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Transcript
• Polymers (long chains) of AMINO ACIDS – arranged in specific sequence – linked by PEPTIDE BONDS – range in length from a few to 1000+ AMINO ACIDS • • • • building blocks of proteins there are 20 common amino acids structure of an amino acid: elements included in a protein: -carbon -hydrogen -oxygen -nitrogen -sulfur (usually) • Amino acids are linked together through DEHYDRATION SYNTHESIS to form PEPTIDE BONDS PROTEIN STRUCTURE • a protein’s function depends on its specific 3-D shape Protein Shape: • determined by environmental conditions • DENATURATION: protein loses its natural shape, and therefore loses its function! This can be caused by: – extreme heat – pH changes Functions of Proteins • structural support (e.g. hair, nails) • signaling (e.g. hormones) Functions of Proteins • movement (contraction of muscles) • transporting oxygen in the blood Functions of Proteins • defense (antibodies of immune system) • catalysis of reactions (ENZYMES) PROTEINS WORKING AS ENZYMES ENZYMES: • are proteins • control the speed of reactions (often they increase the speed of reactions) • are not changed or “used up” by a reaction; can be used over and over • each enzyme is specific to a SUBSTRATE • SUBSTRATE = the substance the enzyme acts on Substrate ==> enzyme-sub.==> product + complex + enzyme enzyme • ACTIVE SITE = region of an enzyme which binds to the substrate – is usually a pocket or groove on surface – compatible “fit” between shape of enzyme’s active site and shape of substrate Factors Affecting Enzyme Activity 1. Temperature: – as temp increases, reaction rate increases – BUT, if temp gets too high, enzyme denatures and loses its shape and function – optimal range for human enzymes: 35-40°C 2. pH: -optimal range for most enzymes: pH 6-8 *some enzymes operate best at extremes of pH (e.g. digestive enzyme pepsin, found in the acidic environment of the stomach, works best at pH 2) • nucleic acids store and transmit hereditary information • Two types of nucleic acids: 1. DNA 2. RNA Structure of Nucleic Acids • polymers made up of monomers called NUCLEOTIDES • Elements present: -carbon -hydrogen -oxygen -nitrogen -phosphorus • each nucleotide consists of: 1. a simple sugar -deoxyribose in DNA -ribose in RNA 2. phosphate group 3. a base (e.g. in DNA, the bases are A, G, C, and T) • nucleotides are joined together in DEHYDRATION SYNTHESIS • results in a “backbone” with a repeating pattern of sugar-phosphatesugar-phosphate... 1. DNA = Deoxyribonucleic acid • forms the genetic code - the instructions for the proteins (amino acid sequences) of an organisms’ proteins • is copied and passed from one generation of cells to another 2. RNA = Ribonucleic acid • functions in the actual synthesis of proteins coded for by DNA