Bio Exam 4 Questions

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

All of these choices are correct.

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

All of these choices are correct.

Proto-oncogenes: 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. are the normal forms of genes that can mutate to cause cell division to be hyperactive.

All of these choices are correct.

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

Cyclins activate kinases that regulate passage of cell cycle checkpoints.

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

Select the correct order of steps during PCR. denaturation, annealing, extension initiation, extension, termination denaturation, extension, termination annealing, initiation, termination 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: different single-nucleotide polymorphisms. first-division nondisjunctions. copy-number variations. All of these choices are correct. different numbers of tandem repeats.

different numbers of tandem repeats.

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

exon, gene; chromosome; genome

All cancers are caused by viruses. true false

false

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 true

false

In gel electrophoresis, DNA fragments migrate toward the negative pole of the electric field. false true

false

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

germ; stem; somatic

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

haploid cells.

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

if the homologous chromosome lacks the deletion

A Southern blot is a technique that relies on hybridization of: proteins to DNA. a nucleic acid probe to a complementary RNA. None of the answer options is correct. a nucleic acid probe to a complementary 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. DNA repair mechanisms fail. a single base pair is replaced by another.

a single base pair is replaced by another.

Which of the mutations would most likely have the least severe consequences? addition of three nucleotides deletion of one nucleotide addition 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.

In a normal cell, tumor suppressors are responsible for: signaling that DNA replication should begin. allowing the cell to correct replication errors. 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): reciprocal translocation inversion. duplication. insertion. None of the other answer options is correct.

inversion

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

mismatch repair

The polymerase chain reaction (PCR) is used to generate: single 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. multiple copies of whole chromosomes.

multiple copies of a targeted region of DNA.

Approximately how much of the human genome varies between individuals? 0.1% 50% 97% 99% 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. 10 100 10,000 2 1000

100

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

3'; 5' to 3'

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'-GTTTCA-3' and 5'-AATCAG-3' 5'-TGAAAC-3' and 5'-CTGATT-3' 5'-GTTTCA-3' and 5'-CTGATT-3' 5'-TGAAAC-3' and 5'-AATCAG-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? 92 23 None of the answer options are correct. 46 69

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: DNA polymerase. helicase. topoisomerase II. DNA ligase. DNA replicase.

DNA ligase.

Why are primers needed for DNA replication? 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 primers help with the proofreading function of DNA polymerase. A tiny amount of RNA is needed to tell the cell where genes are located.

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 ligase. DNA replicase. 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. Dideoxynucleotides are needed in Sanger sequencing but not in PCR. DNA polymerase is needed in Sanger sequencing but not in PCR. DNA polymerase is needed in PCR but not in Sanger sequencing. Primers are 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. The estimate must be wrong; nobody could live with so many mutations. Many of the mutations are likely to be in nonprotein-coding DNA. Most of the mutations have little or no effect on survival or health. None of the other answer options is correct.

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

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

None of the other answer options is correct. The Rous sarcoma virus from chickens can carry among its normal viral genes the src gene, which can increase cell division rates. Human viruses such as the HPV can also contribute to cell division and lead to cancer.

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? The effect depends on the environment (i.e., whether malaria is present). Having the allele is always harmful. The effect depends on whether the allele occurs in its homozygous or heterozygous form, and the environment (i.e., whether malaria is present). Having the allele is always beneficial. The effect depends on whether the allele occurs in its homozygous or heterozygous form.

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

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

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

copy number variation.

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

none of the other choices are correct

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

nonsense

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

nonsynonymous (missense) mutation.

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

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). many; many one; one one; many many; one

one; many

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

plasmid

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

the number of base pairs.

Whole genome sequencing is often approached by a shotgun sequencing technique in which large genomes are: randomly digested, short fragments are sequenced, and the overlapping sequences are assembled in order. 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.

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

recombinant DNA

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

replication bubble; replication fork

What process can account for the phenomenon wherein a normal XY male produces a sperm carrying two Y chromosomes? copy-number variation translocation disjunction first-division nondisjunction second-division nondisjunction

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.

What process can account for the phenomenon wherein a normal XY male produces a sperm carrying two Y chromosomes? copy-number variation second-division nondisjunction disjunction translocation first-division nondisjunction

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.

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

somatic; germ-line

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

synonymous (silent) mutation.

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

template; daughter

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

transgenic organisms.

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

transposable elements.

A chemical agent that interferes with DNA repair may be considered a mutagen. true false

true

Each end of a eukaryotic chromosome is capped by a repeating DNA sequence called the telomere. true false

true

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. false true

true

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

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 one quarter four times

twice