Premium
THE UPTAKE OF GLUCOSE BY CHLAMYDOMONAS SP. 1 2
Author(s) -
Bennett M. Elwanda,
Hobbie John E.
Publication year - 1972
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.1972.tb04053.x
Subject(s) - chlamydomonas , biology , maltose , fructose , photosynthesis , liter , cellobiose , saturation (graph theory) , respiration , michaelis–menten kinetics , substrate (aquarium) , biochemistry , botany , zoology , sucrose , cellulose , enzyme , enzyme assay , ecology , endocrinology , mathematics , gene , mutant , cellulase , combinatorics
SUMMARY The glucose uptake of a species of Chlamydomonas was studied at various concentrations of d ‐glucose plus glucose‐1‐ 14 C (0.003–10.0 mg/liter) and at various light levels (0–220 ft‐c). The alga grows at 4 C either in the light or in the dark with added glucose, cellobiose, maltose, or fructose. Uptake of glucose could be described by the Michaelis‐Menten equation, and both the maximum velocity of uptake and the half‐saturation constant increased when the cells were exposed to glucose in the dark. However, the high value of the half‐saturation constant (5 mg glucose/liter) compared with the low levels of glucose in nature (5–10 μg/liter) makes it unlikely that a transport system is effective under natural conditions. Even if a total of 10.0 mg/liter of glucose plus other organic compounds were available as substrate, the rate of photosynthesis would still be more than 10 times higher (at 220 ft‐c) than the rate of organic substrate uptake. Light had no effect on the total uptake of glucose but did reduce the percentage of 14 CO 2 evolved from 61% of the total 14 CO taken up in the dark to 0% at 220 ft‐c. This decrease could be due to either preferential use of the 14 CO 2 in photosynthesis or of the photosynthate in respiration.