Name: membrane proteins in liposome models
Uploaded: 2023-04-30T06:31:34.000Z
Duration: 7 min 5 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

High School

Life Science

Structure and Function

HS-LS1-3.

Reconstitution of Membrane Proteins

复构是指将分离的生物大分子恢复至其原始形态或功能的过程。这一技术对于研究膜蛋白尤其有用，因为膜蛋白能够介导重要的细胞功能，并影响邻近脂质的行为。为了在原位研究纯化后膜蛋白的功能，必须通过将其整合到人工脂质膜中来实现复构。
本视频介绍了膜蛋白重建的相关概念和实验步骤，包括使用去垢剂分离蛋白质、利用脂质形成人工囊泡、将分离得到的蛋白质整合至人工囊泡中，以及从溶液中去除去垢剂。最后，介绍了两个应用实例：膜转运蛋白的重建和光捕获蛋白的重建。&#160;

膜蛋白的重建

复原是指将分离的生物大分子恢复至其原始形态或功能的过程。这一技术对于研究膜蛋白尤其有用，因为膜蛋白能够介导重要的细胞功能，并影响邻近脂质的行为。为了在原位研究纯化后膜蛋白的功能，必须通过将其整合到人工脂质膜中来实现复原。
本视频介绍了膜蛋白重建的相关概念及操作步骤，包括使用去垢剂分离蛋白、利用脂质形成人工囊泡、将分离的蛋白整合至人工囊泡中，以及从溶液中去除去垢剂。最后，介绍了两个应用实例：膜转运蛋白的重建和光捕获蛋白的重建。&#160;
<div class="chapter_text" id="script_0">
复现是指将分离的生物大分子恢复至其原始形态或功能的过程。该方法常用于研究膜蛋白，因为膜蛋白介导许多重要的细胞过程，并影响邻近脂质的行为。然而，细胞环境的复杂性使得在原位（in situ）研究膜蛋白功能十分困难。虽然膜蛋白可以被提取并纯化，但在缺乏膜结构的情况下，其真实功能无法被评估。因此，通常通过将分离的膜蛋白整合到人工脂质膜（如脂质体）中来实现其复现。本视频将介绍膜蛋白复现的基本原理、通用的复现操作流程，以及其在生物化学领域中的若干应用。
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<div class="chapter_text" id="script_1">
细胞膜主要由磷脂和膜蛋白组成。磷脂形成双分子层，其中亲水性的磷酸头部与细胞内外的水环境相互作用，而疏水性的脂肪酸尾部则在双分子层内部彼此相互作用。
某些膜蛋白仅通过静电作用或非共价相互作用与膜结合。另一些被称为“整合蛋白”的蛋白则嵌入在脂质双分子层中。
与脂双层类似，整合蛋白具有亲水性的末端和疏水性的中心区域，并通过疏水相互作用固定在膜中。贯穿整个膜的整合蛋白被称为“跨膜蛋白”。
这些蛋白与膜之间的相互作用非常强，即使裂解细胞也无法将其分离。因此需要使用一种特殊的表面活性剂——去垢剂来提取这些蛋白。与磷脂类似，去垢剂具有亲水性头部和亲脂性尾部，能够自由进入膜结构。
在膜内部，去垢剂的亲脂性尾部与蛋白的疏水核心相互作用，从而在蛋白周围形成一层由去垢剂亲水性头部构成的外壳，破坏了蛋白与脂质之间的相互作用。
蛋白-去垢剂复合物现在可轻易从膜中分离出来。去垢剂使该复合物在水溶液中具有良好的溶解性，便于进一步在人工膜中进行重组。
蛋白常被重组到脂质体的膜中，脂质体是一种人工囊泡。制备脂质体时，将干燥的脂质水化并加以振荡以诱导囊泡形成。当加入去垢剂时，它会整合进脂质体的膜中。
为了实现蛋白的重组，将溶解的蛋白与脂质体混合，然后通过透析或化学吸附的方式从溶液中去除去垢剂。蛋白和脂质体会迅速组装成蛋白脂质体，使得只有亲水基团暴露在外。此时蛋白的功能与在细胞膜中相同，可在分离状态下进行研究。
在了解了蛋白重组的基本原理之后，接下来我们将介绍一种将膜蛋白重组到脂质体中的实验方案。
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<div class="chapter_text" id="script_2">
为了开始分离膜蛋白，首先裂解细胞，并通过离心去除未破碎的细胞。
上清液在更高转速下离心，以沉淀膜组分。将沉淀重新悬浮后加入去垢剂，以提取蛋白质。
通过进一步离心去除残留的细胞碎片。随后利用柱层析从上清液中纯化蛋白质，并根据需要进行浓缩或进一步纯化。
为了开始制备脂质体，将有机溶剂中的磷脂悬浮液在氮气或氩气环境下干燥。
用水合缓冲液对磷脂进行水合，并通过超声处理完成脂质体的制备。
加入去垢剂使脂质体溶解，然后与蛋白质混合。
通过聚苯乙烯珠吸附、透析或去垢剂结合柱去除去垢剂。所得的蛋白脂质体即可用于后续实验的纯化和使用。
</div>
<div class="chapter_text" id="script_3">
现在您已经熟悉了膜蛋白重建实验的基本步骤，接下来让我们了解蛋白重建在生物化学中的一些应用。
一种膜转运蛋白被成功重建，以更清晰地理解其转运机制。通过碘离子外流实验验证了该蛋白在重建后的功能，随后在多种小分子离子通道抑制剂和增强剂存在的情况下研究其转运活性。通过这种方法，可以直接研究这些小分子与转运蛋白之间的相互作用。
植物中结合叶绿素和类胡萝卜素的膜蛋白具有捕获光能、促进电荷分离以及减轻光损伤的作用。通过重建这些捕光蛋白，可以研究其折叠动力学及其与色素分子的相互作用。利用该技术重建的捕光蛋白表现出与天然蛋白非常相似的光学特性。随后可采用荧光发射光谱法研究色素向重建捕光蛋白的能量传递过程。
</div>
<div class="chapter_text" id="script_4">
您刚刚观看了JoVE关于膜蛋白重建的视频。蛋白重建是一种将重要蛋白质转移至细胞模拟体系以进行进一步研究的方法。本视频介绍了蛋白重建的原理、一种重建实验方案，以及其在生物化学中的若干应用。感谢观看！
</div>

重建是指将分离的生物分子恢复至其原始形态或功能的过程。这对于研究膜蛋白……尤为有用。

复原是指将分离的生物大分子恢复至其原始结构或功能的过程。该方法常用于研究膜蛋白，因为膜蛋白介导许多重要的细胞过程，并影响邻近脂质的行为。然而，由于细胞环境的复杂性，膜蛋白的功能难以在原位进行研究。虽然膜蛋白可以被提取并纯化，但在缺乏膜结构的情况下，其真实功能无法被评估。因此，通常通过将分离的膜蛋白整合到人工脂质膜（如脂质体）中来实现其复原。本视频将介绍膜蛋白复原的基本原理、通用的复原操作流程，以及其在生物化学领域中的若干应用。细胞膜主要由磷脂和膜蛋白组成。磷脂形成双层结构，其中亲水的磷酸头部与细胞内外的水环境相互作用，而疏水的脂肪酸尾部则在双层内部彼此相互作用。某些膜蛋白仅通过静电作用或非共价相互作用与膜结合。另一些被称为“整合蛋白”的膜蛋白则嵌入脂质双分子层中。与脂双层类似，内在蛋白具有亲水的末端和疏水的中心，并通过疏水相互作用固定在膜中。贯穿整个膜的内在蛋白被称为“跨膜蛋白”。这些蛋白质与膜之间的相互作用非常强烈，即使裂解细胞也无法将其分离。因此需要使用一种称为去垢剂的特殊表面活性剂来提取这些蛋白质。去垢剂与磷脂类似，具有亲水头部和亲脂尾部，能够自由进入膜内。在膜内，去垢剂的疏水尾部与蛋白质的疏水核心相互作用，从而在蛋白质周围形成一层亲水性去垢剂头部的外壳，破坏蛋白质与脂质之间的相互作用。蛋白质-去垢剂复合物现在可轻松地从膜中分离。去垢剂使该复合物在水溶液中具有溶解性，并可用于在人工膜中进行重建。蛋白质通常在脂质体（一种人工囊泡）的膜中进行重建。制备脂质体时，将干燥的脂质水合并搅拌以诱导囊泡形成。当加入去垢剂时，它会被整合到脂质体膜中。为了重组蛋白质，将溶解的蛋白质与脂质体混合，然后通过透析或化学吸附法从溶液中去除去垢剂。蛋白质和脂质体会迅速组装成蛋白脂质体，仅暴露出亲水基团。随后，这些蛋白质便如同在细胞膜中一样发挥功能，并可被单独研究。在了解了蛋白质重构的基本原理之后，接下来我们将介绍一种在脂质体中重构膜蛋白的实验方案。为了开始分离膜蛋白，需对细胞进行裂解，然后通过离心去除未破碎的细胞。将上清液以更高的速度离心，以沉淀膜组分。将沉淀物重新悬浮，并加入去垢剂以提取蛋白质。通过进一步离心去除剩余的细胞碎片。使用柱层析法从上清液中纯化蛋白质，然后根据需要进行浓缩或进一步纯化。开始制备脂质体时，将有机溶剂中的磷脂悬浮液在氮气或氩气条件下干燥。将磷脂用水合缓冲液进行水合，并通过超声处理完成脂质体的制备。加入去垢剂以溶解脂质体，然后与蛋白质混合。然后通过聚苯乙烯珠吸附、透析或去垢剂结合柱去除去垢剂。所得的蛋白脂质体即可用于后续实验的纯化和使用。现在您已经熟悉了膜蛋白重建实验的基本步骤，接下来让我们探讨一下蛋白质重建在生物化学领域的一些应用。通过重建膜转运蛋白，以更清晰地理解其转运机制。重建后，通过碘离子外排实验验证了该蛋白的功能。随后，在多种小分子离子通道抑制剂和增强剂存在的情况下，研究了其转运活性。通过这种方法，可直接研究这些小分子与转运蛋白之间的相互作用。植物中的叶绿素和类胡萝卜素结合膜蛋白能够捕获光能、促进电荷分离并减轻光损伤。通过重建这些光捕获蛋白，可以研究其折叠动力学及其与色素的相互作用。利用该技术重建的光捕获蛋白具有与天然蛋白非常相似的光学特性。随后可利用荧光发射光谱法研究色素向重建光捕获蛋白的能量转移。您刚刚观看了 JoVE 关于膜蛋白重建的视频。膜蛋白重建是一种将重要蛋白质转移至细胞模拟体系以进行进一步研究的方法。本视频介绍了蛋白质重建的原理、一种重建实验方案，以及其在生物化学领域中的若干应用。感谢观看！

Education

教育

JoVE Science Education

Chemistry

化学

Biochemistry

生物化学

膜蛋白的重组

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 proteins attach by noncovalent or electrostatic interactions, while integral proteins are embedded in the bilayer. Transmembrane proteins are integral proteins that span the full membrane, and their strong interactions with the membrane are not broken just by lysing cells.

Detergent is used to extract these proteins. Detergents have hydrophilic heads and lipophilic tails, so they can enter the membrane. Their tails interact with the hydrophobic protein core and surround it with detergent heads, which breaks protein-lipid interactions. The protein-detergent complex becomes soluble in water and is ready for reconstitution.

Liposomes are artificial vesicles often used for this step. They are made by hydrating dried lipids and agitating them to form vesicles. When detergent is added, it becomes part of the liposome membrane. The purified protein and liposomes are then mixed, and the detergent is removed by dialysis or chemical adsorption. As the detergent leaves, the protein and lipids assemble into proteoliposomes, with hydrophilic groups exposed to water. The reconstituted proteins can then work in a membrane-like setting and be studied in isolation.

A general liposome protocol starts with cell lysis. Unbroken cells are removed by centrifugation, and the membranes are pelleted at higher speed. The pellet is resuspended, detergent is added to extract the proteins, and more centrifugation removes leftover debris. The protein is then purified by column chromatography and concentrated if needed.

Liposome preparation follows a separate path. Phospholipids in organic solvent are dried under nitrogen or argon, then hydrated with buffer. Sonication finishes the liposome formation. After detergent is added to solubilize the liposomes, the proteins are combined with them. The detergent is removed with polystyrene beads, dialysis, or a detergent-binding column, leaving proteoliposomes that can be purified and used in later experiments.

Reconstituted membrane proteins have several uses in biochemistry. One transport protein was reconstituted to better understand how it moves molecules. Its activity was checked by the efflux of iodide ions. Researchers also tested small-molecule ion channel inhibitors and potentiators to study how they interact with the transport protein directly.

Plant light-harvesting proteins are another example. These chlorophyll- and carotenoid-binding membrane proteins help harvest light, support charge separation, and reduce light damage. After reconstitution, scientists can study folding dynamics and pigment interactions. The reconstituted proteins showed optical properties very similar to native proteins, and fluorescence emission spectroscopy can be used to follow energy transfer from pigments to the proteins.

Membrane Proteins in Liposome Models

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

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...

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 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。

See how membrane proteins are extracted with detergent and reinserted into liposomes so students can study transport and light-harvesting function.

Membrane Proteins in Liposome Models | JoVE K12

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

Matter and Energy in Organisms and Ecosystems

HS-LS1-5.

HS-LS1-6.

Overview

Principles of Membrane Protein Reconstitution

Protocol for Reconstitution of Membrane Proteins in Liposomes

Applications

Summary

Characteristics of Life

Biology is a natural science that studies life and living organisms, including their structure, function, development, interactions, evolution, ...

https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10647.jpg

Cell Structure

Background
Cells represent the most basic biological units of all organisms, whether it be simple, single-celled organisms like bacteria, or large, ...

Visualizing Onion and Cheek Cells
ExpandImmediately before the experiment, wash and peel onion bulbs for the class.
Remove the entire brown outer skin and ...

Visualizing Onion and Human Cells
ExpandIn this experiment you will prepare different types of cells from a plant and animal, onion and human ...

What are Cells?

Cell Diversity

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term &#34;cell&#34; based on the ...

Cytoplasm

The cytoplasm consists of organelles and a framework of protein scaffolds called the cytoskeleton suspended in an aqueous solution, the cytosol. The ...

The Nucleus

The nucleus is a membrane-bound organelle that acts as a control center in a eukaryotic cell. It contains chromosomal DNA, which controls gene expression ...

The Central Dogma

The DNA Helix

Nucleic Acids

DNA as a Genetic Template

Structure of a Gene

A gene is the fundamental unit of heredity. Every individual has two copies of each gene, one inherited from each parent. Although most people contain the ...

Chromosome Structure

Base-pairing and DNA Repair

What is Gene Expression?

A gene is a stretch of DNA that serves as the blueprint for functional RNAs and proteins. Since DNA is comprised&#160; of nucleotides and proteins are ...

RNA Structure

The basic structure of RNA consists of a string of ribonucleotides attached by phosphodiester bonds. Although most RNA is single-stranded, it can form ...

Types of RNA

Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse ...

Transcription

Transcription is the synthesis of RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. ...

Translation

Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes ...

Ribosomes

Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that ...

Protein and Protein Structures

Proteins: From Genes to Degradation

From DNA to Protein

The flow of genetic information in cells from DNA to mRNA to protein is described by the central dogma, which states that genes specify the sequence of ...

Protein Folding

Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to ...

An Overview of Gene Expression

Gene expression is the complex process where a cell uses its genetic information to make functional products. This process is regulated at multiple ...

an-introduction-to-caenorhabditis-elegans

An Introduction to Caenorhabditis elegans

Caenorhabditis elegans is a microscopic, soil-dwelling roundworm that has been powerfully used as a model organism since the early 1970&rsquo;s.  It was ...

An Overview of Genetic Analysis

An organism&#8217;s physical traits, or phenotype, are a product of its genotype, which is the combination of alleles (gene variants) inherited from its ...

An Introduction to Cell Death

Necrosis, apoptosis, and autophagic cell death are all manners in which cells can die, and these mechanisms can be induced by different stimuli, such as ...

An Overview of Genetic Engineering

Genetic engineering &#8211; the process of purposefully altering an organism&#8217;s DNA &#8211; has been used to create powerful research tools and model ...

An Introduction to Cell Division

Cell division is the process by which a parent cell divides and gives rise to two or more daughter cells. It is a means of reproduction for single-cell ...

An Overview of Genetics and Disease

Many human diseases are associated with mutations or variations in genetic sequences. Some of these genetic variants are heritable, passed down from ...

an-introduction-to-cellular-and-molecular-neuroscience

An Introduction to Cellular and Molecular Neuroscience

Cellular and molecular neuroscience is one of the newest and fastest growing subdisciplines in neuroscience. By investigating the influences of genes, ...

Annexin V and Propidium Iodide Labeling

Staining with annexin V and propidium iodide (PI) provides researchers with a way to identify different types of cell death&#8212;either necrosis or ...

an-introduction-to-developmental-genetics

An Introduction to Developmental Genetics

Development is the complex process through which a single-celled embryo transforms into a multicellular organism. Developmental processes are guided by ...

Bacterial Transformation: Electroporation

The term &#x201C;transformation&#x201D; refers cellular ingestion of foreign DNA.  In nature, transformation can occur in certain types of bacteria.  In ...

an-introduction-to-molecular-developmental-biology

An Introduction to Molecular Developmental Biology

Molecular signals play a major role in the complex processes occurring during embryonic development. These signals regulate activities such as cell ...

bacterial-transformation-the-heat-shock-method

Bacterial Transformation: The Heat Shock Method

Transformation is the process that occurs when a cell ingests foreign DNA from its surroundings. Transformation can occur in nature in certain types of ...

an-introduction-to-saccharomyces-cerevisiae

An Introduction to Saccharomyces cerevisiae

Saccharomyces cerevisiae (commonly known as baker&rsquo;s yeast) is a single-celled eukaryote that is frequently used in scientific research.  S. ...

Cell Cycle Analysis

Cell cycle refers to the set of events through which a cell grows, replicates its genome, and ultimately divides into two daughter cells through the ...

An Introduction to Transfection

Transfection is the process of inserting genetic material, such as DNA and double stranded RNA, into mammalian cells. The insertion of DNA into a cell ...

Chromatin Immunoprecipitation

Histones are proteins that help organize DNA in eukaryotic nuclei by serving as &#8220;scaffolds&#8221; around which DNA can be wrapped, forming a complex ...

An Overview of Epigenetics

Since the early days of genetics research, scientists have noted certain heritable phenotypic differences that are not due to differences in the ...

community-dna-extraction-from-bacterial-colonies

Community DNA Extraction from Bacterial Colonies

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Author: Luisa Ikner
Traditional methods of analysis ...

Cytogenetics

Cytogenetics is the field of study devoted to chromosomes, and involves the direct observation of a cell&#8217;s chromosomal number and structure, ...

embryonic-stem-cell-culture-and-differentiation

Embryonic Stem Cell Culture and Differentiation

Culturing embryonic stem (ES) cells requires conditions that maintain these cells in an undifferentiated state to preserve their capacity for self-renewal ...

DNA Gel Electrophoresis

DNA gel electrophoresis is a technique used for the detection and separation of DNA molecules. An electric field is applied to a gel matrix comprised of ...

Enzyme Assays and Kinetics

Enzyme kinetics describes the catalytic effects of enzymes, which are biomolecules that facilitate chemical reactions necessary for living organisms. ...

DNA Ligation Reactions

In molecular biology, ligation refers to the joining of two DNA fragments through the formation of a phosphodiester bond.  An enzyme known as a ligase ...

explant-culture-for-developmental-studies

Explant Culture for Developmental Studies

Explant culture is a technique in which living cells or tissues are removed from an embryo for continued development outside of the organism. This ex vivo ...

DNA Methylation Analysis

Methylation at CpG dinucleotides is a chemical modification of DNA hypothesized to play important roles in regulating gene expression. In particular, the ...

Expression Profiling with Microarrays

Microarrays are important tools for profiling gene expression, and are based on complementary binding between probes that are attached to glass chips and ...

Density Gradient Ultracentrifugation

Density gradient ultracentrifugation is a common technique used to isolate and purify biomolecules and cell structures. This technique exploits the fact ...

F&#246;rster Resonance Energy Transfer (FRET)

F&#246;rster resonance energy transfer (FRET) is a phenomenon used to investigate close-range biochemical interactions. In FRET, a donor photoluminescent ...

detecting-environmental-microorganisms-with-polymerase-chain-reaction

Detecting Environmental Microorganisms with the Polymerase Chain Reaction and Gel Electrophoresis

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - Arizona University
Demonstrating Author: Bradley Schmitz
Polymerase chain reaction (PCR) is ...

Gel Purification

Gel purification is used to recover DNA fragments after electrophoretic separation. DNA recovery from an agarose gel includes three basic steps: binding, ...

Detecting Reactive Oxygen Species

Reactive oxygen species are chemically active, oxygen-derived molecules capable of oxidizing other molecules. Because of their reactive nature, there are ...

Gene Silencing with Morpholinos

Morpholino-mediated gene silencing is a common technique used to study roles of specific genes during development. Morpholinos inhibit gene expression by ...

development-and-reproduction-of-the-laboratory-mouse

Development and Reproduction of the Laboratory Mouse

Successful breeding of the laboratory mouse (Mus musculus) is critical to the establishment and maintenance of a productive animal colony. Additionally, ...

Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells.

HS-LS1-1.

Membrane Proteins in Liposome Models

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