Unit 2

1. Unit 2 The Chemistry of Life

2. Learning Targets • Identify elements common to living things. • Describe how ions work. • Compare ionic and covalent bonds • Recognize the importance of hydrogen bonding. • Explain why many compounds dissolve in water. • Compare acids and bases. • Describe the bonding properties of carbon atoms • Compare and understand the importance of the four macromolecules: carbohydrates, lipids, proteins, and nucleic acids. • Describe how bonds break and reform during chemical reactions • Explain why and how chemical reactions release or absorb energy. • Explain the effect of catalysts on activation energy. • Describe and explain how enzymes regulate chemical reactions.

3. Unit Opener-How can this plant digest a frog?

4. Like other carnivores, the Venus flytrap eats animals to get nutrients that it needs to make molecules such as proteins and nucleic acids. Other chemical compounds made by plant’s cells enable the Venus flytrap to digest the animals that it eats. These chemicals are similar to the chemicals that allow you to digest the food that you eat.

5. ???????? If plants can make their own food through photosynthesis, why would a plant species evolve a mechanism to capture and eat animals?

6. The animal must be supplying nutrients that the plant cannot get from other sources.

7. Venus fly traps grow in swampy areas that have nitrogen poor soil. These plants get the nitrogen they need for survival by trapping and digesting animals.

8. Video http://www.youtube.com/watch?v=O7eQKSf0LmY

9. What is everything made up of? • Atoms- the building block of matter • Matter- anything that takes up space

10. Atoms are made up of: • Protons-> positively charged particles and dense • Neutrons-> neutral charge / no charge • Electrons-> negatively charged particles and small • Protons and neutrons live in the nucleus (center of the cell) • Electrons are in the outer levels= electron cloud

11. Draw and label the atom

12. What do the numbers mean? • Atomic mass= sum of protons and neutrons in the nucleus • Atomic number = the amount of protons and electrons in a neutral atom

13. Element • A type of atom that cannot be broken down into simpler substances. • Can also be a group of atoms of the same type. • Ex-> gases such as hydrogen and oxygen. Metals= aluminum and gold.

14. Atoms are made up of the same types of particles, so what makes one element different from another? • Different elements differ in the number of protons they have. Atomic number= number of protons Atomic Mass

15. How many protons does hydrogen have? Oxygen? • Hydrogen= 1 • Oxygen= 8

16. Energy levels • Different energy levels can hold a different number of electrons. • 1st energy level= hold 2 electrons • 2nd level= hold 8 electrons • Stable atoms have a full outermost energy level

17. 91 elements that occur naturally • 4 that make up 96 % of your body= carbon, oxygen, nitrogen, and hydrogen • The other 4% are called trace elements because they are found in little amounts but we need them to survive-> such as calcium, iron, potassium

18. Why does your blood need iron? • To transport oxygen in your blood

19. Why does your body need chromium? • Your cells need it to break down sugars for usable energy

20. Compounds • Atoms of elements found in organisms are usually linked or bonded to other atoms= compound. • Common compounds= water (H2O), carbon dioxide (CO2)

21. Ions • Atom that has gained or lost one or more electrons. • Forms because an atom is more stable when its outermost energy level is full. The gain or lose results in a full outer level. • Either positive or negative • Atoms with few electrons= lose electrons and becomes more positive • Gains electrons= more negative.

22. NaCl • Transfers electron from sodium atom to chlorine atom • When sodium loses electron it becomes positive-> full charged because it has a filled outermost energy level. • The electron lost goes to the chlorine ion, causing the chlorine to become more negative and have a full energy level.

24. End product is an ionic bond-> bond that forms when two oppositely charged particles exchange electrical forces. • Opposites attract (+ / -)

25. What determines whether an atom becomes a positive ion or a negative ion? • Atoms with few outer electrons tend to lose electrons and form positive ions; atoms with almost full outer energy levels tend to gain electrons and form negative ions.

26. Molecule • Two or more atoms held together by covalent bonds.

27. Covalent Bonds • The strongest of bonds • Form when atoms share a pair of electrons. • Need 4 electrons to fill its outermost energy level

28. CO2= Carbon Dioxide • An oxygen atom needs 2 electrons to fill its outer energy level. In Carbon dioxide, carbon makes a double bond, or shares two pairs of electrons with each oxygen atom. O C O

29. Properties of Water!!!!! Waters unique properties allow life to exist on Earth.

30. Polar: Water and some gases Uneven distribution of electrons Nonpolar= liquids, CO2, Oxygen, oils, fats electrons are distributed more evenly around the outer shell and cancel each other out Polar vs. Nonpolar They both tend to remain separate that is why they say “oil and water don’t mix.”

31. Life depends on hydrogen bonds • Water is polar-> Have regions with a slight positive and slight negative charge. • Waters oxygen atoms are slightly negative and hydrogen is slightly positive= HYDROGEN BOND • The weakest of bonds • Important structures in DNA and proteins.

32. Properties of Hydrogen Bonds • Weakest of the bonds • High specific heat= water resists changes in temperature, therefore water must absorb more heat energy to increase temperature. • Very important with cells because our cells release a lot of heat and water absorbs that heat which allows us to regulate cell temperatures.

33. Properties Continue • Cohesion-> attraction among molecules of a substance. • Makes water molecules stick together. • Ex- beads on a car when it is washed • Spider walking on top of the water (surface tension). • http://www.youtube.com/watch?v=8O8PuMkiimg

34. Properties Cont. • Adhesion-> attraction among molecules of different substances. • Water molecules stick to other things. • Ex- upward curve of the surface of the water-> graduated cylinder • Ex- plants transport water up their roots to their leaves. • http://www.youtube.com/watch?v=45yabrnryXk • http://www.youtube.com/watch?v=WpXHpXKZtws

35. Many compounds dissolve in water- Universal Solvent • Molecules and ions can’t take part in chemical processes inside cells unless they dissolve in water. • Materials such as sugar and oxygen cannot be transported from one part of an organism to another unless they are dissolved in blood, plant sap, or water based fluids.

36. Solvent-> substance that is present in the greatest amount, and is the substance that dissolves solutes. Example= Water Solute-> substance that dissolves. Example= kool aid powder Solution= mixture of substances that is the same throughout= homogeneous mixture

37. Solubility • The ability of the solute to dissolve into the solvent. • Typically measured by how fast or the rate. • Temperature increases the rate at which the solute dissolves. • Pressure increases the rate • The nature of the solute and solvent (what its made up of).

38. Your plasma (liquid part of your blood) is 95% water. Which is the solvent and solute? • Solvent= water; Solute is the other 5% which is made up of proteins, sugars, minerals, platelets, etc

39. Why do the solutes such as proteins and sugars dissolve in the water of blood plasma? • Answer-> polar= because the attraction between the water molecules and the solute molecules is greater than the attraction among the molecules of the solutes.

40. Sum it up! Properties of Water: • Hydrogen Bonding- strong cohesion (insects walking on water) • Capillary Action- water moves upward (Roots to leaves) • Strong Adhesion- attraction between two unlike substances • Universal Solvent- dissolves everything • High Specific Heat- cools / heats up slowly to allow temperatures in organisms to maintain homeostasis • Expands when freezes making it less dense

41. 2. In a solution (which is a mixture of a solute and a solvent) which do you typically have more of? Solute Solvent Same amount of both • What is the most comment solvent in everyday life? • A. carbon containing chemicals • B. ethanol • C. water • D. All of the above 4. How does temperature affect solubility? Solubility is not affected by temperature. Solubility decreases with an increase in temperature. Solubility increases with an increase in temperature. 3. What is solubility? The ability of a given substance(solute) to dissolve into a solvent. The ability of a given substance(solvent) to dissolve into a solute.

42. 5. How does a solute dissolve into a solvent? Polar solvent molecules separate the molecules of other polar substances. Polar solvent molecules separate the molecules of other non-polar substances. Non-polar solvent molecules separate the molecules of other non-polar substances. 6. What are the main factors that affect solubility? Temperature Pressure Nature of solute and solvent All of the above

43. Answers • 1. C- Water • 2. B • 3. A • 4. C • 5. A • 6. D

44. Acids Releases a hydrogen ion (H+) when it dissolves in water. 0 to 7= acids Bases Removes H+ ions from a solution 7-14= basic Acids and Bases Weak base Strong Base Strong Acid Weak Acid pH of 7=Neutral-> neither acidic or basic

45. pH Scale (Potential Hydrogen)

46. How is Ph regulated in our bodies? • Through buffers-> compounds that can bind to H+ ion when the H+ concentration increases and can release an H+ ion when the H+ ion decreases. • Buffer “locks up or stops” the H+ ions in order for our bodies to maintain homeostasis. • Example-> normal Ph of blood is 7.35-7.45 (slightly basic), therefore a small change in this could really disrupt your cells and can be fatal.

47. Carbon Based Molecules

48. Carbons unique bonding properties • Building blocks of life because they are the basis of most molecules that make up living things. • Organisms obtain energy (food) and turn it into ATP (cells power source for all life processes). • Unique atomic structure because it has four unpaired electrons on the outer energy level and can form covalent bonds with up to four other atoms!!!!!!

49. Three types of molecular structures • Straight Chain • Branched Chain • Ring

50. Monomer / Polymer Polymer= molecule that contains many Monomers bonded together. Monomer= small molecular subunit How many monomers are above?