Name: tracking cell chemistry with metabolic labels
Uploaded: 2023-04-30T06:31:10.000Z
Duration: 8 min 28 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

High School

Physical Science

HS. Waves and Electromagnetic Radiation

HS-PS4-5.

Metabolic Labeling

代谢标记用于研究细胞内发生的生化转化和修饰过程。该方法通过使用模拟天然生物分子结构的化学类似物来实现。细胞在其内源性生化过程中利用这些类似物，生成带有标记的化合物。这种标记可引入检测和亲和标签，进而结合其他生化分析技术（如SDS-PAGE和核磁共振）来阐明代谢通路。
本视频介绍了代谢标记的概念，并展示了两种通用实验方法。&#160; 第一种方法采用同位素标记，用于表征蛋白质的磷酸化修饰；第二种方法采用光反应性标记，用于表征蛋白质-蛋白质相互作用。此外，还介绍了代谢标记的三个应用：植物材料的标记、RNA标记以测定动力学，以及发育胚胎中糖链的标记。

代谢标记

代谢标记用于研究细胞内发生的生化转化和修饰过程。该方法通过使用模拟天然生物分子结构的化学类似物来实现。细胞在其内源性生化过程中利用这些类似物，生成带有标记的化合物。这种标记使得检测标签和亲和标签得以引入，随后可结合其他生化分析技术（如SDS-PAGE和核磁共振，NMR）来阐明代谢通路。
本视频介绍了代谢标记的概念，并展示了两种通用实验方法。&#160; 第一种方法采用同位素标记，用于表征蛋白质的磷酸化修饰；第二种方法采用光反应性标记，用于表征蛋白质-蛋白质相互作用。此外，还介绍了代谢标记的三个应用：植物材料的标记、RNA标记以测定动力学，以及发育胚胎中糖链的标记。

<div class="chapter_text" id="script_0">
代谢标记用于研究细胞的分子机制。该方法利用化学类似物来探查所发生的生化转化和修饰过程。本视频将介绍代谢标记的原理、典型的同位素标记和光反应标记方法，以及一些应用实例。
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<div class="chapter_text" id="script_1">
代谢标记可通过多种策略实现。本文将介绍同位素标记、光反应标记和生物正交标记。
同位素标记使用与天然分子化学结构相同但含有非常见同位素的结构类似物。例如，在这种L-赖氨酸类似物中，碳和氮原子被碳-13和氮-15取代。在含有同位素类似物的培养基中培养细胞，细胞会将其整合到自身的生物化学结构中。随后从细胞中收集并纯化代谢物用于分析。含有稳定同位素的样品可通过质谱或核磁共振波谱等技术进行分析；而含有放射性标记的样品则使用液体闪烁计数和X射线胶片进行分析，具体操作将在同位素标记实验方案中展示。
光反应标记是将功能基团引入蛋白质中，这些基团在未暴露于紫外光时保持稳定，一旦受到紫外光照射，便会形成反应性自由基，并与邻近的蛋白质共价结合。一个常见的例子是L-光反应亮氨酸（L-photo-leucine），其含有二氮杂环丙烷环（diazirine ring），这是一种光反应交联剂。与同位素标记不同，光反应化学类似物与其天然对应物之间存在一定的化学差异，细胞可能优先摄取天然化合物而非类似物。因此，在进行光反应标记时，必须使用不含所模拟化合物的培养基。当标记蛋白暴露于紫外辐射后，其内部的光反应基团变得不稳定并高度活化，从而与相互作用的蛋白质发生交联，形成蛋白质复合物。这些交联的复合物如同“快照”，可通过SDS-PAGE和质谱方法进行分析，有助于识别代谢通路中发生的反应种类、反应物之间的相互作用以及结合位点。
生物正交标记策略利用带有小功能基团的类似物，这些基团与天然生物分子几乎不发生反应。例如，叠氮基（azides）是一种小功能基团，其反应性被认为与生物化学反应正交。在施陶丁格连接反应（Staudinger ligation）中，磷酰基攻击叠氮基，形成一个过渡态，该过渡态在分子内与邻近的酯基反应，最终生成带有胺键的配体。整合到生物分子中的生物正交功能基团可与检测标签（如荧光基团）或亲和标签（如抗原）进行连接。
在了解了代谢标记的一些基本概念和策略之后，接下来我们将观察其在实验室中的实际操作过程。
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<div class="chapter_text" id="script_2">
代谢标记实验的第一步是收集目标蛋白。为此，需将细胞培养在培养板上，并采用某种表达方法促进目标蛋白的合成。在本示例中，表达的是富含亮氨酸重复序列的激酶（leucine-rich repeat kinases，简称 LRRK）。实验中使用含放射性磷-32 的磷酸氢二钠作为标记类似物。必须采取适当措施以防止电离辐射危害，包括设置专用工作区域、穿戴适当的防护装备以及检测放射性污染。在完成安全防护措施后，制备含有同位素类似物的培养基。移除原有培养液，替换为含有同位素化学类似物的新培养基，并进行孵育。孵育结束后，裂解细胞，收集裂解液并进行纯化。
纯化后，通过 SDS-PAGE 分离蛋白质，随后将其转移至 PVDF 膜上。通过将膜暴露于X射线胶片进行自显影，并使用磷屏成像仪进行检测。利用蛋白质印迹（Western blotting）测定 PVDF 膜上蛋白质的相对含量。在本示例中，检测了在 293T 细胞中合成的富含亮氨酸重复序列激酶的磷酸化水平。自显影图像显示了蛋白中掺入的磷元素量，而蛋白质印迹则揭示了 LRRK 蛋白的表达水平。使用图像分析软件对蛋白磷酸化水平进行定量分析。
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<div class="chapter_text" id="script_3">
在接下来的实验中，将演示光反应性标记技术。首先，制备并培养细胞。在细胞处于对数生长中期时，加入光反应性类似物并进行孵育。本实验中使用的是对苯甲酰基苯丙氨酸（p-benzoylphenylalanine）。在不同时间点收集样品，并立即置于冰上。随后对样品进行光照处理，以获得随时间变化的生物化学通路的瞬时快照。目标蛋白质随后通过SDS-PAGE进行纯化和分离。
采用光反应性标记策略可鉴定与目标蛋白质相互作用的化合物。通过Western blot免疫检测显示，在经光照处理的样品中出现分子量更高的蛋白质条带。这些条带来源于紫外照射期间发生的蛋白质-蛋白质交联。
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在回顾了代谢标记的实验流程后，让我们来看看该技术的一些具体应用方式。
代谢标记的概念可扩展至多细胞生物。将植物培养在富含稳定同位素的密闭环境中，以获得标记的植物材料。向密闭环境中添加含碳-13的二氧化碳，并使用富含氮-15的肥料。最终收获的植物材料可用于研究生态系统中碳和氮的循环过程。
标记技术能够区分新合成的RNA与原有的RNA。通过改变标记类似物的初始浓度，可测定新RNA合成的动力学参数。实验结果表明，4-硫代尿苷的浓度会影响新转录RNA的产量。此外，还可利用分光光度计直接定量测定标记物掺入RNA的速率。
利用生物正交点击化学技术，可对斑马鱼胚胎中的糖类分子（glycans）进行标记。将标记化合物注射到卵细胞中，使糖类分子上带有炔基标记。在胚胎发育至特定阶段后，将幼虫中的糖类分子与染料化合物进行连接反应，进而对胚胎中的糖类分子进行成像。通过在不同发育阶段使用不同颜色的标记，可识别在不同时间点生成的糖类分子。
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<div class="chapter_text" id="script_5">
您刚刚观看了 JoVE 关于代谢标记的视频。该视频介绍了代谢标记背后的原理及其策略，概述了两种通用实验流程，并讲解了这些技术的一些应用。
感谢观看！
</div>

代谢标记用于研究细胞内发生的生化转化和修饰过程。该方法通过使用化学类似物来实现……

代谢标记用于研究细胞的分子机制，通过使用化学类似物来探查所发生的生化转化和修饰过程。本视频将介绍代谢标记的基本原理、典型的同位素标记和光反应标记方法，以及一些应用实例。代谢标记可通过多种策略实现。本文将介绍同位素标记、光反应标记和生物正交标记。同位素标记是利用在化学结构上与其天然对应物完全相同，但含有稀有同位素的结构类似物来实现的。在此L-赖氨酸类似物中，碳和氮原子被碳-13和氮-15所取代。在含有同位素类似物的培养基中培养的细胞会将其整合到自身的生化结构中。从细胞中收集代谢物并进行纯化以供分析。含有稳定同位素的样品可采用质谱或核磁共振波谱等技术进行分析；而含有放射性标记的样品则使用液体闪烁计数和X射线胶片进行分析，后者将在同位素标记实验方案中予以演示。光反应性标记物是一类被引入蛋白质中的功能基团，在未暴露于紫外光时保持稳定。该功能基团在紫外光照射下会形成高活性的自由基，进而与邻近的蛋白质共价结合。一个常见的例子是L-光反应性亮氨酸（L-photo-leucine），其含有二氮杂环丙烷环结构，是一种光反应性交联剂。与同位素标记不同，光反应性化学类似物与其天然对应物在化学结构上存在一定差异。细胞可能优先利用天然化合物而非类似物。因此，进行光反应性标记时，必须在不含被模拟化合物的培养基中进行。一旦暴露于紫外辐射，标记蛋白中的光反应性基团将变得不稳定并高度活化，从而与相互作用的蛋白质发生交联，形成蛋白质复合物。这些交联的复合物相当于相互作用的“快照”，可利用SDS-PAGE和质谱技术进行分析。通过鉴定反应中的分子种类及其结合位点，该方法有助于揭示代谢通路中发生的反应过程及分子间的相互作用方式。生物正交标记策略利用带有小功能基团的类似物，这些基团对天然生物分子几乎没有或完全没有反应性。例如，叠氮基团是一种小功能基团，其反应性被认为与生化反应正交。在施陶丁格连接反应中，一个膦基团攻击叠氮基团，生成一个过渡态，该过渡态与邻近的酯基发生分子内反应，形成一个通过胺键连接的配体。整合到生物分子中的生物正交功能基团可以与检测标签（如荧光功能基团）以及亲和标签（如抗原）进行连接。在讨论了一些代谢标记的概念和策略后，让我们来看看在实验室中如何进行这一过程。代谢标记实验的第一步是收集目标蛋白。为此，需在培养板上培养细胞，并采用某种表达方法促进目的蛋白的合成。在本示例中，表达的是富含亮氨酸重复序列的激酶（leucine-rich repeat kinases，LRRK）。实验中使用含放射性磷-32的磷酸氢二钠作为标记类似物。必须采取适当措施以防止电离辐射危害，包括设置专用工作区域、穿戴合适的防护装备以及检测放射性污染。在完成安全防护措施后，制备含有同位素类似物的培养基。移除原有培养液，替换为含有同位素化学类似物的新培养基，并进行孵育。孵育结束后，裂解细胞，收集裂解液并进行纯化。纯化后，蛋白质通过SDS-PAGE分离，然后转移至PVDF膜。将膜暴露于X射线胶片进行放射自显影，并使用磷屏成像仪进行检测。通过蛋白质印迹法（Western blotting）测定PVDF膜中蛋白质的相对含量。在此示例中，检测了在293T细胞中合成的富含亮氨酸重复序列激酶（leucine-rich repeat kinases）的磷酸化水平。放射自显影图像显示了蛋白质中掺入的磷含量。蛋白质印迹法揭示了LRRK蛋白的表达水平。使用图像分析软件获取蛋白质磷酸化水平的定量数据。在接下来的实验步骤中，将演示光反应性标记技术。首先，制备并培养细胞。在细胞对数生长中期加入光反应性类似物，并进行孵育。本实验中使用对苯甲酰基苯丙氨酸（p-benzoylphenylalanine）。在不同时间点收集样品，并立即置于冰上。随后对样品进行光照处理，以获得随时间变化的生物化学通路的瞬时快照。目标蛋白随后通过SDS-PAGE进行纯化与分离。采用光反应性标记策略来鉴定与目标蛋白相互作用的化合物。通过蛋白质印迹免疫检测显示，照射样品中出现指示较高分子量蛋白存在的蛋白条带，这些条带源于紫外照射期间因蛋白质-蛋白质相互作用而发生的交联。在回顾了代谢标记步骤之后，让我们来看看该过程的一些应用方式。代谢标记的概念可扩展至多细胞生物体。将植物生长在富含稳定同位素的密闭环境中，以产生标记的植物材料。向密闭环境中添加含碳-13的二氧化碳，并使用富含氮-15的肥料。所获得的收获植物材料可用于研究生态系统中碳和氮的循环问题。标记技术能够将新合成的RNA与较早存在的RNA区分开来。通过改变标记类似物的初始浓度，可以确定新RNA合成的动力学特征。结果表明，4-硫代尿苷的浓度会影响新转录RNA的量。此外，可通过分光光度计直接定量测定标记物掺入RNA的速率。利用生物正交点击化学反应，可以对斑马鱼胚胎中的糖类分子进行标记。将标记化合物注射到卵中，使糖类分子上带有炔基标记。随后，在胚胎发育的特定阶段，将幼虫中的糖类分子与染料化合物进行连接反应。接着对胚胎中的糖类分子进行成像。通过在胚胎发育的不同阶段使用不同颜色的染料进行标记，可以识别在不同时间点产生的糖类分子。您刚刚观看了 JoVE 关于代谢标记的视频。该视频介绍了代谢标记背后的原理及其策略，概述了两种通用实验流程，并探讨了这些技术的一些应用。感谢观看！

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Biochemistry

生物化学

tracking cell chemistry with metabolic labels

Metabolic labeling tracks cell chemistry by using chemical analogs that cells take up and build into biomolecules. These labels help scientists follow biochemical changes and modifications inside cells. The labeled products can then be studied with tools such as SDS-PAGE and NMR to learn more about metabolic pathways.

Several labeling strategies are shown here. Isotopic labeling uses analogs that match the natural molecule but contain uncommon isotopes, such as carbon-13 and nitrogen-15 in an L-lysine analog. Photoreactive labeling uses groups that stay stable until they are exposed to ultraviolet light. Bioorthogonal labeling uses small functional groups, such as azides, that do not normally react with other biomolecules.

Isotopic labels are added to cultured cells, and the cells build them into their proteins and metabolites. The collected samples are purified and then analyzed by mass spectrometry or NMR spectroscopy when stable isotopes are used. When radioactive labels are used, liquid scintillation counting and x-ray film are used for detection. The protocol shown uses radioactive phosphorus-32 to study phosphorylation of leucine-rich repeat kinases, or LRRK, in 293T cells.

Proper safety steps are needed when working with radioactive material. The work area must be set up carefully, protective equipment must be worn, and the samples must be checked for contamination. After incubation with the labeled medium, the cells are lysed, the lysate is collected, and the proteins are purified. The proteins are then separated by SDS-PAGE, transferred to a PVDF membrane, and detected by autoradiography and Western blotting. Image analysis software is used to quantify phosphorylation levels.

Photoreactive labeling is used to capture protein-protein interactions. In this method, p-benzoylphenylalanine is added to cells during mid-log growth, and samples are collected over time and kept on ice. After UV exposure, the photoreactive group becomes highly reactive and cross-links with nearby proteins. The cross-linked complexes are then purified, run on SDS-PAGE, and examined by Western blotting. Higher molecular weight bands in irradiated samples show that cross-linking has occurred.

Bioorthogonal labeling uses reactions that are separate from normal cell chemistry. In the Staudinger ligation, a phosphine reacts with an azido group and forms a labeled product that can carry detection or affinity tags. This approach is useful for adding fluorescent tags or antigen tags to biomolecules without strongly disturbing their natural behavior.

The same labeling ideas can also be applied to plants, RNA, and embryos. Plants grown in a sealed environment can be labeled with carbon-13 carbon dioxide and nitrogen-15 fertilizer to study carbon and nitrogen cycling. New RNA can be separated from older RNA to measure synthesis kinetics, and the amount of 4-thiouridine affects how much new RNA is transcribed. In zebrafish embryos, glycans can be labeled by click chemistry, dyed at different developmental stages, and imaged in different colors to track when they are made.

Tracking Cell Chemistry with Metabolic Labels

tracking-cell-chemistry-with-metabolic-labels

dialysis: diffusion based separation

Dialysis for Buffer Exchange in Biochemistry

Dialysis is a common biochemistry technique for buffer exchange and desalting. It separates molecules by diffusion through a semipermeable membrane, which lets small molecules pass while holding larger biomolecules inside the sample. The membrane is the key part of the setup. Its pores create a molecular weight cutoff, so a membrane such as a 10 kDa membrane usually keeps molecules larger than 10 kilodaltons inside. This cutoff is not exact, because membranes have a range of pore sizes.

enzyme assays and kinetics

Measuring Enzyme Reaction Rates

Enzyme reaction rates can be measured with assays that track how substrate or product levels change over time. Enzymes are proteins, or sometimes RNAs, that speed up chemical reactions by lowering the activation energy needed to start them. They act on a specific substrate and help form a product that supports life processes. Enzymatic reactions are often described in three steps. First, the substrate binds to the enzyme active site and forms an enzyme-substrate complex. That complex can fall...

maldi-tof mass spectrometry

How MALDI-TOF Reads Biomolecules

MALDI-TOF mass spectrometry reads biomolecules by using a laser, a matrix, and a time-of-flight analyzer. MALDI, or matrix-assisted laser desorption ionization, helps fragile molecules keep their structure while they are moved into the mass analyzer. The analyzer then separates compounds based on size and charge. In MALDI, the sample is mixed into a matrix, usually an organic compound with aromatic and conjugated double bonds. A laser pulse strikes the spot, and the matrix absorbs most of the...

tandem mass spectrometry

Tandem Mass Spectrometry for Biomolecule Analysis

Tandem mass spectrometry is used to isolate a biomolecule and break it into smaller pieces so its makeup can be studied. Because biomolecules often have large, complex structures, it can be hard to identify their molecular composition and sequence from a single measurement. By linking mass spectrometers in series, the technique first selects one ion and then analyzes the fragments it produces. The process starts with an ion source that converts the sample into ions. A mass analyzer then...

protein crystallization

Protein Crystals for Structure Analysis

Protein crystals help scientists study protein structure and function. A crystal is a solid lattice made from purified protein molecules. These crystals are useful in structural biology because they reveal details that methods like mass spectrometry and SDS-PAGE cannot show on their own. Protein crystallization is paired with recombinant protein expression and x-ray diffraction to support this work. The process starts with a large amount of very pure protein. Researchers often make that...

chromatography-based biomolecule purification methods

chromatography-based-biomolecule-purification-methods

Protein Purification with SEC and IMAC

Protein purification with size-exclusion chromatography and affinity chromatography helps isolate biomolecules from complex mixtures. These methods are common in biochemistry because purified samples are needed before a biomolecule’s properties and activity can be studied. The video focuses on the principles behind size-exclusion chromatography, affinity chromatography, and immobilized metal affinity chromatography, or IMAC. Size-exclusion chromatography, or SEC, separates molecules by size. A...

two-dimensional gel electrophoresis

Protein Mapping with 2D Gel Electrophoresis

Protein mapping with 2D gel electrophoresis separates complex protein mixtures across two steps. The method combines isoelectric focusing, or IEF, with sodium dodecyl sulfate polyacrylamide gel electrophoresis, or SDS-PAGE. Together, these methods can resolve thousands of biomolecules from a single sample by their isoelectric point and molecular weight. The first dimension is IEF. Each protein has an isoelectric point, or pI, which is the pH where its net charge is zero. Proteins are loaded...

metabolic labeling

Metabolic labeling tracks cell chemistry by using chemical analogs that cells take up and build into biomolecules. These labels help scientists follow biochemical changes and modifications inside cells. The labeled products can then be studied with tools such as SDS-PAGE and NMR to learn more about metabolic pathways. Several labeling strategies are shown here. Isotopic labeling uses analogs that match the natural molecule but contain uncommon isotopes, such as carbon-13 and nitrogen-15 in an...

electrophoretic mobility shift assay (emsa)

electrophoretic-mobility-shift-assay-emsa

Detecting Protein-DNA Binding by EMSA

Electrophoretic mobility shift assay, or EMSA, is a biochemical method used to detect binding between proteins and nucleic acids. It is also called a gel shift assay. The test compares how a labeled nucleic acid moves through a gel before and after it binds a protein. EMSA is used to see whether a specific protein binds to a specific nucleic acid. First, the nucleic acid is labeled to make a probe. The transcript describes radioactive phosphorus-32 as a common label. The probe is then mixed...

photometric protein determination

Measuring Protein Concentration with Absorbance

Measuring protein concentration with absorbance is a key step in many biochemical assays. Photometric methods use the fact that samples with more light-absorbing material transmit less light. Because concentration and absorption are directly related, this makes it possible to measure an unknown sample. The core idea comes from the Beer-Lambert Law. This law states that the concentration of a light-absorbing species is proportional to its absorbance. The video also introduces the Bradford assay...

density gradient ultracentrifugation

Sucrose Gradient Separation in an Ultracentrifuge

Sucrose gradient separation in an ultracentrifuge is a lab method for isolating cell parts and biomolecules. It uses differences in density to make particles sink or rise in a liquid. A high-speed ultracentrifuge speeds up this process so components can be separated without destroying them. The basic idea starts with a suspension, which is particles mixed in a liquid solvent. Particles that are denser than the solvent sediment, while less dense particles float. A rotor inside the...

co-immunoprecipitation and pull-down assays

co-immunoprecipitation-and-pull-down-assays

Protein Interaction Capture Methods in Cells

Co-immunoprecipitation and pull-down assays are laboratory methods used to capture stable protein-protein interactions. Protein-protein interactions help control many biological functions, but many of them have not yet been identified. These assays are related to immunoprecipitation, which isolates a target protein from a mixed sample using an antibody. In co-immunoprecipitation, or CoIP, an antibody binds the target protein, and that protein is already attached to another protein that the...

reconstitution of membrane proteins

Membrane Proteins in Liposome Models

Membrane proteins can be moved into liposome models so their function can be studied outside a cell. Reconstitution means restoring an isolated biomolecule to a working form. For membrane proteins, that usually means placing a purified protein into an artificial lipid membrane. Cell membranes are made mainly of phospholipids and membrane proteins. The phospholipids form a bilayer with hydrophilic phosphate heads facing water and hydrophobic fatty acid tails facing inward. Some membrane...

f&#246;rster resonance energy transfer (fret)

FRET as a Molecular Ruler in Cells

Föster resonance energy transfer, or FRET, is a way to study close-range biochemical interactions using light-emitting molecules. A donor fluorophore can pass energy to an acceptor fluorophore when their emission and absorption spectra overlap. This transfer happens only when the pair is very close together, usually within 10 nm. Because FRET depends on distance, it is often called a molecular or spectroscopic ruler. The strength of the signal is measured as FRET efficiency, which describes...

surface plasmon resonance (spr)

SPR Biosensors for Tracking Binding Kinetics

Surface plasmon resonance, or SPR, is a way to track biomolecular binding on a label-free biosensor. It is used to measure molecular affinity, kinetics, specificity, and concentration. The method works with a thin metal layer on a prism, where changes in reflected light reveal interactions in real time. SPR sensors use a thin layer of a noble metal on the face of a prism. Light is reflected from the prism-metal interface into a photodetector. At one specific angle, called the surface plasmon...

biochemistry

本系列介绍了常用的纯化方法, 如亲和层析, 以及分析方法, 如 MALDI。此外, 视频展示了评估生物相互作用和功能的方法, 如 co-immunoprecipitation 和代谢标记。

Learn how metabolic labels help trace protein changes, protein interactions, RNA synthesis, plant growth, and glycan development in cells and embryos.

Tracking Cell Chemistry with Metabolic Labels | JoVE K12

Life Science

matter-and-energy-in-organisms-and-ecosystems

Matter and Energy in Organisms and Ecosystems

HS-LS1-6.

HS-LS2-4.

Overview

Principles of Metabolic Labeling

Isotopic Labeling Procedure

Photoreactive Labeling Procedure

Applications

Summary

Travelling Waves

A wave is a disturbance that propagates from its source, repeating itself periodically, and is typically associated with simple harmonic motion. ...

Wave Parameters

The simplest mechanical waves are associated with simple harmonic motion and repeat themselves for several cycles. These simple harmonic waves can be ...

Equations of Wave Motion

Mathematically, the motion of a wave can be studied using a wavefunction. Consider a string oscillating up and down in simple harmonic motion, having a ...

Graphing the Wave Function

Consider the wave equation for a sinusoidal wave moving in the positive x-direction. The wave equation is a function of both position and time. From the ...

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Velocity and Acceleration of a Wave

A wave propagates through a medium with a constant speed, known as a wave velocity. It is different from the speed of the particles of the medium, which ...

Speed of a Transverse Wave

The speed of a wave depends on the characteristics of the medium. For example, in the case of a guitar, the strings vibrate to produce the sound. The ...

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problem-solving-tuning-of-a-guitar-string

Problem-Solving: Tuning of a Guitar String

In the case of stringed instruments like the guitar, the elastic property that determines the speed of the sound produced is its linear mass density or ...

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Kinetic and Potential Energy of a Wave

All forms of waves carry energy; this is directly visualized in nature. For instance, the waves of earthquakes are so intense that they can shake huge ...

Energy and Power of a Wave

The total energy associated with a wavelength is the sum of the potential energy and the kinetic energy. The average rate of energy transfer associated ...

Interference and Superposition of Waves

When two waves of the same nature occur in the same region simultaneously, they result in interference. Interference of waves implies that the net effect ...

Reflection of Waves

When a wave travels from one medium to another, it gets reflected at the boundary of the second medium. A common example of this is when a person yells at ...

Propagation of Waves

When a wave propagates from one medium to another, part of it may get reflected in the first medium, and part of it may get transmitted to the second ...

Standing Waves

Sometimes waves do not seem to move; rather, they just vibrate in place. Unmoving waves can be seen on the surface of a glass of milk kept in a ...

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Modes of Standing Waves - I

A close look at earthquakes provides evidence for the conditions appropriate for resonance, standing waves, and constructive and destructive interference. ...

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Modes of Standing Waves: II

The starting point for expressing the modes of standing waves is understanding the boundary conditions that the waves must follow. The boundary conditions ...

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Sound Waves

Sound waves can be thought of as fluctuations in the pressure of a medium through which they propagate. Since the pressure also makes the medium&#39;s ...

Sound as Pressure Waves

Sound waves, which are longitudinal waves, can be modeled as the displacement amplitude varying as a function of the spatial and temporal coordinates. As ...

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Perception of Sound Waves

The human ear is not equally sensitive to all frequencies in the audible range. It may perceive sound waves with the same pressure but different ...

Speed of Sound in Solids and Liquids

Most solids and liquids are incompressible&#8212;their densities remain constant throughout. In the presence of an external force, the molecules tend to ...

Speed of Sound in Gases

The speed of sound in a gaseous medium depends on various factors. Since gases constitute molecules that are free to move, they are highly compressible. ...

Shock Waves

While deriving the Doppler formula for the observed frequency of a sound wave, it is assumed that the speed of sound in the medium is greater than the ...

Echo

The human ear cannot distinguish between two sources of sound if they happen to reach within a specific time interval, typically 0.1 seconds apart. More ...

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Use mathematical representations to support a claim regarding relationships among the period, frequency, wavelength, and speed of waves traveling and transferring energy (amplitude, frequency) in various media.

HS-PS4-1.

Using GIS to Investigate Urban Forestry

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Urban forests broadly include urban parks, street trees, landscaped ...

Evaluate questions about the advantages of using a digital transmission and storage of information.

HS-PS4-2.

concept-of-resonance-and-its-characteristics

Concept of Resonance and its Characteristics

If a driven oscillator needs to resonate at a specific frequency, then very light damping is required. An example of light damping includes playing piano ...

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Sound Waves: Resonance

Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical ...

Sound Waves: Interference

Sound waves can be modeled either as longitudinal waves, wherein the molecules of the medium oscillate around an equilibrium position, or as pressure ...

Interference: Path Lengths

Consider two sources of sound, that may or may not be in phase, emitting waves at a single frequency, and consider the frequencies to be the same.
Two ...

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The Wave Nature of Light

The nature of light has been a subject of inquiry since antiquity. In the seventeenth century, Isaac Newton performed experiments with lenses and prisms ...

The Electromagnetic Spectrum

The electromagnetic spectrum consists of all the types of electromagnetic radiation arranged according to their frequency and wavelength. Each of the ...

The Quantum-Mechanical Model of an Atom

Shortly after de Broglie published his ideas that the electron in a hydrogen atom could be better thought of as being a circular standing wave instead of ...

Quantum Numbers

It is said that the energy of an electron in an atom is quantized; that is, it can be equal only to certain specific values and can jump from one energy ...

Interference and Diffraction

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
Interference and diffraction ...

Photoelectric Effect

Source: Yong P. Chen, PhD, Department of Physics &#38;&#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
Photoelectric effect ...

Reflection and Refraction

Source: Derek Wilson,&#160;Asantha Cooray, PhD, Department of Physics &#38; Astronomy, School of Physical Sciences, University of California, Irvine, CA
...

Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model (quantum theory), and that for some situations one model is more useful than the other.

HS-PS4-3.

Electric Charge in a Magnetic Field

Source: Andrew Duffy, PhD, Department of Physics, Boston University, Boston, MA
This experiment duplicates J.J. Thomson's famous experiment at the end of ...

Electromagnetic Fields

Electric fields generated by static charges, often referred to as electrostatic fields, are characteristically different from electric fields created by ...

Electromagnetic Waves

James Clerk Maxwell formulated a single theory combining all the electric and magnetic effects scientists knew during that time, calling the phenomena his ...

Electromagnetic waves are categorized according to their wavelengths and frequencies, giving the electromagnetic spectrum. These waves are classified as ...

Plane Electromagnetic Waves I

The existence of combined electric and magnetic fields that propagate through space as electromagnetic (EM) waves is the most significant prediction of ...

Plane Electromagnetic Waves II

Consider a plane wavefront traveling in position x-direction with a constant speed. This wavefront can be utilized to obtain the relationship between ...

propagation-speed-of-electromagnetic-waves

Propagation Speed of Electromagnetic Waves

Electromagnetic waves are consistent with Ampere&#39;s law. Assuming there is no conduction current Ampere&#39;s law is given as:


Consider a plane ...

Electromagnetic Waves in Matter

Electromagnetic waves can travel in the vacuum as well as in matter. For example light, which is an electromagnetic wave, can travel through air, water, ...

Energy Carried By Electromagnetic Waves

Anyone who has used a microwave oven knows there is energy in electromagnetic waves. Sometimes, this energy is obvious, such as in the summer sun&#39;s ...

Intensity Of Electromagnetic Waves

The energy transport per unit area per unit time, or the Poynting vector, gives the energy flux of an electromagnetic wave at any specific time. For a ...

Momentum And Radiation Pressure

An object absorbing an electromagnetic wave would experience a force in the direction of propagation of the wave. This force occurs because ...

Cardiac Magnetic Resonance Imaging

Source: Frederick W. Damen and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
In this video, high ...

an-introduction-to-drosophila-melanogaster

An Introduction to Drosophila melanogaster

Drosophila melanogaster, also known as the fruit fly, is a powerful model organism widely used in biological research that has made significant ...

an-introduction-to-the-zebrafish-danio-rerio

An Introduction to the Zebrafish: Danio rerio

Zebrafish (Danio rerio) are small freshwater fish that are used as model organisms for biomedical research. The many strengths of these fish include their ...

Evaluate the validity and reliability of claims in published materials of the effects that different frequencies of electromagnetic radiation have when absorbed by matter.

HS-PS4-4.

Tracking Cell Chemistry with Metabolic Labels

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