1. Chapter 2
The Chemistry of Life

2. Chapter Outline Section 1: The Nature of Matter
Section 2: Water and Solutions
Section 3: Chemistry of Cells
Section 4: Energy and Chemical Reactions

3. Section 2.1 Nature of Matter
Why look at chemistry in a biology class?
All living organisms have chemical “machinery”
2.1 Covers:
Atoms, Elements, Chemical Bonding

4. Atoms
Atom is the smallest unit of matter that cannot be broken down by chemical means
Very small and always changing
3 particles make up an atom
Electrons (-)
Protons (+)
Neutrons (neutral)
Attract each other…
*Therefore atom itself has no charge (negative electron cancels out positive proton)

5. Atomic Structure Electron Cloud made of electrons (-)
Nucleus made up of protons (+) and neutrons (neutral), nucleus has a (+) charge

6. Element An element is a pure substance made of only one kind of atom
Represented by chemical symbols (C, N, H)
Elements have different atomic numbers (C=6, O=8)
Atomic number = # of protons

7. Differences in Elements
Atomic Number all atoms of a particular element have the same number of protons which is called the atomic number.
Ex: Helium = b/c it has 2 protons

8. Isotopes Different number of neutrons than protons Carbon 12, 13, 14
6 Protons in each but Carbon 13 has 7 neutrons and carbon 14 has 8 neutrons

9. Energy Levels

10. Chemical Bonding Atoms can join together to form a stable substance
The force that joins atoms together is called a chemical bond
A compound is a substance made of 2 or more elements.
3 Types of Bonds
Covalent
Hydrogen
Ionic

11. Arrangement of electrons determine how atoms bond together
Electron levels
Closest to nucleus = 2 electrons
Second level = 8 electrons
Atom becomes stable when the outer electron level is full

12. Covalent bonds Hydrogen =H has only 1 electron in its outer most level
Form when 2+ atoms share electrons to form a molecule.
Hydrogen =H has only 1 electron in its outer most level
Oxygen =O has only 6 electrons in its outer most level
They react to fill each ones outer most level 2 2 2 3 1 6 4 5

13. Ionic Bonding
Atoms gain or lose an electron, causing them to be charged.
They become charged because they contain an unequal number of electrons and protons

14. Gaining/Loosing an Electron
Gaining an electron makes the atom negative
You have more electrons (-) than protons (+)
Loosing an electron makes the atom positive
You have more protons (+) than electrons (-)

15. Ionic Bond Example Na LOST an e- so it became more positive
Cl GAINED an e- so it became more negative

16. Hydrogen bonds
Electrons more strongly attracted to the oxygen nucleus than by the hydrogen’s
This unequal distribution of electrical charge are called polar molecules
Partially positive end of one molecule is attracted to the partially negative end of another

17. Polar Molecule (Water)
Which pole attracts which pole?

18. Exit Ticket Draw a carbon atom (Atomic number = 6)
Label all the parts and correctly show the number of electrons in the right levels
Write 3 things you learned today

19. Begin 2.1 Section Review
Page 30
Questions 1-4
Finish for HW

20. Chapter 2 Section 2
Water and Solutions

21. Water in Living Things 70% of your body is made of water
Water helps move nutrients and other substances into and out of your cells
Certain properties of water make it such an important substance for life
Storage of heat
Cohesion & Adhesion

22. Storage of Heat
Water heats more slowly and retains heat longer than many other substances
Many organisms release heat through water evaporation
Sweating
Helps maintain homeostasis

23. Cohesion & Adhesion
The hydrogen bonds between water molecules cause the cohesion of liquid water
Cohesion
Attraction between substances of the same kind
Surface tension prevents water from breaking easily
Adhesion
Attraction between substances of a different kind
Substances get wet
Capillary action water molecules move up through a narrow tube (stem of plant)
Because of these water can move up the stems of leaves

24. Aqueous Solutions Many substances dissolve in water
Solution is: a mixture in which one or more substances are evenly distributed in another substance.
Because certain substances can dissolve in water they can more easily move throughout the body

25. Polarity Enables many substances to dissolve in water
When ionic compounds are dissolved in water, the ions become surrounded by polar water molecules
Ions and molecules become evenly distributed in the water
Non polar molecules do not dissolve in water well (oils)

26. Acids and Bases
Pure water always has a even concentration of hydrogen ions (H+) and hydroxide ions (OH-)
Acids have a higher concentration of hydrogen ions.
Bases have a higher concentration of hydroxide ions.

27. pH Scale

28. 2.3 Chemistry of Cells Most matter in your body that isn’t water
IS an organic molecule
Organic = Carbon based
4 classes of organic molecules in your body (can’t function w/o them)
Carbohydrates
Lipids
Proteins
Nucleic Acids

29. Carbohydrates Organic molecules made of carbon, hydrogen and oxygen
Major source of energy for the body
Found in most foods (fruits, veggies, grain) in the form of sugars
3 types of sugars
Monosaccharide (1 sugar unit)
Disaccharide (2 sugar units)
Polysaccharide ( 3+ sugar units)
Macromolecule large molecule made of many smaller

30. Examples of Sugars (Carbs)
Polysaccharides storehouses for energy
starch, glycogen, cellulose
Starch – made by plants
Glycogen- made by animals
Both made from linked glucose molecules (pg 34)
Cellulose- made by plants (for structure)

31. Lipids Non-polar molecules… soluble or non-soluble?
Fats, phospholipids, steroids and waxes
Steroids (cholesterol, estrogen, testosterone)
Important for structure and function of cell membranes
Lipids store energy

33. Structure 3 fatty acids bonded to a glycerol molecule backbone (pg 35)
Fatty acid is long chain of carbon atoms with hydrogen bonded to them
Strong bonds between carbon and hydrogen  can store lots of energy

34. Saturated and Unsaturated
All carbons are bonded to 2+ hydrogen
Most animal fats
Butter, lard, grease
Usually solids at room temperature
Unsaturated
Some carbons linked by a double covalent bond
Causes kinks in chain
Plant oils, olive oil, fish oils
Liquids at room temperature

35. Unsaturated Fats

36. Proteins
Large molecules formed by linked smaller molecules called amino acids (AA)
AA are building blocks of proteins
Only 20 AA
Cause various shapes of proteins
Some proteins are enzymes (help chemical reactions)
Others used for structure
Skin, ligaments, bone (Collagen)
Hair & nails (keratin)
Muscle (myoglobin)
Blood (hemoglobin)

37. Example of a Protein??? Enzymes!
Lower the amount of energy needed to start the reaction without changing the original reactants.
Reaction runs faster!

38. Energy Chemical Reaction
Reactant Products +
Reactant 2
Hydrogen
Oxygen
water

39. Enzymes Shape specific - Fits like puzzle piece
Active site
Each enzyme has its own specific substrate (reactant)

41. Enzymes
What affects enzymes?
pH, temperature, environment

42. Collagen
Hemoglobin

43. Nucleic Acids All cells contain nucleic acids (in all cells)
Long chain of smaller molecules (nucleotides)
3 parts
Sugar
Base
Phosphate group (P& O)
2 types of nuclei acids
DNA- deoxyribonucleic acid
RNA- ribonucleic acid

44. DNA 2 strands of nucleotides that spiral around each other
Chromosomes contain long strands of DNA (stores heredity)

45. RNA Single strand of nucleotides Key roles in protein synthesis
Acts as enzyme
 helping chemical reactions link AA to form proteins