approximate composition in molar percentage Glycerol These phospholipids play many roles in cells, but one of their most important is in the cell membrane.
Carbohydrates The carbohydrates are a large, very widely distributed class of compounds found in almost all animals and plants. They are so named because of their basic chemical composition, which is usually some variation on the general formula CH2O. The smallest molecule to be generally considered a carbohydrate is glyceraldehyde, with only three carbon atoms in a short chain. Larger, single, molecules can have up to seven carbon atoms in a chain, but the most common members of this class have 5, or 6 carbon atoms in their structure. The largest molecules are huge polymers of smaller carbohydrate units. The carbohydrate class can be subdivided into three smaller groups, monosaccharides ('single sugars'), Oligosaccharides (two and three sugars joined together), and Polysaccharides (polymers of many sugars in long chains). Glucose, a monosaccharideGlucose is a hexose sugar (meaning it has 6 carbon atoms in it's structure). All the carbon atoms are joined to one another in a chain. Each of the carbon atoms is also joined to at least one hydrogen atom and to one oxygen atom. The presence of all this oxygen in the structure of the glucose molecule ensures that it is strongly hydrophilic ('loves' water). Most monosaccharides, like glucose, contain a lot of energy in their bonds, but, unlike the hydrocarbons, they dissolve readily in water. Cyclic structure of glucose When scientists shone polarized light through a freshly prepared solutions of glucose, they often got very different results from one solution to the next. Sometimes the polarized light would be rotated +112.2 degrees, and sometimes only +18.7 degrees. What was going on? The solution to this puzzle turned out to be the three dimensional structure of the glucose molecule itself. Two different forms of the molecule could exist (called isomers), both of which had the same chemical structure, but different arrangements of the molecular shape. This, seemingly trivial difference, in molecular structure turned out to be very important when these different types of the glucose molecule participated in 'joining' reactions to form larger structures. Joining sugars togetherIndividual sugar molecules, the monosaccharides, can be used as monomers joined together to form larger structures. For example, two glucose molecules can be joined to form the disaccharide called maltose. Or two different sugars (fructose and glucose) can be joined together to form the disaccharide sucrose. Polysaccharides The vast majority of carbohydrates in nature are found in the form of very large polymers, made up by joining together various monosaccharide sugars. Glucose is the most abundant sugar used this way, but mannose, galactose, xylose, and arabinose are also used as monomers. Polysaccharides vary in their monosaccharide composition, in the number of monomers in a chain (its molecular weight) and structural features such as branching.Almost all polysaccharides are polydisperse, meaning that, even when in a pure form, any given sample of the substance could vary in its size or number of monomer units in its structure. The very common polysaccharide starch is a mixture of branched chains of glucose that can have as little as a 100 sugars per chain, all the way up to chains as long as 10,000 glucose monomers. StarchMade by plants as a way of storing chemical energy, starch comes in two common forms. Amylose is believed to be a long, unbranched chain of alpha-glucose molecules, in which the fourth carbon atom of one sugar is joined to the first carbon atom of the next sugar. Amylopectin is a branched series of glucose chains. Glucose molecules are joined to each other by links between their first and fourth carbon atoms (as above), but then branches occur when other glucose molecules are also joined to the sixth carbon atom of a sugar in the chain. Such a branch occurs about every 24 to 30 units along the chain. Cellulose These giant molecules are probably the most prevalent and abundant substance in nature. It has been calculated that, of all the organic carbon on the planet, a full 50 percent is in the form of cellulose. This molecule is most commonly found in plants (although a small amount has been found in tunicates) and in its purest form in cotton (about 90 percent cellulose). It is formed when beta-glucose molecules are joined together using their first and fourth carbon atoms. There are no branches in these polysaccharides which can reach lengths of between 300 and over 2,000 units. Glycogen This polysaccharide molecule is the animal equivalent of starch. It is found stored in the liver and muscles, where it can be seen under the microscope as small particles. Glycogen is a branched molecule, with a new branch occurring about every 10 or so units along the chain, but there is a lot of variety in this molecule both with regards to its size and structure. Science at a Distance © 1997, 1998, 1999 Professor John Blamire Does glucose have 5 carbon atoms?Glucose is a hexose, with six carbon atoms (Fig. 5.41), and an aldehyde-aldose monosaccharide.
How many atoms are in glucose ring?This means that glucose contains six atoms of carbon, twelve atoms of hydrogen, and six atoms of oxygen. Glucose may exist in two forms, a ring structure which is the most common as it is the most stable, and a linear chain form.
Are there 24 atoms in glucose?It is also known as blood sugar, and dextrose. Its chemical formula is C6H12O6, and this empirical formula is shared by other sugars - called hexoses - 6 carbon sugars. You may wish to know in some detail how these 24 atoms are arranged in the molecule of glucose - the structural formula.
How many carbon atoms are in 2 glucose molecules?ONE GLUCOSE MOLECULE HAS SIX CARBON ATOMS AND EACH PYRUVIC ACID MOLECULE HAS THREE. THEREFORE, THERE HAS TO BE TWO MOLECULES TO CONTAIN ALL SIX CARBON ATOMS.
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