The ability of a population of fibroblasts to migrate along the surface of a tissue culture dish depends on adhesion between the cell surface and the extracellular matrix molecules coating the dish. The dish is coated with laminin, and the only cell-surface protein capable of binding laminin is a cell-adhesion protein called an integrin. Integrins are integral plasma-membrane proteins that function as heterodimers. Under these conditions the rate at which a fibroblast can migrate along the laminin coated culture dish is proportional to the strength of adhesion between the cell and the laminin substrate. The table below lists the rate of cell migration observed for fibroblasts genetically engineered to generate the indicated phenotypes.

 Which of the following is the most likely explanation for failure of overexpression of the integrin alpha subunit to alter the rate of fibroblast migration?

#Question id: 1000

#Unit 1. Molecules and their Interaction Relevant to Biology

 Which of the following is (are) true of the B oxidation of long-chain fatty acids?

1. The enzyme complex that catalyzes the reaction contains biotin.

2. FADH2 serves as an electron carrier.

3. NADH serves as an electron carrier.

4. Oxidation of an 18-carbon fatty acid produces six molecules of propionyl-CoA.

5. Oxidation of a 15-carbon fatty acid produces at least one propionyl-CoA.

#Question id: 1001

#Unit 1. Molecules and their Interaction Relevant to Biology

The following fatty acid, in which the indicated carbon is labeled with ¹⁴C, is fed to an animal:  ¹⁴CH₃(CH₂)₉COOH After allowing 30 minutes for fatty acid B oxidation, the label would most likely be recovered in:

#Question id: 1002

#Unit 1. Molecules and their Interaction Relevant to Biology

What would be the product of the transamination of the structure shown below? (The unionized forms are shown.)

#Question id: 1003

#Unit 1. Molecules and their Interaction Relevant to Biology

The glucose-alanine cycle provides ________.

#Question id: 1004

#Unit 1. Molecules and their Interaction Relevant to Biology

Which structure below is PRPP?

#Question id: 1005

#Unit 1. Molecules and their Interaction Relevant to Biology

The first step in the de novo biosynthesis of IMP is a reaction between glutamine and PRPP. Which statement is not true about this reaction?