formation of twins?
a cyclin that usually acts in G1, now that the cell is in G2
Which of the following is most likely to have a small protein called ubiquitin attached to in?
ability of the infected cell to undergo normal cell division
Which of the following is the best predictor of how much damage a virus causes?
the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA
Which of the following is the first event to take place in translation in eukaryotes
the newly emerging virus will die out rather quickly or will mutate to be far less lethal
Which of the following is the most probable fate of newly emerging virus that causes high mortality in its host?
they can give ride to all cell types in the organism
Which of the following is true of embryonic stem cells but not of adult stem cells?
There is only one kind of RNA polymerase.
Which of the following is true of transcription in domain Archaea?
a specific combination of control elements in each gene's enhancer coordinates the simultaneous activation of the genes
Which of the following mechanisms is used to coordinate the expression of multiple, related genes in eukaryotic cells?
cloning fragments from many copies of an entire chromosome, sequencing the fragments, and then ordering the sequences
Which of the following most correctly describes the whole-genome shotgun technique for sequencing a genome?
a single nucleotide deletion in an exon coding for an active site
Which of the following mutations is most likely to cause a phenotypic change? A) a duplication of all or most introns
a triplet in the same reading frame as an upstream AUG
Which of the following nucleotide triplets best represents a codon?
abnormal gene regulation due to variant methylation
Which of the following problems with animal cloning might result in premature death of the clones?
DNA polymerase uses primer, usually made of RNA
Which of the following provides some evidence that RNA probably evolved before DNA?
an animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, and the virus mutates and can be transmitted to humans
Which of the following series best reflects what we known about how the flu virus moves between species?
RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript
Which of the following statements best describes the termination of transcription in prokaryotes?
they can code for proteins associated with cell growth
Which of the following statements describes proto-oncogenes?
the phage genome replicates along with the host genome
Which of the following statements describes the lysogenic cycle of lambda phage?
translation can begin while transcription is still in progress.
Which of the following statements is true about protein synthesis in prokaryotes?
RT-PCR
Which of the following techniques involves reverse transcriptase, PCR amplification, and gel electrophoresis?
a deletion of two nucleotides
Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?
inducer
Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator?
cloning each fragment into a plasmid
Which procedure is NOT required when the shotgun approach to sequencing is modified sequencing by synthesis, in which many small fragments are sequenced simultaneously?
a base deletion near the start of a gene
Which small-scale mutation would be most likely to have a catastrophic effect on the functioning of a protein?
retroviruses
Which viruses have single-stranded RNA that acts as the template for DNA synthesis?
replication of their genomes does not involved proofreading
Why do RNA viruses appear to have higher rates of mutation?
it might substitute a different amino acid in the active site
Why might a point mutation in DNA make a difference in the level of a protein's activity?
crickets must have more noncoding DNA
Why might the cricket genome have 11 times as many base pairs as that of Drosophila melanogaster?
you measure the quantity of the appropriate pre-mRNA in various cell types and find they are all the same
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. Which of the following might best give you an answer?
pattern formation
Your brother has just purchased a new plastic model airplane. He places all the parts on the table in approximately the position in which they will be located when the model is complete. His actions are analogous to which process in development?