According to the special features of the dynamic heterogeneous grid environment, a loose-coupled and scalable resource model is described by a hybrid multi-level tree reflecting actual networks for organizing distributed resources. The resource model is maintained in a distributed way, making it loose-coupled and scalable, which is practical for many grid applications, especially for sequence analysis in Bioinformatics. Algorithms of resource location and job scheduling are discussed. The divisible load theory (DLT) is introduced to grid computing through applying divisible load scheduling on the model, an algorithm called recursively equivalence is presented to overcome difficulties in developing DLT analysis on the dynamic heterogeneous tree. Experiment result is presented to evaluate the model.