You and a friend are student assistants in a research laboratory that investigates the anticancer properties of proteins isolated from marine organisms. Your friend mentions that she is using a BAC vector to insert shark DNA into Escherichia coli, but after repeated attempts, has found that the bacterial cells fail to synthesize the encoded protein. What is your advice?
A. If the shark DNA is unmodified, it contains introns that are not recognized by bacteria, therefore protein synthesis will not occur.
B. Because Escherichia coli is not naturally competent, it cannot serve as the cloning host for foreign DNA.
C. Since shark DNA is eukaryotic, the cloning vector should be a YAC derived from yeast rather than a BAC derived from bacteria.
D. It is impossible to clone eukaryotic DNA into a bacterial host, since eukaryotic DNA has introns and prokaryotic DNA does not.
Answer: A
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In common English, "linkage" refers to one event that tends to occur when another does. In genetics, linkage has a precise meaning. It refers to the transmission of
A) two genes that have the same effect. B) two genes on different chromosomes. C) two genes on the same chromosome. D) genotype and phenotype to an offspring.
Endosymbiosis is an evolutionary theory that explains the origin of eukaryotes and suggests a specific order in which this might have occurred. Ancestral cells engulfed and then began to use the metabolic processes of the smaller cells
Based on shared core processes and features, which statement most accurately describes the order, the theory and the evolutionary implications for all organisms within domain Eukarya? A) Ancestral heterotrophic eukaryotes most likely engulfed both a heterotrophic and an autotrophic prokaryote, whereas ancestral photosynthetic eukaryotes probably provided the host cell for the first mitochondria. Over time, natural selection favored these relationships and these cells became ancestors of all eukaryotes. B) All ancestral eukaryotes would have most likely consumed a nucleus-like prokaryote that eventually became the eukaryotic nucleus. These new eukaryotic cells would have had an advantage over prokaryotic cells by acquiring a nuclear command center for regulating cellular activities. C) As carbon dioxide levels were increasing over time, natural selection would have favored organisms that acquired a photosynthetic prokaryote to convert carbon dioxide into sugars. These would have likely been the first eukaryotic cells. At which point, these ancestral cells engulfed mitochondria-like prokaryotes that would have provided an even greater advantage for cells in this environment. D) As Earth was becoming more aerobic, mitochondria would have provided an advantage to host cells by converting "toxic" oxygen into energy for heterotrophic cells. Since mitochondria are found in all eukaryotes, these combinations likely evolved first. Photosynthetic eukaryotes probably acquired an autotrophic prokaryote, which developed an advantageous symbiotic relationship with the host cell.
Which of the following does NOT describe the autonomic nervous system?
A) Neurons release norepinephrine or acetylcholine onto their target organ. B) It is subdivided into sympathetic and parasympathetic divisions. C) It regulates heart rate. D) It controls voluntary movements. E) It forms synapses with smooth muscles in blood vessels.
E = unattached earlobes. e = attached earlobes. In the cross of Ee and Ee, the chance of a child with unattached earlobes is _____.
a. 3/4 b. 1/4 c. 1/2