Polysaccharides Quiz

Synthesis and Breakdown of Organic Molecules and Macromolecules

• Monomers are small organic molecules that can be used to form larger molecules (polymers) consisting of many repeating units of the monomer.
• Polymers are large molecules formed by linking many smaller molecules called monomers through condensation reactions.

Condensation Reactions and Dehydration Reactions

• Condensation reactions are chemical reactions in which two or more molecules are combined into a larger molecule by covalent bonding, with the loss of a small molecule.
• Dehydration reactions are a type of condensation reaction in which a molecule of water is lost, resulting in the formation of a larger molecule.
• Dehydration reactions involve the loss of water from the reacting molecules or ions, extending the length of a polymer with each reaction.

Formation and Breakdown of Polymers

• Monomers combine to form polymers in living organisms through dehydration reactions.
• Hexose (glucose, C6H12O6) is a very water-soluble molecule that can be broken down into smaller molecules, releasing energy that is stored in adenosine triphosphate (ATP).
• Glucose and galactose differ in the position of the -OH group attached to the carbon atom.
• D-Glucose is an isomer of glucose found in living cells, recognized by enzymes that can use it as a monomer to synthesize polymers like starch.

Carbohydrates

• Monosaccharides can be linked together by dehydration reactions to form larger carbohydrates.
• Disaccharides are carbohydrates composed of two monosaccharides, formed through the removal of a hydroxyl group from one monosaccharide and a hydrogen atom from another.
• Glycosidic bonds are covalent bonds formed between two sugar molecules via dehydration reactions.
• Polysaccharides are long carbohydrate polymers formed of many monosaccharides linked together.
• Starch is a polysaccharide composed of repeating glucose units produced by plant cells and some algal protists.
• Glycogen is a polysaccharide found in animal cells, especially in the liver and skeletal muscle, and is a major storage carbohydrate in fungi.
• Cellulose is a linear polymer made of thousands of glucose monomers, found in the cell walls of plants and many algae.
• Chitin is a tough, nitrogen-containing polysaccharide that forms the external skeleton of many insects and crustaceans and is found in the cell walls of fungi.

Lipids

• Lipids are molecules composed predominantly of hydrogen and carbon atoms, which are nonpolar and insoluble in water.
• Lipids include fats (triglycerides), phospholipids, waxes, and steroids.
• Triglycerides are molecules composed of three fatty acids linked by ester bonds to a molecule of glycerol.
• Fatty acids are chains of carbon and hydrogen with a carboxyl group (-COOH) at one end.
• Saturated fatty acids have all carbons linked by single covalent bonds, while unsaturated fatty acids contain one or more C=C double bonds.
• Essential fatty acids are necessary for good health but cannot be synthesized by the body.

Proteins

• Amino acids are the building blocks of proteins, with a common structure consisting of a carbon atom linked to an amino group (NH2), a carboxyl group (-COOH), a hydrogen atom, and a side chain that distinguishes the specific amino acid.
• Proteins are composed of carbon, hydrogen, oxygen, and nitrogen.
• Amino acids are joined together by dehydration reactions that link the carboxyl group, forming a peptide bond.
• Polypeptides are linear sequences of amino acids, with the term denoting a structural unit composed of a linear sequence of amino acids.
• N-terminus and C-terminus refer to the location of the first and last amino acids in a polypeptide, respectively.