• 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.

• The Journal of Korean Association of Computer Education
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• v.4 no.2
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• pp.135-143
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• 2001

Teachers' cognitive understanding of subject matter content have direct impact on the quality of students learning. In order to understand this, we need to investigate the relationships between the teachers' level of knowledge about the content and the instruction teacher provide for students. Professional development programs for computer education teachers include courses in computer science, curriculum studies, and the application of computers in the classroom. Effective teachers, however, have expertise in the subject matter content, know curriculum, and understand contextual knowledge for teaching computers in the classrooms. Although computer education have evolved for last 20 years, we have not yet made significant progress on researching "what" is the professional knowledge of computer teachers, and "how" they could be trained. Teacher's knowledge includes pedagogical and contextual knowledge of teaching the specific subject. The purpose of this paper is to understand the professional knowledge of computer teachers, and the adoption of PCK (pedagogical content knowledge). As a result of this paper, I hope to initiate further discussions and researches on PCK and its' implication for computer teachers and teacher preparation programs in Korea.

• Journal of the Korean Chemical Society
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• v.59 no.6
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• pp.520-532
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• 2015

The purposes of this study were to examine what kinds of educational activities were carried out during the practice teaching based on CoRe and to identify the role of CoRe and its influence on the development of expertise of student teachers. This study was performed as qualitative case study. The subjects of this study were one practice supervisor teacher and two student teachers. Data were collected through recording CoRe discussion process, student teachers' instructional scene, and semi-constructed interview, and analyzed by an inductive method. Student teachers noticed their own misconceptions, and clarified the concepts based on CoRe during the discussion with supervisor teacher. They also supplemented their lack of knowledge and made up new strategies through the process of sharing their ideas. During the discussion, the supervisor teacher conveyed his teaching experience based on his own orientations toward science teaching. In this course, CoRe plays roles as follows. Firstly, CoRe played a role as guiding supervisor teacher's coaching process. Secondly, CoRe helped for the supervisor teacher to recognize their own PCK. Thirdly, CoRe served as a tool of helping their communication. In turn CoRe proved to be a useful frame for teaching student teachers during practice teaching. Student teachers were provided with a useful framework for preparing lessons by developing CoRe for the topic they teach. Developing CoRe with supervisor teacher at the planning stage of lessons enhenced student-teachers' subject matter knowledge and their PCK including knowledge of science curricula and knowledge of student's understanding of science. Also student teachers understood the components of PCK and experienced the positive understanding toward students, teaching activities, and themselves as a science teacher.

• Journal of Korean Elementary Science Education
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• v.29 no.3
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• pp.350-363
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• 2010

Recently there has been increasing emphasis on pedagogical content knowledge (PCK) for fostering science teachers' teaching professionalism that needs to be done from teacher training courses systematically. We investigated what were the PCK factors considered in planning instruction and the difficulties encountered in implementing it by pre-service teachers. In this study, 26 sophomores at an university of education in Gyeonggi province were asked to perform teaching demonstrations using scientific instruction models. They were also requested to write reflective journals and interview. Analyses of the results revealed that many pre-service teachers considered the teaching strategies such as the instruction organization and implementation when planning instruction. They had also regard to the learners' cognitive affective aspects, whereas the pre-knowledge of them was not properly considered. Especially, the curriculum and assessment were almost disregarded. Most of the difficulties encountered in planning instruction and implementing it were appeared in terms of the teaching strategies. For example, they had difficulties in considering the characteristics of each stage presented by the instruction models when planning instruction and implementing it. The frequencies of the difficulties in implementing experiment were especially higher than those of the other PCK factors. Educational implications of these findings are discussed.

• Journal of The Korean Association For Science Education
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• v.40 no.5
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• pp.543-563
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• 2020

This study explores how the teaching practices of two teachers changed during scientific modeling classes. It also aims to understand these changes in terms of the teachers' modeling pedagogical content knowledge (PCK) development. The study participants were two elementary school teachers and their fifth-grade students. The teachers taught eight lessons of scientific modeling classes about the human body. The data analysis was conducted for lessons 1-2 and 7-8, which best showed the change in teaching practice. The two teachers' teaching practices were analyzed in terms of feedback frequency, feedback content, and the time allocated for each stage of model generation, evaluation, and modification. Teacher A led the evaluation and modification stages in a teacher-driven way throughout the classes. In terms of feedback, teacher A mainly used answer evaluation feedback in lesson 1-2; however, in lesson 7-8, the feedback content changed to thought-provoking feedback. Meanwhile, teacher B mostly led a teacher-driven model evaluation and modification in lesson 1-2; however, in lesson 7-8, she let her students lead the model evaluation and modification stages and helped them develop models through various feedbacks. The analysis shows that these teaching changes were related to the development of modeling PCK components. Furthermore, the two teachers' modeling PCK differed in teaching orientation, in understanding the modeling stages, and in recognizing the value of modeling, suggesting the importance of these in modeling teaching practice. This study can help improve the understanding of modeling classes by revealing the relationship between teaching practices and modeling PCK.

• Journal of The Korean Association For Science Education
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• v.40 no.5
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• pp.565-582
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• 2020

The purpose of this study is to investigate middle school science teachers' pedagogical content knowledge for science practice-based instruction developed by five middle school science teachers in a teacher learning community. Science teachers in this study collaborated to examine lesson plans and reflect on teaching practice and collaboratively analyzed science curriculum, discussed video-recordings of teaching practice, and discussed to design detailed and elaborated lesson plans. Data collection consisted of pre and post questionnaire and interview, audio-recording of teacher discussion in a teacher learning community for one year, lesson plans, teacher written reflection, and video-recording of teaching practice. Data analysis reveals that science teachers developed pedagogical content knowledge for science practice-based instruction that consists of eleven sub-components of knowledge of science curriculum for science practice, knowledge of science practice-based instructional strategy, knowledge of students' science practice-based learning, and knowledge of science practice-based learning assessment. Science teachers in this study developed highly structured pedagogical content knowledge for science practice-based instruction.

• Journal of the Korean earth science society
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• v.45 no.3
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• pp.239-259
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• 2024

In this study, a qualitative meta-analysis was conducted on research papers on earth science education to derive knowledge of students' understanding of specific science topics-greenhouse effect, global warming, and climate change-within the context of collective Pedagogical Content Knowledge (PCK). Twenty-two research papers addressing students' alternative conceptions (misconceptions) about these topics were selected and analyzed for their respective definitions, causes (mechanisms), and impacts. Semantic network analysis and a mental model framework were applied to synthesize the findings. The meta-analysis revealed several key insights: (1) Regarding the greenhouse effect, students often used the terms "greenhouse effect" and "global warming" interchangeably, lacked knowledge about the types of greenhouse gases, and misunderstood their roles. They commonly associated the greenhouse effect with environmental pollution or changes in the ozone layer, failing to recognize its relation to the heat balance between the surface and atmosphere. (2) Concerning global warming, students confused it with sea level rise and linked it to pollution, ozone layer changes, and glacier melting. They understood global warming as a disruption of the heat balance between the surface and atmosphere but had misconceptions about its environmental impacts. (3) In terms of climate change, students used the term interchangeably with global warming, weather change, and climate anomalies. They associated climate change with atmospheric pollution and ozone layer depletion but misunderstood its environmental impacts. As result, three mental models-categorical, mechanistic, and hierarchical misconceptions-were identified as collective PCK. The implications for enhancing earth science teachers' PCK were discussed based on these findings.

• Journal of the Korean Chemical Society
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• v.62 no.5
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• pp.386-397
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• 2018

In this study, we investigated the characteristics of the PCK components in the chemistry units of middle school science teacher's guidebooks developed under the 2009 Revised National Curriculum. The analysis of the results revealed that the sub-components of topic-specific strategies, vertical articulation, and lesson objectives were systematically handled in most teacher's guidebooks. However, subject-specific strategies, assessment methods, and curricular changes were mainly dealt with only in the general guidelines. Experiments and inquiries, assessment questions, and assessment dimensions were lack of constructivist approaches in the aspect of presented contents or forms. Horizontal articulation and knowledge of students were either lacked in relevant content or presented in the form of simple presentation. Concepts and theories accounted for the largest proportion of teachers' guidebooks, but some of them were beyond appropriate levels. On the bases of the results, the implications for the development of the teacher's guidebooks are discussed.

• Journal of The Korean Association For Science Education
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• v.39 no.1
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• pp.73-88
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• 2019

The purpose of this study is to explore elementary teachers' difficulties on teaching science by analyzing questions that have been posted for a long time in an autonomous online teacher community named Indischool. For this purpose, 409 question postings(the 2007 and 2009 revised curriculum, third to sixth grade) were analyzed using the framework for analyzing questions about elementary teachers' science teaching(modified from Alake-Tuenter et al., 2013). The study revealed that there were more science-SMK questions than science-PCK questions, and most of the questions were 'about lenses' and 'in 2014 and 2015, when the curriculum was changing from the 2007 to the 2009 revised curriculum'. The long-standing difficulties in science-SMK were 'an application of facts and concepts in lenses' and 'an unexpected experimental error in electricity'. In particular, there are the principle of transparent cup-shaped objects acting as lenses, the process of image formation by convex lenses, experimental errors of 'compass movement due to current flow change' and experimental errors 'serial connection of bulbs'. The long-standing difficulties in science-PCK were 'understanding and response to context' and 'understanding and response to aims mentioned in standard document' and these are not related to physical units but to others. In particular, there are request class materials, activity ideas at the end of the semester and understanding the national curriculum guidelines. These teachers' difficulties should be reflected in the science teaching support system like a teacher's guide compilation, teacher's training curriculum development, etc.

• 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.