Biofuels Image Gallery

Title :

Simplified Model of a Primary Cell Wall

Description :

Cellulose in higher plants is organized into microfibrils, each measuring about 3 to 6 nm in diameter and containing up to 36 glucan chains having thousands of glucose residues. Like steel girders stabilizing a skyscraper’s structure, the primary cell-wall’s mechanical strength is due mainly to the microfibril scaffold. A microfibril’s crystalline and paracrystalline (amorphous) cellulose core is surrounded by hemicellulose, a branched polymer composed of pentose (5-carbon) and hexose (6-carbon) sugars. In addition to cross-linking individual microfibrils, hemicellulose in secondary cell walls (not shown) forms covalent associations with lignin, a rigid aromatic polymer whose structure and organization within the cell wall are poorly understood. The crystallinity of cellulose and its association with hemicellulose and lignin are two key challenges preventing efficient cellulose breakdown into glucose molecules convertible to ethanol.

Citation :

"Genomics:GTL Transforming Cellulosic Biomass," U.S. Department of Energy Office of Science and Office of Energy Efficiency and Renewable Energy, June 2006, http://genomicsgtl.energy.gov/biofuels/ and U.S. DOE. 2006. "Breaking the Biological Barriers to Cellulosic Ethanol: A Joint Research Agenda," DOE/SC/EE-0095, U.S. Department of Energy Office of Science and Office of Energy Efficiency and Renewable Energy, http://genomicsgtl.energy.gov/biofuels/.

Credit or Source :

Figure adapted with permission from C. Somerville, Stanford University, 2004. Source: Genome Management Information System, Oak Ridge National Laboratory

Hi Res :

High-Resolution Image

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Almost all the images on these pages are original graphics created by the U.S. Department of Energy Genome Program's Genome Management Information System (GMIS). You will recognize GMIS images by their credit line. Permission to use these graphics is not needed, but please credit the U.S. Department of Energy Genome Programs and provide the website http://genomics.energy.gov. All other images were provided by third parties and not created by the U.S. Department of Energy. You must contact the person listed in the credit line before using those images.