Genetics test 4
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 protein is expressed in a cell type where it is not normally found. - The amount of protein produced from the oncogene is significantly increased. - The structure of the protein is altered so that it is overly active.
A malignant tumor ______.
- can invade nearby healthy tissue - has cells with cancerous mutations leading to uncontrolled growth - can form secondary tumors after spreading to other locations
In a normal distribution, what percentage of all individuals have phenotypic values within one standard deviation of the mean?
68%
If a population fits a normal distribution, then what percentage of individuals have phenotypic values within two standard deviations above or below the mean?
95%
Which best describes a haplotype?
A haploid genotype showing linkage of alleles or molecular markers along a simple chromosome
Tumor-suppressor genes whose normal gene products help maintain genome integrity are ______.
BRCA-1, p53
Which field of genetics involves the statistical study of biological traits?
Biometrics
Ras protein is in its active form when it is bound to ______.
GTP
Which type of growth has cells that can invade other tissues and migrate to other areas of the body to form secondary tumors?
Malignant growth
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?
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.
In which two ways have tumor-suppressor genes been shown to act within cells?
Regulating the rate of cell division and maintaining genomic integrity
Examples of quantitative traits
Speed of flight in birds, blood pressure in humans, number of bristles in Drosophila
Which change from proto-oncogene to oncogene occurred by a missense mutation?
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.
What is the focus of the biometric field of genetics?
The statistical study of biological traits
Cancer can result from inactivation of which type of gene?
Tumor-suppressor gene
How many genes control hull color in bread wheat?
Two
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.
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 recessive
Uncontrolled cell division may result from ______.
a decrease in the expression of tumor suppressor genes
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?
autosomal dominant
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
During the initial stage of cancer development, cells with a precancerous genetic change form a(n) ______.
benign growth
When a proto-oncogene is converted to an oncogene, which pattern of inheritance is usually observed for the mutated allele?
dominant
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
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
An invasive cancer cell ______.
grows into the healthy tissue surrounding the tumor
A signaling molecule that can promote division of cells throughout the body of a multicellular organism is called a(n) ______.
growth factor
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
The linkage of alleles or molecular markers along a single chromosome is called a ______.
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
A cancer cell is a cell that ______.
has accumulated genetic changes that allow it to grow uncontrollably
For a particular population in a particular environment, the fraction of phenotypic variance that is due to genetic variance is called
heritability
A cancer-causing change occurs when a tumor-suppressor gene is ______.
inactivated
When a cancer cell grows into surrounding healthy tissue nearby, it is described as ________.
invasive
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 ______.
locus heterogeneity
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; tumor-suppressor gene
Tumor-suppressor genes normally act to ______.
maintain genome integrity and 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 ______.
markers in a haplotype that are located nearby
The sum of all of the values of a parameter within a group divided by the number of individuals in the group is defined as the ______.
mean
A _________ cancer cell can migrate to another part of the body and cause secondary tumors.
metastatic
When cancer cells migrate to other parts of the body and cause secondary tumors, they are described as ______.
metastatic
Most carcinogens, such as UV light and specific chemicals in cigarette smoke, are ___________ that promote genetic changes in somatic cells.
mutagens
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 ______.
mutation
A frequency distribution is a graph that shows the ______.
number of individuals in various phenotypic categories
Cancerous growths are clonal in origin because cancer cells ______.
originate from a single cell that has accumulated genetic changes during cell division
Which gene plays a significant role in detecting DNA damage in a cell?
p53
When phenotypic variance is determined solely by genotypic and environmental variance, and genetic and environmental factors are independent of one another, then total phenotypic variance is equal to genetic variance __________ environmental variance.
plus
Quantitative traits tend to show a continuum of variation because they are usually __________, meaning that they are controlled by multiple
polygenic
Heritability is a measurement of the ______.
proportion of phenotypic variance due to genetic variance
A normal, nonmutated gene that has the potential to become an oncogene is called a ________-oncogene.
proto
An oncogene is formed by mutation that increases the expression of a normal gene called a(n) ______.
proto-oncogene
Which type of gene has the potential to become an oncogene?
proto-oncogene
The length of an ear of corn is an example of a(n) _____ trait. Multiple choice question.
quantitative
Approximately how many human diseases have a genetic basis?
thousands
The region of the p53 protein that corresponds to its main function is the ______ domain.
transcriptional activation
The standard deviation of a data set is equal to the square root of the ______.
variance
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?
x-linked recessive
Proto-oncogenes that can mutate into oncogenes fall into which of the following categories?
- growth factors - transcription factors - growth factor receptors - intracellular signaling proteins
Which types of genetic changes can convert a proto-oncogene to an oncogene?
- missense mutation - gene amplification - chromosomal translocation - viral integration
Which is the correct order of events in the normal pathway by which growth factors stimulate cell division?
1. A growth factor binds to a specific receptor on the surface of a cell. 2. A signal transduction pathway activates intracellular proteins to amplify the signal. 3. Genes coding for proteins that control cell division are activated
To stimulate the growth of epidermal cells, such as skin cells, which event would occur first?
An epidermal growth factor, EGF, binds to a receptor on the surface of a skin cell.
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
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 ______.
a missense mutation
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
In the development of retinoblastoma, a retinal cell is more likely to divide if ______.
both copies of the rb gene are inactivated
Which disease is characterized by genetic changes that lead to uncontrolled cell growth?
cancer
Chemicals in the environment that cause cancer are called ______.
carcinogens
Most cancer cells are descendants of an original cell that acquired genetic changes. Therefore, cancerous growths are considered to be ______ in origin.
clonal
Characteristics that are determined by several genes and are also influenced by environmental factors are called _______ traits.
complex
Quantitative traits are ______.
controlled by multiple genes
The tumor-suppressor gene p53 has a significant role in ______.
detecting DNA damage in a cell
An oncogenic allele typically shows a ________ pattern of inheritance due to a gain-of-function mutation in a proto-oncogene.
dominant
A carcinogen is a(n) ______.
environmental agent that causes cancer
True or false: A disease with a genetic origin in a mouse is unlikely to be an inherited disease in humans.
false
A graph that presents phenotypic categories on the x-axis and the number of individuals that fall into a category on the y-axis is called a(n) _________ distribution.
frequency
A benign tumor is a(n) ______.
localized growth with a precancerous genetic change
The chromosomal location of one or more genes that influence a quantitative trait is called a quantitative trait
locus
A situation where a disease may be caused by mutations in two or more different genes is called ______.
locus heterogeneity
The majority of carcinogens promote cancer development by increasing the rate of ______ in somatic cells.
mutation
Simple Mendelian inheritance is a pattern observed when a human disorder is caused by ______.
mutation in a single gene
An oncogene is formed when a proto-oncogene gains a ______.
mutation that causes its expression to be abnormally active
Four types of genetic changes that can convert a proto-oncogene to an oncogene are missense ________ , gene _________, chromosomal ____________ and _______ integration.
mutation; amplification; translocation; viral
A mutant gene that is overexpressed and contributes to cancerous growth is called a(n) ______.
oncogene
A(n) __________ is a mutant gene that is overexpressed and contributes to cancerous growth.
oncogene
A cancer-causing mutation in the ras gene leads to an altered Ras protein that ______.
remains bound to GTP
The p53 protein functions as an activator of _________
repair
A complex trait is a trait that is influenced by ______.
several genes and the environment
A growth factor is a ______.
signaling molecule that can stimulate cells throughout the organism's body to divide
When a human disease is caused by a mutation in a single gene, the pattern of inheritance is called __________ Mendelian inheritance.
simple
When a defect in a single gene causes a human disease, the mutant gene often follows ______.
simple Mendelian inheritance patterns
The square root of the variance is equal to the ______________ _____________of a data set.
standard deviation
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
Which type of gene normally prevents cancers but can allow cancerous growth when mutated?
tumor-suppressor gene
In bread wheat, the color of the hull can be dark red, white, or various intermediate shades of red. Genetic analysis of this trait has demonstrated that it is controlled by ______.
two loci with additive effects on hull color
The AMER1 gene encodes 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. Mutations in the AMER1 gene are observed in childhood kidney cancer and in breast, stomach and colon cancers in adults. The type of mutation that contributed to cancer development in these cases would be called a ______-of-function mutation in a(n) ______.
loss; tumor-suppressor gene
_________ promote cancer by increasing transcription of genes that regulate cell division.
oncogenes
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?
Autosomal dominant
