Movement of molecular oxygen (O2) and carbon dioxide (CO2) across the cell membrane Choose one: A. occurs only unidirectionally, such that oxygen is allowed to enter and carbon dioxide (waste) is able to leave. B. only occurs when the O and C atoms are part of some other molecule (e. g., a sugar or amino acid). C. requires energy in the form of ATP or the proton motive force. D. occurs passively, but membrane transporters are required to facilitate their movement. E. occurs by passive diffusion.

Penicillin is hydrolyzed and thereby rendered inactive by penicillinase (also known as β-lactamase), an enzyme present in some resistant bacteria. the mass of this enzyme in staphylococcus aureus is 29.6 kd. the amount of penicillin hydrolyzed in 1 minute in a 10-ml solution containing 10-9 g of purified penicillinase was measured as a function of the concentration of penicillin. assume that the concentration of penicillin does not change appreciably during the assay. penicillin(μm) amount hydrolyzed(nmol) 1 0.11 3 0.25 5 0.34 10 0.45 30 0.58 50 0.61 (a) plot v0 versus [s] and 1/v0 versus 1/[s] for these data. does penicillinase appear to obey michaelis-menten kinetics? if so, what is the value of km? (b) what is the value of vmax? (c) what is the turnover number of penicillinase under these experimental conditions? assume one active site per enzyme molecule.