CHAPTER 2 The Chemical Level of Organization

Transcription

1 The objectives of tonight's lecture is to: 4. Explain the structure of the atom, including the subatomic particles. Define isotope ion, anion,cation and electrolytes. 5. Differentiate among elements, molecules and compounds. 6. Differentiate among ionic, polar covalent, nonpolar covalent and hydrogen bonds. 7. Describe the classes of macromolecules: carbohydrates, lipids, nucleic acids, and proteins. 8. Explain the properties of water. CHAPTER 2 The Chemical Level of Organization 9. Explain metabolism and relate it to examples of the following chemical reactions: anabolism, catabolism, dehydration synthesis, hydrolysis, and reversible. Vocabulary: acid, base, buffer, enzyme, inorganic, organic, ph

2 Basic Principles of Chemistry: Matter 1. Chemistry is the science of structure and interactions of matter 2. Matter is anything that has mass and takes up space 3. Mass is the amount of matter a substance contains, whereas weight is the force of gravity acting on a mass

3 Chemical Elements Matter exists in 3 forms: 1. Solid 2. Liquid 3. Gas All forms of matter are composed of chemical elements

4 Elements Element: a substance that cannot be split into simpler substances by ordinary occurring elements chemical means 115 recognized elements 92 naturally occurring elements Each has a specific chemical symbol One or two letter of name in English, Latin, or another language 26 elements normally present in humans O,C,H,N = 96% of body mass Ca, P, K, S, Na, Cl, Mg, Fe = 3.6% Remaining 0.4% are trace elements (14 elements)

5 Atoms Chemical elements are composed of units of matter of the same type called atoms. Atoms are the smallest units of matter that retain the properties and characteristics of an element Atoms are composed Protons (positive particles in the nucleus) Neutrons (neutral particles in the nucleus Electrons (negative particles that move about in a large space surrounding the nucleus.

6 Isotopes Isotopes are atoms of elements with different numbers of neutrons. Radioactive Isotopes in Physiology Injected into the body Different types taken up by different organs Can be detected in the body Can be used to destroy specific tissues Commonly used. Iodine-131 for thyroid function Thallium-201 for heart function Gallium-67 and Cobalt-60 for cancer

7 Molecules and Compounds Molecule 2 or more atoms sharing electrons May consist of two of the same kind of atoms or different atoms. Compound a substance that can be broken down into 2 or more different elements

8 Chemical Bonding: Covalent Bonding A chemical bond occurs when atoms are held together by forces of attraction The number of electrons in the outside shell determines the likelihood that an atom will form a chemical bond with another atom. Covalent Bond: exist between atoms that share electrons to form a molecule. Single, Double, Triple Covalent bonds Non-polar covalent non-polar covalent bonds Polar covalent bonds: Have a positive and negative charge. Example: Hydrogen bonds that occur when hydrogen covalently bonds with another element creating unequal electron distribution on the molecule (called a dipole). Water is termed polar because of polar covalent bonding Non-polar covalent liquids will separate in polar liquids (think oil and water)

9 Covalent vs. Polar Covalent Bonds

10 Ionic Bonding Ionic bonding is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds. The ions are atoms that have lost one or more electrons (known as cations) and atoms that have gained one or more electrons (known as anions).

11 Ions and Electrolytes Ion an atom that has lost or gained an electron Cation- an ion that has gained electrons Will have a positive (+) charge Are attracted to anions Anion- an atom that has lost electrons Will have a negative charge Are attracted to cations Electrolytes Electrolytes are minerals in your blood and other body fluids that carry an electric charge. Electrolytes affect the amount of water in your body, the acidity of your blood (ph), your muscle function, and other important processes. You lose electrolytes when you sweat.

12 Chemical Reactions A chemical reaction occurs when new bonds are formed or old bonds are broken Reactants starting substances Products ending substances Types of reaction Anabolic Reactions: Reactions that require energy create complex molecules Dehydration synthesis = Removing water to build. Catabolic Reactions: Reaction that release energy destroy complex molecules Hydrolysis = Using water to break bonds of complex molecules Reversible Reactions: reactions that can go backward from products to reactants

13 Exergonic vs Endergonic Reaction

14 Properties of Water Water polar solvent (dissolves other polar compounds) Solvents dissolve other compounds in a solution. Likes dissolve likes Solutes are compounds that are dissolved in a solution. Solution: a mixture containing a solvent and a solute (example: saltwater) Water in Physiology most abundant compound in living material major component of all body fluids that creates sol important role in transporting chemicals in the body can absorb and transport heat a major component of our body fluids and helps reduce friction as membranes and organs slide over one another.

15 Acids and Bases Acids & Bases = electrolytes that ionize and dissociate (break-up) in water causing electrical conduction. Acids - release Hydrogen ions (H+). Sour or sharp taste, tomato juice, coffee, vinegar Bases release Hydroxide ions (OH-) Bitter taste, become slippery when wet, MOM, ammonia, household cleaners & detergents Neutralization reaction Acids and bases react to form water and a salt

16 Acids, Bases, & Salts ph Scale: Measures relative concentration of hydrogen ions. Each rise or drop in ph is by a magnitude of 10X (gastric juice is 1000X more acidic than coffee) ph 7.0 = neutral ph below 7.0 = acidic ph above 7.0 = basic Buffers: chemicals that regulate ph change ph needs to be maintain in humans in order to maintain homeostasis.

17 Buffer Systems Maintenance of body fluid homeostasis is critical Buffer systems help to regulate ph by converting strong acids or bases into weak acids or bases Buffers remove or replace hydrogen ions in solution Buffer systems maintain the ph of body fluids

18 Inorganic vs. Organic Compounds Inorganic compounds usually lack carbon and are simple molecules Water is the most important and abundant inorganic compound in all living things Organic compounds always contain H, usually contain O, and always have covalent bonds 1. Organic compounds always contain carbon 2. Many carbons can combine in a variety of shapes 3. Carbon compounds do not dissolve easily in water 4. Carbon compounds are a good source of energy 5. May are polymers = any molecule made up of several repeating units called monomers.

19 Metabolic Processes and Biomolecules Metabolism Human metabolic processes depend on four types of organic macromolecules: 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids Metabolism is a term that is used to describe all chemical reactions involved in maintaining the living state of the cells and the organism. Metabolism can be conveniently divided into two categories: Catabolism - the breakdown of molecules to obtain energy Anabolism - the synthesis of all compounds needed by the cells

20 Carbohydrates Carbohydrates provide most of the energy needed for life. Also called saccharides Contain carbon, hydrogen and oxygen in a ratio of 1:2:1 Names end in -ose Account for less that 1% of body weight Used as a primary cellular energy source.

21 Carbohydrates Disaccharides Monosaccharides Polysaccharides

22 Polysaccharides Polymers of sugars costs little energy to build easily reversible = release energy Function: energy storage starch (plants) Can be digested by humans glycogen (animals) in liver & muscles structure cellulose (plants) Cannot be broken down in digestion of humans and passes through feces. chitin (exoskeleton of arthropods & fruiting body of mushrooms)

23 Hydrolysis and Dehydration Synthesis Reaction Hydrolysis a reaction involving the breaking of a bond in a molecule using water. Hydro: Water Lysis: To Break Dehydration Syntheis is the process of joining two molecules (or compounds) together following the removal of water. When you see the word dehydration the first thing that may come to mind is, 'losing water' or 'lacking water.' This is a perfect way to remember what occurs during a dehydration reaction.

24 Lipids Commonly referred to as fats Hydrophobic: insoluble in polar solutions (repelled by water, or water fearing ) Long chain hydrocarbons containing carbon, hydrogen, and oxygen but the ratio of C:H is 1:2 (much less O) May also contain other elements, phosphorous, nitrogen, and sulfur Form essential structures in cells Are important energy stores Used to cushion organs for protection Building block (monomer) is called a fatty acid.

25 Triglycerides Consist of 3 fatty acids and glycerol Triglycerides proved protection, insulation, and energy Fatty acids can be saturated or unsaturated

26 Saturated Fats All C bonded to H No C=C double bonds long, straight, linear chain most animal fats solid at room temp. contributes to cardiovascular disease (atherosclerosis) = plaque deposits

27 Unsaturated fats C=C double bonds in the fatty acids plant & fish fats vegetable oils liquid at room temperature the kinks made by double bonded C prevent the molecules from packing tightly together More biologically reactive in catabolic reactions in the human body.

28 Phospholipids Structure: glycerol + 2 fatty acids + PO 4 (phosphate) PO 4 = negatively charged Hydrophobic or hydrophilic? fatty acid tails = Hydrophobic PO 4 head = Hydrophilic Hydrophilic heads attracted to H 2 O Hydrophobic tails hide from H 2 O can self-assemble into membranes can also form a phospholipid bilayer

29 Steroids Structure: 4 fused C rings + functional groups and/or side chains different steroids created by attaching different functional groups to rings different structure creates different function examples: cholesterol, sex hormones

30 Cholesterol Important cell component animal cell membranes precursor of all other steroids including vertebrate sex hormones high levels in blood may contribute to cardiovascular disease

31 Proteins Catalytic function: Nearly all chemical reactions in biological systems are catalyzed by specific enzymes. Transport and storage: For example; Hemoglobin transports oxygen in erythrocytes Myoglobin carries & stores oxygen in muscle. Albumin transports free fatty acids in blood. Transferrin transports iron in blood. building blocks are amino acids amino acids held together with peptide bonds Coordinated motion: Actin and myosin are contractile proteins in muscle. Other Functions structural material energy source hormones receptors antibodies

32 Amino acids Structure central carbon amino group carboxyl group (acid) R group (side chain) variable group different for each amino acid confers unique chemical properties to each amino acid like 20 different letters of an alphabet can make many words (proteins) H O H N C C OH H R

33 Amino Acids Proteins are formed by combining various amino acids

34 Building proteins Peptide bonds covalent bond between NH 2 (amine) of one amino acid & COOH (carboxyl) of another C N bond dehydration synthesis H 2 O peptid e bond

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36 Protein denaturation Unfolding a protein conditions that disrupt H bonds, ionic bonds, disulfide bridges temperature ph salinity alter 2 & 3 structure alter 3-D shape destroys functionality some proteins can return to their functional shape after denaturation, many cannot A protein that loses it s Structure loses it s Function

37 Enzymes An enzyme is a biological catalyst in a living cell that facilitates a chemical reaction to allow it to occur more readily. Enzymes are: Highly specific Extremely efficient Subject to cellular controls Are reused in reactions over and over

38 Enzyme Functions and ATP

39 Nucleotides: DNA & RNA Deoxyribonucleic acid (DNA) forms the genetic code in the nuclei of body cells and it regulates most of the cell s activities Ribonucleic acid (RNA) guides protein formation

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41 DNA vs. RNA

42 Adenosine Triphosphate (ATP) ATP is the principal energy-storing molecule in the body