1. Unit 2 (Biochemistry) Notes, Part 2: Properties of Water

2. Why do we study water properties in biology class?
About 2/3 of the mass of a cell is water!
Most life-sustaining reactions occur in water solutions (mixtures of water and dissolved substances)

3. Water Molecule
2 atoms of hydrogen linked by covalent bonds to 1 atom oxygen (H2O)
Polar Molecule: has positive hydrogen end and negative oxygen end

4. Water is Polar
Polarity: The electrons are unevenly distributed between the Oxygen and the two Hydrogen atoms.
Oxygen has 8 protons. Each hydrogen has 1.

5. Water is Polar
The atom with more protons (Oxygen) pulls shared electrons towards itself  this atom ends up with a slight negative charge. The other atom ends up with a slight positive charge.

6. Water forms Hydrogen Bonds
Hydrogen Bonds: Form due to attraction between different water molecules (because opposites attract).
Not as strong as ionic/covalent bonds

7. Water forms Hydrogen Bonds
Water can form up to 4 hydrogen bonds at once
A diagram of what’s going on:

8. Water is Cohesive
Cohesion: Water molecules are drawn tightly together (due to hydrogen bonding)
Water molecules on the surface of a lake or pond attract (through cohesion) and form a film that requires force to break through (this is called surface tension)
Explains why:
Water beads on a surface (like the lab table)
Insects can walk on water

9. Cohesion  Surface Tension

10. Water is Adhesive =
Adhesion = Water adheres (sticks) to different surfaces
Ex: Measuring water in a graduated cylinder
Water adheres (sticks) to the glass more than it sticks to itself
That’s why there is a dip (aka meniscus) in the water when you read the volume

11. Cohesion Adhesion
Ex: Water Bubble
Ex: Water and Paper Towels

12. Water can undergo Capillary Action
Capillary Action= Water can flow up a tube, against gravity
Ex: Plants absorbing water through their roots and up their stems

13. Capillary Action (Draw this!)

14. Water is an Excellent Solvent
Water often found as part of a mixture called a solution
Solution: one substance (solute) dissolves into another (solvent); water is called the “universal solvent”
Why is this important in humans?
Salt (NaCl) in Water

15. Water as a Solvent

16. Water Has a Neutral pH
pH: measure of how acidic or basic a solution is
scale is 0 to 14
If pH = 7, then substance is neutral (not acid or base)

17. Water is less dense in its solid form
Water is less dense in its solid form than it is in its liquid form (Ice floats!)… as water cools, more hydrogen bonds form and push water molecules farther apart from one another
Why might it be a bad thing for ice to sink in a pond?

18. What does ice look like at the molecular level?

20. Water has a High Heat Capacity
Water absorbs a lot of heat from the air without having a large temperature change because it takes a lot of energy to break bonds between water molecules before the water can increase in temperature!
So…lakes and oceans often stabilize air temperatures
Water absorbs heat when it evaporates; this is why sweating helps us cool down!

21. High Heat Capacity of Water

22. Unit 2 (Biochemistry) Notes, Part 3: Macromolecules

23. What elements are most common in our cells?
Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur.
Remember CHNOPS!

24. What have we already talked about?
Water…which elements are found in water?

25. A carbon atom can form four covalent bonds with other atoms
Carbon Compounds
A carbon atom can form four covalent bonds with other atoms

26. Carbon Compounds
Organic chemistry is the study of all compounds that contain bonds between carbon atoms.
Lipids (Fats)
Nucleic Acids (DNA)
Carbohydrates
Proteins

27. Carbon Compounds
macromolecules: large molecules formed by process called polymerization
polymer: forms when many smaller molecules (called monomers) bond together, usually in long chains

29. Macromolecules in Living Things
4 Types
1) Carbohydrates
2) Lipids
3) Nucleic Acids
4) Proteins

30. 1) Carbohydrates
Functions: source of short-term energy; also used in plant cell walls
Made of: Carbon, Hydrogen, Oxygen (1 C: 2H: 1O)
Glucose

31. 1. Carbohydrates (Sugars)
monosaccharide: carbohydrate monomer, simple sugars
Example: glucose and fructose
disaccharide: 2 monosaccharides form 2-sugar carbohydrate
Example: sucrose

32. 1. Carbohydrates
polysaccharide: carbohydrate polymer (forms when monosaccharides join together in a long chain)
Examples:
1) starch: plant energy storage
2) glycogen: animal energy storage
3) cellulose: cell walls in plants

34. 2. Lipids (Fats) Made of: Carbon and Hydrogen (with a few Oxygens)
Functions: long-term energy storage, insulation, cell membranes
Examples: fats, oils, and waxes

35. 2. Lipids
Structure: Usually 3 fatty acids (carbon-hydrogen chains) bonded to 1 glycerol molecule

36. Saturated Fat (Butter)
2. Lipids
Saturated vs. Unsaturated Fat…which is “worse” for you and why?
Saturated Fat (Butter)
Unsaturated Fat (Oil)

37. 3. Nucleic Acids
Functions: store & transmit information in cells in form of a code
Made of: C, H, O, N, and P
Nucleotide: monomer of a nucleic acid
DNA or RNA: polymers made by linking nucleotides in a chain

38. 3. Nucleic Acids
Nucleotide
DNA

39. 3. Nucleic Acids
DNA : deoxyribonucleic acid; master copy of organism's genetic code
RNA: ribonucleic acid; forms copy of DNA; used to make proteins (protein synthesis)

40. 4. Proteins Made of: C,H,N,O and sometimes S Functions:
1) Structure (proteins in hair and nails)
2) Transport (hemoglobin in blood)
3) Movement (proteins in muscle)
4) Defense (antibodies)
5) Controlling signals between cells and reactions inside cells (hormones and enzymes)

41. 4. Proteins
Amino Acids : Monomers of proteins; 20 common amino acids ; Consists of a central Carbon atom bonded to 4 groups
4 Groups
1) Hydrogen Atom
2) Amino Group
3) Carboxyl Group
4) R group (changes in each Amino Acid!)

42. 4. Proteins Polypeptide: polymer; one chain of amino acids
Proteins: several polypeptides folded around each other (shape  function)

43. Unit 2 (Biochemistry) Notes, Part 4: Enzymes

44. Why do we study chemical reactions in biology?
Chemistry isn’t just what life is made of, chemistry is also what life does
Everything that happens in an organism is based on chemical reactions (growth, response to environment, etc.)

45. Chemical Reaction A process that changes reactants into products.
Slow Reactions vs. Fast Reactions

46. Chemical reactions  breaking bonds in reactants and forming bonds in products

47. Energy Changes Some reactions release energy and some absorb energy
Activation Energy: the energy required to start a reaction

48. Speeding up Reactions
Slow reactions or reactions with high activation energies need a catalyst
Catalyst = any substance that lowers the activation energy of a reaction to “speed it up”
Enzymes are catalysts that are protein molecules.

50. Enzymes
Enzymes provide a site where reactants can be brought together to react.
In an enzyme-catalyzed reaction, the reactants are called substrates.
Each enzyme has a specific shape and a specific portion called the active site, where substrates bind.

51. The substrates must fit exactly into the active site
The substrates must fit exactly into the active site. This is called the lock and key model.
Once the reaction is complete, the enzyme releases the products of the reaction.
Enzymes can join or break substrates into products.

52. G:\Teacher Resources\Downloaded Videos\Enzyme Action.avi
Breaking 1 Substrate into 2 Products
G:\Teacher Resources\Downloaded Videos\Enzyme Action.avi

53. Joining 2 Substrates into 1 Product

54. Enzymes can break or join substrates into products.
Enzymes work best at a certain pH and temperature.
Roles of Enzymes:
1) regulating chemical pathways
2) making materials
3) releasing energy
4) transferring info