MCB 100 1st Edition Lecture 7 Outline of Last Lecture I. Polar and nonpolar covalent bonds II. DNAOutline of Current Lecture I. Biological polymers II. Proteins III. Polysaccharides IV. Nucleic acids V. LipidsVI. Bonds that join biological polymers A. EsterB. –amide (peptide)C. phosphodiesterD. glycosidic VII. Water Current LectureI. Biological PolymersA. Large molecules that are made of many smaller molecules joined together by covalent bonds to make a long chain (with or without branches) II. Proteins A. Long un-branching chains/polymers of amino acids (organic compounds that contain carbon- with an amino group and carboxylic acid groupB. Are large globular molecules (globular means that each have a unique shape and the surface has certain functional groups arranged in specific orders) C. There are many different types of proteins found in a typical cell and each type has a different functionD. Some are found in the cytoplasm and others are embedded in cell membraneE. Functions: i. Some act as part of the structure of the cellii. Many act as enzymes that catalyze biochemical reactionsiii. Others transport substances through the cell membraneiv. Some regulate expression of genes or control other cell functions v. (the function of a protein is determined by its solubility, shape, and the 3D arrangement of organic functional groups on its surface) These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.III. Polysaccharides (AKA complex carbohydrates) A. Chains/polymers of sugars and modified sugars (these often have branching chains) B. Making a polysaccharide (or a protein, or a nucleic acid) by joining together manysimple sugar molecules (or amino acids, or nucleotides) releases water (dehydration synthesis) C. Breaking down a polysaccharide into simple sugars (or a protein to amino acids, or RNA to nucleotides) consume water. Thus the digestion of starch or other biological polymers is called hydrolysis. IV. Nucleic acidsA. Polymers of nucleotides (no branching)B. DNAC. LipidsD. Large amphipathic molecules that form the matrix of cell membranes E. In a lipid molecule, part of the molecule is attracted to water (hydrophilic) while part of the molecule is repelled by water (hydrophobic)V. Bonds that join biological polymers A. Ester: joins a carboxylic acid to an alcohol, seen in the attachment of fatty acids to glycerol to make fats and lipids. i. Carboxylic acid + alcohol (through dehydration synthesis or hydrolysis) <--> ester + water B. -amide (peptide): joins a carboxylic acid to an amino group, seen in the union of amino acids to form proteins. i. Carboxylic acid + amine (through dehydration synthesis or hydrolysis) <-->peptide bond + water C. Phosphoester and phosphodiester: joins a phosphoric acid group to an alcohol, seen in nucleic acids i. Phosphoric acid + alcohol <--> phosphoester + waterD. Glycosidic: joins a hemiacetal group on a cyclized sugar to an alcohol, seen in the joining of sugars to form disaccharides and polysaccharidesi. Hemiacetal + alcohol <--> glycosidic bond + waterVI. Water A. Water molecules are held together by polar covalent bonds because oxygen atoms have a greater electronegativity than hydrogen atomsB. Molecules are polar enough that a small fraction of water molecules will always ionize C. Water constant = 1 x 10^-14 M = [H+] x [OH-] D. A high concentration of H+ causes a low concentration of OH- and vice versa E. A low pH: higher concentration of free protons (stronger acid) F. A high pH: a higher concentration of free hydroxyl ions (stronger base) G. Acids: vinegar (pH 2); wine (pH 3); cheese and beer (pH 4)i. Organic Acid: carboxylic acid ii. Organic base:
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