Assessing prior knowledge types as predictors of academic achievement in the introductory phase of biology and physics study programmes using logistic regression

Background: Increasingly, high dropout rates in science courses at colleges and universities have led to discussions of causes and potential support measures of students. Students’ prior knowledge is repeatedly mentioned as the best predictor of academic achievement. Theory describes four hierarchically ordered types of prior knowledge, from declarative knowledge of facts to procedural application of knowledge. This study explores the relevance of these four prior knowledge types to academic achievement in the introductory phase of the two science subjects, biology and physics. Results: We assessed the knowledge types at the beginning and student achievement (measured by course completion) at the end of the first study year. We applied logistic regression models to evaluate the relationship between the knowledge types and academic achievement. First, we controlled for a well-established predictor of academic achievement (high school grade point average). Second, we added the knowledge types as predictors. For biology, we found that only knowledge about principles and concepts was a significant predictor in the first year. For physics, knowledge about concepts and principles as well as the ability to apply knowledge to problems was related to academic achievement. Conclusion: Our results concerning the knowledge types, which are of special relevance in biology and physics studies, could lead to effective measures, e.g. for identifying at-risk students and course guidance. Furthermore, the results provide a profound starting point for controlled intervention studies that systematically foster the identified relevant knowledge types in each subject and aim at a theory- and empirical-based optimization of pre- and introductory courses

The Endoplasmic Reticulum Grp170 Acts as a Nucleotide Exchange Factor of Hsp70 via a Mechanism Similar to That of the Cytosolic Hsp110*

Grp170 and Hsp110 proteins constitute two evolutionary distinct branches of the Hsp70 family that share the ability to function as nucleotide exchange factors (NEFs) for canonical Hsp70s. Although the NEF mechanism of the cytoplasmic Hsp110s is well understood, little is known regarding the mechanism used by Grp170s in the endoplasmic reticulum. In this study, we compare the yeast Grp170 Lhs1 with the yeast Hsp110 Sse1. We find that residues important for Sse1 NEF activity are conserved in Lhs1 and that mutations in these residues in Lhs1 compromise NEF activity. As previously reported for Sse1, Lhs1 requires ATP to trigger nucleotide exchange in its cognate Hsp70 partner Kar2. Using site-specific cross-linking, we show that the nucleotide-binding domain (NBD) of Lhs1 interacts with the NBD of Kar2 face to face, and that Lhs1 contacts the side of the Kar2 NBD via its protruding C-terminal α-helical domain. To directly address the mechanism of nucleotide exchange, we have compared the hydrogen-exchange characteristics of a yeast Hsp70 NBD (Ssa1) in complex with either Sse1 or Lhs1. We find that Lhs1 and Sse1 induce very similar changes in the conformational dynamics in the Hsp70. Thus, our findings demonstrate that despite some differences between Hsp110 and Grp170 proteins, they use a similar mechanism to trigger nucleotide exchange