Chemistry in Biology

1. Chemistry in Biology Chapter 6 Honors Biology EQ: How is chemistry related to the growth and survival of living organisms?

2. 6.1: Atoms, Elements, and Compounds • Chemistry is the study of matter. • Matter is anything that has mass and takes up space. • Atoms are the building blocks of matter. • THE STRUCTURE OF ATOMS: • Billions of atoms could fit on the head of a pin! • Atoms are made up of even smaller particles – • Neutrons • Protons • Electrons

3. The Structure of Atoms: • Nucleus – the center of an atom • Within this nucleus are protons and neutrons. • Neutrons – particles that have no charge • Protons – particles with a positive charge • Electrons – negatively charged particles located outside the nucleus. • Constantly move around the nucleus in energy levels. • Are attracted to the protons • Atoms contain an equal number of protons and neutrons so the overall charge of an atom is neutral.

4. An Atom:

5. Elements:

6. Elements: • An element is a pure substance that cannot be broken down into other substances by chemical or physical means. • Are made of only one type of atom. • Information collected about each element has been organized into a chart called the periodic table of elements. • Organized into horizontal rows called periods, • And vertical columns called groups.

7. Isotopes: • Isotopes – atoms of the same element that have different numbers of neutrons. • Mass (A) = # of protons + # of neutrons • Atomic number (Z)= number of protons How many neutrons in Carbon 14? 14 (mass#) – 6 (atomic #) = 8 neutrons • Carbon 14 is a radioactive isotope.

8. Radioactive Isotopes: • A change in the number of neutrons CAN change the stability of the nucleus causing it to decay (or break apart). • When a nucleus decays, it gives off radiation that can be detected and used for many applications. • Isotopes that give off radiation are called radioactive isotopes. • Carbon 14 is a radioactive isotope found in all living things. • Half life – the amount of time it takes for half of the carbon 14 to decay.

9. Compounds • Elements can combine to form more complex substances. • Compounds are pure substances formed when two or more different elements combine. • NaCl • CaCl • H2O • CO2

10. Chemical Bonds: • A chemical bond is the force that holds substances together. • Electrons are directly involved in forming chemical bonds. • Each energy level has a specific number of electrons that it can hold at any time. • The first energy level (the one closest to the nucleus) can hold up to two electrons. • The second energy level can hold up to eight electrons.

11. Chemical Bonds (continued) • A partially filled energy level is not as stable as an energy level that is empty or completely filled. • Atoms become more stable by losing electrons or attracting electrons from other atoms. • THIS RESULTS IN THE FORMATION OF CHEMICAL BONDS BETWEEN ATOMS. • It is the forming of chemical bonds that stores energy and the breaking of chemical bonds that provides energy for growth, development, adaptation, and reproduction in living things.

12. The Two Main Types of Chemical Bonds Are: • 1. Covalent Bonds 2. Ionic Bonds

13. Types of Compounds: • 1. Molecule - a compound in which the atoms are held together by covalent bonds. • 2. Ionic compound– a substance formed by ionic bonds.

14. Van Der Waals Forces: • Attractive forces between molecules due to the random movement of electrons which can cause an unequal distribution of electrons around the molecule. • Not as strong as a covalent bond or an ionic bond but they play a key role in biological processes.

15. Activity: • Turn to page 155 in the text and answer questions 1-6.

16. 6.2: Chemical Reactions • Chemical reactions allow living things to grow, develop, reproduce, and adapt. • The human body is a 24 hour reaction factory! • A chemical reaction is the process by which atoms or groups of atoms in substances are reorganized into different substances. Chemical bonds are broken and/or formed during chemical reactions.

17. Two Examples of Chemical Reactions are: • The formation of rust on metal. • Glow sticks

18. Rust forms when oxygen in the air reacts with iron:

19. A light stick consists of a glass vial, containing one chemical solution, housed inside a larger plastic vial, containing another solution. When you bend the plastic vial, the glass vial breaks, the two solutions flow together, and the resulting chemical reaction causes a fluorescent dye to emit light.

20. Physical Changes • It’s important to know that substances can undergo changes that do not involve chemical reactions. • Water, for example, can undergo physical changes:

21. Reactants and Products • A chemical equation shows the reactants on the right side of an arrow, and the products on the left. • Reactants – the starting substances of a chemical reaction. • Products – The substances formed during the reaction. • Reactants Products • C6H12O6 + O2 6CO2 + 6H2O

22. Balanced Equations: C6H12O6 + O2 6CO2 + 6H2O • The number of atoms of each element on the reactant side must equal the number of atoms of the same element on the product side. • 1. Use coefficients to make the number of atoms on each side of the equation equal. • 2. Multiply the coefficient by the subscript for each element. • Is the above equation balanced?

23. Energy of Reactions • The key to starting a chemical reaction is energy. • Activation energy is the minimum amount of energy needed for reactants to form products in a chemical reaction. + =

24. Activation Energy Video Clip • http://www.youtube.com/watch?v=VbIaK6PLrRM

25. Exothermic Reaction Energy Heat is given off Progress of Reaction

26. Endothermic Reaction

27. Enzymes • Sometimes, the activation energy required for a reaction to take place is too high. The reaction can’t take place unless additional substances are present to reduce the activation energy. • A catalyst is a substrate that lowers the activation energy needed to start a chemical reaction. • Does not increase how much product is made • Doesn’t get used up in a reaction • Enzymes – special proteins that act as biological catalysts to speed up the rate of reactions.

28. Enzymes Without Enzyme With Enzyme Free energy released by the reaction

29. How Enzymes Work: Active Sites

30. Factors that affect enzyme function: • Temperature – if…. • Too high – enzyme will denature • Too cold – enzyme activity will slow • pH – enzymes will denature if pH is • Too acidic (H+ ions) • Too basic (OH- ions)

31. Section 6.3: Water and Solutions • Properties of water (H2O): • Water is a polar molecule – it has an unequal distribution of charges. • Hydrogen bonds – a weak attraction involving a hydrogen atom and an oxygen atom. Van derWaals forces are responsible for keeping water molecules together. • Water has surface tension due to Van der Waals forces. • Water striders can stand on water. • Water droplets can form.

32. Water is a Polar Molecule

33. Mixtures • A mixture is a combination of two or more substances in which each substance retains its individual characteristics and properties. • Homogenous mixture – uniform composition throughout • Heterogenous mixture – components remain distinct, do not dissolve • A solution is a homogenous mixture. Two components of a solution are: • Solvent – substance in which another substance is dissolved • Solute – the substance that is dissolved in the solvent.

34. Acids and Bases: • Acids are substances that release hydrogen ions when dissolved in water. • The more hydrogen ions a substance releases, the more acidic the solution becomes. • Substances that release hydroxide ions (OH-) when dissolved in water are called bases. • NaOH is a common base that breaks apart in water to release Na+ and OH- ions. The more OH- ions present, the more basic a solution is.

35. pH: The amount of hydrogen ions or hydroxide ions in a solution determines the strength of an acid or a base. We can easily measure the pH of a solution using a pH meter or pH paper. See the pH scale to the right. Water is neutral (pH 7) Acids have a pH lower than that of water. Bases have a pH higher than that of water. What’s a buffer?

36. 6.4: The Building Blocks of Life • Organisms are made up of carbon-based molecules. • Carbon is a component of almost all biological molecules. • Organic chemistry – the study of organic compounds (compounds containing carbon).

37. Carbon: • Has 4 electrons in its outer energy level. This energy level can hold 8 electrons so one carbon atom… • Can form 4 covalent bonds with other atoms. • Carbon atoms can bond to each other in different ways: • Straight chain molecules: • Branched molecules: • Ring molecules:

38. Macromolecules - • Are large molecules that are formed by joining smaller organic molecules together. • Monomer – a single molecule that can bind to several others just like it to form a polymer. • Polymer – many monomers linked together by covalent bonds.

39. There are 4 major categories of macromolecules: • Carbohydrates • Lipids • Proteins • Nucleic Acids

40. Carbohydrates • Compounds composed of carbon, hydrogen, and oxygen (CH2O)n. • This glucose monosaccharide plays a central role as an energy source for organisms. • Monosaccharides can be linked to form disaccharides (sucrose) or Polysaccharides. Glucose (Monosaccharide)

41. Lipids • Fats, oils, waxes • Lipid molecules are made up of carbon and hydrogen. • Store energy • Basic structure of a lipid includes fatty acid chains (tails): • Tails are chains of carbon bonded together by either single or double bonds. Hydrogen atoms are bonded to the carbon atoms. • Saturated – single bonds between carbon atoms so no more hydrogens can bond. • Unsaturated – one double bond between C atoms, so at least one hydrogen can bond.

43. Phospholipids and Steroids • Phospholipidbilayer • Steroids • Cholesterol • Hormones

44. Proteins • Compounds made of small carbon compounds called amino acids. • Amino acids are small compounds made of carbon, nitrogen, oxygen, hydrogen and sometimes sulfur. • All amino acids share the same general structure: Peptide bonds

45. Proteins (cont.) • Can have up to 4 levels of structure: • Primary • Secondary • Helix • pleat • Tertiary – a globular arrangement (hemoglobin) • Quaternary – proteins bound to other proteins • Structure depends on the number of amino acids in a chain and how they are arranged.

47. Proteins (cont.) • Muscle, skin, hair are made up of proteins • Are involved in almost every function of your body • Cells contain 10,000 different proteins that provide • Structural support • Transport substances • Communicate signals between cells • Catalysts for enzymatic reactions • Control cell growth

48. Nucleic Acids: • Nucleic acids are complex macromolecules that store and transmit genetic information. Two types: • DNA (deoxyribonucleic acid) • RNA (ribonucleic acid) • Made of smaller repeating subunits called nucleotides which are composed of • Carbon • Nitrogen • Oxygen • Phosphorus • Hydrogen

49. Nucleotide: