Proteins are made of up amino acids 20 different amino acids Sampling of protein functions Proteins can catalyze chemical reactions by accelerating the rate at which chemical reactions take place in the cell enzymes proteins that catalyze reactions Proteins play a role in storage replication transmission and regulation of genetic information DNA Help move substances in and out of the cell where proteins can be embedded in cell membrane Some soluble proteins can transport materials throughout body like Hemoglobin that carries O from lungs to tissues Can recognize specific molecules Can facilitate mechanical movement like flex muscles Can help maintain structure in organism Type of Proteins and their functions antibodies identify and neutralize foreign substances enzymes speed up chemical reactions hormones regulate the rate of cell processes mechanical provide flexibility elasticity and support for movement nutrient provide support for growth and overall health structural provide organisms with structure support and elasticity transport carry substances from one part of the organism to another function of most proteins involves binding to something else ligands molecules that bind to proteins without being modified small molecules but CAN be larger than protein to which they are binding ex when protein bind to DNA DNA ligand binding site ligand binds to protein by interacting with amino acids in the proteins binding site a protein looks like a string of beads bead amino acid peptide bond covalent bond between the amino acids amino acid small organic chemical made of of four parts two groups amino group and carboxylic acid which are linked by a single carbon atom called the alpha carbon R group attached to alpha carbon 20 different R groups commonly found in nature so all amino acids are identical except for R groups also called side chains properties of protein depend on arrangement of amino acids peptide bond forms when amino group of one amino acid reacts with the carboxylic acid of another amino acid dipeptide two amino acids joined together polypeptide longer chains of connected amino acids when polypeptide are synthesized new amino acids are only added to carboxylic acid end of existing chain the linear chain of amino acids spontaneously fold into 3D shape which is usually active form of protein reaching lowest energy most stable state many of these folded proteins bind small organic molecules folding process is reversible occurs with extremes of temp and pH The Hydrophobic Effect on Folding denatured state unfolded proteins tangle with each other forming aggregate and precipitating out of solution Amino acids with non polar hydrophobic side chains are driven into central core of protein because being repelled by water hydrophobic effect results in proteins that have amino acids with hydrophilic side chains on surface of proteins and folding continues to bury non polar side chains within molecule shape of folded form of protein depends on order of hydrophobic amino acids in protein less stable higher in energy and more stable lower energy Complementary molecules leading to tighter binding and specific interaction shape of ligand matches shape of binding pocket on the protein better the match the stronger the bond any charges on ligand molecule can be aligned close to opposite charges on protein s binding site opposites attract H bonds often form between ligand and protein binding site nonpolar ligands bind more favorably to nonpolar surfaces on the protein ground rules for protein ligand bonding reversible bound ligands can be released by protein concentration dependent level of binding depends on ligand concentration concentration increases so does amt of protein bond limited once all proteins are ligand bound no additional ligand can bind and the protein is said to be saturated Enzymes can bind substrate to active site and chemically modify bound substrate converting it to a diff molecule reaction product substrates bind to enzymes like ligands bind to proteins and more than one substrates can bind together or reduce to simpler products substrates converted to products as bind to enzyme and undergo induced chemical change enzymes often end with ase enzymes themselves are not altered by reaction substrates look like they fit into enzyme amino acids in active site of enzymes have two roles binding substrate and or facilitating chem reaction If initial energy requirement for chem reactions is small then reaction will happen quickly and easily enzymes reduce activation energy required for reactions enzyme binds to substrate and slightly distorts shape which activates molecule and decreases total activation energy required for substrate to be turned into product as of activated substrate increase so does conversion of substrate to product Influencing Enzyme Function denatures and becomes inactive temp as increases Ke of substrate molecules increases allowing more substrate molecules to become activated if temp is too high then enzyme unfolds pH protein structure affected by pH of solution surrounding it substrate concentration as increases of substrate molecules that bind to enzyme increases increases substrate activation presence of inhibitors inhibitors reduce enzyme activity in two ways competitive inhibitors bind to active site and prevent substrate form attaching Noncompetitive inhibitors mixed type bind to enzyme somewhere other than binding site changing shape of active site there are drugs to treat this inhibitor presence of activators change shape of active site by binding elsewhere on enzyme which converts from inactive to active form Nucleic acids carry out two main function in cell storage of genetic info and synthesis of proteins DNA is genetic material that stores info for making proteins in all living organisms while some viruses store info using RNA which translates info coded for DNA for production of proteins inside cells Nucleic acid consists of chain of nucleotides ATP adenosine triphosphate nucleotide that acts as energy currency of cell Each nucleotide contains 3 building blocks phosphate sugar and nitrogenous base nitrogenous base type of organic molecule that consists of 1 or 2 ring structures Adenine A guanine G cytosine C thymine T and an RNA version of thymine uracil U nucleotides contain different type of sugars even though all types pentose sugars 5 carbons deoxyribose vs ribose for example nucleotides can contain different number of phosphate