Genetics Chapter 24, 25
Select observations that are consistent with a disease having a genetic basis.
* A person with a disease is more likely to have genetic relatives with the disease than are people in the general population. * There is a correlation between a human disease and a mutant gene or chromosomal alteration. * Identical twins share the disease more often than non-identical twins. * Different populations tend to have different disease frequencies. * A human disorder may resemble a disorder known to have a genetic basis in animals. * The disease has a characteristic age of onset. * The disease doesn't spread to individuals sharing similar environmental situations.
Select the human disorders that are inherited in an autosomal recessive fashion
* Phenylketonuria Sickle cell disease Cystic fibrosis
Place the steps by which a cloned gene is transferred into human cells using a retroviral technique in order, with the first step at the top.
1. A gene of interest is placed into a viral vector. 2. The virus is taken up by cells via endocytosis 3. The viral coat disassembles, releasing the viral genome into the cytosol. 4. The genome is reversed-transcribed into DNA 5. The viral CNA is imported into the nucleus. 6. The gene of interest is integrated into a chromosome of the target cell by recombination.
Which disease is characterized by genetic changes that lead to uncontrolled cell growth?
Cancer
Which method can identify genes that are active in cancer cells but inactive in normal cells?
DNA microarray analysis
A disease with a genetic origin in a mouse is unlikely to be an inherited disease in humans.
False
What tool do scientists use to follow a human pattern of inheritance from generation to generation?
Pedigree analysis
A method for obtaining fetal cells in a sample of the fluid surrounding the fetus is called ______.
amniocentesis
A small portion of the fetal part of the placenta is removed to prepare a karyotype in the process called ______.
chorionic villus sampling
A single individual who first had a disease-causing allele is called a
founder
The first individual who carried a disease called allele is called a ______.
founder
A dominant genetic disorder can be caused by a ______ mutation, where the product of an altered gene gains a new or abnormal function.
gain-of-function
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
A normal, nonmutated gene that has the potential to become an oncogene is called a -oncogene.
proto
The International HapMap Project is an effort to identify differences in human DNA sequences by identifying ______.
single-nucleotide polymorphisms
In a genome-wide association study, the goal is to identify ______ which show a significantly different frequency between a control group and a group of individuals affected by a specific disease.
single-nucleotide polymorphisms (SNPs)
Pharmacogenetics is the ______.
study of genetic variations that cause differing responses to drugs
To study the distribution of disease-causing genes, genetic ______ refers to determining if an individual carries the faulty gene, while genetic ______ relates to assessing the presence of the gene throughout a population.
testing; screening
Gene is the introduction of cloned genes into somatic cells to treat disease.
therapy
The autosomal recessive human disorder albinism (type I) is caused by a mutation in the gene for ______.
tyrosinase
Scientists have been working on reducing the inflammatory response evoked by vectors, to improve the safety of gene therapy.
viral
Which of the following characteristics of inheritance for hemophilia can be observed in the accompanying partial pedigree for the family of Queen Victoria and Prince Albert?
* Males are more likely to be affected than females. * Mothers of affected males often have brothers with the disease.
Personalized medicine can be used to select a ______.
* medication * therapy * preventative measure
Place the steps by which a cloned gene is transfered into human cells via liposomes in order, with the first step at the top.
1. The DNA containing the gene of interest is complexed with liposomes. 2. DNA liposome complexes are taken ton cells via endocytosis. 3. DNA is released into the cytosol. 4. DNA is imported into the nucleus. 5. DNA is integrated into a chromosome of the target cell recombination.
Which best describes a haplotype?
A haploid genotype showing linkage of alleles or molecular markers along a single chromosome
The accompanying pedigree shows the inheritance of Huntington disease with filled symbols and also indicates which combination of four possible forms (A, B C, D) of a molecular marker called G8 that the person has inherited. Although there are some exceptions, the inheritance of Huntington disease is most closely associated with which form of the G8 marker in this pedigree?
C
Dizygotic twins share a genetic disease more frequently than monozygotic twins.
False
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
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
Consider the accompanying partial pedigree showing inheritance of hemophilia in the family of Queen Victoria and Prince Albert. If Xh is the allele for hemophilia and XH is the allele for normal blood clotting, which genotypes are missing among the children of Alice of Hesse and her husband, in the middle of the figure?
XHXH XHY
DNA microarrays can be used to ______.
compare gene activity in cancer cells and normal cells
The linkage of alleles or molecular markers along a single chromosome is called a ______.
haplotype
The odds ratio is the odds of ______ a disease for individuals carrying a specific SNP versus the odds of ______ a disease for individuals not carrying the same SNP.
having; having
Chorionic villus sampling is a procedure for ______.
obtaining a sample of the fetal part of the placenta
Amniocentesis is a procedure for ______.
obtaining fetal cells in a sample from the fluid surrounding the fetus
One form of severe combined immune deficiency disease (SCID) is caused by inheriting two defective copies of the ______ gene that encodes an enzyme involved in purine metabolism crucial to the maintenance of healthy immune system cells.
ADA
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
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 a trait occurs with the same frequency in both sexes and an affected offspring can have two unaffected parents?
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
A worldwide effort to identify human genetic variation observed for SNPs and other variants is called the International Project.
HapMap
What types of human diseases are the most straightforward targets for gene therapy?
Inherited diseases involving a single gene abnormality
Which statement is true of X-linked dominant disorders such as Rett syndrome and Aicardi syndrome?
Males die at an early stage of development
Select treatments for patients with adenosine deaminase (ADA) deficiency.
PEG-ADA treatment Gene therapy Bone marrow transplant
Which of these is a common example of widespread genetic screening of newborns to identify certain disorders?
Test for excess phenylalanine indicating phenylketonuria (PKU)
Approximately how many human diseases have a genetic basis?
Thousands
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
Identical twins share a genetic disease more often than fraternal twins.
True
Consider the children of II-6 and II-7 in the accompanying pedigree for a family affected by Tay-Sachs disease. What is one genotype that could have been produced by these two parents but was not observed?
Unaffected homozygote
In which way are viruses used for gene transfer different from their wild-type counterparts?
Viruses used in gene transfer cannot replicate within target cells.
Chemicals in the environment that cause cancer are called ______.
carcinogens
An advantage of using liposomes as vectors to transfer cloned genes is that liposomes ______.
do not elicit an immune response
Preimplantation genetic diagnosis is a method testing for genetic diseases in ______.
embryos produced by in vitro fertilization
A carcinogen is a(n) ______.
environmental agent that causes cancer
Genetic testing is used to determine whether a(n) ______ has a disease-causing gene, while genetic screening is used to determine how frequently the gene is found in a(n) ______.
individual; population
The most common nonviral technique to transfer a cloned gene into human cells involves lipid vesicles called
liposomes
A situation where a disease may be caused by mutations in two or more different genes is called ______.
locus heterogeneity
A prion is a disease-causing agent made ______.
only of protein
Cancerous growths are clonal in origin because cancer cells ______
originate from a single cell that has accumulated genetic changes during cell division
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 use of information about a patient's genotype in order to select a medication or therapy that is specifically suited to the patient is called
Blank 1: personalized Blank 2: medicine
A patient with ADA deficiency can be treated with a bone marrow , injections of purified enzyme coupled with polyethylene glycol, or gene
Blank 1: transplant Blank 2: ADA, adenosine deaminase, or adenosinedeaminase Blank 3: therapy
During the initial stage of cancer development, cells with a precancerous genetic change form a(n) ______.
benign growth
Genetic variation in the ability to metabolize the anticoagulant drug warfarin is shown by polymorphisms in the CYP2C9 gene, which encodes a liver enzyme called P450.
cytochrome
Patients taking the anticoagulant drug warfarin vary in the ability to metabolize the drug due to polymorphisms in the CYP2C9 gene that encodes a ______ expressed in the liver.
cytochrome P450 enzyme
When an experiment or treatment involves genetic manipulation outside of the body, followed by reintroduction into the body, it is called an ______ approach.
ex vivo
An invasive cancer cell ______
grows into the healthy tissue surrounding the tumor
The study of genetic variations that cause differing responses to drugs is called ______.
pharmacogenetics
Embryos produced by in vitro fertilization can undergo genetic testing by ______.
preimplantation genetic diagnosis
A malignant tumor ______.
* Can invade nearby healthy tissue * Can form secondary tumors after spreading to other locations * Has cells with cancerous mutations leading to uncontrolled growth
In the accompanying pedigree, a filled symbol indicates an individual with Huntington disease while a clear symbol shows an unaffected individual. Which of the following characteristics of inheritance can be observed for this affected family?
* An affected individual has at least one affected parent. * The trait occurs in both males and females.
Tay-Sachs disease is inherited with an autosomal recessive allele that leads to a defect in the enzyme hexosaminidase A. When cells are collected from patients, cells with different genotypes exhibit different amounts of enzymatic activity. Rank the amount of enzymatic activity that would be detected in a biochemical assay on cells from patients of these genotypes, with the genotype producing the LEAST amount of enzymatic activity on top.
Homozygous recessive Heterozygous Homozygous dominant
A dominant genetic disorder can be caused by ______, a situation where one functional copy of an allele is not sufficient to produce a normal phenotype.
haploinsufficiency
A major disadvantage of using liposomes as vectors to transfer cloned genes is ______.
low gene transfer efficiency
The process of identifying the genes that play a role in the development of a specific type of cancer is called ______.
molecular profiling
Simple Mendelian inheritance is a pattern observed when a human disorder is caused by ______.
mutation in a single gene
A disease-causing agent made only of protein is called a ______.
prion
To identify SNPs for which the frequency is significantly different between a control group and a group of individuals affected by a disease, a(n) is determined and its significance can be evaluated based on the calculation of a(n) value.
Blank 1: odds Blank 2: ratio Blank 3: P
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
A cancer cell is a cell that ______.
has accumulated genetic changes that allow it to grow uncontrollably.
In the accompanying pedigree, a filled symbol indicates an individual with Huntington disease while a clear symbol shows an unaffected individual. Considering the symbol for individual II-5, you conclude that her father, I-1 is ______ allele for Huntington disease.
heterozygous for the autosomal dominant
Molecular profiling is ______.
identification of the genes that play a role in the development of a specific type of cancer
A cancer cell can migrate to another part of the body and cause secondary tumors.
metastatic
When a human disease is caused by a mutation in a single gene, scientists follow the pattern of inheritance by analyzing charts called human
pedigrees
To conduct a genome-wide association study, the ______ of a large group of individuals who are afflicted with the same disease are compared to those of a large group of people without the disease.
single-nucleotide polymorphisms (SNPs)
The major disadvantage to using viral vectors to transfer cloned genes is ______.
the potential for an immune response
Which of the following factors related to proper dosing of drugs would tend to reduce the amount of drug available to provide effective therapy for the patient?
* Rate of excretion of drug from the body * Drug uptake and metabolism by the liver
Which factors determine the proper dose of a drug to prescribe for a patient?
* Ability of drug to be metabolized by the liver * Rate of transport of an orally-administered drug from the digestive tract into the bloodstream * Ability of drug to affect the function of a target protein * Rate of excretion of drug from the body * Rate of transport of the drug into cells where the it will have its effect
Which observations are consistent with a disease having a genetic basis?
* The sleep disorder called narcolepsy has been related to an allele for a faulty neural receptor in dogs. Some humans also suffer from narcolepsy. * A cancerous growth of immature nerve cells called neuroblastoma is associated with a deletion in a specific region of chromosome 11. * Tay-Sachs disease can occur in 1/2500 births in a specific eastern European population while the frequency is 1/250,000 across Europe.
Which of the following characteristics of inheritance can be observed in the accompanying pedigree of a family affected by Tay-Sachs disease?
* The trait occurs in both males and females. Affected individuals are offspring of heterozygous parents. An affected offspring can have two unaffected parents.
The accompanying pedigree shows the inheritance of Huntington disease with filled symbols and also indicates which combination of four possible forms (A, B C, D) of a molecular marker called G8 that the person has inherited. What is the one possible phenotype and marker combination that is missing among the children of the couple surrounded by the circle?
BB with Huntington disease
Suppose a disease-causing allele shows autosomal recessive inheritance. How could a carrier of this disease-causing allele be identified?
Carriers often show reduced activity for the enzyme encoded by the allele.
If both copies of the gene are defective, deoxyadenosine accumulates within the individual, which can lead to a severely compromised system.
Blank 1: ADA Blank 2: immune
Which observations are consistent with a disease having a genetic basis?
* One family in the neighborhood has one parent and several children with severe hearing loss. No one in any of the other nearby families has deafness. * Someone with a diagnosis of retinitis pigmentosa has learned that there are family members in the preceding three generations who had the disease. * Nephroblastoma is a cancer of the kidney that typically develops in children and is only rarely found in adults.
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
Blank 1: association Blank 2: study
A technique where genetic manipulations occur outside of the body, and then the products are reintroduced into the body is called a(n) approach.
Blank 1: ex Blank 2: vivo
Most cancer cells are descendants of an original cell that acquired genetic changes. Therefore, cancerous growths are considered to be ______ in origin.
clonal
What is the inheritance pattern for a trait that is more likely to occur in females when it is lethal to males?
X-linked dominant
