The Chemical Level of Organization professor edit

Transcription

1 2 The Chemical Level of Organization professor edit PowerPoint Lecture Presentations prepared by Jason LaPres Lone Star College North Harris

2 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.

3 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.

4 An Introduction to the Chemical Level of Organization Learning Outcomes 2-10 Discuss the structures and functions of lipids Discuss the structures and functions of proteins Discuss the structures and functions of nucleic acids Discuss the structures and functions of highenergy compounds Explain the relationship between chemicals and cells.

5 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

6 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

7 2-1 Atoms and Atomic Structure Subatomic Particles Proton Positive charge, 1 mass unit Neutron Neutral, 1 mass unit Electron Negative charge, low mass

8 2-1 Atoms and Atomic Structure Atomic Structure Atomic number Number of protons Nucleus Contains protons and neutrons Electron cloud Contains electrons

9 Figure 2-1 The Structure of Hydrogen Atoms Electron shell A typical hydrogen nucleus contains a proton and no neutrons.

10 Table 2-1 Principal Elements in the Human Body

11 Table 2-1 Principal Elements in the Human Body

12 2-1 Atoms and Atomic Structure Elements Elements are determined by the atomic number of an atom Remember atomic number = number of protons Elements are the most basic chemicals

13 2-1 Atoms and Atomic Structure Atomic Weights Exact mass of all particles

14 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

15 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

16 Figure 2-2 The Arrangement of Electrons into Energy Levels The second and third energy levels can contain more energy levels

17 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

18 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

19 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 Opposites attract!

20 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.

21 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).

22 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

23 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

24 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

25 Figure 2-5 Polar Covalent Bonds and the Structure of Water Hydrogen atom Hydrogen atom Oxygen atom Hydrogen atom Oxygen atom 2

26 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 Because of the extensive hydrogen bonding in water, the molecules tend to stick to each other in a regular pattern. The tension on the surface of water occurs when water molecules on the outside of the system align and are held together by hydrogen bonding to create an effect similar to a net made of atoms. For example, the surface tension of water allows water spiders to literally walk on water.

27 Figure 2-6 Hydrogen Bonds between Water Molecules KEY Hydrogen Oxygen Hydrogen bond Do you see the net/regular pattern being formed?

28 2-2 Molecules and Compounds States of Matter Solid Constant volume and shape Liquid Gas Constant volume but changes shape Changes volume and shape

29 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

30 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

31 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

32 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

33 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 )

34 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

35 2-3 Chemical Reactions Types of Chemical Reactions

36 2-3 Chemical Reactions Breaking chemical bonds AB A + B Hydrolysis (You are breaking up A-B [hydro = water; lysis = break]; A-H and HO-B are the products) A-B + H 2 O A-H + HO-B Forming chemical bonds Breaking A-B A + B AB Dehydration synthesis (You are removing water from A and B [dehydrating them]; water and A-B are the products) A-H + HO-B A-B + H 2 O Forming A-B

37 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

38 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

39 Energy Figure 2-8 The Effect of Enzymes on Activation Energy Activation energy required Without enzyme Reactants With enzyme Stable product Progress of reaction

40 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

41 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 Concentration The amount of solute in a solvent

42 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 (think about joints)

43 2-6 Properties of Water High Heat Capacity When molecules are heated, they get excited. They move around faster as they gain more energy. Water is a polar molecule (has a plus end and a minus end). Positive attracts to negative and water molecules stick together through strong bonds. Because the molecules are being held tightly in place by these bonds, the H 2 O molecules do not move much when heated. It takes more and more heat to move the molecules, causing water to have a high specific heat capacity.

44 2-6 Properties of Water The Properties of Aqueous Solutions Ions and polar compounds undergo ionization, or dissociation in water NaCl becomes Na+ ion and Cl- ion in water

45 Table 2-2 Important Electrolytes that Dissociate in Body Fluids

46 2-6 Properties of Water The Properties of Aqueous Solutions Electrolytes and body fluids Electrolytes are inorganic ions that conduct electricity in solution (Why is electricity important in our body? How does our brain tell our muscles and body to move?) Electrolyte imbalance seriously disturbs vital body functions

47 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

48 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

49 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

50 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

51 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)

52 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

53 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.

54 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

55 2-9 Carbohydrates Carbohydrates Ex: Monosaccharide simple sugar Disaccharide two sugars Polysaccharide many sugars

56 2-9 Carbohydrates Monosaccharides Simple sugars Glucose, fructose, galactose Disaccharides Two simple sugars combined by a chemical reaction Sucrose, maltose Polysaccharides Many monosaccharides combined by a chemical reaction Glycogen, starch, cellulose

57 Table 2-4 Carbohydrates in the Body Why are carbohydrates important? What are the consequences of a low carb diet?

58 2-10 Lipids Lipids Mainly hydrophobic molecules such as fats, oils, and waxes Made mostly of carbon and hydrogen atoms with a COOH at the end (carbon, oxygen, and hydrogen) Include: Fatty acids Eicosanoids Glycerides Steroids Phospholipids and glycolipids

59 2-10 Lipids Fatty Acids Long chains of carbon and hydrogen Are relatively nonpolar 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 A double covalent bond is where two pairs of electrons are shared between the atoms rather than just one pair

60 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 ( COOH) at one end.

61 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 also known as a kink

62 2-10 Lipids Eicosenoids: Leukotrienes Active in immune system Prostaglandins Local hormones, short-chain fatty acids

63 2-10 Lipids Glycerides Fatty acids attached to a glycerol molecule Have three important functions 1. Energy source 2. Insulation 3. Protection

64 2-10 Lipids Steroids Types of steroids: Cholesterol Component of plasma (cell) membranes Estrogens and testosterone Sex hormones Corticosteroids and calcitriol Metabolic regulation Bile salts Derived from steroids

65 2-10 Lipids Phospholipids and Glycolipids Contain 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

66 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

67 Table 2-5 Representative Lipids and Their Functions in the Body

68 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

69 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

70 2-11 Proteins Protein Structure Long chains of amino acids

71 Figure 2-19 Amino Acids Structure of an Amino Acid Nitrogen containing group Central carbon -COOH group R group Different amino acids have different R groups.

72 2-11 Proteins Hooking Amino Acids Together Requires a dehydration synthesis Forms a peptide bond Resulting molecule is a peptide

73 Figure 2-20 The Fomation of Peptide Bonds Peptide Bond Formation Glycine (gly) Alanine (ala) DEHYDRATION SYNTHESIS HYDROLYSIS Peptide bond

74 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

75 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)

76 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

77 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

78 Figure 2-22 A Simplified View of Enzyme Structure and Function Substrates bind to active site of enzyme

79 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

80 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

81 Figure 2-22 A Simplified View of Enzyme Structure and Function Product detaches from enzyme; entire process can now be repeated

82 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

83 2-11 Proteins Effects of Temperature and ph on Enzyme Function Denaturation Loss of shape and function due to heat or ph We will talk about RNA and DNA in the next chapter.