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A translocation may lead to cancer if it
moves genes from one chromosome to another.
compacting the chromatin of one of their X chromosomes allows them to inactivate it and produce the same amount of gene product as a male.
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?
A positive genetic test for telomerase indicates that
a cell is probably cancerous.
Cancer will occur if one copy of a mutant tumor suppressor gene is inherited.
Prokaryotes do not regulate gene expression at the level of DNA transcription.
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.
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 ________.
Why do adult stem cells currently have fewer uses in therapeutic cloning than embryonic stem cells?
Embryonic stem cells may become any type of cell, whereas adult stem cells may only become a limited number of cell types.
do not undergo apoptosis
to force the cells into G0 stage so that the nuclei removed from them will respond to cytoplasmic growth signals
Cells from the root of a carrot may be used to generate an entire carrot plant. This illustrates that
histones still block the binding of RNA polymerase to the promoter.
A point mutation in the operator of the lac operon would most likely cause
The protein derived from a particular gene is different in a neuron than in a muscle cell. This is most likely due to
alternative mRNA processing.
Specialized cells differ from one another because
d. transcription activators slow transcription, while transcription factors accelerate transcription.
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.
In eukaryotes, one gene may specify the construction of several proteins.
Histone displacement is necessary for transcription to occur in euchromatin.
A woman inherits a mutant BRCA1 allele from her mother. She has an increased risk of developing breast cancer because
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.
Heterochromatin differs from euchromatin in that heterochromatin
b. is transcriptionally inactive.
What would be the most likely result on the regulation of the lac operon from a non-functional repressor protein?
transcription of the lactose metabolizing genes, even when lactose is absent
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?
The cell no longer responds to signals that cause it to stop dividing or undergo apoptosis.
If cells of a tumor have faulty, non-functional proteinase, they will be unable to undergo which of the following processes?
Prokaryotes cannot regulate gene expression at which of the following levels?
alternative mRNA processing and chromatin compaction
Which of the following series of events is in the correct order?
chemical binds to receptor, signal transduction pathway stimulates transcription activator, target gene is transcribed and translated
In prokaryotes, an operon includes
In the absence of lactose,
the repressor binds to the operator, and the genes of the lac operon are not transcribed.
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.
An embryo produced by in vitro fertilization (IVF) may be tested for genetic disorders prior to implantation. How is this accomplished?
A single cell is removed from a 6 to 8-celled embryo, and its DNA analyzed with a DNA microarray.***Removing a single cell from an embryo at the 6 to 8-cell stage does not damage the embryo, and allows testing. Since only a single cell is removed, PCR is necessary to obtain enough DNA for genetic analysis.
A missing piece of chromosome 5 may result in a child whose glottis and larynx do not develop properly resulting in an abnormal cry. This is called ________.
Cri du chat syndrome
***Cri du chat, or "cat's cry" syndrome, is caused by a deletion of the end piece of chromosome 5.
Which one of the following diseases or disorders has not been treated using gene therapy methods?
cri du chat syndrome
***Cri du chat syndrome is caused by a deletion on chromosome 5. Scientists currently do not understand which deleted genes would be necessary for treatment. Furthermore, most of the symptoms arise from abnormal embryonic development, and it is not currently possible to use gene therapy at this early stage of development.
A child can show a genetic disorder even if neither parent has the disorder.
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.
Defective chloride ion channels in the plasma membrane cause thick mucus of tissues lining the airways and parts of the digestive system. This is an inherited disorder called ________.
Most cases of cystic fibrosis are caused by defects in the movement of chloride ions through channels in the plasma membrane, causing the accumulation of thick mucus that causes breathing difficulties and digestive symptoms.
What are the current known methods of delivering genes to cells for gene therapy?
viruses, liposomes, and nasal sprays
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 translocation chromosomal mutation is the exchange of segments between two homologous chromosomes.
A parent has a deletion on one homologue of a pair of chromosomes. What is the probability of this individual's child carrying the same deletion?
***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.
viral DNA in an individual's cells.
***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.
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.
It is not always possible to determine an individual's genotype from a pedigree. Likewise, it is not always possible to determine the mode of inheritance of a trait from a pedigree. Pedigrees do, however, document family histories of genetic traits, and the exhaustive analysis of pedigrees for the same genetic trait often yield useful information regarding the trait's mode of inheritance.
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