What type of macromolecules are starch and glycogen

Organic molecules that naturally occur in organisms are called biomolecules. Besides carbon and hydrogen, biomolecules also contain other elements such as oxygen, nitrogen, phosphorus, and sulfur.

In general, smaller units of biomolecules come together, as repetitive sequences, to form larger biomolecules. These small modular units of biomolecules are called monomers. Two monomers typically join each other to form a dimer through a process known as dehydration synthesis , which is simply the removal of a hydrogen atom from one monomer and a hydroxyl OH - ion from the other monomer to create a water molecule to be expelled out while linking the two monomers with a covalent bond.

The reverse of this process is called hydrolysis , in which the molecule splits back into its original monomers with a water molecule providing a hydrogen atom to one monomer and a hydroxyl ion to the other. Many monomers can be attached together by dehydration to form polymers. Sometimes different polymers can come together to form even larger and more complex molecules, which are known as biological macromolecules. Biomolecules are classified based on the elements that compose them, and their structure and function inside living organisms.

Almost all biomolecules can be classified into one of the four general categories: carbohydrates, lipids, proteins, and nucleic acids. Carbohydrate monomers are known as monosaccharides, which are also referred to as simple sugars.

Glucose C 6 H 12 O 6 is the most common monosaccharide in living organisms and is a subunit of many polysaccharides. Numerous organisms also synthesize other six-carbon monosaccharides with the same chemical formula as glucose but slightly different structures, such as fructose and galactose. When two monosaccharides are linked together, they form disaccharides.

For example, sucrose is composed of glucose and fructose, whereas lactose contains glucose and galactose. These monosaccharides and disaccharides are used for short-term energy storage in living organisms.

Maltose is another disaccharide that is made up of two glucose molecules and is usually formed when polysaccharide chains such as starch and glycogen are broken down during digestion. Starch is a polysaccharide that serves as an energy storage molecule in plants and is made up of two types of glucose polymers: amylose and amylopectin. Amylopectin makes up the bulk of the starch and is a branched polymer of glucose.

Glycogen is virtually the same as starch, however it is synthesized, stored and used in animal liver and muscle tissues. Besides serving as energy stores, carbohydrates also have other functions in organisms. The five-carbon monosaccharides, ribose and deoxyribose, are integrated into the nucleic acid structure and are present in every living cell. Moreover, the polysaccharide cellulose, which is a long polymer made up of glucose, serves as a rigid structural material in plants.

Humans do not have digestive enzymes to break down cellulose in food, which is also called dietary fiber. However, dietary fiber consumption helps to maintain a healthy gut flora, which in turn contributes to the health of digestive and immune systems 1.

Similar to plants, some animals and fungi use another polysaccharide, chitin, as a structural molecule. Arthropods use chitin to build and maintain their exoskeletons, whereas fungi incorporate it into their cell walls to maintain rigidity.

The second class of biological macromolecules are lipids, which include fats, oils, and waxes. Lipids are hydrophobic molecules that are almost entirely made up of carbon and hydrogen atoms. Often, lipids are grouped in three major categories; triglycerides, phospholipids, and steroids.

The most common type of lipid is triglycerides, which include fats from animals and oils from plants. Triglycerides generally serve as long-term energy storage molecules, except indigestible waxes, which are instead used as a waterproofing substance in both plants and animals. Triglycerides contain three fatty acid chains, which can be either saturated or unsaturated, connected to a glycerol molecule.

Saturated fatty acid chains are linear molecules with a maximum number of hydrogen atoms, where every carbon in the chain is connected via a single bond.

On the other hand, unsaturated fatty acid chains have kinks due to the presence of at least one double bond.

While trans fats occur naturally, they are generated during industrial production of saturated vegetable oils with hydrogen. The central component is a pentose sugar. This base can either be a purine with two fused rings as in adenine and guanine or a pyrimidine with a single ring as in cytosine and thymine. In RNA, the thymine base is replaced by uracil.

The phosphate group, the base, and the sugar make up a complete nucleotide. More specifically, a guanine only pairs with a cytosine forming three hydrogen bonds, indicated by the green circle , and an adenine only pairs with a thymine forming two hydrogen bonds, indicated by the red circle. The fatty acids attach to the glycerol molecule by a covalent ester bond. The long hydrocarbon chain of each fatty acid makes the triglyceride molecule nonpolar and hydrophobic.

It is called a saturated fatty acid, because all the carbon atoms in the chain are single bonded to each other and are fully "saturated" with hydrogen atoms. In this process, oleic acid is formed by adding two carbon atoms to palmitic acid, and then by inserting a double bond between carbons 9 and Because oleic acid has one double bond, it is considered a monounsaturated fatty acid. The double bonds kink these molecules and prevent them from packing tightly together. The loose packing results in triglycerides that are liquid at room temperature.

Mammals cannot make linoleic acid; it is required in the diet. The covalent bonds form by condensation reactions in which water is a byproduct. They provide a concentrated store of energy. A macromolecule's structure is intimately connected with its function. Consider, for example, a nucleic acid. This type of polymer is made up of a chain of nucleotides that are strung together in a precise sequence.

Both starches and glycogen are polymers formed from sugar molecules called glucose. Each independent molecule of glucose has the formula C6H12O, and joining these subunits together in a certain way forms the long chains that make up glycogen and starch. There are two types of starch: amylose and amylopectin. Of these two, glycogen is more similar to amylopectin, since the sugar chains in glycogen and amylopectin are highly branched, while amylose is strictly linear.

Glucose can exist in multiple forms called isomers. In each of these, the molecular formula is the same, but the way the atoms are arranged is different. Starch and glycogen are both formed from alpha glucose, an isomer in which a hydroxy or -OH group on the first of the six carbons is on the opposite side of the ring from carbon 6. Another way to say this is that carbon 6 and the hydroxy group are trans to each other in the alpha glucose isomer. Your digestive system can break up both starch and glycogen, so they make good sources of energy.

They are both very different in this regard from cellulose. Like starch and glycogen, cellulose is a glucose polymer, but unlike starch and glycogen, it contains only beta glucose molecules.

Consequently, each glucose molecule is "flipped" with respect to its neighbor, creating a long and highly rigid chain.