Evaluační standardy ve fyzikálním vzdělávání.

Evaluační standardy fyzikálního vzdělávání jsou klíčovou součástí inovované vzdělávací technologie výuky na základních a středních školách. Článek se zabývá definováním, funkcí a tvorbou těchto standardů.Evaluation standards of physics education are the core part of inovated primary and secondary school teaching technology. Paper deals with identification, function and creation of these standards

PCK a didaktika fyziky

Příspěvek se zabývá vztahem didaktických znalostí obsahu a didaktiky fyziky.Příspěvek se zabývá vztahem didaktických znalostí obsahu a didaktiky fyziky.Paper deals with the relation between pedagogical content knowledge and didactics of physics

Fyzika v jednoduchých pokusech

Článek se zabývá problematikou jednoduchých experimentů ve výuce přírodovědy s využitím ICT.Článek se zabývá problematikou jednoduchých experimentů ve výuce přírodovědy s využitím ICT.The paper deals with problematics of simple experiments in science education using ICT

Evaluation of technology for the biomass incineration.

Cílem této bakalářské práce je podat jejímu čtenáři základní informace o biomase a technologiích pro její využití. Vypracování je rozděleno do čtyř hlavních částí. První část popisuje zdroje biomasy, její úpravy a zpracování pro energetické účely. V části druhé, obsáhlejší jsou uvedeny jednotlivé technologie a možnosti konečného využití biomasy. Třetí část shrnuje ekologické dopady a vlivy produkce biomasy na životní prostředí. Část čtvrtá pojednává o ekonomice a porovnává náklady při využívání nejdostupnějších technologií k získání tepelné energie.The objective of this bachelor‘s thesis is to provide general information about biomass and technologies for its using. The thesis is diveded into four main parts. The first part describe sources of biomass, its adaptation and its processing for energy purposes. The second part is more comprehensive and mentions individual technoligies and possibilities of final using of biomass. The third part sums sup ecological falls and efects of production biomass on environment. The fourth part deals with economics and compares costs of the most available technolgies for gaining thermal energy.

Initiator tRNA genes template the 3\u27 CCA end at high frequencies in bacteria.

BACKGROUND: While the CCA sequence at the mature 3\u27 end of tRNAs is conserved and critical for translational function, a genetic template for this sequence is not always contained in tRNA genes. In eukaryotes and Archaea, the CCA ends of tRNAs are synthesized post-transcriptionally by CCA-adding enzymes. In Bacteria, tRNA genes template CCA sporadically. RESULTS: In order to understand the variation in how prokaryotic tRNA genes template CCA, we re-annotated tRNA genes in tRNAdb-CE database version 0.8. Among 132,129 prokaryotic tRNA genes, initiator tRNA genes template CCA at the highest average frequency (74.1%) over all functional classes except selenocysteine and pyrrolysine tRNA genes (88.1% and 100% respectively). Across bacterial phyla and a wide range of genome sizes, many lineages exist in which predominantly initiator tRNA genes template CCA. Convergent and parallel retention of CCA templating in initiator tRNA genes evolved in independent histories of reductive genome evolution in Bacteria. Also, in a majority of cyanobacterial and actinobacterial genera, predominantly initiator tRNA genes template CCA. We also found that a surprising fraction of archaeal tRNA genes template CCA. CONCLUSIONS: We suggest that cotranscriptional synthesis of initiator tRNA CCA 3\u27 ends can complement inefficient processing of initiator tRNA precursors, bootstrap rapid initiation of protein synthesis from a non-growing state, or contribute to an increase in cellular growth rates by reducing overheads of mass and energy to maintain nonfunctional tRNA precursor pools. More generally, CCA templating in structurally non-conforming tRNA genes can afford cells robustness and greater plasticity to respond rapidly to environmental changes and stimuli

Initiator tRNA genes template the 3' CCA end at high frequencies in bacteria.

BackgroundWhile the CCA sequence at the mature 3' end of tRNAs is conserved and critical for translational function, a genetic template for this sequence is not always contained in tRNA genes. In eukaryotes and Archaea, the CCA ends of tRNAs are synthesized post-transcriptionally by CCA-adding enzymes. In Bacteria, tRNA genes template CCA sporadically.ResultsIn order to understand the variation in how prokaryotic tRNA genes template CCA, we re-annotated tRNA genes in tRNAdb-CE database version 0.8. Among 132,129 prokaryotic tRNA genes, initiator tRNA genes template CCA at the highest average frequency (74.1%) over all functional classes except selenocysteine and pyrrolysine tRNA genes (88.1% and 100% respectively). Across bacterial phyla and a wide range of genome sizes, many lineages exist in which predominantly initiator tRNA genes template CCA. Convergent and parallel retention of CCA templating in initiator tRNA genes evolved in independent histories of reductive genome evolution in Bacteria. Also, in a majority of cyanobacterial and actinobacterial genera, predominantly initiator tRNA genes template CCA. We also found that a surprising fraction of archaeal tRNA genes template CCA.ConclusionsWe suggest that cotranscriptional synthesis of initiator tRNA CCA 3' ends can complement inefficient processing of initiator tRNA precursors, "bootstrap" rapid initiation of protein synthesis from a non-growing state, or contribute to an increase in cellular growth rates by reducing overheads of mass and energy to maintain nonfunctional tRNA precursor pools. More generally, CCA templating in structurally non-conforming tRNA genes can afford cells robustness and greater plasticity to respond rapidly to environmental changes and stimuli

Didaktika přírodovědy a rámcové vzdělávací programy

Příspěvek se zabývá ustavením didaktiky přírodovědy jako vědecké disciplíny.Příspěvek se zabývá ustavením didaktiky přírodovědy jako vědecké disciplíny.Paper deals with problem of creating of science education as a science

5\u27-Terminal nucleotide variations in human cytoplasmic tRNAHisGUG and its 5\u27-halves.

Transfer RNAs (tRNAs) are fundamental adapter components of translational machinery. tRNAs can further serve as a source of tRNA-derived noncoding RNAs that play important roles in various biological processes beyond translation. Among all species of tRNAs, tRNA(HisGUG) has been known to uniquely contain an additional guanosine residue at the -1 position (G-1) of its 5\u27-end. To analyze this -1 nucleotide in detail, we developed a TaqMan qRT-PCR method that can distinctively quantify human mature cytoplasmic tRNA(HisGUG) containing G-1, U-1, A-1, or C-1 or lacking the -1 nucleotide (starting from G1). Application of this method to the mature tRNA fraction of BT-474 breast cancer cells revealed the presence of tRNA(HisGUG) containing U-1 as well as the one containing G-1 Moreover, tRNA lacking the -1 nucleotide was also detected, thus indicating the heterogeneous expression of 5\u27-tRNA(HisGUG) variants. A sequence library of sex hormone-induced 5\u27-tRNA halves (5\u27-SHOT-RNAs), identified via cP-RNA-seq of a BT-474 small RNA fraction, also demonstrated the expression of 5\u27-tRNA(HisGUG) halves containing G-1, U-1, or G1 as 5\u27-terminal nucleotides. Although the detected 5\u27-nucleotide species were identical, the relative abundances differed widely between mature tRNA and 5\u27-half from the same BT-474 cells. The majority of mature tRNAs contained the -1 nucleotide, whereas the majority of 5\u27-halves lacked this nucleotide, which was biochemically confirmed using a primer extension assay. These results reveal the novel identities of tRNA(HisGUG) molecules and provide insights into tRNA(HisGUG) maturation and the regulation of tRNA half production

Post-transcriptional regulation of the steady-state levels of mitochondrial tRNAs in HeLa cells

In human mitochondrial DNA (mtDNA), the tRNA genes are located in three different transcription units that are transcribed at three different rates. To analyze the regulation of tRNA formation by the three transcription units, we have examined the steady-state levels and metabolic properties of the tRNAs of HeLa cell mitochondria. DNA excess hybridization experiments utilizing separated strands of mtDNA and purified tRNA samples from exponential cells long term labeled with [32P]orthophosphate have revealed a steady-state level of 6 x 10(5) tRNA molecules/cell, with three-fourths being encoded in the H-strand and one-fourth in the L-strand. Hybridization of the tRNAs with a panel of M13 clones of human mtDNA containing, in most cases, single tRNA genes and a quantitation of two-dimensional electrophoretic fractionations of the tRNAs have shown that the steady-state levels of tRNA(Phe) and tRNA(Val) are two to three times higher than the average level of the other H-strand-encoded tRNAs and three to four times higher than the average level of the L-strand-encoded tRNAs. Similar experiments carried out with tRNAs isolated from cells labeled with very short pulses of [5-3H]uridine have indicated that the rates of formation of the individual tRNA species are proportional to their steady-state amounts. Therefore, the approximately 25-fold higher rate of transcription of the tRNA(Phe) and tRNA(Val) genes relative to the other H-strand tRNA genes and the 10-16-fold higher rate of transcription of the L-strand tRNA genes relative to the H-strand tRNA genes are not reflected in the steady-state levels or the rates of formation of the corresponding tRNAs. A comparison of the steady-state levels of the individual tRNAs with the corresponding codon usage for protein synthesis, as determined from the DNA sequence and the rates of synthesis of the various polypeptides, has not revealed any significant correlation between the two parameters