#Question id: 7261
#Unit 5. Developmental Biology
The Turing model provides a framework for limb development. Following statements are regarding to this model:
A. In Turing’s model, morphogen A promotes the production of more morphogen A (autoactivation) as well as production of morphogen I. Morphogen I, however, inhibits the production of morphogen A (lateral inhibition).
B. In Turing’s model, morphogen A inhibits the production of more morphogen A (autoinhibition) as well as production of morphogen I. Morphogen I, however, promotes the production of morphogen A (lateral activation).
C. In Turing’s model, the reaction-diffusion dynamics can tell us how the limb bud acquires its proximal- distal polarity as well as how the number of digits is regulated at the distal tip of the limb.
D. The reaction-diffusion system has been proposed to be sufficient for establishing patterns of precartilage and noncartilage tissues.
E. According to this model, along the proximal-distal axis the AER dividing into two domains 1-the inhibitory domain 2-the active domain.
F. According to this model, along the proximal-distal axis the AER dividing into three domains 1-the inhibitory domain 2-the active domain 3-frozen domain.
Which of the following combinations are incorrect?
#Question id: 4096
#Unit 3. Fundamental Processes
The lambda repressor binds as a dimer to critical sites on the bacteriophage lambda genome to keep the lytic genes turned off, which allows the bacteriophage lambda genome to be maintained as a silent resident in the bacterial genome. Each molecule of the repressor consists of an N-terminal DNA-binding domain and a C-terminal dimerization domain. Upon induction (for example, by irradiation with ultraviolet light), the genes for lytic growth are expressed, bacteriophage lambda progeny are produced, and the bacterial cell lyses to release the viral progeny. Induction is initiated by cleavage of the lambda repressor at a site between the DNA-binding domain and the dimerization domain. In the absence of bound repressor, RNA polymerase initiates transcription of the lytic genes, triggering lytic growth.
A. Binding as monomers will be sufficiently weak that they do not compete with the binding of RNA polymerase. As a result, the genes for lytic growth will be turned on.
B. Binding as monomers will be sufficiently strong that they will compete with the binding of RNA polymerase. As a result, the genes for lysogenic growth will be turned on
C. The affinity of the dimeric lambda repressor for its binding site is the sum of all the interactions made by each DNA-binding domain. An individual DNA-binding domain will make just half the contacts and provide just half the binding energy as the dimer.
D. The affinity of the dimeric lambda repressor for its binding site is the sum of all the interactions made by each DNA-binding domain. An individual DNA-binding domain will make just double the contacts and provide just double the binding energy as the dimer.
Given that the number (concentration) of DNA-binding domains is unchanged by cleavage of the repressor, which of above outcomes will be possible?
#Question id: 12613
#Unit 10. Ecological Principles
#Question id: 4227
#Unit 3. Fundamental Processes
Which of the following statements supports the one gene-one enzyme hypothesis?
#Question id: 10973
#Unit 7. System Physiology – Animal
An 11-year-old premenstrual female presents with a painful knee after mild trauma. Upon further evaluation you observe soft tissue bruises. The child is an orphan and there is no family history. The foster mother reports no other problems. The aPTT is prolonged and the PT is normal. A complete hematologic workup would yield