The Chemistry of Life

Transcription

1 The Chemistry of Life

2 Things you should be able to do 1. Describe how the unique properties of water support life on Earth. 2. Explain how carbon is uniquely suited to form biological macromolecules. 3. Describe how biological macromolecules form from monomers. 4. Compare the structure and function of carbohydrates, lipids, proteins and nucleic acids in organisms. 5. Describe the role of an enzyme as a catalyst in regulating a specific biochemical reaction. 6. Explain how factors such as ph, temperature and concentration levels can affect enzyme function.

3 Vocabulary atom nucleus electron element isotope compound ionic bond ion covalent bond molecule Van der Waals forces Hydrogen bond Cohesion Adhesion Mixture Solution Solute Solvent Suspension ph scale acid base buffer monomer polymer carbohydrate monosaccharide lipid nucleic acid nucleotide protein amino acid chemical reaction reactant product activation energy catalyst enzyme substrate

4 Nature of Matter Atom = basic unit of matter Atomic Structure Protons positively charged; found in nucleus of atom Neutrons no charge; found in nucleus of atom Electrons negatively charged; orbit the nucleus of the atom; involved in bonding Atoms are neutral when they have equal numbers of protons and electrons. The charges balance each other out.

5 Nature of Matter How many protons? How many electrons? How many neutrons? Is the atom neutral?

6 Nature of Matter Element = pure substance that consists entirely of one type of atom Think periodic table of elements Atomic # = element ID = # of protons

7 Nature of Matter Isotopes = atoms of the same element with different number of neutrons Same # of protons Same # of electrons

8 Nature of Matter Radioactive Isotopes= atoms whose nuclei break down over time, releasing energy Uses determine age of rocks treat cancer Kill bacteria that may spoil food Tracers to follow movement of material

9 Nature of Matter Compounds = Substances formed by the chemical combination of 2 or more elements in definite proportions Physical and chemical properties of compound are different from the properties of the elements

10 Nature of Matter 1. Ionic bonds transfer of electrons from one atom to another An atom that loses an electron = + ion An atom that gains an electron = - ion Example : NaCl

11 Nature of Matter 2. Covalent bonds sharing of electrons between atoms Stronger than ionic bonds Most common in living things Can be single, double or triple

12 Nature of Matter 3. Van der Waals forces intermolecular forces (not really bonds) between oppositely charged regions of adjacent molecules Hydrogen bonds are an example

13 Build Molecular Models To demonstrate Single, double, triple covalent bonds

14 Water 1. Water is a polar molecule Uneven sharing of electrons between oxygen and hydrogens Oxygen = negative Hydrogens = positive

15 Water 2. Hydrogen Bonds form between water molecules Negative oxygen of one water molecule and the positive hydrogen of another water molecule Explain many other properties of water Cohesion, adhesion, high heat capacity,

16

17 Water 3. Water is the universal solvent Water can dissolve things that are also polar, such as ionic compounds Water cannot dissolve non-polar substances like oil Dissolving animation

18 Explore Properties of Water Visit each water station and follow the directions to complete the activity. Answer the questions that pertain to each activity on your handout.

19 Water ph = measure of H+ ions Acids form H+ in solution have high H+ concentration have ph less than 7 Bases Form OH- in solution have low H+ concentration have ph greater than 7

20 Water Control ph in most living things Prevent sharp changes in ph Important in maintaining homeostasis

21 Quick Lab READ ONLY Determining ph of household items 1. Predict whether the food samples provided are acidic or basic 2. Test ph of each item with universal indicator Use the scale provided by your teacher to determine the ph 3. Construct a ph scale (1-14) and write each item you tested in the appropriate place on the ph scale

22 Chemistry of Carbon Carbon can form 4 bonds (4 unpaired valence electrons) Carbon can bond with other elements (H, O, N, P,) Carbon can bond with itself Can be single, double or triple bonds Can form chains unlimited in length Carbon chains can be branched or form rings

23 Chemistry of Carbon

24 Chemistry of Carbon Formed by polymerization reaction Monomer = subunit Polymer = many monomers linked together Four groups of macromolecules make up living things 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids

25 Chemistry of Carbon Structure: Contain carbon, hydrogen and oxygen Hydrogen : oxygen ratios is 2:1 Function: Quick energy Structural support (cell walls and cell membranes) Other info: Monomer a.k.a monosaccharide (simple sugar) Examples: glucose, sucrose, lactose Polymer a.k.a polysaccharide Examples: glycogen, starch, cellulose

26 What does each brown shape represent? Is each brown shape a monomer or polymer?

27 Chemistry of Carbon Structure: Contain carbon, hydrogen and oxygen (NO 2:1 hydrogen : oxygen ratio) Contain long hydrocarbon chains Function: Long-term energy (storage) Structural support (cell membranes) Waterproof coverings (bird feathers) Hormones (chemical messengers Other info: Hydrophobic (not soluble in water) Not a true polymer: made up of glycerol and fatty acids Saturated vs unsaturated lipids

28 Chemistry of Carbon Other info: Saturated fatty acids have all single bonds between carbons in chain unsaturated fatty acids may have one or more double bonds between carbons in chain

29 Chemistry of Carbon Which of the four fatty acids is saturated? Which of the fatty acids are unsaturated? How does melting point change as the # of carbon-carbon double bonds increases? Which fatty acid is solid at room temperature? Which is liquid at room temperature?

30 Saturated or Unsaturated?

31 Carb or Lipid?

32 Carb or Lipid? Venn diagrams

33 Chemistry of Carbon Structure: contain C, H, O, N AND P Function: store and transmit hereditary material Other info: monomer = nucleotide Polymer = DNA and RNA

34 Chemistry of Carbon Structure: Contain C, H, O and N Function: Control chemical reaction rate Regulate cell processes (transport) Help fight disease Transport substances around the body Other info: Monomer = amino acid Polymer = polypeptide chain Shape is crucial for a proteins function Amino acid sequence determines shape of protein ENERGY

35

36

37 WHO AM I? 1. I store hereditary material. 2. I am made up of monosaccharides. 3. I give cells QUICK energy. 4. I contain the elements C, H, O and N. 5. My monomer is the nucleotide. 6. My monomer is the amino acid. 7. I am used for long-term energy storage. 8. I am the form of sugar stored in animal cells. 9. I am a hydrocarbon chain with NO double bonds.

38 Carb, lipid, protein or NA?

39 Carb, lipid, protein or NA?

40 Carb, lipid, protein or NA?

41 Carb, lipid, protein or NA?

42 Monomer or polymer? Glucose monosaccharide Starch Nucleotide cellulose Protein Amino acid Glycogen polysaccharide

43 Chemical Reactions One set of chemicals is changed/transformed into another Bonds between atoms are broken and new bonds are formed Mass and energy are conserved

44 Chemical Reactions Energy is either released or absorbed Chemical reactions that release energy are exothermic Chemical reactions that absorb energy are endothermic Need a source of energy (sun, heat, carbohydrate, etc)

45 Chemical Reactions

46 Chemical Reactions

47 Chemical Reactions Activation Energy: the energy needed to get a reaction started Required for all chemical reactions A catalyst in general speeds up a chemical reaction Enzymes are biological catalysts they speed up chemical reactions by lowering the activation energy Enzymes are specific for a reaction Enzymes are not used up during a reaction

48

49 Chemical Reactions Enzymes are specific One enzyme generally catalyzes one reaction For every reaction that occurs Reactants of the reaction are called the substrates Enzyme binds to substrate at an active site Shape of the active site fits the shape of the substrates

50

51 Chemical Reactions 1. Temperature Optimum temp = the temp at which the enzyme works the best High temperatures denature or unfold an enzyme, making it useless At low temperatures, enzymes are inactive

52 Chemical Reactions 2. ph Optimum ph = the ph at which the enzyme works the best Different enzymes have different optimums Enzymes in the stomach work best at a ph of 2 but enzymes in the small intestine work best at a ph of 8

53 Chemical Reactions 3. Substrate concentration Remember, substrate = reactant of reaction Initially, increasing substrate concentration will increase enzyme activity but eventually the reaction rate will level off

54 Chemical Reactions 4. Enzyme concentration Increasing enzyme concentration will increase the rate of the reaction

55 Keystone Review Questions 1. Which statement best describes an effect of the low density of frozen water in a lake? a. When water freezes, it contracts, decreasing the water level in a lake b. Water in a lake freezes from the bottom up, killing most aquatic organisms c. When water in a lake freezes, it floats, providing insulation for organisms below d. Water removes thermal energy from the land around a lake, causing the lake to freeze

56 Keystone Review Questions 2. Which statement correctly describes how carbon s ability to form four bonds makes it uniquely suited to form macromolecules? a. It forms short, simple carbon chains b. It forms large, complex diverse molecules c. It forms covalent bonds with other carbon atoms d. It forms covalent bonds that can exist in a single plane.

57 Keystone Review Questions Use the diagram below to answer the question 3. The diagram shows a reaction that forms a polymer from two monomers. What is this type of reaction called? a. Glycolysis b. Hydrolysis c. Photosynthesis d. Dehydration synthesis

58 Keystone Review Questions 4. Carbohydrates and proteins are two types of macromolecules. Which functional characteristic of proteins distinguishes them from carbohydrates? a. Large amount of stored information b. Ability to catalyze biochemical reactions c. Efficient storage of usable chemical energy d. Tendency to make cell membranes hydrophobic

59 Keystone Review Questions 5. Substance A is converted to substance B in a metabolic reaction. Which statement best describes the role of an enzyme during this reaction? a. It adjusts the ph of the reaction medium b. It provides energy to carry out the reaction c. It dissolves substance A in the reaction medium d. It speeds up the reaction without being consumed