Biochemistry Flashcards
Inorganic and Organic Compounds
Inorganic does not contain carbon, including salts and HCl.
Organic are made by living systems and contain carbon. Include carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates
Composed of the elements carbon, hydrogen, and oxygen in a 1:2:1 ratio, respectively. They’re used as storage forms of energy or as structural molecules.
Monosaccharide
Singular sugar subunits. Like glucose and fructose.
Disaccharide
Compsoed of two monosacchatide subunits joined by dehydration synthesis, which involves loss of a water molecule. Examples include maltose and sucrose.
Polysaccharide
Polymers or chains of repeating monosaccharide subunits. Glycogen and starch are examples of polysaccharides. Cellulose is a polysaccharide that serves a structural role in plants. These polysaccharides are insoluble in water.
Formed by removing water (dehydration). By adding water, large polymers can be broken down into smaller subunits in a process called hydrolysis.
Lipids
Also compsoed of C, H, and O, but their H:O ratio is much greater than 2:1 because they have much more H than O. A triglyceride is a type of lipid that consists of 3 fatty acid molecules bonded to a single glycerol backbone. Fatty acids have long carbon chains that give them their hydrophobic (fatty character) and carboxylic acid groups that make them acidic. Three dehydration reactions are needed to form one fat molecule. Lipids don’t form polymers.
Chief means of food storage in animals. They release more energy per gram weight than any other class of biological compounds. They also provide insulation and protection against injury because they’re a major component of fatty (adipose) tissue.
Phospholipids
Lipid derivative. Contain glycerol, two fatty acids, a phosphate group, and nitrogen-containing alcohol; e.g., lecithin (a major constituent of cell membranes) and cephalin (found in brain, nerves, and neural tissue).
Waxes
Lipid derivative. Esters of fatty acids and monohydroxylic alcohols. They’re found as protective coverings on skin, fur, leaves of higher plants, and on the exoskeleton of many insects.
Steroids
Lipid derivative. Have 3 fused cyclohexane rings and one fused cyclopentane ring. They include cholesterol, the sex hormones testosterone and estrogen, and corticosteroids.
Carotenoids
Lipid derivative. Fatty, acid-like carbon chains containing conjugated double bonds and carrying six-membered carbon rings at each end. These compounds are the pigments that produce red, yellow, orange, and brown colors in plants and animals. Two subgroups are the carotenes and the xanthophylls.
Porphyrins
Lipid derivative. Also called tetrapyrroles. Contain four joined pyrrole rings. They’re often complexed with a metal. For example, the polyphyrin heme complexes with Fe in hemoglobin. Chlorophyll is complexed with Mg.
Proteins
Compsoed primarily of C, H, O, and N but may also contain P and S. They are polymers of amino acids.
Amino acids are joined by peptide bonds through dehydration reactions. Chains of such bonds produce a polymer called a polypeptide, or simply peptide. This is another term for protein. The sequence or amino acids in a protein is referred to as the primary structure. Proteins can also coil or fold to form alpha-helices and beta-pleated sheets. These are considered part of the protein’s secondary structure.
Protein: Primary Structure
Sequence of amino acids.
Protein: Secondary Structure
Based on hydrogen bonding between adjacent amino acids and results in beta-pleated sheets of alpha helices.
Protein: Tertiary Structure
3D structure that’s based on R-group interactions between adjacent amino acids. Results in globular or fibrous proteins. The hydrophobic amino acids are crowded in the center with hydrophilic amino acids at the outer edge and periphery.
Protein: Quaternary Structure
The interaction and joining of two or more independent polypeptide chains.