Naive B and T lymphocytes are small, quiescent cells with little cytoplasm and low metabolic activity. Yet within hours after being activated following encounter with their antigen, these cells enlarge and up-regulate many biosynthetic and metabolic pathways. Approximately one day later, the cells begin dividing, and for several days they are the most rapidly dividing cells in the body, undergoing 2-4 rounds of cell division every day. In order to maintain this phenomenal rate of cell division, lymphoblasts must:
A) Use the large energy stores accumulated by them when they were naive quiescent cells prior to their activation
B) Engulf their neighboring small quiescent lymphocytes in order to take their lipids and proteins for raw material
C) Up-regulate synthesis of mRNA and proteins, some of which encode for glucose transporters and enzymes used for glycolysis
D) Phagocytose extracellular proteins and lipids and degrade them for energy production
E) Macropinocytose metabolites and sugars from the blood for use in glycolysis

Question

Quizplus · Accepted Answer

The lymphoblasts up-regulate many biosynthetic and metabolic pathways including those involved in glucose transport and glycolysis. This suggests that they rely on glucose as a primary source of energy. Therefore, we can eliminate choices A, B, D, and E. Choice C is the best answer as it accurately describes the up-regulation of glucose transporters and glycolysis enzymes to meet the high metabolic demand of rapidly dividing lymphoblasts.

Naive B and T Lymphocytes Are Small, Quiescent Cells with Little