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FUNCTIONAL GROUPS & MAJOR MACROMOLECULES Functional Groups An organic compound has unique properties that depend upon – The size and shape of the molecule and – The groups of atoms (functional groups) attached to it A functional group affects a biological molecule’s function in a characteristic way Functional groups affect the properties of molecules Compounds containing functional groups are hydrophilic (water-loving) – They are soluble in water – Necessary for their roles in water-based life Functional Groups The functional groups are – Hydroxyl group—consists of a hydrogen bonded to an – – – – – oxygen Carbonyl group—a carbon linked by a double bond to an oxygen atom Carboxyl group—consists of a carbon double-bonded to both an oxygen and a hydroxyl group Amino group—composed of a nitrogen bonded to two hydrogen atoms and the carbon skeleton Phosphate group—consists of a phosphorus atom bonded to four oxygen atoms Methyl group-not a functional group, but important in methylating certain compounds (CH3) There are four classes of biological molecules – Carbohydrates – Proteins – Lipids – Nucleic acids Macro=Big The four classes of biological molecules contain very large molecules – Called macromolecules because of their large size – Called polymers because they are made from identical building blocks strung together – Building blocks=monomers Monomer to Polymer A cell makes a large number of polymers from a small group of monomers – Proteins=20 different amino acids – DNA=four kinds of nucleotides Monomers used to make polymers are universal Makin and Breakin Molecules Dehydration reactions remove water to link monomers together Polymers are broken apart by hydrolysis, the addition of water These biological reactions rely on enzymes to speed the process up Carbohydrates Small monosaccharide sugars like glucose to larges polysaccharide sugars like starch – Monosaccharides=glucose/fructose – Polysaccharides=starch, glycogen, cellulose, chitin – Don’t forget the deydration reactions and hydrolysis needed to make or break these guys Monosaccharides are small carbs Monosaccharides like glucose are important for cellular work and contribute to bigger molecules Disaccharides can be formed from two monosaccharides (Dehydration or Hydrolysis) Ex. sucrose HFCS So what’s the deal with High Fructose Corn Syrup? Polysaccharides Polysaccharides=Polymer (storage/structure) Starch is a storage polysaccharide composed of glucose monomers and found in plants Glycogen is a storage polysaccharide composed of glucose, which is hydrolyzed by animals when glucose is needed Cellulose is a polymer of glucose that forms plant cell walls (glucose energy not available to us b/c we lack enzymes to digest it, cows/termites have help from bacteria Chitin is a polysaccharide used by insects and crustaceans to build an exoskeleton Polysaccharides Polysaccharides are hydrophilic (water-loving) – Cotton fibers, such as those in bath towels, are water absorbent Lipids=Fats Lipids water insoluble (hydrophobic, or water fearing) important in energy storage contain twice as much energy as a polysaccharide Fats made from glycerol and fatty acids Fatty acid Fatty acids link to glycerol by a dehydration reaction – A fat contains one glycerol linked to three fatty acids – Fats are often called triglycerides because of their structure Glycerol Fatty acid Saturated vs. Unsaturated Some fatty acids contain double bonds – causes kinks or bends in the carbon chain – maximum number of hydrogen atoms cannot bond to the carbons at the double bond – called unsaturated fats because they have fewer than the maximum number of hydrogens – Fats with the maximum number of hydrogens are called saturated fats Liquid at room temp Solid @ room temp Phospholipids Phospholipids are structurally similar to fats and are an important component of all cells – major part of cell membranes – cluster into a bilayer of phospholipids – hydrophilic heads are in contact with the water of the environment and the internal part of the cell – The hydrophobic tails band in the center of the bilayer Steroids Steroids (the good ones) are lipids composed of fused ring structures – Cholesterol is an example of a steroid that plays a significant role in the structure of the cell membrane – In addition, cholesterol is the compound from which we synthesize sex hormones Proteins The idea of structure fitting function is never more apparent than with this group They are polymers built from 20 different amino acid monomers (ex. tryptophanphenylalanine-glycine) Many proteins are enzymes=metabolic catalysts that regulate chemical reactions within cells Proteins have many functions Structural- provide associations between body parts Contractile- found within muscle Defensive- include antibodies of the immune system Signal- hormones Receptor- serve as antenna for outside signals Transport-carry oxygen (hemoglobin) Storage-storage of amino acids, ex. Casein Amino Acids Amino acids-building blocks of proteins, Consist of an amino group and a carboxyl group covalently bonded to a central carbon atom Also bonded to the central carbon is a hydrogen atom and some other chemical group symbolized by R This R group determines the amino acid’s properties Amino Acids Some R groups are nonpolar and hydrophobic & some R groups are polar and hydrophilic These properties will affect how the protein folds (remember, structure equals function) Amino Acids and Polypeptides Amino acid monomers join to form polypeptides This process uses a dehydration reaction and help from enzymes (covalent bond between each amino acid is called a peptide bond) Shape is essential to function Different factors can cause a protein to lose its shape or become denatured Ex. Temp, Salinity, pH, inhibitors Levels of protein structure A protein can have four levels of structure – Primary structure – Secondary structure – Tertiary structure – Quaternary structure 4 Levels of structure Primary-specific amino acid sequence Secondary-polypeptide folds or coils (hydrogen bonding is important at this level) Tertiary-Overall 3D shape of polypeptide (interactions between R groups is important) Quaternary-Two or more subunits join together to create functioning protein DNA & RNA DNA-Deoxyribonucleic Acid RNA-Ribonucleic Acid Both composed of monomers called nucleotides Nucleotide has 3 parts – A five-carbon sugar called ribose in RNA and deoxyribose in DNA – A phosphate group – A nitrogenous base Nitrogenous Bases DNA’s nitrogenous bases are Adenine (A), Guanine (G), Cytosine (C), and Thymine (T) RNA has all of these except Uracil (U), instead of Thymine DNA is a double helix with sugar-phosphate backbones The bases pair up in the middle, A pairs with T, and G pairs with C (hydrogen bonds hold pairs together) RNA is a single nucleotide strand DNA Structure DNA and Genes A particular nucleotide sequence that can instruct the formation of a polypeptide is called a gene – Most DNA molecules consist of millions of base pairs and, therefore, many genes – These genes, many of which are unique to the species, determine the structure of proteins and, thus, life’s structures and functions