Biology Test 3
In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein?
RNA polymerase II
During which of the following processes do sister chromatids separate from each other?
during both mitosis and meiosis II
Crossing over of chromosomes normally takes place during which of the following processes?
meiosis I
A group of scientists is interested in analyzing the genomes of the various microbial species found in the Deas Sea and sequence the DNA found in the sample, they are using the
metagenomics approach
If all chromosomes are not attached to the mitotic spindle at the M phase checkpoint, the cells would most likely be arrested at which of the following points in the cell division cycle or mitosis?
metaphase
During which of the following processes do homologous pairs of chromosomes align adjacent to one another at the metaphase plate of a cell?
metaphase I of meiosis
Which of the following cellular events occur in the G1 phase of the cell division cycle?
normal growth and cell function
If a cell at metaphase of mitosis contains 32 sister chromatids, how many chromosomes will be present in a G1 cell?
16
In a diploid cell with four chromosome pairs (2n = 8), how many sister chromatids will be found in a nucleus at prophase of mitosis?
16
Which of the following processes occurs in prokaryotes but not in eukaryotes?
simultaneous transcription and translation of the same mRNA
After DNA replication, each duplicated chromosome consists of two of which of the following structures?
sister chromatids
In DNA polymerization, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and which of the following atoms or molecules of the last nucleotide in the polymer?
the 3' OH
FtsZ is a bacterial protein that forms a contractile ring involved in binary fission. Its function is analogous to which of the following structures in eukaryotic cells?
the cleavage furrow of eukaryotic animal cells
Which of the following phrases defines the term genome?
the complete set of an organism's genes and other DNA sequences
What are telomeres?
the ends of linear chromosomes
Which of the following pairs of molecules make up an active MPF?
cyclin and a cyclin-dependent kinase
Which of the following results is most likely to occur if acetylation of histone tails in the chromatin of embryonic cells is increased
decreased chromatin condensation
Which of the following events characterizes the beginning of anaphase?
enzymatic cleavage of cohesin
DNA methylation and histone acetylation are examples of which of the following processes?
epigenetic phenomena
How many chromosomes are in the middle cell?
1
A sample of double-stranded DNA contains 28% thymine. Approximately what percent of the nucleotides in this sample will be guanine
22%
A particular triplet of bases in the coding sequence of DNA is 5'-AAA-3'. The anticodon on the tRNA that binds the mRNA codon is ________.
3'-AAA-5'
An mRNA molecule with the sequence 5'-CCG-ACG-3'is being read by a ribosome.During translation which of the following tRNA anticodons will be the first to productively bind with this mRNA?
3'-GGC-5'
A particular triplet of bases in the template strand of DNA is 5'-AGT-3'. What would be the corresponding codon for the mRNA that is transcribed?
3'-UCA-5'
Beginning with a fertilized egg (zygote), how many cells will be present in the embryo following five rounds of cell division?
32
Quaking aspen trees usually reproduce by extending underground stems that then push above ground and grow into trees. Sexual reproduction is not as common, but when it does happen, the haploid gamete have 19 chromosomes. How many chromosomes are in cells of the underground stems?
38
Quaking aspen trees usually reproduce by extending underground stems that then push aboveground and grow into trees. Sexual reproduction is not as common, but when it does happen, the haploid gametes have 19 chromosomes. How many chromosomes are in the cells of the underground stems?
38
The figure represents the nucleus of an animal cell about to enter mitosis. How many non-homologous pairs of chromosomes are present?
4
The sequence of nucleotides below is present at a DNA location where the chain opens to form a replication fork:3' C C T A G G C T G C A A T C C 5'An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?
5' A C G U U A G G 3'
In a sample of double-stranded DNA containing 42% cytosine. Approximately what percent of the nucleotides in this sample will be thymine?
8%
DNA strands are antiparallel. Which of the following statements defines "antiparallel"?
A 5' to 3' DNA strand is paired with the 3' to 5' DNA strand
Which of the following statements describes an example of alternation of generations?
A diploid plant (sporophyte) produces a spore by meiosis that gives rise to a multicellular, haploid pollen grain (gametophyte).
Cells from a diploid protein with n=1 are followed through mitosis and meiosis. The drawings in the figure below represent the chromosomes. Which diagram represents anaphase I?
I
During a normal translation cycle, where would you expect to find tRNA attached to a single amino acid?
A site
During the elongation phase of translation, which site in the ribosome represents the first location where a codon pairs with an anticodon?
A site
Cohesins at centromeres of sister chromatids breakdown.
Anaphase II
In which phase the cohesion's at centromeres of sister chromatids breakdown?
Anaphase II
genes of an operon
Are arranged sequentially after the promoter.
Which of the following statements accurately describes the structure of a eukaryotic chromosome?
It is a single linear molecule of double-stranded DNA plus proteins.
What is the 5'->3' sequence of the anticodon of the methoinine (Top) tRNA
CCA
The cAMP receptor protein (CRP) is said to be responsible for positive regulation of the lac operon because ________.
CRP bound to the CRP-binding site stimulates the transcription of the lac operon
Which of the following molecules is maintained at a relatively constant level throughout the cell cycle but requires a cyclin to become catalytically active?
Cdk
Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. Which of the following best explains the association between malignant tumors and chromosomal abnormalities?
Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities
Exposure to the UV radiation in sunlight causes DNA changes in skin cells. Why are these changes more harmful when they occur in an individual with xeroderma pigmentosum (XP) than in an individual who does not have this disorder?
Compared to XP individuals, non-XP individuals have more effective nucleotide excision repair enzymes.
Which of the following results when homologous chromosomes cross over in meiosis?
Corresponding segments of non-sister chromatids are exchanged.
Suppose that Mendel's hypothesis that inheritance is "particulate" rather than due to blending were wrong. Which observation would he have not made?
Crossing two purple-flowered and white-flowered heterozygotes and white-flowered plants.
Use the figure to answer the following question: in the late 1950's meselson and stay; grew bacteria in a medium containing "heavy" (radioactive) nitrogen (15N) and then transferred them to a medium containing 14N (non-radioactive). Which of the results in the figure would be expected after one round of DNA replication in the presence of 14N?
D (DNA in the middle)
Which of the following characteristics allowed Hershey and chase to determine whether the genetic material was made of DNA or protein
DNA contains phosphorus, whereas protein does not
In bacteria, which of the following proteins is responsible for removing nucleotides from the RNA primer that is used for initiation DNA synthesis?
DNA pol I
Much of the human genome does not code for proteins. Which of the following types of DNA are found in these regions of the genome?
DNA that is transcribed into several kinds of small RNAs with biological function
Which of the following is a reason that a new DNA strand elongates only in the 5' to 3' direction during DNA replication?
Dehydration reactions require a free -OH group.
Which of the following processes occur during meiosis but not mitosis?
Diploid cells form haploid cells.
A (hypothetical) diploid organism has different genes that control wing color and wing length. A female of this species has a paternal chromosome set containing one orange-wing allele and one long-wing allele and a maternal set containing one blue-wing allele and one short-wing allele. Which of the following types of eggs would she be expected to produce after meiosis?
Each egg has a one-fourth chance of having either blue long, blue short, orange long, or orange short combinations.
Which of the following statements correctly describes the primary difference between enhancers and proximal control elements?
Enhancers are located considerable distances from the promoter; proximal control elements are close to the promoter.
Which of the following investigators was (were) responsible for determining that DNA contains equal amounts of adenine and thymine, and equal amounts of guanine and cytosine?
Erwin Chargaff
Which of the following explanations correctly describes a reproductive approach?
In asexual reproduction, a single individual is the sole parent and passes copies of its genes to its offspring without the fusion of gametes.
Which of the following processes is the best way to determine whether alternative splicing of a given gene occurs?
Isolate mRNA from the given gene and compare the sequences.
What is the function of the release factor during translation in eukaryotes?
It binds to the stop codon in the A site in place of a tRNA.
A mutation in E. coli results in a molecule known as a "super-repressor" because the operon is permanently repressed. Which of the following describes the most likely effect of the mutation on the repressor protein?
It cannot bind to the inducer.
Which of the following statements about the human X chromosomes is correct?
It carries genes that influence an individual's biological sex.
Which of the following statements describes the effect of a nonsense mutation on a gene?
It introduces a premature stop codon into the mRNA.
Which of the following statements best describes the significance of the TATA box in the promoters of eukaryotes?
It is the recognition site for the binding of a specific transcription factor.
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
It joins Okazaki fragments together.
Under which condition do high levels of transcription of structural genes occur in an inducible operon?
It starts when the pathway's substrate is present
Which of the following properties is associated with a protein that will be secreted from a eukaryotic cell?
Its signal sequence must target it to the ER.
At what part of the cell cycle would you see a chromosome that looks like this?
M
Which of the following statements describes a major difference between meiosis II and mitosis in a diploid animal?
Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells.
Who performed classic experiments that supported the semiconservative model of DNA replication?
Meselson and Stahl
Once researchers identified DNA as the molecule responsible for transmitting heritable traits, they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm. Which of the following statements correctly describes the mechanism of information transfer that accomplishes this task in eukaryotes?
Messenger RNA is transcribed from a single gene and transfers information to the cytoplasm, where protein synthesis takes place
Asexual reproduction occurs during which of the following processes?
Mitosis
In E. coli, a mutation in a gene called dnaB prevents the helices from binding at the origin of replication. Which of the following events would you expect to occur as a result of this mutation?
No replication fork will be formed
In E. coli, a mutation in a gene called dnaB prevents the helicase from binding at the origin of replication. Which of the following events would you expect to occur as a result of this mutation?
No replication fork will be formed.
The Rh blood factor in humans is perhaps the most important after the ABO system. The + phenotype is dominant to the - phenotype and is encoded on a separate autosomes from the ABO locus (i.e., the two loci assort independently). A child is born to a woman of blood type A+ and a man of blood type AB+. Which of the following blood types could not be possible for the child?
O+
The diagram shows an intact DNA sequence (top) and three experimental DNA sequences. A red X indicated the possible control element (1,2, or 3) that was deleted in each experimental DNA sequence. The area between the slashes represents the approximately 8 kilobases.of DNA located between the promoter and the enhancer region, The horizontal bar graph shows the amount of reporter gene mRNA that was present in each cell culture after 48 hourse relative to the amount that was in the culture containing the intact enhancer region (top bar=100%). Do the data suggest that any of these possible control elements are actual control elements?
Only control element 3 appears to be a control element
The insulin gene is transcriptionally expressed in a certain pancreatic cells, but not in skin cells. Which statement explains this?
Pancreas cells express an activator protein that binds the insulin enhancer
If a bacteria contained a mutant aminoacyl-tRNA synthetase that attaches a lysine instead of the normal phenylalanine to tRNAs with the anticodon AAA which of the following would occur?
Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
Which of the following is a reason that the low error rate of DNA replication is important to evolution?
Rare errors are the source of variation.
In DNA replication in E. coli, the enzyme primase is used to attach a 5 to 10 base ribonucleotide strand complementary to the parental DNA strand. The RNA strand serves as a starting point for the DNA polymerase that replicates the DNA. If a mutation occurred in the primase gene, which of the following results would you expect?
Replication would not occur on either the leading or lagging strand.
Which of the following statements about RNA processing is correct?
Ribozymes may function in RNA splicing
Two different species of protists living in a tide pool. Species A reproduces both sexually and asexually, and Species B reproduce only asexually. The pool gradually becomes infested with disease-causing viruses. Which species are more likely to survive in the changing environment?
Species A only
Which of the following conditions is most likely to result in transcription of the lac operon?
The cAMP and lactose levels are both high within the cell
A triploid cell contains three sets of homologous chromosomes. Which of the following describes the chromosomes in a triploid cell where n = 6?
The cell has 18 total chromosomes in 6 sets.
How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I?
The cells have half the number of chromosomes and one-fourth the amount of DNA
Which of the following statements best describes cells in culture that do not exhibit either density-dependent inhibition or anchorage dependence?
The cells show characteristics of tumors.
Which of the following statements best describes what would happen if MPF (maturation-promoting factor) is introduced into immature frog oocytes that are arrested in G2?
The cells would enter mitosis.
If a researcher moves the operator to the far end of the operon, which of the following processes would likely occur when the cell is exposed to lactose?
The genes of the lac operon will be transcribed continuously.
The somatic cells of a particular plant each contain a total of 46 chromosomes. How do the chromosomes of this plant differ from the chromosomes of humans, who also have a total of 46?
The genes on this plant's largest chromosome are significantly different than those on the largest human chromosome.
Which of the following statements correctly describes the difference between ATP used in metabolism and the nucleotides used as a building block during DNA synthesis?
The nucleotides have the sugar deoxyribose; ATP has the sugar ribose.
Researchers found a strain of bacteria that had mutation rates one hundred times higher than normal. Which of the following statements correctly describes the most likely cause of these results?
The proofreading mechanism of DNA polymerase was not working properly.
Two students decided to repeat the Hershey and Chase experiment, with modifications. Like Hershey and Chase they used radioactive sulfur but they substituted radioactive nitrogen for radioactive phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogen atoms. Thus, labeling the nitrogen atoms would provide a stronger signal than labeling the phosphates. Which of the following is the biggest shortcoming in their experimental design?
The radioactivity would not distinguish between DNA and proteins because proteins contain nitrogen.
A researcher introduced many copies of a double-stranded RNA into a culture of mammalian cells and used a fluorescent probe to follow it. Later she finds that the introduced strands separate into single-stranded RNAs and she hypothesizes that the molecules is acting as an miRNA. Which of the following pieces of evidence would support her claim?
The rate of accumulation of the polypeptide encoded by the target mRNA is reduced.
Which of the following describes how steroid hormones regulate gene expression?
They bind to intracellular receptors and alter transcription of specific genes.
Which of the following statements best describes homologous chromosomes?
They carry information for the same traits.
If deletion of a control element causes an increase in gene expression, what must be the normal role of that control element?
To repress gene expression. Without the control element, repressors are not able to bind to the enhancer, and the level of gene expression increases.
Which of the following statements is true about protein synthesis in prokaryotes?
Translation can begin while transcription is still in progress.
proteins are made up of domains that are associated with a certain function. Different proteins may have similar domains. If I have a partial nucleotide sequence for a domain in my unknown protein, I can use this to search for similar known sequences. Which of the following could help be guess the function of my unknown protein
Use BLAST to compare the unknown sequence to known sequence
DNA strands are antiparallel. Which of the following statements defines "antiparallel"?
a 5' to 3' strand is paired with the 3' to 5' DNA strand
Which of the following statements best describes the characteristics of siRNA?
a double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA
Which of the following statements best describes a cleavage furrow?
a groove in the plasma membrane between daughter nucle
Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely ________.
a plant cell in the process of cytokinesis
repressor
a protein that inhibits gene transcription. In prokaryotes, this protein binds to the DNA in or near the promoter.
Promoter
a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.
inducer
a specific small molecule that binds to a bacterial regulatory protein and changes its shape so that it cannot bind to an operator, thus switching an operon on.
Translation termination occurs when a ribosome interacts with which of the following structures?
a stop codon
operon
a stretch of DNA consisting of an operator, a promoter, and genes for a related set of proteins, usually making up an entire metabolic pathway.
Which of the following characteristics are part of the sexual life cycle of most fungi but are not part of the sexual life cycles of plants or animals?
a unicellular haploid stag
For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes based on the independent assortment of chromosomes during meiosis?
about 8 million
Prokaryote's ability to regulate patterns of gene expression most likely promotes the organism's survival by
allowing an organism to adjust to changes in environmental conditions
Rosalind Franklin's X-ray crystallography data suggested DNA is double stranded and has a uniform diameter. These observations can be used to rule out base pairing between two of the same nucleotide because ________.
an A-A pair is wider than a C-C pair
Which of the following processes will most likely produce a human zygote with 45 chromosomes?
an error during anaphase II while the sperm was produced
A phosphorescent red strain of bacteria is heat-killed and mixed with a living, colorless strain. Further observations of the mixture show that some of the living cells are now red. Which of the following observations would provide the best evidence that red color is a heritable trait?
as the living cells divide the number of red cells increases
How does breakdown of glucose inhibit transcription of the lac operon?
by reducing the levels of intracellular cAMP
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol prevents microtubule depolymerization, which interferes with which of the following processes?
chromosome separation
The drug cytochalasin B blocks the polymerization of actin microfilaments. Which of the following events of the cell cycle in animal cells would be most directly disrupted by cytochalasin B?
cleavage furrow formation and cytokinesis
Regulatory Gene
codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes.
Which of the following methods are used by eukaryotes to control gene expression but are not used by bacteria
control of both RNA splicing and chromatin remodeling
Which of the following is a molecule that helps to "turn off" the expression of genes in a cell?
corepressor
Frederick Griffith heat-killed a culture of pathogenic bacteria. He split the sample and injected half of it into mice. The mice lived. He then mixed the other half of the sample with a living, nonpathogenic bacteria strain and injected the mixture into mice. The mice died. Which of the following describes a treatment that would help clarify interpretation of these data?
examining tissue from the dead mice (injected with mixed sample) for the presence of pathogenic bacteria
RNA is single stranded, can hydrogen-bond with other nucleic acids, and has functional groups that can function in catalysis. These characteristics support that RNA could have which of the following cellular roles?
forming peptide bonds
What experimental technique could be used to test the hypothesis that humans and chimpanzees have a significantly different pattern of gene expression?
hybridization of RNA from various human and chimpanzee tissues to a DUNA microarray containing all 21,000 human genes
Students in a biology lab isolated cells in various phases of the cell cycle. A population of cells that have 1 1/2 times the DNA of G1 phase cells was most likely isolated from which of the following parts of the cell cycle?
in the S phase
Which of the following pairs of processes make the greatest contribution to genetic diversity between generations of a diploid insect?
independent assortment and random fertilization
Which of the following pairs of processes make the greatest contribution to genetic diversity between generations of a diploid insect?
independent assortments and random fertilization
Which of the following molecules binds with a repressor to alter its conformation and therefore affect its function?
inducer
Imagine an E. coli cell in which the top operator has a mutation that renders it unable to bind the top repressor. Under what circumstances would its top operon be "on"?
it would always be on
DNA is isolated from bacteria undergoing DNA replication. After heat treatment to disrupt H-bonds the DNA is centrifuged and it separates into two classes. One class of DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). Which types of DNA do the two classes most likely represent?
leading strands and Okazaki fragments
Aminoacyl-tRNA synthetase is an enzyme whose function is to
link a tRNA to its corresponding amino acid
Which of the following molecular structures contains codons
mRNA
Which of the following molecules carries information from DNA and directs incorporation of amino acids at the ribosome?
mRNA
Semiconservative replication involves a template. Which of the following best describes the template molecule?
one strand of the DNA molecule
Which of the following types of cells are affected most by telomere shortening?
only eukaryotic cells
You are observing a line of rat cells and see that they repeatedly make mistake in the cell cycle by going through G2 checkpoint too early. This could be due to a
problem with the expression of cyclins
Which of the following processes has just occurred when chiasmata can first be viewed under a microscope?
prophase I
Which of the following is not used in the whole-genome shotgun approach to gene sequencing?
purify mRNA; make DNA
What is the function of the enzyme topoisomerase in DNA replication?
relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix
Which of the following events would be most likely to produce cells with several nuclei?
repeated mitosis without cytokinesis
Which of the following is a reason that a new DNA strand elongates only in the 5' to 3' direction during DNA replication?
replication must progress toward the replication fork
The mitotic spindle plays a critical role in which of the following processes?
separation of sister chromatids
Which answer correctly compares the primary transcript in a prokaryotic cell with the functional mRNA?
the primary transcript is the same size as the mRNA
Histone proteins contain internal cores that are hydrophobic and surface amino acids that are positively charged. Which of the following characteristics of DNA would best support tight binding between DNA and histones?
the ring structures in DNA bases that disperse charge promote hydrophobic interactions with histone core
In eukaryotes which of the following is the first step in translation?
the small subunit of the ribosome recognizes and attaches near the 5' cap of mRNA
Which of the following characteristics is directly related to the coding of a single amino acid during the process of translation?
the three-base sequence of mRNA
In the structure of many eukaryotic genes, individual exons parallel which of the following?
the various domains of the protein product
Gene expression is often assayed by measuring the level of mRNA produced from a gene. Which of the following levels of the control of gene expression can by analyzed by this type of assay?
transcriptional control
operator
where the regulatory protein binds to in order to to control expression of the operon.
which of the following statements best describes the process of transformation in bacteria?
External DNA is taken into a cell, becoming a part of the cell's genome
The mass of DNA per nucleus in a certain fungus ranges from 4 to 10 picograms. Nuclei with 5 picograms of DNA are most likely derived from cells in which of the following parts of the cell cycle?
G1
Which of the following statements correctly describes the structure of chromatin?
Heterochromatin is highly condensed, whereas euchromatin is less compact.
Which of the following events happens at the conclusion of meiosis I?
Homologous chromosomes of a pair are separated from each other.
According to the lac operon model proposed by Jacob and Monod, what is predicted to occur if the operator is removed from the operon?
The lac operon would be transcribed continuously.
Which of the following statements correctly describes the difference between the leading and the lagging strand of DNA in DNA replication?
The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction
Two mRNAs (mRNA X and mRNA Y) are synthesized with the same exon sequences but poly-A tails of very different lengths. mRNA X is 7,500 bases long. mRNA Y is 6,900 bases long. The mRNA's are added to separate in vitro translation mixtures containing radioactive methionine and the reactions are allowed to proceed for 30 minutes. When the mixtures are analyzed which of the following outcomes will most likely occur?
The mRNA X mixture will contain more radioactive proteins than the mRNA Y mixture.