An animal cell lacking carbohydrates on the external surface of its plasma membrane would likely be impaired in which function?

#Question id: 5130

#Unit 5. Developmental Biology

Regulation by gradients of paracrine factor concentration was elegantly demonstrated by the specification of different mesodermal cell types in the frog Xenopus laevis by activin, a paracrine factor of the TGF-beta family. Which of the following observations are correct from this graph?

#Question id: 32403

#Unit 1. Molecules and their Interaction Relevant to Biology

#Question id: 4107

#Unit 3. Fundamental Processes

Imagine that you have created a fusion between the Trp operon, which encodes the enzymes for tryptophan biosynthesis, and the Lac operon, which encodes the enzymes necessary for lactose utilization. Under which set of conditions (A–F below) will β-galactosidase be expressed in the strain that carries the fused operon?

A. Only when lactose and glucose are both absent.

B. Only when lactose and glucose are both present.

C. Only when lactose is absent and glucose is present.

D. Only when lactose is present and glucose is absent.

E. Only when tryptophan is absent.

F. Only when tryptophan is present.

#Question id: 439

#Unit 1. Molecules and their Interaction Relevant to Biology

The amount of energy recovered as ATP can be estimated by measuring free energy of hydrolysis of

#Question id: 19710

#Unit 3. Fundamental Processes