How can a mutation in a tumor-suppressor gene behave as a recessive allele at the cellular level, but appear as a dominant allele in pedigree analysis?
A) Some functional protein can still be produced in a cell heterozygous for a loss-of-function allele; however, an additional mutation can inactivate the second allele, eliminating all functional protein allowing cancer to occur in many family members.
B) A single functional allele is sufficient to regulate the cell cycle, but not sufficient to promote apoptosis, allowing cancer to develop in every generation.
C) A cell with half the amount of the functional tumor-suppressor protein can form benign tumors that will occur in every generation in the pedigree.
D) Some functional protein can still be produced in a cell heterozygous for a loss-of-function allele; but loss-of-function tumor-suppressor alleles are so common in the population that many individuals are homozygous.
A) Some functional protein can still be produced in a cell heterozygous for a loss-of-function allele; however, an additional mutation can inactivate the second allele, eliminating all functional protein allowing cancer to occur in many family members.
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Chronic myelogenous leukemia (CML) results from a translocation between human chromosomes 9 and 22. The resulting chromosome 22 is significantly shorter than usual, and it is known as a Philadelphia (Ph') chromosome
The junction at the site of the translocation causes overexpression of a receptor tyrosine kinase. A new drug (Gleevec or imatinib) has been found to inhibit the disease if the patient is treated early. Which of the following would be a reasonably efficient technique for confirming the diagnosis of CML? A) searching for the number of telomeric sequences on chromosome 22 B) looking for a Ph' chromosome in a peripheral blood smear C) enzyme assay for receptor tyrosine kinase activity D) fluorescent labeling to determine the chromosomal location of all chromosome 22 fragments E) identification of the disease phenotype in review of the patient's records
We refer to water as a solvent. Why do oil and water not mix then?
a. Oil cannot break the surface tension of water. b. Oil forms hydration shells around the water molecules. c. Water can only dissolve polar molecules and ionic compounds. Oils (lipids) are nonpolar. d. Water can only dissolve nonpolar compounds. Oils (lipids) are polar.
A sensillum is
a. a hollow hair-like tube characterized by a pore on the end and multiple chemoreceptor cells inside. b. located on the antennae, foot, or mouthparts of aquatic insects. c. a specialized smell receptor in invertebrates. d. common to earthworms, insects, and cnidarians. e. a type of taste receptor in vertebrates.
The allele for sickle cell anemia is maintained in populations by frequency dependent selection
_______________ Indicate whether the statement is true or false.