The glucose uniporter GLUT1 has a Km of 1.5 mM for d-glucose and 30 mM for d-galactose.At a concentration of 5 mM for each,what is the rate of glucose transport relative to galactose transport? The Vmₐₓ may be assumed to be the same for both.
A)3.7-fold slower
B)equal
C)5.5-fold faster
D)20-fold faster

Question

Quizplus · Accepted Answer

To calculate the rate of glucose transport relative to galactose transport, we need to use the formula for Michaelis-Menten kinetics:

v = (Vmax[S])/(Km + [S])

where v is the initial rate of transport, Vmax is the maximum transport rate, Km is the Michaelis constant (a measure of substrate affinity), and [S] is the substrate concentration.

Since the Vmax can be assumed to be the same for both glucose and galactose transport, we can compare the rates by looking at the ratio of their respective v values:

v(glucose)/v(galactose) = [(Vmax * 5)/(1.5 + 5)] / [(Vmax * 5)/(30 + 5)]
v(glucose)/v(galactose) = [(5/6)Vmax] / [(5/35)Vmax]
v(glucose)/v(galactose) = 5.5

Therefore, glucose is transported 5.5-fold faster than galactose, and the answer is C.

The Glucose Uniporter GLUT1 Has a Km of 1