sb 11
Which best describes a haplotype? A haploid genotype showing linkage of alleles or molecular markers along a single chromosome Phenotypic variation that is observed, on average, in half of the offspring A recombinant chromosome carrying half of the molecular markers from one parent and half from the other parent Genetic variation in which someone has half the normal number of molecular markers
A haploid genotype showing linkage of alleles or molecular markers along a single chromosome
Which of the following accurately describes the genetic change(s) leading to malignancy? Multiple, simultaneous gene changes occur, involving oncogene activation and tumor-suppressor gene inactivation. Reason: Cancer-causing mutations happen in a sequence, rather than simultaneously. A single genetic change occurs, involving activation of an oncogene. A single genetic change occurs, involving inactivation of a tumor-suppressor gene. A series of successive gene changes occurs, involving oncogene activation and inactivation of tumor-suppressor genes.
A series of successive gene changes occurs, involving oncogene activation and inactivation of tumor-suppressor genes.
to stimulate the growth of epidermal cells, such as skin cells, which event would occur first? MAPK activates transcription factors for genes promoting cell division. An epidermal growth factor, EGF, binds to a receptor on the surface of a skin cell. A multi-step signal transduction pathway leads to the activation of a protein kinase called MAPK.
An epidermal growth factor, EGF, binds to a receptor on the surface of a skin cell.
During which stages of the cell cycle do checkpoints exist to determine if DNA has incurred damage? S phase metaphase prophase G1 G2
G1 G2
__ promote cancer by increasing transcription of genes that regulate cell division.
Oncogenes
Which change from proto-oncogene to oncogene occurred by a missense mutation? a) Creation of a new protein through the fusion of chromosomal segments from two different chromosomes b) Increase in the number of copies of the gene for a growth factor receptor in breast cancer cells c) Decreased transcription of the tumor-suppressor gene p53 following the integration of DNA from the HTLV-1 retrovirus into T cells d) Substitution of valine for glycine at position 12 in the amino acid sequence of the rasH protein e) Movement of the portion of chromosome 8 carrying the myc oncogene to a region of chromosome 14 where its transcription level will be increased
Substitution of valine for glycine at position 12 in the amino acid sequence of the rasH protein
For the non-inherited development of retinoblastoma, which correctly describes inactivation of the rb tumor-suppressor alleles by the "two-hit" model? The person is born with two active copies of the rb allele; separate mutation events are required to inactivate each of these alleles. The person is born with two inactive copies of the rb allele; followed by two more mutations in the allele causing further inactivation. The person is born with one inactive copy of the rb allele; a mutation inactivates the second rb allele. The person is born with two inactive copies of the rb allele.
The person is born with two active copies of the rb allele; separate mutation events are required to inactivate each of these alleles.
Cancer cells may carry gain-of-function mutations that increase the activity of an oncogene. In which of the following ways could the expression of the protein encoded by the oncogene be altered by this type of mutation? The structure of the protein is altered so that it is overly active. The structure of the protein is altered so that it is no longer active. The amount of protein produced from the oncogene is significantly decreased. The amount of protein produced from the oncogene is significantly increased. The protein is expressed in a cell type where it is not normally found.
The structure of the protein is altered so that it is overly active. The amount of protein produced from the oncogene is significantly increased. The protein is expressed in a cell type where it is not normally found.
Approximately how many human diseases have a genetic basis? Hundreds Hundred Thousands Millions Thousands
Thousands
What is the normal role of Rb protein during the process of cell division? Unphosphorylated Rb protein prevents progress through the cell cycle by binding to transcription factor E2F. Phosphorylated Rb protein prevents progress through the cell cycle by binding to transcription factor E2F. Reason: After phosphorylation, Rb protein is released from E2F. Unphosphorylated Rb protein stimulates the action of transcription factor E2F, speeding up the cell cycle. Rb protein interacts with a cyclin-CDK complex to slow progress through the cell cycle.
Unphosphorylated Rb protein prevents progress through the cell cycle by binding to transcription factor E2F.
What is the inheritance pattern for a trait that more commonly affects males than females and which will occur in about 50% of the sons born to the unaffected daughter of an affected male? Autosomal recessive Autosomal dominant X-linked recessive X-linked dominant
X-linked recessive
Uncontrolled cell division may result from ______. regulated expression of tumor suppressor genes an increase in the expression of tumor suppressor genes a decrease in the expression of tumor suppressor genes
a decrease in the expression of tumor suppressor genes
The proto-oncogene raf codes for an enzyme that participates in a signal transduction pathway promoting cell division. Changing the amino acid valine to glutamic acid at position 599 in the RAF enzyme leads to a type of skin cancer called melanoma. This change from proto-oncogene to oncogene occurred as a result of ______. gene amplification viral DNA integration in an adjacent region. a nonsense mutation chromosomal translocation a missense mutation
a missense mutation
To prevent cells with damaged DNA from dividing, the tumor-suppressor protein p53 can ______. phosphorylate proteins to slow progress through the cell cycle activate genes involved with DNA repair stimulate the expression of the p21 gene to inhibit the G1 to S transition of the cell cycle initiate apoptosis
activate genes involved with DNA repair stimulate the expression of the p21 gene to inhibit the G1 to S transition of the cell cycle initiate apoptosis
An examination of the genomes of many different individuals to determine if a specific genetic variant is associated with a human disease is called a genome-wide __ __
association study
During the initial stage of cancer development, cells with a precancerous genetic change form a(n) ______. invasive growth benign growth metastatic tumor malignant tumor
benign growth
In the development of retinoblastoma, a retinal cell is more likely to divide if ______.. both copies of the rb gene are inactivated one copy of the rb gene is activated the Rb protein remains bound to the E2F protein both copies of the E2F gene are inactivated
both copies of the rb gene are inactivated
Viruses that cause cancer are ______. DNA viruses only both retroviruses and DNA viruses retroviruses only neither retroviruses nor DNA viruses
both retroviruses and DNA viruses
The formation of activated cyclin-CDK complexes is regulated by ______. checkpoint proteins. tumor suppressors hormones oncogenes transcription factors
checkpoint proteins.
Most cancer cells are descendants of an original cell that acquired genetic changes. Therefore, cancerous growths are considered to be ______ in origin. benign malignant clonal hereditary invasive
clonal
The purpose of the HapMap project is to ______. find genes associated with observable human phenotypes collect and organize information about human genetic variation find genes associated with specific diseases
collect and organize information about human genetic variation
The tumor-suppressor gene p53 has a significant role in ______. preventing viral DNA insertion preventing apoptosis promoting the formation of new alleles through mutation speeding up progress through the cell cycle detecting DNA damage in a cell
detecting DNA damage in a cell
When a proto-oncogene is converted to an oncogene, which pattern of inheritance is usually observed for the mutated allele? mitochondrial recessive dominant X-linked
dominant
The event that induces expression of the p53 tumor suppressor gene is a __ -__ break in damaged DNA.
double stranded
True or false: A disease with a genetic origin in a mouse is unlikely to be an inherited disease in humans. T/F
false
When a cancer cell grows into surrounding healthy tissue nearby, it is described as
invasive
A benign tumor is a(n) ______. cancerous tumor that can spread to additional sites throughout the body invasive tumor that can grow within healthy tissues localized growth with a precancerous genetic change
localized growth with a precancerous genetic change
A situation where a disease may be caused by mutations in two or more different genes is called ______. a linkage abnormality locus heterogeneity locus heterozygosity a pleiotropic effect
locus heterogeneity
The disease hemophilia is caused by a deficiency in any one of three blood clotting factors. Two of these factors are encoded by genes on the X chromosome and the other clotting factor gene is located on an autosome. Since mutations in more than one gene can cause hemophilia, this represents ______. pleiotropy a linkage abnormality locus heterogeneity locus heterozygosity
locus heterogeneity
The majority of carcinogens promote cancer development by increasing the rate of ______ in somatic cells. DNA replication mutation histone modification DNA repair
mutation
Simple Mendelian inheritance is a pattern observed when a human disorder is caused by ______. interaction between two or more genes inheritance of a dominant allele inheritance of a recessive allele mutation in a single gene
mutation in a single gene
True or false: Comparing someone with a genetic disease to another person in the general population, the person with the disease is more likely to have a family member with the same disease.
true
Tumor-suppressor protein p53 inhibits the division of cells with damaged DNA by promoting which process(es)? DNA repair only Apoptosis only Apoptosis and inhibition of cell cycle progression only Apoptosis, DNA repair and inhibition of cell cycle progression Inhibition of cell cycle progression only
Apoptosis, DNA repair and inhibition of cell cycle progression
What is the inheritance pattern for a trait that occurs with equal frequency in both sexes and will be inherited, on average, by 50% of the offspring of an affected individual who had only one affected parent? X-linked recessive X-linked dominant Autosomal dominant Autosomal recessive
Autosomal dominant
What is the inheritance pattern for a trait that occurs with the same frequency in both sexes and two affected heterozygous individuals have, on average, 25% unaffected offspring? X-linked dominant Autosomal dominant Autosomal recessive X-linked recessive
Autosomal dominant
What is the inheritance pattern when a trait occurs with the same frequency in both sexes and an affected offspring can have two unaffected parents? Autosomal recessive Autosomal dominant X-linked dominant X-linked recessive
Autosomal recessive
What is the inheritance pattern when the trait occurs with the same frequency in both sexes and two unaffected heterozygotes have, on average, 25% affected children? Autosomal recessive Autosomal dominant X-linked recessive X-linked dominant
Autosomal recessive
Tumor-suppressor genes whose normal gene products help maintain genome integrity are ______. rb p16 BRCA-1 p53
BRCA-1 p53
Inherited breast cancer is associated with inactivation of the BRCA1 allele. Suppose a woman whose genotype is BRCA1+ BRCA1- develops breast cancer. What is the genotype of her breast cancer cells? BRCA1- BRCA1- BRCA1+ BRCA1+ BRCA1+ BRCA1-
BRCA1- BRCA1-
Four types of genetic changes that can convert a proto-oncogene to an oncogene are missense __, gene ___, chromosomal ___ and ___ integration
Blank 1: mutations or mutation Blank 2: amplification Blank 3: translocations or translocation Blank 4: viral
A loss-of-function mutation in a __ __ gene can allow cancerous growth to occur.
Blank 1: tumor or tumour Blank 2: suppressor
Which mechanism accounts for the conversion of c-myc to an oncogene for lymphomas occurring in birds? DNA from the avian leukosis virus integrates within the sequence for the the chromosomal c-myc gene, reducing its expression. Infection with the avian leukosis virus stimulates a missense mutation in the c-myc gene. Infection with the avian leukosis virus triggers the fusion of two different host chromosomes, adding c-myc to the sequence of another gene. DNA from the avian leukosis virus integrates next to the chromosomal c-myc gene and increases its level of transcription.
DNA from the avian leukosis virus integrates next to the chromosomal c-myc gene and increases its level of transcription.
For the inherited tendency to develop retinoblastoma in the first few years of life, which correctly describes inactivation of the rb tumor-suppressor alleles by the "two-hit" model? Both alleles are eliminated by chromosomal deletions prior to birth. Both alleles are inactivated by environmental factors early in life. One allele is inactivated prior to birth, the other becomes inactivated early in life. Both alleles are inactivated prior to birth.
One allele is inactivated prior to birth, the other becomes inactivated early in life.
Which event activates progression through the cell cycle? Phosphorylation of Rb protein so that it no longer binds to transcription factor E2F. Removal of a phosphate group from Rb protein so that it binds to transcription factor E2F. Phosphorylation of transcription factor E2F so that it no longer binds to Rb protein. Formation of a cyclin-CDK complex that removes a phosphate group from Rb protein.
Phosphorylation of Rb protein so that it no longer binds to transcription factor E2F.
For the non-inherited development of retinoblastoma, which correctly describes inactivation of the rb tumor-suppressor alleles by the "two-hit" model? The person is born with two inactive copies of the rb allele; followed by two more mutations in the allele causing further inactivation. The person is born with two active copies of the rb allele; separate mutation events are required to inactivate each of these alleles. The person is born with two inactive copies of the rb allele. The person is born with one inactive copy of the rb allele; a mutation inactivates the second rb allele.
The person is born with two active copies of the rb allele; separate mutation events are required to inactivate each of these alleles.
How can integration of viral DNA into a host chromosome convert a proto-oncogene into an oncogene? a) Replication of viral DNA sequences leads to the production of viral proteins stimulating host cell division. Viral DNA causes two different chromosomes to fuse, creating an oncogene from coding regions of two different genes. Viral DNA alters the DNA sequence of the proto-oncogene, creating a missense mutation. Viral promoter or enhancer sequences increase transcription of a nearby proto-oncogene.
Viral promoter or enhancer sequences increase transcription of a nearby proto-oncogene.
What is the inheritance pattern for a trait that more commonly affects males than females and can often be observed in brothers or fathers of a woman who has affected sons? Autosomal dominant Autosomal recessive X-linked dominant X-linked recessive
X-linked recessive
What is the inheritance pattern for a trait that more commonly affects males than females and can often be observed in brothers or fathers of a woman who has affected sons? Autosomal dominant X-linked dominant X-linked recessive Autosomal recessive
X-linked recessive
What is the inheritance pattern for a trait that more commonly affects males than females and can often be observed in brothers or fathers of a woman who has affected sons? X-linked dominant X-linked recessive Autosomal dominant Autosomal recessive
X-linked recessive
Two types of proteins that form activated complexes to promote a cell's progress through the cell cycle are ______. cyclins and cyclin-dependent protein kinases. cyclin-dependent protein kinases and RNA polymerase cyclins and tumor suppressors cyclins and transcription factors cyclin-dependent protein kinases and proteins encoded by proto-oncogenes
cyclins and cyclin-dependent protein kinases.
A single individual who first had a disease-causing allele is called a
founder
The ERBB2 receptor normally plays a role in promoting cell division. Cells from many breast cancer patients show an increase in the number of ERBB2 receptors available on the plasma membrane. The type of mutation that contributed to cancer development in these cases would be called a ______-of-function mutation in a(n) ______. gain; oncogene gain; tumor-suppressor gene loss; oncogene loss; tumor-suppressor gene
gain; oncogene
Which types of genetic changes can convert a proto-oncogene to an oncogene? gene amplification missense mutation covalent modifications of histones chromosomal translocation chromatin remodeling DNA methylation viral integration
gene amplification missense mutation chromosomal translocation viral integration
The goal of a ______ study is to find a relationship between one or more single-nucleotide polymorphisms (SNPs) and a disease or other human trait. genome-wide association HapMap Microarray preimplantation genetic
genome-wide association
Which of the following categories of proto-oncogenes would encode a product that would be released from one cell and would travel to and affect another cell? growth factor receptor growth factor transcription factor intracellular signaling protein
growth factor
Proto-oncogenes that can mutate into oncogenes fall into which of the following categories? growth factor receptors replication factors transcription factors genes encoding DNA repair enzymes intracellular signaling proteins growth factors
growth factor receptors transcription factors intracellular signaling proteins growth factors
The linkage of alleles or molecular markers along a single chromosome is called a ______. genetic variation haplotype phenotype diplotype
haplotype
An association between a disease-causing allele and nearby molecular markers can be established because ______. haplotypes do not usually change from generation to generation mutation rates are high in the vicinity of disease-causing alleles recombination occurs frequently between chromosomal sites that are close to each other
haplotypes do not usually change from generation to generation
A cancer cell is a cell that ______. divides more frequently than other cells, even though both types of cells have similar genetic compositions no longer divides because most of its genes have been silenced no longer divides because it receives fewer signals to initiate cell division has accumulated genetic changes that allow it to grow uncontrollably
has accumulated genetic changes that allow it to grow uncontrollably
Most individuals who are born with an inherited form of cancer susceptibility are ______ for a defect in a ______. heterozygous; proto-oncogene. homozygous; tumor-suppressor gene homozygous; proto-oncogene. heterozygous; tumor-suppressor gene
heterozygous; tumor-suppressor gene
The loss of function of a normal allele when the other allele for that gene was already inactivated is called ______. loss of recessiveness incomplete dominance loss of heterozygosity loss of dominance loss of homozygosity
loss of heterozygosity
Patients with the childhood kidney cancer called Wilms tumor show mutations in the AMER1 gene. This gene encodes the APC membrane recruitment protein 1 that regulates the Wnt intracellular signaling pathway involved with cell division. Functional copies of the AMER1 gene product can repress the pathway and prevent cells from growing and dividing in an uncontrolled way. The type of mutation that contributes to cancer development in Wilms tumor patients would be called a ______-of-function mutation in a(n) ______. loss; oncogene loss; tumor-suppressor gene gain; tumor-suppressor gene gain; oncogene
loss; tumor-suppressor gene
Tumor-suppressor genes normally act to ______. inhibit DNA repair speed up cell division promote mutation maintain genome integrity negatively regulate cell division
maintain genome integrity negatively regulate cell division
When a new mutation establishes a disease-causing allele in a family member, the allele's location can be traced through ______. a pedigree showing the descendants of the family member who gained the mutation recombination with a normal allele on the opposite homolog markers in a haplotype that are located nearby
markers in a haplotype that are located nearby
A checkpoint monitored by proteins that sense if a chromosome is not correctly attached to the spindle apparatus occurs during which stage of the cell cycle? G2 prophase metaphase anaphase S phase G1
metaphase
If the function of Rb protein is lost in a retinal cell, that cell is ______. stimulated to undergo apoptosis less likely to divide more likely to divide less prone to accumulating mutations unable to repair its DNA damage
more likely to divide
Li-Fraumeni syndrome is an inherited tendency toward cancer development that relates to changes in the tumor-suppressor protein p53. A common change is the substitution of tryptophan for arginine at position 248 in the amino acid sequence. This is an example of inactivating a tumor-suppressor gene through ______. aneuploidy chromosomal translocation methylation of cytosines near the gene's promoter region mutation
mutation
An oncogene is formed when a proto-oncogene gains a ______. deletion that causes it to produce an inactive protein mutation that causes its expression to be abnormally active promoter mutation that prevents transcription of the coding region mutation that reduces its expression by 50%
mutation that causes its expression to be abnormally active
a(n) __ is a mutant gene that is overexpressed and contributes to cancerous growth.
oncogene
Cancerous growths are clonal in origin because cancer cells ______. can form a tumor that is localized only at one site can migrate to other areas of the body and form secondary tumors at the new sites can invade healthy tissues originate from a single cell that has accumulated genetic changes during cell division
originate from a single cell that has accumulated genetic changes during cell division
A wide spectrum of tumors develops with Li-Fraumeni syndrome, due to the inheritance of a mutated version of the tumor-suppressor gene rb ADA NF1 BRCA-1 p53
p53
Which gene plays a significant role in detecting DNA damage in a cell? myc p53 rb e2f ras
p53
Which gene stimulates the expression of p21 to slow progress through the cell cycle when DNA damage is detected? myc p53 ras rb e2f
p53
A normal, nonmutated gene that has the potential to become an oncogene is called a ___ -oncogene.
proto
Tumor-suppressor genes whose normal gene products negatively regulate cell division are ______. rb BRCA-1 p53 p16
rb p16
The binding of a specific cyclin and cyclin-dependent protein kinase forms an activated protein complex that ______. regulates a cell's progress through the cell cycle digests cellular proteins in a cell that has accumulated significant DNA damage stimulates mutations that promote cell division repairs double-stranded DNA breaks provides a signal for programmed cell death
regulates a cell's progress through the cell cycle
During the 1970s, researchers discovered the src gene, an example of an oncogene named for causing the type of cancer called
sarcoma
When a defect in a single gene causes a human disease, the mutant gene often follows ______. complex inheritance patterns that cannot be easily studied epigenetic inheritance patterns simple Mendelian inheritance patterns
simple Mendelian inheritance patterns
The first example of an oncogene, called ______, was discovered as a cause of sarcoma in studies using chicken fibroblast cells. ras c-myc abl raf src
src
The p53 protein functions as an activator of
transcription
