• Journal of The Korean Association For Science Education
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• v.44 no.5
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• pp.361-378
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• 2024

This study explores elementary teachers' PCK change through the knowledge exchange between ePCK (enacted PCK) and pPCK (personal PCK) during modeling-based science inquiry instruction. For this purpose, three elementary school teachers were selected as research participants, and the CoRes(content representations) written by the participants before and after the lessons. The CoRes were, then, analyzed using qualitative content analysis to explore changes in pPCK, and the data related to the modeling-based science inquiry instruction (such as lesson plan, lesson videos, in-depth interviews) were analyzed using grounded theory research methods. The research indicated that the pPCK of elementary teachers who enacted modeling-based science inquiry instruction changed in regard to curricular knowledge, knowledge of students, pedagogical knowledge, and assessment knowledge. The data from the modeling-based science inquiry instruction showed that the changes of the teachers' pPCK was influenced by the knowledge exchange between ePCK and pPCK during the process of planning, teaching, and reflecting on the lessons. Based on the findings, this study discussed the need to identify personal factors that influence elementary teachers' knowledge exchange between PCK realms and suggested the need to develop effective modeling-based science inquiry teaching methods.

• Journal of Korean Elementary Science Education
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• v.43 no.1
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• pp.95-107
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• 2024

In this study, we explored the mediating effect of grit in the relationship between elementary school science teachers' perceived personal pedagogical content knowledge (pPCK) and enacted pedagogical content knowledge (ePCK). Drawing on insights from a review of the literature, we developed a research hypothesis model that set pPCK, ePCK, and grit as latent variables. Pearson correlation was conducted to examine the interrelationships among the latent variables. Structural equation modeling (SEM) was then employed to analyze the model fit. Additionally, bootstrap analysis was performed to specifically investigate the mediating effect of grit in the relationship between pPCK and ePCK. The Pearson correlation analysis indicated statistically significant correlations among the measurement variables. Meanwhile, the SEM analysis revealed that the measurement model aligned with the research hypothesis model. Furthermore, the bootstrap analysis demonstrated that grit had a statistically significant mediating effect in the relationship between elementary school science teachers' perceived pPCK and ePCK. These findings quantitatively examine the importance and impact of grit in the teacher expertise domain, providing valuable insights for the development of teachers' expertise and teacher education research within elementary school science classes.

• Microbiology and Biotechnology Letters
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• v.34 no.1
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• pp.35-39
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• 2006

One of the fermentative metabolism of enteric Escherichia coli was imitated after rumen bacteria, which have high C4 metabolism. E. coli expresses phosphenolpyruvate carboxylase (PPC) for the pathway between phosphoenolpyruvate (PEP) and oxaloacetate (OAA) during glycolytic condition while expresses phosphoenolpyruvate carboxykinase (PCK) during gluconeogenic condition. In contrast to enteric E. coli, rumen bacteria express the PEP-OAA pathway only by PCK. To verify the effect of the regulation imitation on the C4 metabolism of E. coli, PPC-deficient E. coli strain with PCK expression in glycolytic condition was constructed. The PEP-OAA regulation modified E. coli strain increased 2.5-folds higher C4 metabolite than the wild type strain. The potential use of C4 metabolism by regulation control is discussed.

• Journal of the Korean Chemical Society
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• v.66 no.6
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• pp.472-492
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• 2022

The purpose of this study was to investigate secondary science teachers' PCK components and subcomponents that are specific to online and offline learning environment. Data collection consisted of survey, class observation, and individual interviews of twelve science teachers. This study used a theoretical framework of PCK for deductive data analysis and articulated codes and themes through the following inductive analysis. Data analysis revealed that each of PCK components showed different specificity to the online and offline learning environment. And subcomponents of each PCK component were different according to the specificity of the online and offline learning environment. Teaching orientation toward science had a specific orientation for the online learning environment, i.e., 'learning science concept' and 'lecture centered instruction.' Knowledge of the science curriculum had online-offline mixed learning environment specific knowledge, i.e., 'reorganization of curriculum' and online learning environment specific knowledge, i.e., 'development of learning goal' and 'science curricular materials.' Knowledge of science teaching strategies had online learning environment specific knowledge, i.e., 'topic-specific strategy', 'subject-specific strategy', and 'interaction strategy' and COVID-19 offline learning environment specific knowledge, i.e., 'topic-specific strategy' and 'interaction strategy'. Knowledge of student science understanding had online learning environment specific knowledge, i.e., 'student preconception', 'student learning difficulty', 'student motivation and interest', and 'student diversity' and COVID-19 offline learning environment specific knowledge, i.e., student learning difficulty'. Knowledge of science assessment had online-offline mixed learning environment specific knowledge and online learning environment specific knowledge, i.e., assessment contents and assessment methods for each.

• Journal of Microbiology and Biotechnology
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• v.16 no.9
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• pp.1448-1452
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• 2006

The effects of amplifying the gluconeogenic phosphoenolpyruvate carboxykinase of Escherichia coli ($pck_{Ec}$) on succinic acid production in E. coli were examined under anaerobic condition. No significant increase in succinic acid production was observed in E. coli overexpressing the $pck_{Ec}$ gene without supplementing $NaHCO_{3}$ or $MgCO_{3}$. On the other hand, succinic acid production was enhanced as the $NaHCO_{3}$ concentration was increased. When 20 g/l of $NaHCO_{3}$ was added, succinic acid production in recombinant E. coli overexpressing PCK was 2.2-fold higher than that observed in the wild-type strain. It was concluded that the gluconeogenic $pck_{Ec}$ overexpression enabled E. coli to enhance succinic acid production only under the high bicarbonate supplementation condition.

• Journal of The Korean Association For Science Education
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• v.44 no.1
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• pp.105-117
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• 2024

The purpose of this study was to explore changes in elementary teachers' modeling pPCK (personal PCK) resulting from knowledge exchange within the realms of PCK described in the Refined Consensus Model (hereafter RCM). For this purpose, a professional learning community (hereafter PLC) was established for three elementary school teachers to facilitate knowledge exchange specifically focused on science modeling instructions. The study then analyzed the CoRe (content representations) written by the research participants twice to explore any changes in modeling pPCK (personal PCK). In addition, the discourse shared by the participants in the PLC and the data from the in-depth interviews were also analyzed using grounded theory research methods. The results of the study showed that there was no significant change in knowledge of the science curriculum in elementary teachers' modeling pPCK, but there were changes in orientations toward teaching science, knowledge of students' understanding in science, knowledge of instructional strategies and representations, and knowledge of assessment of science learning. Furthermore, the analysis of PLC discourse and in-depth interviews showed that modeling instructions reflection (ePCK; enacted PCK) and educational research-based modeling cPCK (collective PCK) influenced these changes in teachers' modeling pPCK. Accordingly, this study suggests recommendations for pedagogical approaches aimed at improving teachers' modeling PCK.

• Journal of The Korean Association For Science Education
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• v.41 no.2
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• pp.155-169
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• 2021

This study aims at exploring the features of science teaching orientation (STO) and its relationships with other PCK (pedagogical content knowledge) components. To do this, based on the definition of STO by Friedrichsen, Driel, & Abell(2011) and PCK model by Magnusson, Krajcik, & Borko(1999), we observed one experienced elementary teacher's science lessons for 21 lesson hours (10 hours of 'Motion of Objects' and 11 hours of 'Light and Lens') and carried out qualitative analyses of the data obtained from lessons observation, teacher interviews, and CoRe (content representation) responses. We analyzed the teacher's three aspects of STO (i.e. beliefs about the goals and purpose of science teaching, beliefs about the nature of science, and beliefs about science teaching and learning) which can converge into an overall STO of 'inquiry'. And these aspects of STO appear to interact differently with four PCK components (i.e. curriculum knowledge, learner knowledge, instructional knowledge, and assessment knowledge) depending on the topic of the lesson. It is hoped that this in-depth understanding of the features of STO and its relationship with other PCK components would provide useful information on how to monitor and improve STO and PCK of elementary teachers.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.95-99
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• 2002

A pckA gene encoding phosphoenolpyruvate carboxykinase (PEPCK) was cloned and sequenced from the succinic acid producing bacterium Mannheimia succiniciproducens MBEL55E. The gene encoded a 538 residue polypeptide with a calculated molecular mass of 58.8 kDa and a calculated pI of 5.03. The deduced amino acid sequence of the M. succiniciprodutens MBEL55E PEPCK was similar to those of all known ATP-dependent PEPCKS.

• Journal of Microbiology and Biotechnology
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• v.26 no.8
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• pp.1452-1456
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• 2016

Overexpression of the genes encoding phosphoeneolpyruvate carboxykinase (pckA) and NAD-dependent malic enzyme (maeA) facilitates higher intracellular ATP and NAD(P)H concentrations, respectively, under aerobic conditions in Escherichia coli. To verify a hypothesis that higher intracellular energy reserves might contribute to H₂ fermentation, wild-type E. coli strains overexpressing pckA and maeA were cultured under anaerobic conditions in a glucose minimal medium. Overexpression of pckA and maeA enabled E. coli to produce 3-times and 4-times greater H₂ (193 and 284 nmol, respectively) than the wild type (66 nmol H₂). The pckA and maeA genes were further overexpressed in a hydrogenase-3-enhanced E. coli strain. The hydrogenase-3-enhanced strain (W3110+fhlA) produced 322 nmol H₂, whereas the ATP-enhanced strain (W3110+fhlA+pckA) produced 50% increased H₂ (443 nmol). Total H₂ in the NAD(P)H-enhanced strain (W3110+fhlA+maeA) was similar to that in the control strain at 319 nmol H₂. Possible explanations for the contribution of the increased cellular energy reserves to the enhanced hydrogen fermentation observed are discussed based on the viewpoint of metabolic engineering strategy.

• Communications of Mathematical Education
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• v.32 no.3
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• pp.297-314
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• 2018

This article aims at providing implication for teacher preparation program through interpreting pre-service teachers' knowledge by using Shulman-Fischbein framework. Shulman-Fischbein framework combines two dimensions (SMK and PCK) from Shulman with three components of mathematical knowledge (algorithmic, formal, and intuitive) from Fischbein, which results in six cells about teachers' knowledge (mathematical algorithmic-, formal-, intuitive- SMK and mathematical algorithmic-, formal-, intuitive- PCK). To accomplish the purpose, five pre-service teachers participated in this research and they performed a series of tasks that were designed to investigate their SMK and PCK with regard to students' misconception in the area of geometry. The analysis revealed that pre-service teachers had fairly strong SMK in that they could solve the problems of tasks and suggest prerequisite knowledge to solve the problems. They tended to emphasize formal aspect of mathematics, especially logic, mathematical rigor, rather than algorithmic and intuitive knowledge. When they analyzed students' misconception, pre-service teachers did not deeply consider the levels of students' thinking in that they asked 4-6 grade students to show abstract and formal thinking. When they suggested instructional strategies to correct students' misconception, pre-service teachers provided superficial answers. In order to enhance their knowledge of students, these findings imply that pre-service teachers need to be provided with opportunity to investigate students' conception and misconception.