2 The Chemical Level of Organization PowerPoint Lecture Presentations prepared by Jason LaPres Lone Star College North Harris
An Introduction to the Chemical Level of Organization Learning Outcomes 2-1 Describe an atom and how atomic structure affects interactions between atoms. 2-2 Compare the ways in which atoms combine to form molecules and compounds. 2-3 Distinguish among the major types of chemical reactions that are important for studying physiology. 2-4 Describe the crucial role of enzymes in metabolism.
An Introduction to the Chemical Level of Organization Learning Outcomes 2-5 Distinguish between organic and inorganic compounds. 2-6 Explain how the chemical properties of water make life possible. 2-7 Discuss the importance of ph and the role of buffers in body fluids. 2-8 Describe the physiological roles of inorganic compounds. 2-9 Discuss the structures and functions of carbohydrates.
An Introduction to the Chemical Level of Organization Learning Outcomes 2-10 Discuss the structures and functions of lipids. 2-11 Discuss the structures and functions of proteins. 2-12 Discuss the structures and functions of nucleic acids. 2-13 Discuss the structures and functions of highenergy compounds. 2-14 Explain the relationship between chemicals and cells.
An Introduction to the Chemical Level of Organization Chemistry Is the science of change Topics of this chapter include: The structure of atoms The basic chemical building blocks How atoms combine to form increasingly complex structures
2-1 Atoms and Atomic Structure Matter Is made up of atoms Atoms join together to form chemicals with different characteristics Chemical characteristics determine physiology at the molecular and cellular levels
2-1 Atoms and Atomic Structure Subatomic Particles Proton Positive charge, 1 mass unit Neutron Neutral, 1 mass unit Electron Negative charge, low mass
2-1 Atoms and Atomic Structure Atomic Structure Atomic number Number of protons Nucleus Contains protons and neutrons Electron cloud Contains electrons
Figure 2-1 The Structure of Hydrogen Atoms Electron shell Hydrogen-1 mass number: 1 A typical hydrogen nucleus contains a proton and no neutrons. Hydrogen-2, Hydrogen-3, deuterium tritium mass number: 2 mass number: 3 A deuterium ( 2 H) nucleus contains a proton and a neutron. A tritium ( 3 H) nucleus contains a pair of neutrons in addition to the proton.
Table 2-1 Principal Elements in the Human Body
Table 2-1 Principal Elements in the Human Body
2-1 Atoms and Atomic Structure Elements and Isotopes Elements are determined by the atomic number of an atom Remember atomic number = number of protons Elements are the most basic chemicals
2-1 Atoms and Atomic Structure Elements and Isotopes Isotopes are the specific version of an element based on its mass number Mass number = number of protons plus the number of neutrons Only neutrons are different because the number of protons determines the element
2-1 Atoms and Atomic Structure Atomic Weights Exact mass of all particles Measured in moles Average of the mass numbers of the isotopes
2-1 Atoms and Atomic Structure Electrons and Energy Levels Electrons in the electron cloud determine the reactivity of an atom The electron cloud contains shells, or energy levels that hold a maximum number of electrons Lower shells fill first Outermost shell is the valence shell, and it determines bonding The number of electrons per shell corresponds to the number of atoms in that row of the periodic table
Figure 2-2 The Arrangement of Electrons into Energy Levels The first energy level can hold a maximum of two electrons. Hydrogen, H Atomic number: 1 Mass number: 1 1 electron Helium, He Atomic number: 2 Mass number: 4 (2 protons + 2 neutrons) 2 electrons
Figure 2-2 The Arrangement of Electrons into Energy Levels The second and third energy levels can each contain up to 8 electrons. Lithium, Li Atomic number: 3 Mass number: 6 (3 protons + 3 neutrons) 3 electrons Neon, Ne Atomic number: 10 Mass number: 20 (10 protons + 10 neutrons) 10 electrons
2-2 Molecules and Compounds Chemical Bonds Involve the sharing, gaining, and losing of electrons in the valence shell Three major types of chemical bonds 1. Ionic bonds Attraction between cations (electron donor) and anions (electron acceptor) 2. Covalent bonds Strong electron bonds involving shared electrons 3. Hydrogen bonds Weak polar bonds based on partial electrical attractions
2-2 Molecules and Compounds Chemical Bonds Form molecules and/or compounds Molecules Two or more atoms joined by strong bonds Compounds Two or more atoms OF DIFFERENT ELEMENTS joined by strong or weak bonds Compounds are all molecules, but not all molecules are compounds H 2 = molecule only H 2 O = molecule and compound
2-2 Molecules and Compounds Ionic Bonds One atom the electron donor loses one or more electrons and becomes a cation, with a positive charge Another atom the electron acceptor gains those same electrons and becomes an anion, with a negative charge Attraction between the opposite charges then draws the two ions together
Figure 2-3a The Formation of Ionic Bonds Formation of ions Sodium atom Attraction between opposite charges Sodium ion (Na + ) Formation of an ionic compound Chlorine atom Chloride ion (Cl ) Sodium chloride (NaCl) Formation of an ionic bond. 1 A sodium (Na) atom loses an electron, which is accepted by a chlorine (Cl) atom. 2 Because the sodium (Na + ) and chloride (Cl ) ions have opposite charges, they are attracted to one another. 3 The association of sodium and chloride ions forms the ionic compound sodium chloride.
Figure 2-3b The Formation of Ionic Bonds Chloride ions (Cl ) Sodium ions (Na + ) Sodium chloride crystal. Large numbers of sodium and chloride ions form a crystal of sodium chloride (table salt).
2-2 Molecules and Compounds Covalent Bonds Involve the sharing of pairs of electrons between atoms One electron is donated by each atom to make the pair of electrons Sharing one pair of electrons is a single covalent bond Sharing two pairs of electrons is a double covalent bond Sharing three pairs of electrons is a triple covalent bond
Figure 2-4 Covalent Bonds in Four Common Molecules Molecule Electron Shell Model and Structural Formula Hydrogen (H 2 ) H H Oxygen (O 2 ) O=O Carbon dioxide (CO 2 ) O=C=O Nitric oxide (NO) N=O
2-2 Molecules and Compounds Covalent Bonds Nonpolar covalent bonds Involve equal sharing of electrons because atoms involved in the bond have equal pull for the electrons Polar covalent bonds Involve the unequal sharing of electrons because one of the atoms involved in the bond has a disproportionately strong pull on the electrons Form polar molecules like water
Figure 2-5 Polar Covalent Bonds and the Structure of Water Hydrogen atom Hydrogen atom Oxygen atom Hydrogen atom δ + Oxygen atom δ + 2δ
2-2 Molecules and Compounds Hydrogen Bonds Bonds between adjacent molecules, not atoms Involve slightly positive and slightly negative portions of polar molecules being attracted to one another Hydrogen bonds between H 2 O molecules cause surface tension
Figure 2-6 Hydrogen Bonds between Water Molecules δ + δ + 2δ δ + 2δ δ + 2δ δ + δ + δ + 2δ δ + 2δ δ + 2δ δ + δ + 2δ KEY Hydrogen Oxygen Hydrogen bond
2-2 Molecules and Compounds States of Matter Solid Constant volume and shape Liquid Gas Constant volume but changes shape Changes volume and shape
2-2 Molecules and Compounds Molecular Weights The molecular weight of a molecule is the sum of the atomic weights of its component atoms H = approximately 1 O = approximately 16 H 2 = approximately 2 H 2 O = approximately 18
2-3 Chemical Reactions In a Chemical Reaction Either new bonds are formed or existing bonds are broken Reactants Materials going into a reaction Products Materials coming out of a reaction Metabolism All of the reactions that are occurring at one time
Figure 2-7 Chemical Notation Atoms The symbol of an element indicates one atom of that element. A number preceding the symbol of an element indicates more than one atom of that element. VISUAL REPRESENTATION CHEMICAL NOTATION one atom of hydrogen one atom of oxygen one atom of hydrogen one atom of oxygen two atoms of hydrogen two atoms of oxygen two atoms of hydrogen two atoms of oxygen
Figure 2-7 Chemical Notation Molecules A subscript following the symbol of an element indicates a molecule with that number of atoms of that element. VISUAL REPRESENTATION CHEMICAL NOTATION hydrogen molecule composed of two hydrogen atoms oxygen molecule composed of two oxygen atoms water molecule composed of two hydrogen atoms and one oxygen atom hydrogen molecule water molecule oxygen molecule
Figure 2-7 Chemical Notation Reactions In a description of a chemical reaction, the participants at the start of the reaction are called reactants, and the reaction generates one or more products. An arrow indicates the direction of the reaction, from reactants (usually on the left) to products (usually on the right). In the following reaction, two atoms of hydrogen combine with one atom of oxygen to produce a single molecule of water. VISUAL REPRESENTATION CHEMICAL NOTATION Chemical reactions neither create nor destroy atoms; they merely rearrange atoms into new combinations. Therefore, the numbers of atoms of each element must always be the same on both sides of the equation for a chemical reaction. When this is the case, the equation is balanced. Balanced equation Unbalanced equation
Figure 2-7 Chemical Notation Ions A superscript plus or minus sign following the symbol of an element indicates an ion. A single plus sign indicates a cation with a charge of +1. (The original atom has lost one electron.) A single minus sign indicates an anion with a charge of 1. (The original atom has gained one electron.) If more than one electron has been lost or gained, the charge on the ion is indicated by a number preceding the plus or minus sign. VISUAL REPRESENTATION CHEMICAL NOTATION sodium ion chloride ion calcium ion the sodium the chlorine the calcium atom has lost atom has gained atom has lost one electron one electron two electrons sodium ion chloride ion calcium ion A sodium atom becomes a sodium ion Electron lost Sodium atom (Na) Sodium ion (Na + )
2-3 Chemical Reactions Basic Energy Concepts Energy The power to do work Work A change in mass or distance Kinetic energy Energy of motion Potential energy Stored energy Chemical energy Potential energy stored in chemical bonds
2-3 Chemical Reactions Types of Chemical Reactions 1. Decomposition reaction (catabolism) 2. Synthesis reaction (anabolism) 3. Exchange reaction 4. Reversible reaction
2-3 Chemical Reactions Decomposition Reaction (Catabolism) Breaks chemical bonds AB A + B Hydrolysis A-B + H 2 O A-H + HO-B Synthesis Reaction (Anabolism) Forms chemical bonds A + B AB Dehydration synthesis (condensation reaction) A-H + HO-B A-B + H 2 O
2-3 Chemical Reactions Exchange Reaction Involves decomposition first, then synthesis AB + CD AD + CB
2-3 Chemical Reactions Reversible Reaction A + B AB At equilibrium the amounts of chemicals do not change even though the reactions are still occurring Reversible reactions seek equilibrium, balancing opposing reaction rates Add or remove reactants Reaction rates adjust to reach a new equilibrium
2-4 Enzymes Chemical Reactions In cells cannot start without help Activation energy is the amount of energy needed to get a reaction started Enzymes are protein catalysts that lower the activation energy of reactions
Figure 2-8 The Effect of Enzymes on Activation Energy Activation energy required Without enzyme Energy Reactants With enzyme Stable product Progress of reaction
2-4 Enzymes Exergonic (Exothermic) Reactions Produce more energy than they use Endergonic (Endothermic) Reactions Use more energy than they produce ANIMATION Chemical Reactions: Enzymes
2-5 Organic and Inorganic Compounds Nutrients Essential molecules obtained from food Metabolites Molecules made or broken down in the body Inorganic Compounds Molecules not based on carbon and hydrogen Carbon dioxide, oxygen, water, and inorganic acids, bases, and salts Organic Compounds Molecules based on carbon and hydrogen Carbohydrates, proteins, lipids, and nucleic acids
2-6 Properties of Water Water Accounts for up to two-thirds of your total body weight A solution is a uniform mixture of two or more substances It consists of a solvent, or medium, in which atoms, ions, or molecules of another substance, called a solute, are individually dispersed
2-6 Properties of Water Solubility Water s ability to dissolve a solute in a solvent to make a solution Reactivity Most body chemistry occurs in water High Heat Capacity Water s ability to absorb and retain heat Lubrication To moisten and reduce friction
2-6 Properties of Water The Properties of Aqueous Solutions Ions and polar compounds undergo ionization, or dissociation in water Polar water molecules form hydration spheres around ions and small polar molecules to keep them in solution
Figure 2-9 The Activities of Water Molecules in Aqueous Solutions Hydration spheres Glucose molecule Negative pole Cl H Positive pole Na +
Figure 2-9a The Activities of Water Molecules in Aqueous Solutions Negative pole H Positive pole Water molecule. In a water molecule, oxygen forms polar covalent bonds with two hydrogen atoms. Because both hydrogen atoms are at one end of the molecule, it has an uneven distribution of charges, creating positive and negative poles.
Figure 2-9b The Activities of Water Molecules in Aqueous Solutions Cl Hydration spheres Na + Sodium chloride in solution. Ionic compounds, such as sodium chloride, dissociate in water as the polar water molecules break the ionic bonds in the large crystal structure. Each ion in solution is surrounded by water molecules, creating hydration spheres.
Figure 2-9c The Activities of Water Molecules in Aqueous Solutions Glucose molecule Glucose in solution. Hydration spheres also form around an organic molecule containing polar covalent bonds. If the molecule binds water strongly, as does glucose, it will be carried into solution in other words, it will dissolve. Note that the molecule does not dissociate, as occurs for ionic compounds.
Table 2-2 Important Electrolytes that Dissociate in Body Fluids
2-6 Properties of Water The Properties of Aqueous Solutions Electrolytes and body fluids Electrolytes are inorganic ions that conduct electricity in solution Electrolyte imbalance seriously disturbs vital body functions
2-6 Properties of Water The Properties of Aqueous Solutions Hydrophilic and hydrophobic compounds Hydrophilic hydro- = water, philos = loving Interacts with water Includes ions and polar molecules Hydrophobic phobos = fear Does NOT interact with water Includes nonpolar molecules, fats, and oils
2-6 Properties of Water Colloids and Suspensions Colloid A solution of very large organic molecules For example, blood plasma Suspension A solution in which particles settle (sediment) For example, whole blood Concentration The amount of solute in a solvent (mol/l, mg/ml)
2-7 ph and Homeostasis ph The concentration of hydrogen ions (H + ) in a solution Neutral ph A balance of H + and OH Pure water = 7.0
2-7 ph and Homeostasis Acidic ph Lower Than 7.0 High H + concentration Low OH concentration Basic (or alkaline) ph Higher Than 7.0 Low H + concentration High OH concentration ph of Human Blood Ranges from 7.35 to 7.45
2-7 ph and Homeostasis ph Scale Has an inverse relationship with H + concentration More H + ions mean lower ph, less H + ions mean higher ph
Figure 2-10 ph and Hydrogen Ion Concentration 1 mol/l hydrochloric acid Stomach acid Beer, vinegar, wine, Tomatoes, pickles grapes Urine Saliva, milk Blood Ocean water Pure water Eggs Household bleach Household ammonia 1 mol/l sodium hydroxide Oven cleaner Extremely acidic Increasing concentration of H + Neutral Increasing concentration of OH Extremely basic ph 0 [H + ] 10 0 (mol/l) 1 10 1 2 10 2 3 10 3 4 10 4 5 10 5 6 10 6 7 10 7 8 10 8 9 10 10 9 10 10 11 10 11 12 10 12 13 10 13 14 10 14
2-8 Inorganic Compounds Acid A solute that adds hydrogen ions to a solution Proton donor Strong acids dissociate completely in solution Base A solute that removes hydrogen ions from a solution Proton acceptor Strong bases dissociate completely in solution Weak Acids and Weak Bases Fail to dissociate completely Help to balance the ph
2-8 Inorganic Compounds Salts Solutes that dissociate into cations and anions other than hydrogen ions and hydroxide ions
2-8 Inorganic Compounds Buffers and ph Control Buffers Weak acid/salt compounds Neutralize either strong acid or strong base Sodium bicarbonate is very important in humans Antacids Basic compounds that neutralize acid and form a salt Alka-Seltzer, Tums, Rolaids, etc.
2-9 Carbohydrates Organic Molecules Contain H, C, and usually O Are covalently bonded Contain functional groups that determine chemistry Carbohydrates Lipids Proteins (or amino acids) Nucleic acids
Table 2-3 Important Functional Groups of Organic Compounds
2-9 Carbohydrates Carbohydrates Contain carbon, hydrogen, and oxygen in a 1:2:1 ratio Monosaccharide simple sugar Disaccharide two sugars Polysaccharide many sugars
2-9 Carbohydrates Monosaccharides Simple sugars with 3 to 7 carbon atoms Glucose, fructose, galactose Disaccharides Two simple sugars condensed by dehydration synthesis Sucrose, maltose Polysaccharides Many monosaccharides condensed by dehydration synthesis Glycogen, starch, cellulose
Figure 2-12a The Formation and Breakdown of Complex Sugars DEHYDRATION SYNTHESIS Glucose Fructose Sucrose
Figure 2-12a The Formation and Breakdown of Complex Sugars DEHYDRATION SYNTHESIS Glucose Fructose Formation of the disaccharide sucrose through dehydration synthesis.
Figure 2-12a The Formation and Breakdown of Complex Sugars DEHYDRATION SYNTHESIS Sucrose During dehydration synthesis, two molecules are joined by the removal of a water molecule.
Figure 2-12b The Formation and Breakdown of Complex Sugars HYDROLYSIS Sucrose Glucose Fructose
Figure 2-12b The Formation and Breakdown of Complex Sugars HYDROLYSIS Sucrose Breakdown of sucrose into simple sugars by hydrolysis.
Figure 2-12b The Formation and Breakdown of Complex Sugars HYDROLYSIS Glucose Fructose Hydrolysis reverses the steps of dehydration synthesis; a complex molecule is broken down by the addition of a water molecule.
Figure 2-13 The Structure of the Polysaccharide Glycogen Glucose molecules
Table 2-4 Carbohydrates in the Body
2-10 Lipids Lipids Mainly hydrophobic molecules such as fats, oils, and waxes Made mostly of carbon and hydrogen atoms Include: Fatty acids Eicosanoids Glycerides Steroids Phospholipids and glycolipids
2-10 Lipids Fatty Acids Long chains of carbon and hydrogen with a carboxyl group (COOH) at one end Are relatively nonpolar, except the carboxyl group Fatty acids may be: Saturated with hydrogen (no covalent bonds) Unsaturated (one or more double bonds) Monounsaturated = one double bond Polyunsaturated = two or more double bonds
Figure 2-14a Fatty Acids Lauric acid (C 12 H 24 O 2 ) Lauric acid demonstrates two structural characteristics common to all fatty acids: a long chain of carbon atoms and a carboxyl group ( COOH) at one end.
Figure 2-14b Fatty Acids Saturated Unsaturated A fatty acid is either saturated (has single covalent bonds only) or unsaturated (has one or more double covalent bonds). The presence of a double bond causes a sharp bend in the molecule.
2-10 Lipids Eicosanoids Derived from the fatty acid called arachidonic acid Leukotrienes Active in immune system Prostaglandins Local hormones, short-chain fatty acids
Figure 2-15 Prostaglandins
2-10 Lipids Glycerides Fatty acids attached to a glycerol molecule Triglycerides are the three fatty-acid tails Also called triacylglycerols or neutral fats Have three important functions 1. Energy source 2. Insulation 3. Protection
Figure 2-16 Triglyceride Formation Glycerol Fatty Acid 1 Fatty acids Saturated Fatty Acid 2 Saturated Fatty Acid 3 Unsaturated DEHYDRATION SYNTHESIS HYDROLYSIS Triglyceride
2-10 Lipids Steroids Four rings of carbon and hydrogen with an assortment of functional groups Types of steroids: Cholesterol Component of plasma (cell) membranes Estrogens and testosterone Sex hormones Corticosteroids and calcitriol Metabolic regulation Bile salts Derived from steroids
Figure 2-17 Steroids Cholesterol Estrogen Testosterone
2-10 Lipids Phospholipids and Glycolipids Diglycerides attached to either a phosphate group (phospholipid) or a sugar (glycolipid) Generally, both have hydrophilic heads and hydrophobic tails and are structural lipids, components of plasma (cell) membranes
Figure 2-18a Phospholipids and Glycolipids Nonlipid group Phosphate group Glycerol Fatty acids The phospholipid lecithin. In a phospholipid, a phosphate group links a nonlipid molecule to a diglyceride.
Figure 2-18b Phospholipids and Glycolipids Carbohydrate Fatty acids In a glycolipid, a carbohydrate is attached to a diglyceride.
Figure 2-18c Phospholipids and Glycolipids In large numbers, phospholipids and glycolipids form micelles, with the hydrophilic heads facing the water molecules, and the hydrophobic tails on the inside of each droplet. Phospholipid Hydrophilic heads Hydrophobic tails Glycolipid WATER
Table 2-5 Representative Lipids and Their Functions in the Body
2-11 Proteins Proteins Are the most abundant and important organic molecules Contain basic elements Carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) Basic building blocks 20 amino acids
2-11 Proteins Seven Major Protein Functions 1. Support Structural proteins 2. Movement Contractile proteins 3. Transport Transport (carrier) proteins 4. Buffering Regulation of ph 5. Metabolic Regulation Enzymes 6. Coordination and Control Hormones 7. Defense Antibodies
2-11 Proteins Protein Structure Long chains of amino acids Five components of amino acid structure 1. Central carbon atom 2. Hydrogen atom 3. Amino group ( NH 2 ) 4. Carboxyl group ( COOH) 5. Variable side chain or R group
Figure 2-19 Amino Acids Structure of an Amino Acid Amino group Central carbon Carboxyl group R group (variable side chain of one or more atoms)
2-11 Proteins Hooking Amino Acids Together Requires a dehydration synthesis between: The amino group of one amino acid and the carboxyl group of another amino acid Forms a peptide bond Resulting molecule is a peptide
Figure 2-20 The Fomation of Peptide Bonds Peptide Bond Formation Glycine (gly) Alanine (ala) DEHYDRATION SYNTHESIS HYDROLYSIS Peptide bond
2-11 Proteins Protein Shape Primary structure The sequence of amino acids along a polypeptide Secondary structure Hydrogen bonds form spirals or pleats Tertiary structure Secondary structure folds into a unique shape Quaternary structure Final protein shape several tertiary structures together
Figure 2-21 Protein Structure A1 A2 A3 A4 A5 A6 A7 A8 A9 Linear chain of amino acids A1 A2 A3 A4 A2 Hydrogen bond A6 Hydrogen bond A10 A9 A8 A7 A6 A5 A1 A3 A5 A7 A9 OR A11 A12 A13 A14 Alpha-helix Pleated sheet OR Heme units Hemoglobin (globular protein) Keratin or collagen (fibrous protein)
Figure 2-21ab Protein Structure A1 A2 A3 A4 A5 A6 A7 A8 A9 Primary structure. The primary structure of a polypeptide is the sequence of amino acids (A1, A2, A3, and so on) along its length. A2 Hydrogen bond Linear chain of amino acids A6 A1 A3 A5 A7 A9 Alpha-helix Secondary structure. Secondary structure is primarily the result of hydrogen bonding along the length of the polypeptide chain. Such bonding often produces a simple spiral (an alpha-helix) or a flattened arrangement known as a pleated sheet.
Figure 2-21ab Protein Structure A1 A2 A3 A4 A5 A6 A7 A8 A9 Linear chain of amino acids Primary structure. The primary structure of a polypeptide is the sequence of amino acids (A1, A2, A3, and so on) along its length. Hydrogen bond A1 A2 A3 A4 A5 A9 A8 A7 A6 A10 A11 A12 A13 A14 Secondary structure. Secondary structure is primarily the result of hydrogen bonding along the length of the polypeptide chain. Such bonding often produces a simple spiral (an alpha-helix) or a flattened arrangement known as a pleated sheet. Pleated sheet
Figure 2-21cd Protein Structure Tertiary structure. Tertiary structure is the coiling and folding of a polypeptide. Heme units Hemoglobin (globular protein) Quaternary structure. Quaternary structure develops when separate polypeptide subunits interact to form a larger molecule. A single hemoglobin molecule contains four globular subunits.
Figure 2-21cd Protein Structure Tertiary structure. Tertiary structure is the coiling and folding of a polypeptide. Heme units Keratin or collagen (fibrous protein) Quaternary structure. Quaternary structure develops when separate polypeptide subunits interact to form a larger molecule.
2-11 Proteins Fibrous Proteins Structural sheets or strands Globular Proteins Soluble spheres with active functions Protein function is based on shape Shape is based on sequence of amino acids
Figure 2-21d Protein Structure OR Heme units Hemoglobin (globular protein) Keratin or collagen (fibrous protein)
2-11 Proteins Enzyme Function Enzymes are catalysts Proteins that lower the activation energy of a chemical reaction Are not changed or used up in the reaction Enzymes also exhibit: 1. Specificity will only work on limited types of substrates 2. Saturation Limits by their concentration 3. Regulation by other cellular chemicals
Figure 2-22 A Simplified View of Enzyme Structure and Function Substrates bind to active site of enzyme
Figure 2-22 A Simplified View of Enzyme Structure and Function Once bound to the active site, the substrates are held together and their interaction facilitated Enzyme-substrate complex
Figure 2-22 A Simplified View of Enzyme Structure and Function Substrate binding alters the shape of the enzyme, and this change promotes product formation
Figure 2-22 A Simplified View of Enzyme Structure and Function Product detaches from enzyme; entire process can now be repeated
2-11 Proteins Cofactors and Enzyme Function Cofactor An ion or molecule that binds to an enzyme before substrates can bind Coenzyme Nonprotein organic cofactors (vitamins) Isozymes Two enzymes that can catalyze the same reaction
2-11 Proteins Effects of Temperature and ph on Enzyme Function Denaturation Loss of shape and function due to heat or ph
2-11 Proteins Glycoproteins and Proteoglycans Glycoproteins Large protein + small carbohydrate Includes enzymes, antibodies, hormones, and mucus production Proteoglycans Large polysaccharides + polypeptides Promote viscosity
2-12 Nucleic Acids Nucleic Acids Are large organic molecules, found in the nucleus, which store and process information at the molecular level Deoxyribonucleic acid (DNA) Determines inherited characteristics Directs protein synthesis Controls enzyme production Controls metabolism Ribonucleic acid (RNA) Controls intermediate steps in protein synthesis
2-12 Nucleic Acids Structure of Nucleic Acids DNA and RNA are strings of nucleotides Nucleotides Are the building blocks of DNA and RNA Have three molecular parts 1. A pentose sugar (deoxyribose or ribose) 2. Phosphate group 3. Nitrogenous base (A, G, T, C, or U)
Figure 2-23a Nucleotides and Nitrogenous Bases Generic nucleotide The nitrogenous base may be a purine or a pyrimidine. Sugar Phosphate group Nitrogenous base
Figure 2-23b Nucleotides and Nitrogenous Bases Purines Adenine Guanine
Figure 2-23c Nucleotides and Nitrogenous Bases Pyrimidines Cytosine Thymine (DNA only) Uracil (RNA only)
2-12 Nucleic Acids DNA and RNA DNA is double stranded, and the bases form hydrogen bonds to hold the DNA together Sometimes RNA can bind to itself but is usually a single strand DNA forms a twisting double helix Complementary base pairs Purines pair with pyrimidines DNA RNA Adenine (A) and thymine (T) Cytosine (C) and guanine (G) Uracil (U) replaces thymine (T)
Figure 2-24 The Structure of Nucleic Acids Phosphate group Deoxyribose Adenine Thymine Hydrogen bond DNA strand 1 DNA strand 2 RNA molecule. Cytosine Guanine DNA molecule.
2-12 Nucleic Acids Types of RNA Messenger RNA (mrna) Transfer RNA (trna) Ribosomal RNA (rrna)
Table 2-6 Comparison of RNA with DNA
2-13 High-Energy Compounds Nucleotides Can Be Used to Store Energy Adenosine diphosphate (ADP) Two phosphate groups; di- = 2 Adenosine triphosphate (ATP) Three phosphate groups; tri- = 3 Phosphorylation Adding a phosphate group to ADP with a high-energy bond to form the high-energy compound ATP Adenosine triphosphatase (ATPase) The enzyme that catalyzes the conversion of ATP to ADP
Figure 2-25 The Structure of ATP Adenine Ribose Phosphate Phosphate Phosphate Adenosine High-energy bonds Adenosine monophosphate (AMP) Adenosine diphosphate (ADP) Adenosine triphosphate (ATP) Adenine Ribose Phosphate groups Adenosine
2-14 Chemicals and Cells Chemicals and Cells Biochemical building blocks form functional units called cells Metabolic turnover lets your body grow, change, and adapt to new conditions and activities Your body recycles and renews all of its chemical components at intervals ranging from minutes to years
Table 2-7 Classes of Inorganic and Organic Compounds
Table 2-8 Turnover Times