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Stem cells can be found in adults.
produces specialized cells to treat human disease
A protein that promotes apoptosis would be considered a
to force the cells into G0 stage so that the nuclei removed from them will respond to cytoplasmic growth signals
Inheritance of mutants forms of some genes may lead to a predisposition to develop cancer. Which of the genes listed below has not been linked to hereditary forms of cancer?
The unpacking of heterochromatin into euchromatin does not immediately result in DNA transcription because...
The protein derived from a particular gene is different in a neuron than in a muscle cell. This is most likely due to...
Proto-oncogenes function by preventing cells from dividing uncontrollably.
In the regulation of the lac operon, when lactose is present,
lactose binds to the repressor, making it unable to bind to the operator and allowing transcription to proceed
A point mutation in the operator of the lac operon would most likely cause
no binding of the repressor protein to the operator even when lactose is absent
A gain of function mutation in a tumor suppressor gene would not likely cause cancer because a tumor suppressor protein
does not promote cell division
If the maternal X chromosome is inactive and seen as Barr body in one cell, then it is the maternal X chromosome that is inactive and seen as a Barr body in every cell of that woman's body.
Cancer will occur if one copy of a mutant tumor suppressor gene is inherited.
A tumor suppressor gene undergoes a mutation that causes it to lose its normal function. What would be the most likely result of this mutation?
In the absence of lactose,
Embryonic cells and cancer cells are similar because
telomerase is active
Female mammals form Barr bodies because
A woman inherits a mutant BRCA1 allele from her mother. She has an increased risk of developing breast cancer because
a mutation in her normal BRCA1 allele may lead to cancer, whereas a normal individual would have to acquire two mutations (one in each allele) to develop cancer
In the absence of growth factors, the retinoblastoma (RB) protein binds a transcription activator called E2F, preventing the cell from entering S stage. A mutation in E2F occurs that causes RB to no longer bind it. This mutant E2F would be considered a
Which of the following reasons explains a possible advantage of using adult stem cells in therapeutic cloning rather than embryonic stem cells?
Adult stem cells may be obtained from the patient and would be less likely to be rejected by the patient's body
What would be the most likely result on the regulation of the lac operon from a non-functional repressor protein?
In pedigrees of autosomal dominant traits, every affected child must have at least one affected parent.
neither increase nor decrease the amount of genetic material in the cell
***An inversion occurs when a portion of a chromosome is turned 180°. Inversions are seldom deleterious, but in a few cases have been linked to changes in gene regulation and thus syndromes. Inversions may also result in gametes carrying abnormal chromosomes when the inverted chromosome undergoes crossing-over with the non-inverted homolog.
Chromosome 7 may lose an end piece resulting in Williams syndrome. This is an example of a…
***A deletion is a change in chromosomal structure in which a portion of the chromosome is lost. Thus, the mutation that results in Williams syndrome would be considered to be a deletion.
Amniocentesis may be preferred over chorionic villus sampling (CVS) for karyotyping because...
amniocentesis has a lower risk of miscarriage than CVS.
***Amniocentesis carries a lower risk of miscarriage, 0.3%, as compared to chorionic villus sampling, 0.8%.
Mutant gene alleles associated with known genetic disorders can be detected using DNA microarray analysis.
A mutation in a gene that causes the protein to acquire an abnormal activity, such as aggregating within the cell, will usually cause a dominant inherited disorder.
Some chromosomal abnormalities, such as Down syndrome and Edwards syndrome, and a few other known inherited disorders.
***Most genetic disorders that cause noticeable anatomical anomalies may be detected by ultrasound, if these anatomical differences are evident during fetal development. Most mutations, including smaller chromosomal mutations, are not evident by this method, but it is useful in diagnosing many of the more severe problems.
A man carrying a translocation may appear normal, but runs the risk of having children with a syndrome because his children...
may inherit one abnormal chromosome with one normal one from the father, and would carry a deletion or duplication
***The risk with a translocation is that unless both abnormal chromosomes are inherited, the translocation becomes unbalanced. This means that there will be missing genes from one chromosome and duplicated genes from another.
If a man has an X-linked recessive disorder, then his daughters...
will be carriers for the disorder
***Since a female child inherits one X chromosome from her mother and her father's X chromosome, all female children of this man will be carriers of the disorder.
Which mode or modes of inheritance are possible for the pedigree shown here?
autosomal dominant, autosomal recessive, or X-linked dominant
***The only mode of inheritance that can be ruled out is X-linked recessive, because there would be an affected daughter with an unaffected father. This is not possible for that mode of inheritance. All others are possible.
A child with bluish-purple skin is found to lack the enzyme diaphorase and is subsequently diagnosed with which genetic disorder?
***Methemoglobinemia is an autosomal recessive disorder that results in a defective version of the enzyme diaphorase that is unable to clear methemoglobin from the blood, resulting in a bluish-purple color to the skin.
could be autosomal recessive or X-linked recessive
***The trait in the pedigree cannot be autosomal dominant because there is an individual with the trait who has two unaffected parents. Likewise, the trait cannot be X-linked dominant because the affected male on the bottom row would have to have a mother that exhibits the trait as well, since a male receives his X-chromosome from his mother. Thus, the trait is recessive, but both X-linked recessive and autosomal recessive are possible.
***Both parents would have the genotype aa, and thus all of their children would be unaffected by the trait. By definition, none of the children of two unaffected parents will exhibit an autosomal dominant disorder.
17. You are a genetic counselor, and a man with the translocation shown in the figure is your client. He and his partner (who has a normal karyotype) wish to have children. You explain to him that the probability of having a child with a normal karyotype is _______.
***By the law of segregation, either chromosome of the first pair may be passed into a gamete with either chromosome of the second pair. Thus, if all four possible gametes that could result are drawn out, there is one possible gamete out of four that would contain both normal chromosomes, so there is a 25% chance of having a child with a normal karyotype.
A person with familial hypercholesterolemia is participating in an ex-vivo gene therapy trial. The procedure involves…
removing a piece of the person's liver, infecting it with a retrovirus containing the normal cholesterol receptor gene, and replacing it after treatment
***Ex vivo gene therapy refers to gene therapy in which the genetic manipulation of the cells occurs outside of the body, and the cells then returned to the patient. Thus, removal of a piece of the liver, treatment outside the body, then replacement of the liver in the patient would be a likely treatment protocol.
Which of the following syndromes is caused by a translocation?
***Alagille syndrome results when chromosomes 2 and 20 exchange segments. This type of change in chromosomal structure is referred to as a translocation. Note that no DNA has been lost, only that the two segments have swapped locations.
***Each gamete will contain one chromosome from each homologous pair; thus, half of the gametes will be normal, and half of the gametes will contain the abnormal chromosome.
Chorionic villus sampling (CVS) may be preferred over Amniocentesis for karyotyping because….
a larger amount of tissue may be taken, allowing the results to be obtained more quickly.
***The primary advantage of CVS is that a larger amount of tissue can be taken. Thus, there is no need to culture enough cells for karyotyping, and the results are usually available within a few days rather than a few weeks.
A DNA microarray detects...
mutant gene alleles associated with disease
***DNA microarrays use DNA probes to detect known disease-associated gene alleles. Since not all mutations that an individual may possess have been characterized, and since many of these mutations do not lead to disease, they would not be detected by a DNA microarray.
banding patterns, size, and shape***The chromosomes are sorted by size and shape, and the banding patterns obtain with Giemsa stain (a procedure called "G-banding") help to identify chromosomes that are similar in size and shape.
A man has an X-linked dominant genetic disorder. If he has a daughter with an unaffected woman, what is the probability that the daughter will inherit the disorder?
100%***Daughters inherit their father's X chromosome. Since the daughter's father exhibits the trait, she will exhibit the trait as well.
an individual's complete genotype, including mutations.
***An individual's genotype for all known genes, including any mutations the individual possesses, is known as a genetic profile. The genetic profile can be useful in fostering a better lifestyle in order to minimize the risk of disease that the individual may face.
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