BIOL2170: Exam 4 HW Questions

Cell division is regulated by: -signals about the nutritional status of the cell. -signals that indicate that the cell has reached a sufficient size. -growth factor signals. -signals that indicate that DNA has been replicated. -All of these choices are correct.

All of these choices are correct.

Knowing an individual's DNA sequence may be beneficial because it makes it possible to: -All of these choices are correct. -predict an individual's susceptibility to a particular disease. -predict an individual's responses to medications. -account for the physical differences between individuals.

All of these choices are correct.

Proto-oncogenes: -are the normal forms of genes that can mutate to cause cell division to be hyperactive. -All of these choices are correct. -can encode growth factors, cell surface receptors, or members of a signal transduction pathway. -can be mutated by cigarette smoke to become triggers for cancer.

All of these choices are correct.

Which is the function of cyclins? -Cyclins remain in constant concentrations in the cell at all times. -Cyclins replicate DNA during S phase. -Cyclins activate kinases that regulate passage of cell cycle checkpoints. -Cyclins function as tumor suppressor genes.

Cyclins activate kinases that regulate passage of cell cycle checkpoints.

T or F: All cancers are caused by viruses.

False

Which of the statements about viruses is true? -Viruses are the root cause of most, if not all, cancers. -Viruses are a type of prokaryotic cell. -Viruses contain multiple genes, and each of these genes is an oncogene. -None of the other answer options is correct. -Human cancers have not been associated with viruses.

Human cancers have not been associated with viruses. (got it wrong on the quiz so hopefully this one is right)

Select the correct order of steps during PCR. -initiation, extension, termination -denaturation, extension, termination -annealing, initiation, termination -denaturation, annealing, extension -initiation, denaturation, extension

denaturation, annealing, extension

Using the polymerase chain reaction (PCR) to amplify the same region of the genome from different individuals can identify differing lengths due to: -All of these choices are correct. -first-division nondisjunctions. -different numbers of tandem repeats. -different single-nucleotide polymorphisms. -copy-number variations.

different numbers of tandem repeats.

Which group lists the levels of genetic information in order from smallest to largest. -exon; gene; genome; chromosome -gene; chromosome; exon; genome -genome; gene; chromosome; exon -exon, gene; chromosome; genome -exon; chromosome; gene; genome

exon, gene; chromosome; genome

T or F: Harmful mutations are always eliminated from the genome in one or a few generations, because they decrease the survival and reproduction rates of the individuals that carry them.

false

T or F: In gel electrophoresis, DNA fragments migrate toward the negative pole of the electric field.

false

Telomerase is fully active in _____ and _____ cells, but almost completely inactive in _____ cells. -germ; stem; somatic -somatic; germ; stem -somatic; blood; germ -germ; somatic; stem -stem; blood; germ

germ; stem; somatic

Polar bodies finish development as: -functional gametes produced by meiosis. -haploid cells. -functional gametes produced by mitosis. -non-functional gametes that are produced by mitosis.

haploid cells

In what situation can a harmful deletion in a chromosome persist in a population? -if it is homozygous -if the homologous chromosome lacks the deletion -if the deletion is in the centromere -if a transposon replaces the deleted region

if the homologous chromosome lacks the deletion

A Southern blot is a technique that relies on hybridization of: -a nucleic acid probe to a complementary RNA. -a nucleic acid probe to a complementary DNA. -None of the answer options is correct. -proteins to DNA.

a nucleic acid probe to a complementary DNA.

In recombinant DNA experiments, ______ is used to cut pieces of DNA, and ______ joins these segments. -DNA polymerase; DNA ligase -RNA polymerase; a restriction enzyme -DNA ligase; helicase -DNA ligase; a restriction enzyme -a restriction enzyme; DNA ligase

a restriction enzyme; DNA ligase

The most frequent kind of mutation, a point mutation, occurs when: -None of the other answer options is correct. -a block of nucleotides is rearranged. -open reading frames are altered. -a single base pair is replaced by another. -DNA repair mechanisms fail.

a single base pair is replaced by another.

Which of the mutations would most likely have the least severe consequences? -addition of one nucleotide -deletion of one nucleotide -addition of two nucleotides -addition of three nucleotides (Addition or deletion of the number of nucleotides that is not divisible by three (the number of nucleotides per codon) results in a frameshift mutation, which has more severe consequences than the addition of a codon.)

addition of three nucleotides

In a normal cell, tumor suppressors are responsible for: -allowing the cell to correct replication errors. -signaling that DNA replication should begin. -increasing the rate of cell division. -signaling that cells should pass a cell cycle checkpoint.

allowing the cell to correct replication errors.

Chromosomal mutations in which the normal order of a block of genes is reversed is called a(n): -insertion. -inversion. -duplication. -reciprocal translocation -None of the other answer options is correct.

inversion

Which type of repair is a backup for the DNA polymerase proofreading function? -DNA ligase -base excision repair -nucleotide excision repair -mismatch repair

mismatch repair

The polymerase chain reaction (PCR) is used to generate: -multiple copies of a targeted region of DNA. -single copies of whole chromosomes. -multiple copies of whole chromosomes. -multiple copies of whole chromosomes and a targeted region of DNA. -a single copy of a targeted region of DNA.

multiple copies of a targeted region of DNA.

Approximately how much of the human genome varies between individuals? -0.1% -50% -99% -97% -3%

0.1%

According to the figure shown, the average number of new mutations that occur across an entire human genome in one generation is approximately _____ times higher than in nematodes. -10,000 -10 -2 -100 -1000

100

A new nucleotide can only be added to the _____ end of a growing DNA strand. DNA therefore always grows in the _____ direction. -3'; 3' to 5' -5'; 5' to 3' -5'; 3' to 5' -3'; 5' to 3'

3'; 5' to 3'

In the figure shown, the horizontal lines represent DNA strands in a double-stranded molecule, the vertical lines mark the positions of cleavage sites for a particular restriction enzyme, the arrows show the positions of primers used in the polymerase chain reaction to amplify the region, and the numbers are the number of nucleotides between successive restriction sites. For the DNA shown, the population contains restriction site polymorphisms for sites X and Y. We will use the symbol X+Y+ to denote the allele containing both sites, X+Y- for the allele containing site X but not Y, X-Y+ for the allele containing the site Y but not X, and X-Y- for the allele containing neither site. If DNA from individuals in the population were amplified with PCR, then cleaved with the restriction enzymes and run on a gel, what bands would be observed in the heterozygous genotype X+Y-/X-Y+? -5 kb, 3 kb, and 1 kb -6 kb, 3 kb, 2 kb, and 1 kb -5 kb and 3 kb -None of the other answer options is correct. -6 kb

5 kb, 3 kb, and 1 kb (One allele when digested gives two fragments of 5 and 1 kb; another allele gives two 3 kb fragments.)

The oligonucleotide primers used in the polymerase chain reaction are typically 20-30 nucleotides in length or longer; however, for purposes of this question, assume that 6 nucleotides is long enough. Suppose you wish to amplify the fragment shown (the raised dots indicate several kilobases of DNA sequence not shown). You decide to design primers corresponding to the regions that are underlined. What primer sequences would you use? 5'-ATGCTGAAACTTCTC···GGGATGAAATCAGTTT-3' 3'-TACGACTTTGAAGAG···CCCTACTTTAGTCAAA-5' -5'-TGAAAC-3' and 5'-AATCAG-3' -5'-GTTTCA-3' and 5'-CTGATT-3' -5'-GTTTCA-3' and 5'-AATCAG-3' -5'-TGAAAC-3' and 5'-CTGATT-3'

5'-TGAAAC-3' and 5'-CTGATT-3' (There are three important things to remember: 1) DNA polymerase can add nucleotides only to 3' end of the primer. 2) The 3' ends of both primers should be pointing to each other in order to amplify the region between them. 3) Sequences of the primers should be complementary and antiparallel to one of the strands that are underlined. Only pair of primers 5'-TGAAAC-3' and 5'-CTGATT-3' fulfill these requirements.)

How many chromosomes are in a human cell that is triploid? -69 -23 -46 -92 -None of the answer options are correct.

69 (The human haploid genome has 23 chromosomes. Three times that is 69.)

The enzyme responsible for joining Okazaki fragments together during DNA replication is: -helicase. -DNA ligase. -DNA polymerase. -topoisomerase II. -DNA replicase.

DNA ligase

Why are primers needed for DNA replication? -The primers help with the proofreading function of DNA polymerase. -DNA polymerase can only add nucleotides to an existing chain. -A tiny amount of RNA is needed to tell the cell where genes are located. -They help with the joining of Okazaki fragments. -They help direct the placement of the telomeres.

DNA polymerase can only add nucleotides to an existing chain.

The enzyme that catalyzes the addition of new nucleotides to a growing DNA strand is: -DNA polymerase. -topoisomerase II. -DNA replicase. -DNA ligase. -helicase.

DNA polymerase.

What is the difference between PCR and Sanger sequencing with regard to the materials needed to perform these reactions? -Primers are needed in Sanger sequencing but not in PCR. -DNA polymerase is needed in Sanger sequencing but not in PCR. -Primers are needed in PCR but not in Sanger sequencing. -Dideoxynucleotides are needed in Sanger sequencing but not in PCR. -DNA polymerase is needed in PCR but not in Sanger sequencing.

Dideoxynucleotides are needed in Sanger sequencing but not in PCR. (Both processes involve DNA replication, which requires DNA, DNA polymerase, and primers. Only Sanger sequencing requires dideoxynucleotides.)

It has been estimated that the average human gamete contains about 30 new nucleotide-substitution mutations and approximately 3 new small insertions or deletions (indels). Which of the answer choices is/are true? Select all that apply. -Most of the mutations have little or no effect on survival or health. -Many of the mutations are likely to be in nonprotein-coding DNA. -The estimate must be wrong; nobody could live with so many mutations. -None of the other answer options is correct.

Most of the mutations have little or no effect on survival or health. Many of the mutations are likely to be in nonprotein-coding DNA.

Refer to the figure shown. What important difference is there between meiosis in males and females? -Genetic recombination only occurs in females. -There are no differences in meiosis between males and females. -The division of cytoplasm differs between males and females. -Females replicate their chromosomes twice, whereas males only replicate their chromosomes once in meiosis.

The division of cytoplasm differs between males and females. (Males have equal division of cytoplasm in both meiotic divisions and produce four sperm from each starting cell. Females divide their cytoplasm unequally in both divisions. In the first division, one of the two daughter cells gets more cytoplasm. That cell will give rise to the egg, but the egg is the larger of the two cells formed by unequal division of cytoplasm in the second meiotic division.)

Which of the statements best describes the effect of having the S allele, which codes for sickle-cell anemia? -Having the allele is always beneficial. -The effect depends on whether the allele occurs in its homozygous or heterozygous form, and the environment (i.e., whether malaria is present). -The effect depends on whether the allele occurs in its homozygous or heterozygous form. -Having the allele is always harmful. -The effect depends on the environment (i.e., whether malaria is present).

The effect depends on whether the allele occurs in its homozygous or heterozygous form, and the environment (i.e., whether malaria is present). (The red blood cells of people homozygous for this mutation, SS, are unable to carry the normal amount of oxygen. In addition, the sickled cells tend to block small capillaries, interrupting the blood supply to vital tissues and organs and resulting in severe pain. In the absence of proper medical care, patients with sickle-cell anemia usually die before adulthood. However, heterozygous AS individuals have only a mild anemia. Furthermore, in Africa, where malaria is widespread, being heterozygous is actually beneficial because it provides some protection against malaria.)

Which statement best describes why genome sequencing can be complicated by repeated sequences? -The repeated sequences are too small to gather usable sequence information from. -Automated sequencing devices interpret repeated sequences as a single-copy sequence. -The repeated sequences are often longer than the sequences obtained by automated sequencing. -Repeated sequences artificially inflate the genome size, leading to an exaggerated interpretation of the complexity of the organism.

The repeated sequences are often longer than the sequences obtained by automated sequencing.

T or F: Each end of a eukaryotic chromosome is capped by a repeating DNA sequence called the telomere.

True

At which checkpoint would a cell become arrested if a chromosome was not properly aligned in the spindle? -None of the answer options is correct. -at a checkpoint late in G1 phase -at a checkpoint early in the mitotic phase -at a checkpoint late in G2 phase

at a checkpoint early in the mitotic phase (The M phase checkpoint is dependent on signals associated with spindle fiber attachment to kinetochores on the chromatids. Only after attachment of every last kinetochore will the cell progress from metaphase to anaphase)

CNV stands for: -central nucleotide variant. -central number variation. -copy number variation. -central natural variation. -copy nucleotide variation.

copy number variation.

What is a single-nucleotide polymorphism (SNP)? -a site where a restriction enzyme makes a cut -any point mutation -a site where RNA polymerase binds to DNA -none of the other choices are correct -the presence of single-nucleotides in the DNA double helix

none of the other choices are correct

A point mutation that creates a premature stop codon is called a _____ mutation. -nonsynonymous (missense) -transition -translation -nonsense -synonymous (silent)

nonsense

A point mutation that causes an amino acid replacement is called a: -nonsynonymous (missense) mutation. -transition mutation. -stop mutation. -synonymous (silent) mutation. -nonsense mutation.

nonsynonymous (missense) mutation.

Each DNA parent strand within a replication bubble acts as a template strand that produces: -two leading strands or two lagging strands. -only leading strands. -only lagging strands. -either a leading strand or a lagging strand. -one leading strand and one lagging strand.

one leading strand and one lagging strand.

As a piece of linear DNA is replicated, the leading strand will have _____ RNA primer(s) and the lagging strand will have _____ RNA primer(s). -one; one -many; one -one; many -many; many

one; many

The extrachromosomal DNA often found in bacteria is called a: -telomere. -vector. -plasmid. -restriction enzyme.

plasmid

Whole genome sequencing is often approached by a shotgun sequencing technique in which large genomes are: -digested in a few specific spots, large fragments are sequenced, and the overlapping sequences are assembled in order. -All of these choices are correct. -randomly digested, short fragments are sequenced, and the overlapping sequences are assembled from smallest to largest. -randomly digested, short fragments are sequenced, and the overlapping sequences are assembled from largest to smallest. -randomly digested, short fragments are sequenced, and the overlapping sequences are assembled in order.

randomly digested, short fragments are sequenced, and the overlapping sequences are assembled in order.

The type of genetic engineering that often involves isolating genes from one species and introducing them into another is called _____ technology. -Sanger sequencing -palindromic -Sanger recombination -DNA hybridization -recombinant DNA

recombinant DNA

In a long DNA molecule, each origin of replication produces a _____ with a _____ on each side. -replication bubble; replication fork -None of the other answer options is correct. -replication fork; DNA ligase -replication fork; replication bubble -replication bubble; DNA ligase

replication bubble; replication fork

What process can account for the phenomenon wherein a normal XY male produces a sperm carrying two Y chromosomes? -first-division nondisjunction -copy-number variation -translocation -disjunction -second-division nondisjunction (If nondisjunction occurred in the first division, the X and Y chromosomes would not separate and sperm would form with X and Y chromosomes. Only nondisjunction in the second division, in which the Y sister chromatids failed to separate, could a sperm be formed that had two Y chromosomes.)

second-division nondisjunction

What process can account for the phenomenon wherein a normal XY male produces a sperm carrying two Y chromosomes? -second-division nondisjunction -If nondisjunction occurred in the first division, the X and Y chromosomes would not separate and sperm would form with X and Y chromosomes. -Only nondisjunction in the second division, in which the Y sister chromatids failed to separate, could a sperm be formed that had two Y chromosomes -translocation -first-division nondisjunction -disjunction -copy-number variation

second-division nondisjunction

Mutations that affect only the individual in which they occur are called _____ mutations; _____ mutations are passed from parent to offspring. -germ-line; somatic -somatic; point -germ-line; heritable -somatic; germ-line -point; germ-line

somatic; germ-line

A point mutation that causes no change in the amino acid sequence of a protein is called a: -transition mutation. -nonsynonymous (missense) mutation. -nonsense mutation. -stop mutation. -synonymous (silent) mutation.

synonymous (silent) mutation.

In DNA replication, each individual parent strand acts as a _____ strand for the synthesis of a _____ strand. -template; daughter -template; duplicate -duplicate; daughter -daughter; template -daughter; duplicate

template; daughter

The size of a genome is measured by: -the number of chromosomes. -the size of organism. -All of these choices are correct. -gene size. -the number of base pairs.

the number of base pairs.

Organisms that have been modified to contain DNA from other species are known as: -Sanger recombinants. -DNA hybrids. -recombinant DNA organisms. -transgenic organisms.

transgenic organisms.

DNA sequences that are capable of moving from place to place in the genome are called: -transition elements. -centromeres. -frameshifts. -telomeric elements. -transposable elements.

transposable elements.

T or F: A chemical agent that interferes with DNA repair may be considered a mutagen.

true

T or F: Restriction enzymes recognize certain DNA sequences and some of them will cut straight through, and others will leave an overhang at both ends of the cut.

true

p53 is an example of a(n): -oncogene. -proto-oncogene. -cyclin-dependent kinase. -tumor suppressor.

tumor suppressor

A cell in prophase I of meiosis has _____ as many copies of chromosomes as each of the daughter cells following cytokinesis of meiosis II. -half -twice -four times -one quarter

twice