Tutor profile: Becky L.
The lac operon is an inducible operator, containing genes that code for proteins essential to the metabolism of lactose. When lactose is present and glucose is absent, which of the following explains the activity of the lac operon? A. no transcription B. medium transcription C. high transcription
C. high transcription Lactose is converted to allolactose, which binds to the repressor, which then is removed from the operator. This would allow transcription to occur. Another important factor here is cAMP levels, which are indirectly related to the level of glucose. The protein that cAMP binds to is CAP. When there is no glucose, there is lots of cAMP and CAP is binded. CAP increases transcription rates.
What are the skeletal muscle pump and respiratory pump, and how do they affect venous return to the heart?
The skeletal muscle pump refers to a group of muscles, primarily located in the calf muscles. When a person is standing upright, blood naturally flows downward due to gravity. When the muscles of the skeletal muscle pump are squeezed, it pushes the blood upward, back towards the heart, and positively affecting venous return to the heart. Valves in the veins prevent the blood from flowing backwards. When a person inhales, the result is an increase in volume and decrease in pressure in the thoracic cage. This leads to an increase in the pressure gradient, resulting in more blood flow (remember, flow = change in pressure / resistance). The use of the respiratory pump also increases venous return to the heart.
Solve the following: f(x)*g(x) Given: f(x)=x-5 g(x)=3x+2
Solution: (x-5)(3x+2) Use the FOIL strategy. F=first, O=outer,I=inner,L=last. Multiply terms based on this order. First, 3x^2. Outer and Inner, 2x-15x=-13x. Last, -10. Answer: 3x^2 - 13x - 10
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