* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download amino acid
Fatty acid synthesis wikipedia , lookup
Metabolic network modelling wikipedia , lookup
Basal metabolic rate wikipedia , lookup
Citric acid cycle wikipedia , lookup
Enzyme inhibitor wikipedia , lookup
Oxidative phosphorylation wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Western blot wikipedia , lookup
Photosynthesis wikipedia , lookup
Peptide synthesis wikipedia , lookup
Genetic code wikipedia , lookup
Protein structure prediction wikipedia , lookup
Photosynthetic reaction centre wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Metalloprotein wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Proteolysis wikipedia , lookup
CP Biology 2014-2015 Name ______ ____________ UNIT 2B: Biochemistry 2 PROTEINS Of all the organic compounds, proteins are the largest, most complex, and most diverse. While 70% of the body is water, most of the other 30% is protein! _amino acid___. • Made of elements C, H, O, N • Made of AMINO ACIDS (the monomer) • PEPTIDE bonds link amino acids together to make polypeptides Many linked amino acids is a _polypeptide__ • One or more polypeptides “fold” into a PROTEIN Proteins are Diverse • Twenty (20) amino acids exist in nature • Different combos of amino acids lead to different functioning proteins • The sequence of DNA directs the sequence of amino acids. Personal notes, summary of lesson, questions: One or more polypeptides folds into a _protein____ 1 AMINO ACIDS Amino acids are compounds with an AMINO group (-NH2) on one end and a CARBOXYL (-COOH) group on EXAMPLES OF SOME SPECIFIC AMINO ACIDS Circle each amino group, box each carboxyl group and label each R group (-R). the other end. Each amino acid consists of one of each of the following, connected to each other by covalent bonds. R R 1) central carbon atom (-C-) 2) carboxyl group (-COOH) 3) amino group (-NH2) R R 4) one hydrogen atom (-H) 5) 'R' (variable) group - one of 20 different side chains On the two amino acids below, circle the atoms that must be removed in order to create a peptide bond. Because of their uniform structure, any amino acid can bond These atoms create a _water_______ molecule, which is a product of the reaction. to any other amino acid using a covalent bond called a peptide bond. THINK ABOUT IT: What process will link together two individual amino acids? _dehydration synthesis _ Glycine Personal notes, summary of lesson, questions: Valine 2 POLYPEPTIDES Segments of amino acids are called polypeptides When they are first assembled, polypeptides are LINEAR (straight) chains. They are not yet functioning proteins! R groups on the amino acids interact with each other causing the polypeptide to fold into a specific 3dimentional shape or structure. Once it is completely and correctly folded, it is considered a protein. (other small changes or modifications may also occur before the protein is completely functional) -How many amino acids are shown in the polypeptide below? ____6___________ (Hint: count the R groups) -How many peptide bonds are shown in the polypeptide below? ____5________ (Hint: peptide bonds are between which two atoms?) carbon and nitrogen The structure of each protein is unique; STRUCTURE (or FORM) leads to FUNCTION! -How many water molecules were released as this polypeptide was formed?_5_____ (Hint: one for each bond made!) Personal notes, summary of lesson, questions: 3 CHEMICAL REACTIONS & ENERGY Everything that happens in an organism is based on a chemical reaction. A chemical reaction: - Changes one set of chemicals into another - Changes chemical bonds - Reactants- elements/compounds that enter the reaction - Products- are produced by the reaction Examples of chemical reactions: _cellular respiration, dehydration synthesis, hydrolysis, digestion, photosynthesis________________________________ Energy for chemical reactions comes from _living things (plants & animals)_________. Plants: _ trap and store energy from sunlight in energyrich compounds, carbs (by performing photosynthesis) When bonds are made or broken… - Energy is absorbed (taken in) or released (given off) Animals: _consuming plants or other animals_______ - Reactions releasing energy can (but not always) occur on their own, or spontaneously. - Reactions absorbing energy will not occur without a source of energy Some reactions are reversible, meaning that the reactants & products can switch places. If the reaction requires (absorbs) energy in one direction, it would release energy in the opposite direction. Paper is made of cellulose which burns in the presence of oxygen, and releases energy in the form of heat and light. But this packet is not spontaneously bursting into flames right now. Why not? What is missing? __the activation energy to begin the reaction_______ *Example of a chemical reaction that releases energy: Activation Energy: Is the amount of _energy___ that a reaction needs to _begin (or get started)_________. Every reaction requires a certain amount of activation energy to get started, regardless of whether it is an energy-absorbing or energy-releasing reaction. Personal notes, summary of lesson, questions: 4 ENERGY ABSORBING REACTIONS (Endergonic) - Products have more energy than the reactants Endergonic, DH - Products larger less stable, and more complex than reactants - It takes more energy to break bonds in the reactants than is released by making new bonds in the products Examples: dehydration synthesis of a dipeptide; photosynthesis Exergonic, Hydrolysis ENERGY RELEASING REACTIONS (Exergonic) - Reactants have more energy than the products - Reactants are larger, less stable, and more complex than products - More energy is released when new bonds are formed in the products than was needed to break the old bonds in the reactants Endergonic, DH Examples: hydrolysis of a dipeptide; cellular respiration Exergonic, Hydrolysis Label the reactions above using the terms :Dehydration synthesis, Hydrolysis, Endergonic, Exergonic Personal notes, summary of lesson, questions: 5 ENZYMES Some chemical reactions would be too slow or have too high an activation energy without a little help. Catalyst- a substance that speeds up a chemical reaction - works by lowering the activation energy Cells make special proteins called enzymes to act as catalysts for chemical reactions. - There is one type of enzyme for each type of chemical reaction (its shape (structure) makes it specific for its job) HOW DO ENZYMES WORK? - They provide a site for the reactants to be brought together to react. - This reduces the energy needed for the reaction. “Enzyme Catalyzed Reaction”- a reaction sped up by an enzyme Substrates- what the reactants are called in an enzyme catalyzed reaction. Will the hill be higher or lower than shown if the activation energy is lowered? _smaller or lower _________ Substrates bind to a place on the enzyme called the active site which has a specific shape. Personal notes, summary of lesson, questions: ALL enzymes are proteins, BUT not all proteins are enzymes! 6 TWO MODELS TO REPRESENT THE ACTION OF ENZYMES: 1. "”Lock and Key Model": The substrates fit the enzymes like a key fits into a lock. A very specific interaction! Substrate / Reactant Enzyme 2. “Induced-fit Model”: The enzyme binds the substrate(s) and the enzyme slightly changes its shape to “hug” the substrate(s) tightly. (like a handshake) - This places “strain” on existing bonds, allowing bonds to break and the chemical reaction to go to completion. WHY aren’t enzymes considered a reactant or a product? (analyze the reaction to the right for a hint) _______________________________________________ _______________________________________________ Enzymes are __Reusable (unchanged) _____! Personal notes, summary of lesson, questions: Example of an enzyme-catalyzed reaction: _carbonic acid_ is formed by combining _CO2 & H2O___ and water in the presence of the enzyme “_induced-fit model___”. 7 Some enzymes help to synthesize larger molecules, other help to break them down (hydrolysis) Examples of some types of biologically-important hydrolytic enzymes The suffix "–ase" commonly indicates that a protein is an enzyme. 1. protease- any enzyme that speeds hydrolysis or breakdown of proteins 2. sucrase (a disaccharidase) - an enzyme which speeds the breakdown of __sucrose____________ 3. lipase - any enzyme which speeds the breakdown of _____lipids____________________ 4. nuclease - any enzyme which speeds the breakdown of ______nucleotides_________________ 5. amylase - an enzyme which speeds the breakdown of amylose (=starch!) FACTORS AFFECTING ENZYME ACTIVITY Temperature, pH, and regulatory molecules affect enzyme activity - An increase in temperature will increase the rate of a reaction to a certain point - After that point, the enzyme will no longer work Think! Why are temperature and pH important factors in Denaturation - when a protein unfolds and loses its overall maintaining homeostasis? shape (and thus function) due to increased temp or changes ________________________________________________ ________________________________________________ in pH. - A denatured enzyme loses the shape of its active site and ________________________________________________ ________________________________________________ will no longer function. 8 pH Order the following substances in order Water is one of the most important inorganic substances of increasing acidity: human blood, in living organisms. acid rain, bleach, seawater, stomach acid. Sometime water molecules will break apart to form ions. Ion- a positively or negatively charged atom (set of atoms) due to loss or gain of electrons 1. _bleach____(least acidic / most basic) 2. _seawater____ 3. __human blood_ 4. _acid rain_____ 5. _stomach acid____(most acidic) About 1 water molecule in 550 million splits in this way. Because the number of positive H+ ions is equal to the number of negative OH- ions, pure water is neutral. The pH scale- measures the concentration of hydrogen ions [H+] in a particular solution. • • • • • Measured 0-14 Each step represents a factor of ten (10). 7 is neutral (like water) Lower than 7 becomes more acidic Higher than 7 becomes more basic Personal notes, summary of lesson, questions: Acid, Base, or Neutral? Strong or weak? pH 7:__N____ pH 13.5:___SB____ pH 8:___WB__ pH 2:___SA__ Which one is more acidic?(circle one) pH of 2 -or- pH of 4 How many times more?___100________ Which one is more basic? (circle one) Tomato juice -or- Soap How many times more?___1,000,000_____ 9 ACID- compound that forms H+ ions in solution BASE- compounds that forms OH- ions in solution • Study the reaction below. Is this substance an ACID or BASE? (circle) Dissociation In Water HCl Hydrogen Chloride H+ Hydrogen ion (Proton) + ClChloride ion ACIDS BASES Solutions have a pH _less than (<)__7 Solutions have a pH greater than (>) 7 Taste sour Taste bitter Can corrode metals Can denature proteins Can denature proteins feel " slippery" In solution: [H+] __>____ In solution: [H+] __<_____ [OH-] [OH-] ACIDIC NEUTRAL Range of pH ______________ Range of pH ______________ BASIC • Study the reaction below. Is this substance an ACID or BASE? (Circle) Dissociation In Water NaOH Sodium Hydroxide Na+ Sodium ion + OHhydroxide ion Range of pH ______________ [H+] _______ [H+] _______ [H+] ______ [OH-] [OH-] in this type of [OH-] in this type of in this type of solution. solution. solution. Personal notes, summary of lesson, questions: 10 BUFFERS Controlling pH is important for maintaining homeostasis in cells. The pH of most cells in the human body must be kept between ___6.5_____ and ___7.5____. Buffers- Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes of pH. Example: Sudden pH changes in blood are prevented by buffers such as bicarbonate and phosphate ions. Personal notes, summary of lesson, questions: 11