C6-The Chemistry of Life

1. C6-The Chemistry of Life Biology Chp 6

2. Chemistry of Life • 6-1 Atoms and Their Interactions • 6-2 Water and Diffusion • 6-3 Biomolecules

3. Atoms & Their Interactions • Everything is made of elements- substances that cannot be broken down into simpler substances

4. Atoms & Their Interactions • Only about 25 elements are essential to human life • C, H, O & N make up 96% of a human bodies mass!

5. Atoms & Their Interactions • One or two letter symbols are abbreviations for the elements. • Also listed in each box are the atomic number and the atomic mass.

6. Atoms & Their Interactions • For carbon, the atomic number 6 indicates its number of protons. • Mass Number = protons +neutrons • Thus, Mass Number- atomic number = number of neutrons

7. Atoms: Building Blocks of Elements • The center of the atom is the nucleus. • Positive protons • Neutral neutrons • The space around the nucleus contains negatively charged electrons. (electron cloud)

8. Atoms: Building Blocks of Elements • Protons=Electrons • Therefore, atom is neutral overall. • Electron energy levels • Level 1 holds 2 • Level 2 holds 8 • Level 3 holds 8-18

9. Atoms: Building Blocks of Elements • Isotopes of an atom have differing numbers of neutrons. • The number of protons in an element always remains the same. • Isotopes are named by the total number of protons & neutrons i.e. Carbon-14

10. Atoms: Building Blocks of Elements • Isotopes are unstable & tend to break apart giving off radiation. • Carbon -14 is used to date things under 55,000 years old by measuring the amount of C-14 left.

11. Compounds & Bonding • Compounds are composed of 2 or more different atoms that are chemically combined. • Properties of a compound are different than the elements.

12. Compounds & Bonding • Atoms combine with other atoms only when it results in more stability. • An atom become more stable when its outermost energy level is full. • One way is to share electrons by covalent bonding.

13. Compounds & Bonding • Hydrogen becomes stable by sharing its atom with the other so that the electrons move about both nuclei. • The attraction of positive nuclei for negative electrons holds them together. Covalent Bond

14. Compounds & Bonding • A molecule is a group of atoms held together by covalent bonds. • In water, the atoms share eight electrons. • Chemical formula H2O

15. Compounds & Bonding • Sometimes atoms combine by gaining or losing electrons (e-). • Ion is a charged particle. • In salt, Na loses one e- to Cl which has 7e- in its outer energy level for a total of 8 forming an Ionic bond.

16. Compounds & Bonding • Ionic bonds are important in biological processes such as: • Transmission of nerve impulses • Muscle contraction • Essential minerals for plant growth

17. Chemical Reactions • All chemical reactions that occur in an organism are referred to as metabolism. • These reactions break down and build molecules important for their functioning. • Chemical equations represent these reactions.

18. Chemical Reactions • In a chemical RXN, atoms are neither created nor destroyed. • Mass is conserved; atoms are rearranged from reactants to products so that numbers of each are equal on both sides. 2Cu + O2 → 2CuO

19. Chemical Reactions + + • Add coefficients to balance this equation: • Cl2 + NaBr  NaCl + Br2

20. Chemical Reactions + + Br2 NaBr Cl2 • Add coefficients to balance this equation: • Cl2 + NaBr  NaCl + Br2 • Cl2 + 2 NaBr  2 NaCl + Br2 • Same number (2) of Cl Na Br on each side!

21. Mixtures and Solutions • A mixture is a combination of substances which retain their own individual properties. • They can be easily separated.

22. Mixtures and Solutions • A solution is a mixture with the solute distributed evenly throughout the solvent. • Simply put, one substance is dissolved in the other so that it won’t settle out.

23. Mixtures and Solutions • Solutions are important to life: • Sugar & mineral ions are dissolved in water • Concentrations of solutions must be regulated • Chemical RxNs only happen in certain conditions

24. Acids and Bases • Reactions depend on available energy, temperature, concentration of the solution & pH. • pH is a measure of how acidic or basic a solution is. It ranges from 0-14. • Acid- pH < 7, makes H+ ions in water, sour • Base- pH > 7, makes OH- ions, bitter, corrosive. • pH = 7 are neutral

25. Acids and Bases • Feedback from pH levels in the blood signals the brain forcing a person holding their breath to breathe.

26. 6.2 Water and Diffusion • Water makes up 70 to 95% of most organisms. • Life processes occur only when molecules & ions are free to move & collide with each other.

27. Water and Diffusion • Transports materials in blood and sap • Water is polar with an unequal distribution of charge. • Attracts ionic and polar substances. • Also attracts water in cohesion

28. Water and Diffusion • Positive hydrogen attracts negative oxygen in weak hydrogen bonds. • These hold biomolecules such as proteins together. • Plants use capillary action & surface tension to pull water into the roots.

29. Water Characteristics • Water resists temperature change which helps maintain homeostasis. • Expands when it freezes becoming less dense so that it floats. • Its expansion helps form soil.

30. Diffusion • The net movement of a substance from an area of greater concentration to an area of lesser concentration. • This random movement results from kinetic energy of molecules or Brownian motion.

31. Diffusion • Three factors affect diffusion: • concentration • More conc faster dif • temperature • Higher faster • pressure • Higher faster

32. Diffusion The result of diffusion is eventual dynamic equilibrium when movement continues but concentration remains the same.

33. Diffusion • Molecular Workbench diffusion simulations

34. Diffusion in Living Systems • Concentration gradient – the difference in concentration of a substance across a space • With the gradient moves higher to lower • Against- lower to higher

35. Diffusion in Living Systems • Oxygen diffuses into the capillaries of the lungs because it is less concentrated there than in the alveoli (air sacs). • It moves with the concentration gradient.

36. 6.3 Biomolecules • C atoms have 4 available electrons for bonding covalently in • Single • Double • Triple bonds • Straight chains • Branched chains • Rings

37. Biomolecules • Built by cells bonding small molecules together in chains or polymers. • Proteins are long chains of amino acids.

38. Biomolecules • Carbohydrates • Made of C, H & O • This is sucrose. • Used by cells to provide energy. • Ratio C:H:O = 1:2:1

39. Biomolecules Polysaccharides

40. Biomolecules • Lipids • Large biomolecules of C, H & a little O • Insoluble in water • Fats, oils, wax, steroids, cholesterol • Nonpolar • Used as energy storage, insulation & protective coverings

41. Biomolecules • Proteins complex biomolecule • C, H, O, N & some. S • Amino acids linked by peptide bonds • Imp to muscle contraction, transporting O, immunity, regulation & chemical RxNs

42. Biomolecules • Enzymesprotein that changes the rate of a chemical RxN • Catalysts increase rate of reaction • Digestion of food • Other metabolic processes • Lock and key

43. Enzymes

44. Nucleic Acids • Organic compound necessary for life • Polymer made of subunit nucleotides • C, H, O, N, P arranged in 3 groups • Nitrogenous base • Simple sugar • Phosphate group Nucleotides

45. Nucleic Acids • DNA -coded instructions for building enzymes & structural proteins • RNA –forms a copy of DNA to make proteins