What Difference Between Agar and Agarose Experts Want You to Know

Nov 20, 2023
Difference Between Agar and Agarose

Agar and Agarose: The main difference between agar (a gelatinous substance) and agarose (a linear polymer) is that agar comes from red seaweeds or agar.

Agar and Agarose are polysaccharide-based products that come either from red alga or seaweed. These polysaccharides are useful in many fields. They can be used for food preparation, or to grow bacteria. These sources are commercially valuable and are being cultivated in Asia and the United States. Structurally, agarose is a linear polymer consisting of alternating D-galactose and 3,6-anhydro-L-galactose units. Agar, on the other hand, is a mixture containing agarose and anhydrous-L-galactose.

Brief explanation of agar and agarose

Figure-01: Agar

Both agarose and agar can play important roles in laboratory research, particularly within microbiology and molecular biology fields.

Agar, made from red algae (seaweed), is an abundance of polysaccharides found within red algae (seaweed). Agar comprises three ingredients; these are agarose, agaropectin and agarose and has the consistency of a gel-like substance; its flexibility comes from its solubility given by Agaropectin which also gives Agar flexibility and solubility; it is extensively used in microbiology for growing and cultivating bacteria as well as molecular biology techniques such as electrophoresis or DNA/RNA analysis techniques but its impurities limit its application further.

Agarose is an extremely pure form of agar. Composed mostly of linear polymers called agarose without any trace of agaropectin, its homogenous and rigid polymer structure allows it to form an extremely stable gel network used mainly in electrophoresis to separate biomolecules like DNA, RNA, and proteins from each other; but also used extensively across biotechnological applications and protein purification processes.

Understanding the differences between agarose and agar can be key when selecting the ideal substance for laboratory or research applications. When making this choice, factors like gel strength and purity should be carefully taken into consideration when choosing one over the other.

The importance of agar and agarose in scientific research and laboratory applications

indispensable tools in scientific research, laboratory applications, and many other areas.

Here are just a few key reasons they’re so crucial:

  • Microbiological Growth and Culture: Agar has long been used in microbiology as an ideal solidifying substance to encourage microorganism growth and cultivation, acting like a matrix supporting their colonization by organisms that form colonies that can then be observed and observed again later for study. Agar can help isolate different bacteria or fungi to study, making it a key tool in research related to this field of science.
  • Gel Electrophoresis: Agarose plays an essential part in gel electrophoresis techniques used for biomolecular separations such as DNA, RNA, and proteins. Agarose serves as a molecular sieve and allows biomolecules to be separated based on size and charge – this makes this a fantastic method for genetic research as it facilitates nucleic acid and protein analysis and identification.
  • DNA/RNA Analysis: Both Agarose and Agar can be utilized in DNA and RNA analyses. Agar can be utilized to purify, extract and isolate genetic material while serving as a stable surface to isolate genetic material. Agarose serves as the core ingredient in gel electrophoresis which has become widespread use for DNA and analyses including genotyping/PCR analyses.
  • Biotechnological Applications, Agarose: and agar-based products such as Agar are extensively utilized for biotechnology processes. Agar, Agarose, and similar materials can be utilized in cell culture processes, enzyme stabilization strategies, and drug delivery applications; Agarose serves as an adaptable biomaterial with its gel formation properties providing numerous opportunities.

Agar and agarose play an indispensable part in laboratory and scientific research due to their role in various biotechnological and microbiological processes, including DNA/RNA analysis and protein purification. Their unique properties make them indispensable when studying biology, genetics, and biochemistry as they serve numerous applications across a range of sciences.

Composition and Source

Agarose and Agar differ significantly when it comes to composition and source; both products possess distinct elements within them that differentiate them.


  1. Agar is composed of an intricate mixture of complex polysaccharides. The main constituents are agarose and agaropectin; with the former acting to create gel-like textures while its counterpart provides flexibility and solubility to agar.
  2. Agar is produced from seaweeds, specifically red algae (Rhodophyta). Seaweed harvested from marine environments and processed into agar is harvested, although different species of red alga may produce different properties and compositions.


  1. Composition: Agarose is a purified version of agar produced by extracting out impurities like agaropectin. It primarily comprises linear polymers called Agarobiose which gel when exposed to moisture.
  2. Source of Agarose: Agarose comes from agar, which in turn comes from seaweed. After extraction from the red alga, purification is necessary so as to separate out and extract only agarose as its final form – usually through enzymes and filtering technology.

Note that composition and properties may differ based on the type of seaweed, its growth conditions, and extraction and purification methods employed, potentially altering performance characteristics for specific applications of Agar/Agarose products.


Agar and Agarose each possess distinct molecular structures and organizational arrangements, here’s an outline of each’s structure:


  1. Agar has an intricate composition. It contains different polysaccharides such as agarose and agaropectin as well as other more unique ones with branching structures – Agaropectin is responsible for giving Agar its flexibility and solubility properties.
  2. Agar qualifies at certain temperatures and changes from solid to liquid when heated, giving this thermoreversible compound numerous laboratory applications and microbiological cultures as a solidifying medium.


  1. Agarose possesses an even, homogenous structure. To create it, purifying agar, and extracting out any trace agaropectins and any impurities from it are the only methods necessary. Agarobise forms from repeated units.
  2. Agarose is an inorganic polymer arrangement. When mixed with water it forms an irreducibly rigid gel structure; its linear chains align in an ordered fashion to form tunnels or pores connected by tunnel walls that have consistent pore sizes; making agarose suitable for applications requiring precise separation and analysis, such as gel electrophoresis or electrochemical separation techniques.

Structure differences are at the root of their various properties and functionalities; Agar’s heterogenous agaropectin structure provides flexibility, and solubility, while Agarose forms defined gel networks ideal for gel electrophoresis applications.

Gel Properties

Agar and agarose gel properties vary with respect to strength, melting temperature, and structure; here is an overview of both material’s gel characteristics:


Agar gels tend to be weaker in terms of gel strength than their agarose counterparts. Agar gels feature a softer consistency with less rigidity – this makes them suitable for applications requiring flexible gel solutions.

  1. Melting Temperature of Agar Gel: The melting point or gel-to-liquid transition temperature for Agar ranges between 85-95%C, where its gel will liquefy when exposed to temperatures exceeding this point and become liquid once heated above this mark, thus serving as a reversible solidifying agent and being easily recycled without loss or degradation to their properties.
  2. Gel Reversibility: Agar gels are thermoreversible, meaning they can melt upon heating before solidifying upon cooling again, making it possible to reuse agar gels for various applications such as bacterial growth and culture.


Gels are widely known for their superior gel strength. This makes them suitable for applications requiring more rigid matrix structures while their high gel strength facilitates separation and support of biomolecules during gel electrophoresis experiments.

  • As with agar gels: the melting point for agarose gels lies between 85-95degC (185-203degF). Agarose melts when heated above this threshold temperature; unlike its agar counterpart however, the further raising of temperature does not induce melting; once agarose has solidified back into a gel it cannot be reconverted without going through another gel formation process.
  • Agarose Gelation Irreversible: Once formed and cooled off, Agarose gel is irreversibly gel-ified – even when heated again! Once solidified it cannot easily liquefy or reform into another state; providing consistent separation for gel electrophoresis as well as other applications.

when selecting an application material, it is crucial to take note of both agarose and agar’s gel properties when choosing which will suit best. Agar may offer thermoreversibility with soft gels which might prove advantageous; on the contrary, rigid matrix applications typically benefit more from Agarose than vice versa.


Agarose for Scientific Applications [Bottom of Page] for scientific applications of these substances in various scientific research settings or laboratories. Agar and Agarose both offer numerous uses in various research applications and laboratory environments.


  • Agar is widely utilized in microbiology as a solidifying substance to facilitate microorganism growth and cultivation, specifically bacteria and fungus growth. Agar acts like an incubator that supports their spread into their respective environments.
  • Antibiotic Sensitivity Tests on Agar Plates, Antibiotic susceptibility tests conducted using Agar Plates allow researchers to better evaluate bacterial growth characteristics. Agar plates allow scientists to count and visualize colonies, study bacterial morphology and perform antibiotic sensitivity tests that detect susceptibilities to different antibiotics.
  • Food Microbiology Agar-based media are essential tools in food microbiology as a method for testing pathogenic bacteria or organisms responsible for food spoilage, while simultaneously isolating and cultivating specific strains of microorganisms.


Agar can be utilized for numerous molecular techniques. It serves as a solid substrate for DNA purification and extraction processes, creating an easily accessible method of isolating genetic material from multiple sources.

  • Agarose Gel Electrophoresis, Agarose gels are widely utilized for gel electrophoresis. This technique allows researchers to separate and analyze biomolecules such as DNA, proteins, or RNA according to size or charge using its porous matrix that allows biomolecules to migrate when an electric current flows, providing visibility as they pass through and allowing separation and analysis.
  • DNA/RNA Analysis, Agarose Gels can be used for DNA and RNA samples using techniques like fragment analysis and sequencing of nucleic acids fragments, electrophoresis analysis of PCR products as well as separation and visualization of nucleic acids fragments of various sizes using Agarose Gels.
  • Agarose gels can be used to efficiently separate proteins by size or isoelectric point, provided they feature sufficient pores. By choosing Agarose gels with appropriate pore sizes, proteins can be separated according to size or isoelectric points.
  • Agarose resins are widely utilized to purify proteins. As these resins contain ligand-based binding sites that selectively attach target proteins, agarose enables complex mixtures to be separated and purified efficiently.
  • Agarose can be used in numerous biotechnological applications such as cell culture, drug delivery, and enzyme immobilization. Agarose matrixes offer stable support structures suitable for drug delivery as well as cell growth or immobilization.

These examples demonstrate the versatility of both Agar and Agarose in various microbiological, molecular biochemistry, protein analysis, and biotech applications. Each application must take its own set of considerations into consideration before choosing between Agar or Agarose for any given experiment or application.

Advantages and Disadvantages

To select the optimal substance for an application, it is crucial to carefully weigh both agarose and agar’s advantages and drawbacks.

Here is a comparison chart detailing their respective advantages and drawbacks:



  1. Agarose can be more expensive; thus making Agar an appealing and economical alternative in certain situations.
  2. Agar can easily be obtained from multiple suppliers.
  3. Agar can be an excellent material to use for certain applications. Due to its their reversibility and a soft gel consistency, Agar makes an ideal material for creating flexible or thermoreversible gels such as in bacterial cultures or molecular biology techniques.


  1. Agarose gels offer greater rigidity for certain applications; therefore they may not be appropriate when you require more rigid matrix structures.
  2. Agar may contain impurities like agaropectin that interfere with certain experiments and reduce reproducibility, potentially impacting the performance and reproducibility of experiments conducted in its use.
  3. Due to impurities and lower gel strength, agar’s application in molecular biology is somewhat limited; therefore it should only be utilized for specific techniques like high-resolution DNA electrophoresis.



  1. Agarose offers several advantages over alternative materials for various uses including gel electrophoresis, protein separation, and other gel-based processes. Agarose’s high gel strength also creates a stable platform suitable for many other techniques like protein separation or electrophoresis.
  2. Pure Composition, Agarose is a purified version of agar that provides more reproducible results without impurities or contamination.
  3. Agarose is an invaluable component in molecular biology. Due to its superior gel strength and purity, agarose is frequently chosen for applications including DNA/RNA analyses.

Disadvantages of Agarose:

  1. Higher Cost, Agarose can be more costly than Agar for budget-constrained projects, and can therefore become prohibitively expensive to use in certain instances.
  2. Agarose, Agarose derived directly from agar requires additional purification steps that increase both its costs and complexity, driving up costs further.
  3. As it gels irreversibly, agarose cannot be used in experiments requiring repeated melting and regulating.

Before selecting an ideal substance for research or laboratory applications, it’s crucial to carefully weigh its advantages and drawbacks. Considerations must include factors like gel strength and purity as well as costs/prices.


While both agarose and agar are derived from the same plant and processing techniques, their distinct characteristics and resulting properties allow them to be used in diverse applications in science. Agar is a diverse material used for the cultivation of microorganisms. Agarose is the purest form and can be used in gel electrophoresis, as well as other molecular biological techniques. When you know the distinctions between agarose and agar, researchers are able to make informed decisions to select the appropriate material for their particular experiments and research, thereby contributing towards the improvement of knowledge and new discoveries.