Anatomy and Physiology I (BSCI 201)- Chapter 2 notes- part 2
Anatomy and Physiology I (BSCI 201)- Chapter 2 notes- part 2 BSCI201
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This 7 page Class Notes was uploaded by mehrnazighani Notetaker on Thursday September 15, 2016. The Class Notes belongs to BSCI201 at University of Maryland - College Park taught by Justicia Opoku-Edusei in Fall 2016. Since its upload, it has received 45 views.
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Date Created: 09/15/16
Chapter 2: Basic Chemistry and Biochemistry- Part 2 by Mehrnaz Ighani .3 main types of chemical reactions: 1. Synthesis reactions: atoms/ molecules combining to form larger molecules (Fig. 2.11a) Used in anabolic processes A+ B AB 2. Decomposition reactions: breakdown of a molecule into smaller molecules (Fig. 2.11b) Used in catabolic processes such as the conversion of glycogen to glucose ABA+B 3. Exchange reactions: (Aka displacement reactions) involve both synthesis and decomposition reactions (Fig. 2.11c) Bonds are broken and formed AB+CDAD+CB Example: acid+ base water +salt . In living systems, reduction-oxidation or redox reactions are critical, atoms are reduced when they gain an electron and oxidized when they lose an electron Ex. Glucose+ oxygen carbon dioxide+ water+ ATP Oxygen is reduced and glucose is oxidized . All chemical rxns are either exergonic or endergonic: 1. Exergonic: net release of energy, products have less potential energy than reactants Example: catabolic and oxidative rxns 2. Endergonic: net absorption of energy, products have more potential energy than reactants Example: anabolic rxns . All chemical rxns are reversible: A+ B ↔AB Chemical equilibrium occurs if neither a forward nor a reverse rxn is dominant . Many biological rxns are not very reversible because energy requirements to go backward are too high or products have been removed . The rate of chemical rxns can be affected by: 1. Temperature: ↑ temperature means ↑ rate of rxns 2. Concentration of rxns: ↑ concentration means ↑ rate rxns 3. Particle size: smaller particles, ↑ rate of rxns 4. Catalysts/ enzymes: increase the rate of rxns without being consumed or altered . Biochemistry: the study of chemical composition and reactions of living matter . All chemicals are either organic or inorganic: 1. Inorganic compounds: water, salts, acids, and bases (don’t contain chains of C) 2. Organic compounds: carbs, proteins, fats, and nucleic acids (contain chains of C, covalently bonded) . Inorganic compounds: Water is the most abundance inorganic compound composing 60- 80% of the volume of living cells Water is important due to its properties: 1. High heat capacity 2. High heat of vaporization 3. Polar solvent properties: dissolves and disassociates ionic substances and it’s body’s major transport medium 4. Reactivity: needed for hydrolysis and dehydration 5. Cushioning: protects organs from physical trauma Salts: ionic compounds that disassociate into separate ions in water Acids and bases are electrolytes that disassociate and ionize in water Acids: proton donors o Release H ions o Important acids: HCl, carbonic acid, and acetic acid Bases: proton acceptors o Pick up H ions o When a bases dissolves it releases a hydroxyl ion (OH) o Important bases: bicarbonate ion and ammonia pH scale: measurement of concentration of H ions in a solution (Fig. 2.13) high H ions results in low pH pH is – log of H ions in moles/liter that ranges from 0-14 pH scale is logarithmic, so each pH unit represents a 10 fold difference Acidic (0-6.99), basic (7.01-14) . Neutralization rxn: acids and bases are mixed ttogether NOTE: Acidity involves only free H ions in a solution, not H ions bound to anions . Buffers: resist abrupt and large swings in pH Release H ions if pH increases (becomes basic) Bind H ions if pH decreases (becomes acidic) Convert strong acids or bases into weak ones . Organic compounds: Contain chains of C except CO2 and CO which are inorganic Carbon is electroneutral : o Shares electrons o Forms 4 covalent bonds Major organic compounds: 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids Synthesized by dehydration synthesis and broken down by hydrolysis rxns (Fig. 2.14) Carbs: o Sugars and starches that contain C, H, and O o 3 classes: 1. Monosaccharides: single sugars (monomers: smallest unit of carb) 2. Disaccharides: 2 sugars 3. Polysaccharides: 3 sugars o Monosaccharides: (Fig. 2.15a) Simple sugars containing 3-7 C atoms General formula (CH2O) Important monosaccharides: Pentose sugars: Ribose and deoxyribose Hexose sugars: Glucose, fructose, and galactose o Disaccharides: (Fig. 2.15b) Double sugars that are too large to pass the cell membrane Formed by dehydration synthesis of 2 monosaccharides Important disaccharides: Sucrose: glucose+ fructose (table sugar) Lactose: glucose+ galactose (milk sugar) Maltose: glucose+ glucose (grain sugar) o Polysaccharides: (Fig. 2.15c) Polymers of monosaccharides that are not very soluble Important polysaccharides: Starch (in plants) Glycogen (in animals) Lipids: Contain C,H,O, and sometimes P Hydrophobic Main types: 1. Triglycerides/ neutral fats 2. Phospholipids 3. Steroids 4. Eicosanoids o Triglycerides: Called fats when solid and oils when liquid Composed of 3 fatty acids bonded to a glycerol molecule Used for energy storage, protection, and insulation Can be constructed of: Saturated fats: Solid at room temp. All Carbons linked via single covalent bonds Molecules with the highest # of H atoms Ex. Animal fats, butter Unsaturated fats: Liquid at room temp One or more carbons are linked via double bonds resulting in low # of H atoms Ex. Olive oil Trans fat: modified oils (unhealthy) Omega-3 fats: heart healthy o Phospholipids: (Fig. 2.16b) Modified triglycerides Glycerol and 2 fatty acids+ a phosphorous containing group Heads are polar and tails are nonpolar Important in cell membrane structures o Steroids: (Fig. 2.16c) 4 interlocking ring structures Common steroids are cholesterol, vitamin D, bile salts, and steroid hormones Cholesterol is the most important: Steroid synthesis Bile salts synthesis Building block of vitamin D Hormones such as estrogen and testosterone Required for cell plasma membrane structure o Eicosanoids: Derived from a fatty acid (arachidonic acid) Most important eicosanoids are Prostaglandins because they play a role in blood clotting, inflammation, labor contractions, and control of blood pressure Prostaglandins have 2 derivatives: Prostacyclins Thromboxanes Proteins: Comprise 20-30% of cell mass Contain C, H, O, N, and sometimes S and P Polymers of amino acid monomers are held together by peptide bonds Have most varied functions of any molecules (structural, chemical, contraction) Shape and function due to four structural levels All proteins made up of 20 types of amino acids Proteins contain an amine group and acid group (Fig. 2.2) Can act as either base or acid . 4 structural levels of proteins: (Fig. 2.18a, b, c, d) 1. Primary: linear sequence of amino acids 2. Secondary: how primary amino acids interact with each other Alpha helix coils resemble a spring Beta pleated sheets resemble accordion ribbons 3. Tertiary : how secondary structures interact 4. Quaternary: how 2 or more different polypeptides interact with each other . Shapes of proteins fall into 2 categories: 1. Fibrous (structural) proteins: Strand like, water insoluble, and stable Most have tertiary or quaternary structure Provide mechanical support Ex. Keratin. Elastin. Collagen, and certain contractile fibers 2. Globular (functional) proteins: Water soluble, compact, spherical, and sensitive Specific functional regions such as active sites Tertiary or quaternary structure Ex. Antibodies, hormones, molecular chaperones, and enzymes . Denaturation: globular proteins unfold and lose their functional 3D shape Active sites become deactivated Can be caused by low pH or high temp. Reversible if normal conditions restored Irreversible if changes are extreme . Enzymes: globular proteins that act as biological catalysts Speed up reactions and decrease activation energy needed to start a reaction Act on specific substrates Name usually ends in –ase . 3 steps in enzyme action: (Fig. 2.20) 1. Substrate binds to enzyme’s active site. Forming enzyme-substrate complex 2. Complex undergoes rearrangement of substrate resulting in final product 3. Product is released from enzyme Nucleic acids: Composed of C, H, O, N, and P Largest molecules in the body Made of monomers called nucleotides (composed of a nitrogenous bases, a pentose sugar, and a phosphate group) 2 major groups: 1. Deoxyribonucleic acid (DNA) 2. Ribonucleic acid (RNA) DNA holds the genetic info for the synthesis of all proteins (Fig. 2.21) Nitrogenous bases: 1. Purines: Guanine (G) and Adenine (A) 2. Pyrimidines: Thymine (T) and Cytosine (C) Complementary base pairing rules: A-T G-C RNA: links DNA to protein synthesis and is single stranded Contains a ribose sugar Active mostly outside the nucleus Thymine (T) is replaced with Uracil (U) 3 types of RNA: 1. mRNA 2. tRNA 3. rRNA They all carry out the DNA orders for protein synthesis ATP: chemical energy released when glucose is broken down that directly powers chemical rxns in cells (Fig. 2.22) Adenine containing RNA nucleotide with 22 additional phosphate groups transports proteins, phosphorylates contractile proteins, and drives chemical rxns (Fig. 2.23) loss of one phosphate group ADP loss of 2 phosphate groups AMP Works Cited Lindsey, Jerri K., Katja Hoehn, and Elaine Nicpon Marieb. Human Anatomy & Physiology, 9th Edition Elaine N. Marieb, Katja Hoehn. Boston, MA: Pearson, 2013. Print.