Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Radical (chemistry) wikipedia , lookup
Photosynthesis wikipedia , lookup
Chemical biology wikipedia , lookup
Cell-penetrating peptide wikipedia , lookup
Protein adsorption wikipedia , lookup
Biomolecular engineering wikipedia , lookup
Carbohydrate wikipedia , lookup
List of types of proteins wikipedia , lookup
Abiogenesis wikipedia , lookup
Anatomy & Physiology I Lecture 1 The Human Body and its Chemistry What is Anatomy? • Anatomy – The study of structure • Subdivisions: – Gross or macroscopic (e.g., regional, systemic, and surface anatomy) – Microscopic (e.g., cytology and histology) – Developmental (e.g., embryology) What is Physiology? • Physiology – the study of the function of the body • Subdivisions based on organ systems (e.g., renal or cardiovascular physiology) – Often focuses on cellular and molecular level – Body's abilities depend on chemical reactions in individual cells Anatomy & Physiology • Anatomy and physiology are inseparable • Function always reflects structure Keys to Success • Mastery of anatomical terminology • Ability to focus at many levels (systemic to cellular to molecular) • Study of basic physical principles (e.g., electrical currents, pressure, and movement) • Study of basic chemical principles Figure 1.1 Levels of structural organization. Atoms Organelle Smooth muscle cell Molecule Chemical level Atoms combine to form molecules. Cellular level Cells are made up of molecules. Cardiovascular system Heart Blood vessels Slide 1 Smooth muscle tissue Tissue level Tissues consist of similar types of cells. Blood vessel (organ) Smooth muscle tissue Connective tissue Epithelial tissue Organ level Organs are made up of different types of tissues. Organismal level The human organism is made up of many organ systems. © 2013 Pearson Education, Inc. Organ system level Organ systems consist of different organs that work together closely. Figure 1.3a The body’s organ systems and their major functions. Hair Skin Nails Integumentary System Forms the external body covering, and protects deeper tissues from injury. Synthesizes vitamin D, and houses cutaneous (pain, pressure, etc.) receptors and sweat and oil glands. © 2013 Pearson Education, Inc. Figure 1.3b The body’s organ systems and their major functions. Bones Joint Skeletal System Protects and supports body organs, and provides a framework the muscles use to cause movement. Blood cells are formed within bones. Bones store minerals. © 2013 Pearson Education, Inc. Figure 1.3c The body’s organ systems and their major functions. Skeletal muscles (c) Muscular System Allows manipulation of the environment, locomotion, and facial expression. Maintains posture, and produces heat. © 2013 Pearson Education, Inc. Figure 1.3d The body’s organ systems and their major functions. Brain Spinal cord Nerves Nervous System As the fast-acting control system of the body, it responds to internal and external changes by activating appropriate muscles and glands. © 2013 Pearson Education, Inc. Figure 1.3e The body’s organ systems and their major functions. Pineal gland Pituitary gland Thyroid gland Thymus Adrenal gland Pancreas Testis Ovary Endocrine System Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells. © 2013 Pearson Education, Inc. Figure 1.3f The body’s organ systems and their major functions. Heart Blood vessels Cardiovascular System Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. The heart pumps blood. © 2013 Pearson Education, Inc. Figure 1.3g The body’s organ systems and their major functions. Red bone marrow Thymus Lymphatic vessels Thoracic duct Spleen Lymph nodes Lymphatic System/Immunity Picks up fluid leaked from blood vessels and returns it to blood. Disposes of debris in the lymphatic stream. Houses white blood cells (lymphocytes) involved in immunity. The immune response mounts the attack against foreign substances within the body. © 2013 Pearson Education, Inc. Figure 1.3h The body’s organ systems and their major functions. Nasal cavity Pharynx Larynx Bronchus Trachea Lung Respiratory System Keeps blood constantly supplied with oxygen and removes carbon dioxide. The gaseous exchanges occur through the walls of the air sacs of the lungs. © 2013 Pearson Education, Inc. Figure 1.3i The body’s organ systems and their major functions. Oral cavity Esophagus Liver Stomach Small Intestine Large Intestine Rectum Anus Digestive System Breaks down food into absorbable units that enter the blood for distribution to body cells. Indigestible foodstuffs are eliminated as feces. © 2013 Pearson Education, Inc. Figure 1.3j The body’s organ systems and their major functions. Kidney Ureter Urinary bladder Urethra Urinary System Eliminates nitrogenous wastes from the body. Regulates water, electrolyte and acid-base balance of the blood. © 2013 Pearson Education, Inc. Figure 1.3k–l The body’s organ systems and their major functions. Mammary glands (in breasts) Prostate gland Ovary Penis Testis Scrotum Ductus deferens Uterus Vagina Male Reproductive System Overall function is production of offspring. Testes produce sperm and male sex hormone, and male ducts and glands aid in delivery of sperm to the female reproductive tract. Ovaries produce eggs and female sex hormones. The remaining female structures serve as sites for fertilization and development of the fetus. Mammary glands of female breasts produce milk to nourish the newborn. © 2013 Pearson Education, Inc. Uterine tube Female Reproductive System Overall function is production of offspring. Testes produce sperm and male sex hormone, and male ducts and glands aid in delivery of sperm to the female reproductive tract. Ovaries produce eggs and female sex hormones. The remaining female structures serve as sites for fertilization and development of the fetus. Mammary glands of female breasts produce milk to nourish the newborn. Homeostasis is the key to A&P • Maintenance of relatively stable internal conditions despite continuous changes in environment • A dynamic state of equilibrium • Maintained by contributions of all organ systems Figure 1.4 Interactions among the elements of a homeostatic control system maintain stable internal conditions. 3 Input: Information sent along afferent pathway to control center. 2 Receptor detects change. Receptor 1 Stimulus produces change in variable. © 2013 Pearson Education, Inc. Control Center Afferent pathway Efferent pathway BALANCE Slide 1 4 Output: Information sent along efferent pathway to effector. Effector 5 Response of effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level. Homeostatic Control • Negative Feedback mechanisms • Positive Feedback mechanisms • Primarily a function of endocrine (BIO202) and nervous system (BIO201) Negative Feedback • Most feedback mechanisms in body • Response reduces or shuts off original stimulus – Variable changes in opposite direction of initial change • Example: sweating when you’re hot, shivering when you’re cold Positive Feedback • Response enhances or exaggerates original stimulus • May exhibit a cascade or amplifying effect • Usually controls infrequent events that do not require continuous adjustment – contraction during labor or blood clotting Homeostatic Imbalance • Disturbance of homeostasis • Increases risk of disease – genetic – age Terminology of Anatomy • Always use directional terms as if body is in anatomical position • Right and left refer to body being viewed, not those of observer Figure 1.7a Regional terms used to designate specific body areas. Cephalic Frontal Orbital Nasal Oral Mental Cervical Upper limb Acromial Brachial (arm) Antecubital Thoracic Sternal Axillary Mammary Antebrachial (forearm) Carpal (wrist) Abdominal Umbilical Manus (hand) Pollex Pelvic Inguinal (groin) Palmar Digital Lower limb Coxal (hip) Femoral (thigh) Patellar Pubic (genital) Crural (leg) Fibular or peroneal Pedal (foot) Tarsal (ankle) Thorax Abdomen Back (Dorsum) Metatarsal Digital Hallux Anterior/Ventral © 2013 Pearson Education, Inc. Figure 1.7b Regional terms used to designate specific body areas. Cephalic Otic Occipital (back of head) Upper limb Acromial Brachial (arm) Cervical Olecranal Antebrachial (forearm) Back (dorsal) Scapular Vertebral Lumbar Manus (hand) Sacral Metacarpal Gluteal Digital Perineal (between anus and external genitalia) Lower limb Femoral (thigh) Popliteal Sural (calf) Fibular or peroneal Pedal (foot) Calcaneal Back (Dorsum) Plantar Posterior/Dorsal © 2013 Pearson Education, Inc. Directional Terms • Superior (cranial) – above • Inferior (caudal) – below • Anterior (ventral) – in front of Directional Terms • Posterior (dorsal – behind • Medial – on the inner side • Lateral – on the outer side Directional Terms • Proximal – closer • Distal – distant or farther • Superficial – close to body surface • Deep – away from body surface Two Divisions of the body • Axial – Head, neck, and trunk • Appendicular – Limbs Body Planes and Sections • Body plane – Flat surface along which body or structure may be cut for anatomical study • Sections – Cuts or sections made along a body plane Body Planes • Three most common • Lie at right angles to each other – Sagittal plane – Frontal (coronal) plane – Transverse (horizontal) plane Figure 1.8 Planes of the body with corresponding magnetic resonance imaging (MRI) scans. Frontal plane Median (midsagittal) plane Transverse plane Transverse section (through torso, inferior view) Pancreas Frontal section (through torso) Median section (midsagittal) Aorta Spleen Arm Liver Heart Left and right lungs © 2013 Pearson Education,Stomach Inc. Liver Spinal cord Subcutaneous fat layer Body wall Rectum Intestines Vertebral column Body Cavities • Two sets of internal body cavities – Closed off to outside environment to provide protection • Dorsal body cavity • Ventral body cavity Figure 1.9 Dorsal and ventral body cavities and their subdivisions. Cranial cavity Cranial cavity (contains brain) Vertebral cavity Superior mediastinum Dorsal body cavity Thoracic Pleural cavity (contains heartcavity Pericardial cavity and lungs) within the mediastinum Vertebral cavity (contains spinal cord) Diaphragm Abdominal cavity (contains digestive viscera) Abdominopelvic cavity Pelvic cavity (contains urinary bladder, reproductive organs, and rectum) Dorsal body cavity Ventral body cavity Lateral view © 2013 Pearson Education, Inc. Anterior view Ventral body cavity (thoracic and abdominopelvic cavities) And it goes on and on and on... The Chemistry of Life • Review • What is energy? • What is the conservation of energy? Forms of Energy • Chemical energy – Stored in bonds of chemical substances • Electrical energy – Results from movement of charged particles • Mechanical energy – Directly involved in moving matter • Electromagnetic energy – Travels in waves (visible light, ultraviolet light, and x-rays) Energy Conversion • The chemical and electrical energy produced by molecules in the cells allows for mechanical energy of tissues and organs. Elements of Life • Four elements make up 96.1% of body mass • • • • Carbon (C) Hydrogen (H) Oxygen (O) Nitrogen (N) Figure 2.1 Two models of the structure of an atom. Nucleus Nucleus Helium atom Helium atom 2 protons (p+) 2 neutrons (n0) 2 electrons (e–) 2 protons (p+) 2 neutrons (n0) 2 electrons (e–) Planetary model Proton Neutron Electron Electron © 2013 Pearson Education, Inc. cloud Orbital model Figure 2.2 Atomic structure of the three smallest atoms. Proton Neutron Electron Hydrogen (H) (1p+; 0n0; 1e–) © 2013 Pearson Education, Inc. Helium (He) (2p+; 2n0; 2e–) Lithium (Li) (3p+; 4n0; 3e–) Atoms to Molecules • Three types of bonds: 1. Ionic bonds 2. Covalent bonds 3. Hydrogen bonds Figure 2.6a–b Formation of an ionic bond. + Sodium atom (Na) (11p+; 12n0; 11e–) Chlorine atom (Cl) (17p+; 18n0; 17e–) Sodium gains stability by losing one electron, and chlorine becomes stable by gaining one electron. © 2013 Pearson Education, Inc. Sodium ion (Na+) — Chloride ion (Cl–) Sodium chloride (NaCl) After electron transfer, the oppositely charged ions formed attract each other. Figure 2.7a Formation of covalent bonds. Reacting atoms Resulting molecules + or Structural formula shows single bonds. Carbon atom Hydrogen atoms Formation of four single covalent bonds: Carbon shares four electron pairs with four hydrogen atoms. © 2013 Pearson Education, Inc. Molecule of methane gas (CH4) Figure 2.7b Formation of covalent bonds. Reacting atoms Resulting molecules + Oxygen atom Oxygen atom Formation of a double covalent bond: Two oxygen atoms share two electron pairs. © 2013 Pearson Education, Inc. or Structural formula shows double bond. Molecule of oxygen gas (O2) Figure 2.7c Formation of covalent bonds. Reacting atoms Resulting molecules or + Nitrogen atom Nitrogen atom Formation of a triple covalent bond: Two nitrogen atoms share three electron pairs. © 2013 Pearson Education, Inc. Structural formula shows triple bond. Molecule of nitrogen gas (N2) Two Types of Covalent Bonds 1. Nonpolar covalent bonds – electrons shared equally between atoms 2. Polar covalent bonds – electrons shared unequally between atoms Figure 2.8a Carbon dioxide and water molecules have different shapes, as illustrated by molecular models. Carbon dioxide (CO2) molecules are linear and symmetrical. They are nonpolar. © 2013 Pearson Education, Inc. Figure 2.8b Carbon dioxide and water molecules have different shapes, as illustrated by molecular models. – + + V-shaped water (H2O) molecules have two poles of charge—a slightly more negative oxygen end (–) and a slightly more positive hydrogen end (+). © 2013 Pearson Education, Inc. Polar vs Non Polar Covalent Bonds • How different in electronegativity are the atoms binding • C – electron neutral • O, N, P, Cl – electronegative • H, Na - electropositive Hydrogen bond • the weak attraction of a partially positive hydrogen to an electronegative atom • produced by the polarity of the molecule – dipole • water, sugars, organic acids and bases and ions can participate Figure 2.10a Hydrogen bonding between polar water molecules. + – Hydrogen bond (indicated by dotted line) + – – + – + + + – The slightly positive ends (+) of the water molecules become aligned with the slightly negative ends (–) of other water molecules. © 2013 Pearson Education, Inc. Question? • How do hydrogen bonds relate to solubility in water? Chemical Reactions • Occur when chemical bonds are formed, rearranged, or broken • Four types – Synthesis (combination) reactions – Decomposition reactions – Exchange reactions Synthesis Reactions • A + B AB – Atoms or molecules combine to form larger, more complex molecule – Always involve bond formation • Anabolic Figure 2.11a Patterns of chemical reactions. Synthesis reactions Smaller particles are bonded together to form larger, more complex molecules. Example Amino acids are joined together to form a protein molecule. Amino acid molecules Protein molecule © 2013 Pearson Education, Inc. Decomposition Reaction • AB A + B – Molecule is broken down into smaller molecules or its constituent atoms – Reverse of synthesis reactions – Involve breaking of bonds • Catabolic Figure 2.11b Patterns of chemical reactions. Decomposition reactions Bonds are broken in larger molecules, resulting in smaller, less complex molecules. Example Glycogen is broken down to release glucose units. Glycogen Glucose molecules © 2013 Pearson Education, Inc. Exchange Reactions • AB + C AC + B – Also called displacement reactions – Involve both synthesis and decomposition – Bonds are both made and broken Figure 2.11c Patterns of chemical reactions. Exchange reactions Bonds are both made and broken (also called displacement reactions). Example ATP transfers its terminal phosphate group to glucose to form glucosephosphate. + Adenosine triphosphate (ATP) Glucose + Adenosine diphosphate (ADP) © 2013 Pearson Education, Inc. Glucosephosphate Oxidation-Reduction Reactions • Are decomposition and exchange reactions – Electron donors lose electrons and are oxidized – Electron acceptors receive electrons and become reduced • “LEO the lion says GER” • C6H12O6 + 6O2 6CO2 + 6H2O + ATP Energy in Chemical Reactions • All chemical reactions are either exergonic or endergonic • Exergonic reactions—net release of energy – Catabolic and oxidative reactions • Endergonic reactions—net absorption of energy – Anabolic reactions Rates of Reactions • Chemical equilibrium occurs if neither a forward nor reverse reaction is dominant • Affected by: – Temperature Rate – Concentration of reactant – Catalysts: Rate • Enzymes are biological catalysts Rate Biochemistry • Study of chemical composition and reactions of living matter • The chemical interactions between water, salts, acids/bases and organic molecules Water • Most abundant inorganic compound – 60%–80% volume of living cells • Most important inorganic compound – Due to water’s properties Properties of Water • High heat capacity – Absorbs and releases heat with little temperature change – Prevents sudden changes in temperature • High heat of vaporization – Evaporation requires large amounts of heat – Useful cooling mechanism Water as a solvent • Polar solvent – Dissolves and dissociates ionic substances – Dissolves polar molecules • Hydrophilic – water loving • Hydrophobic – water fearing (hating) Water as a reactant • Necessary part of hydrolysis and dehydration synthesis reactions Salts • Ionic compounds that dissociate into ions in water • Ions (electrolytes) conduct electrical currents in solution • Ionic balance vital for homeostasis • Common salts in body – NaCl, CaCO3, KCl, CaPO4 Acids and Bases • Acids are proton donors – Release H+ into solution • Bases are proton acceptors – Take up H+ from solution – Release OH- into solution Acids and Bases in the body • Important acids – HCl, HC2H3O2 (HAc), and H2CO3 • Important bases – Bicarbonate ion (HCO3–) and ammonia (NH3) pH – the measure of acidity • pH is a mathematical function pH = - log[H+] the logarithm is a function of exponents Linear relationship between y and x The measure of acidity • pH = - log[H+] • It measures the concentration of protons (H+) in a solution. • High H+ concentration = low pH (acidic) • Low H+ concentration = high pH (basic) H+ vs OH- Figure 2.13 The pH scale and pH values of representative substances. Concentration (moles/liter) [OH−] [H+] pH Examples 1M Sodium hydroxide (pH=14) 100 10−14 14 10−1 10−13 13 10−2 10−12 12 10−3 10−11 11 10−4 10−10 10 10−5 10−9 9 10−6 10−8 8 10−7 10−7 7 Neutral 10−8 10−6 6 10−9 10−5 5 10−10 10−4 4 10−11 10−3 3 10−12 10−2 2 10−13 10−1 1 100 0 © 2013 Pearson Education, Inc. 10−14 Increasingly basic Oven cleaner, lye (pH=13.5) Household ammonia (pH=10.5–11.5) Household bleach (pH=9.5) Egg white (pH=8) Blood (pH=7.4) Increasingly acidic Milk (pH=6.3–6.6) Black coffee (pH=5) Wine (pH=2.5–3.5) Lemon juice; gastric juice (pH=2) 1M Hydrochloric acid (pH=0) Regulation of pH • pH is regulated by kidneys, lungs, and chemical buffers • All biomolecules properties and functions influenced by pH Buffers • Buffers resist abrupt and large swings in pH – Release hydrogen ions if pH rises – Bind hydrogen ions if pH falls • Carbonic acid-bicarbonate system (important buffer system of blood): The Biological Environment • • • • • • water salts acids/bases buffers pH temperature The Biological Players • • • • Carbohydrates Lipids Proteins Nucleic Acids The Primary Reactions • Dehydration synthesis • Hydrolysis • Creating polymers out of monomers • Breaking down polymers to produce monomers Figure 2.14 Dehydration synthesis and hydrolysis. Dehydration synthesis Monomers are joined by removal of OH from one monomer and removal of H from the other at the site of bond formation. Monomer 1 + Monomer 2 Monomers linked by covalent bond Hydrolysis Monomers are released by the addition of a water molecule, adding OH to one monomer and H to the other. + Monomer 1 Monomers linked by covalent bond Example reactions Dehydration synthesis of sucrose and its breakdown by hydrolysis Water is released + Water is consumed Glucose © 2013 Pearson Education, Inc. Fructose Sucrose Monomer 2 Carbohydrates • Sugars and starches • Polymers – Contain C, H, and O [(CH20)n] • Three classes – Monosaccharides – one sugar – Disaccharides – two sugars – Polysaccharides – many sugars Figure 2.15a Carbohydrate molecules important to the body. Monosaccharides Monomers of carbohydrates Example Example Hexose sugars (the hexoses shown here are isomers) Glucose Fructose © 2013 Pearson Education, Inc. Galactose Pentose sugars Deoxyribose Ribose Figure 2.15b Carbohydrate molecules important to the body. Disaccharides Consist of two linked monosaccharides Example Sucrose, maltose, and lactose (these disaccharides are isomers) Glucose Fructose Sucrose Glucose Glucose Maltose Galactose Lactose Glucose Figure 2.15c Carbohydrate molecules important to the body. Polysaccharides Example Long chains (polymers) of linked monosaccharides This polysaccharide is a simplified representation of glycogen, a polysaccharide formed from glucose units. Glycogen Functions of Carbohydrates • Major source of cellular fuel (glucose) • Structural molecules (DNA/RNA) • Give function of proteins • Identification tag for cells and cellular function – ABO blood type Lipids • Insoluble in water • Main types: – Triglycerides or neutral fats – Phospholipids – Steroids – Eicosanoids Triglycerides • Called fats when solid and oils when liquid • Composed of three fatty acids bonded to a glycerol molecule • Main functions – Energy storage – Insulation – Protection Figure 2.16a Lipids. Triglyceride formation Three fatty acid chains are bound to glycerol by dehydration synthesis. + Glycerol © 2013 Pearson Education, Inc. + 3 fatty acid chains Triglyceride, or neutral fat 3 water molecules Saturation of Fatty Acids • Saturated fatty acids – Maximum number of H atoms on C – Solid animal fats (butter) • Unsaturated fatty acids – Reduced number of H atoms on C due to double bonds – Plant oils (olive oil) Phospholipids • Modified triglycerides: – Glycerol + two fatty acids and a phosphorus (P) containing group • “Head” and “tail” regions have different properties • Important in cell membrane structure Figure 2.16b Lipids. Amphipathicity “Typical” structure of a phospholipid molecule Two fatty acid chains and a phosphorus-containing group are attached to the glycerol backbone. Example Phosphatidylcholine Polar “head” Nonpolar “tail” (schematic phospholipid) Phosphorus-containing group (polar “head”) © 2013 Pearson Education, Inc. Glycerol backbone 2 fatty acid chains (nonpolar “tail”) Steroids • Steroids—interlocking four-ring structure – Cholesterol, vitamin D, steroid hormones, and bile salts • Most important steroid – Cholesterol – Important in cell membranes, vitamin D synthesis, steroid hormones, and bile salts Figure 2.16c Lipids. Simplified structure of a steroid Four interlocking hydrocarbon rings form a steroid. Example Cholesterol (cholesterol is the basis for all steroids formed in the body) © 2013 Pearson Education, Inc. Proteins • Proteins are polymers • Amino acids (20 types) are the monomers in proteins – Joined by covalent bonds called peptide bonds • Unique chemical properties of amino acids give proteins their unique function – Contain amine group and acid group Figure 2.17 Amino acid structures. Amine group Acid group Generalized structure of all amino acids. Glycine is the simplest amino acid. © 2013 Pearson Education, Inc. Aspartic acid (an acidic amino acid) has an acid group (—COOH) in the R group. Lysine (a basic amino acid) has an amine group (—NH2) in the R group. Cysteine (a basic amino acid) has a sulfhydryl (—SH) group in the R group, which suggests that this amino acid is likely to participate in intramolecular bonding. Figure 2.18 Amino acids are linked together by peptide bonds. Dehydration synthesis: The acid group of one amino acid is bonded to the amine group of the next, with loss of a water molecule. Peptide bond + Amino acid Dipeptide Amino acid Hydrolysis: Peptide bonds linking amino acids together are broken when water is added to the bond. © 2013 Pearson Education, Inc. Figure 2.19a Levels of protein structure. Amino acid Primary structure: The sequence of amino acids forms the polypeptide chain. Amino acid Amino acid Amino acid Amino acid Figure 2.19b Levels of protein structure. Secondary structure: The primary chain forms spirals (-helices) and sheets (-sheets). -Helix: The primary chain is coiled to form a spiral structure, which is stabilized by hydrogen bonds. -Sheet: The primary chain “zig-zags” back and forth forming a “pleated” sheet. Adjacent strands are held together by hydrogen bonds. Figure 2.19c Levels of protein structure. Tertiary structure: Superimposed on secondary structure. -Helices and/or -sheets are folded up to form a compact globular molecule held together by intramolecular bonds. Tertiary structure of prealbumin (transthyretin), a protein that transports the thyroid hormone thyroxine in blood and cerebrospinal fluid. Figure 2.19d Levels of protein structure. Quaternary structure: Two or more polypeptide chains, each with its own tertiary structure, combine to form a functional protein. Quaternary structure of a functional prealbumin molecule. Two identical prealbumin subunits join head to tail to form the dimer. Proteins are • Diverse in size, structure and function • • • • • Structural support Biological catalysts Chaperones Hormones Cellular signaling Enzymes • The biological catalysts • Regulate and increase speed of chemical reactions • Lower the activation energy, increase the speed of a reaction Figure 2.20 Enzymes lower the activation energy required for a reaction. WITHOUT ENZYME WITH ENZYME Less activation energy required Energy Energy Activation energy required Reactants Reactants Product Progress of reaction Product Progress of reaction Figure 2.21 Mechanism of enzyme action. Substrates (S) e.g., amino acids Energy is absorbed; bond is formed. + Slide 1 Water is released. Product (P) e.g., dipeptide Peptide bond Active site Enzyme (E) Enzyme-substrate complex (E-S) 1 Substrates bind at active site, temporarily forming an enzyme-substrate complex. © 2013 Pearson Education, Inc. 2 The E-S complex undergoes internal rearrangements that form the product. Enzyme (E) 3 The enzyme releases the product of the reaction. Nucleic Acids • Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) • Monomer = nucleotide – Composed of nitrogen base, a pentose sugar, and a phosphate group Figure 2.22 Structure of DNA. Phosphate Sugar: Deoxyribose Base: Adenine (A) Thymine (T) Thymine nucleotide Adenine nucleotide Hydrogen bond Sugarphosphate backbone Deoxyribose sugar Phosphate Adenine (A) Thymine (T) Cytosine (C) Guanine (G) © 2013 Pearson Education, Inc. Sugar Phosphate Functions of Nucleic Acids • DNA – our genome – the vast collection of our genes that code the instructions for all cellular processes • RNA – protein synthesis (mRNA, tRNA, mRNA) – protein expression (siRNA, miRNA) ATP (GTP) • Adenosine triphosphate • Chemical energy in glucose captured in this important molecule • Directly powers chemical reactions in cells • Energy form immediately useable by all body cells Figure 2.23 Structure of ATP (adenosine triphosphate). High-energy phosphate bonds can be hydrolyzed to release energy. Adenine Phosphate groups Ribose Adenosine Adenosine monophosphate (AMP) Adenosine diphosphate (ADP) Adenosine triphosphate (ATP) © 2013 Pearson Education, Inc. Function of ATP/GTP • Phosphorylation – Terminal phosphates are enzymatically transferred to and energize other molecules – Such “primed” molecules perform cellular work (life processes) using the phosphate bond energy – Enzymes, called kinases, are the catalysts for phosphorylating other proteins Cellular Energy • The chemical energy of ATP is transferred via phosphorylation to create mechanical energy used by the cell for work Labs for Today • Lab exercises 1 and 3