The Chemistry of Life

1
Chapter 2

• The Chemistry of Life

2
Section 1 The Nature of Matter
3
Objectives

• What three subatomic particles make up atoms?
• How are all the isotopes of an element similar?
• What are the two types of chemical bonds?

4
The Big Idea

• Life Depends on chemistry
• Chemical reactions keep you alive

5
Atom

• Basic unit of matter

6
Democrites
7
Subatomic particles

• Protons -
• Neutrons -
• Electrons -

• Positively charged ()
• Not charged (neutral)
• Negatively charged (-)

Bind together to form the nucleus
Protons
Electrons
Nucleus
Neutrons
8
(No Transcript)
9
Element

• A pure substance that consists of just one type
  of atom

10
(No Transcript)
11
An elements atomic number number of protons
Atomic number
6
C
Carbon
12.011
12
Isotope

• Atoms of the same element that differ in the
  number of neutrons they contain

13
(No Transcript)
14
The Sum of protons and neutrons in the nucleus of
an atom is its mass number
6
C
Carbon
Mass number
12.011
15

• The weighted average of the masses of an elements
  isotope is called its atomic mass

16
Radioactive isotopes

• Can be dangerous
• Can be used practically
• Radioactive dating
• Treat cancer
• Kill bacteria

17
Compounds

• A substance formed by the chemical combination of
  two or more elements in definite proportions
• Ex) H2O, NaCl

18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
Table Salt
23
Ionic Bonds

• Formed when one or more electrons are transferred
  from one atom to another

24
(No Transcript)
25

• If an atom loses an electron it becomes positive
• If an atom gains an electron it becomes negative

26
Ions

• Positively and negatively charged atoms

27
(No Transcript)
28
Covalent Bonds

• Forms when electrons are shared between atoms

29
(No Transcript)
30
Molecule

• The structure that results when atoms are joined
  together by a covalent bond
• Smallest unit of most compounds

31
Van der Waals Forces

• A slight attraction that develops between the
  oppositely charged regions of nearby molecules
  due to unequal sharing of electrons

32
(No Transcript)
33
(No Transcript)
34
Section 2 Properties of Water
35
Objectives

• Why are water molecules polar?
• What are acidic solutions? What are basic
  solutions?

36
The Big Idea

• Much of our planet is covered in water
• Water is necessary for life to exist
• If life exists on other planets, there most
  likely is water present
• Water has many properties that make life possible

37
Polarity
(-)
The oxygen atom has a stronger attraction for
electrons
()
38
Hydrogen Bonds

• Because of waters partial charges, they can
  attract each other and create hydrogen bonds
• Not as strong as covalent or ionic bonds
• Waters ability to create multiple hydrogen bonds
  gives it many special properties

39
Cohesion

• Attraction between molecules of the same substance

40
(No Transcript)
41
(No Transcript)
42
Adhesion

• Attraction molecules of different substances

43
(No Transcript)
44
Mixture

• Material composed of two or more elements or
  compounds that are physically mixed but not
  chemically combined
• Ex.) salt pepper, earths atmosphere

45
Solutions

• Mixture of two or more substances in which the
  molecules are evenly distributed
• Ex.) salt water
• Settles out over time

46
Solutions
47
Solute

• Substance that is dissolved
• Ex.) salt

48
Solvent

• The substance that does the dissolving
• Ex.) Water

49
Suspensions

• Mixture of water and non-dissolved materials
• Ex.) sugar solution, blood
• Separate into pieces so small, they never settle
  out

50
The pH scale

• Indicated the concentration of hydrogen ions in a
  solution

51
Acid
Neutral
Base
52
Acids

• Any compound that forms H (hydrogen) ions in
  solution

53
Base

• A compound that produces OH- (hydroxide) ions in
  solution

54
Buffers

• Weak acids or bases that can react with strong
  acids or bases to prevent sharp, sudden pH changes

55
Section 3 Carbon Compounds
56
Objective

• What are the functions of each group of organic
  compounds?

57
Lifes backbone
Interest Grabber
Section 2-3

• Most of the compounds that make up living things
  contain carbon. In fact, carbon makes up the
  basic structure, or backbone, of these
  compounds. Each atom of carbon has four electrons
  in its outer energy level, which makes it
  possible for each carbon atom to form four bonds
  with other atoms.
• As a result, carbon atoms can form long chains. A
  huge number of different carbon compounds exist.
  Each compound has a different structure. For
  example, carbon chains can be straight or
  branching. Also, other kinds of atoms can be
  attached to the carbon chain.

58
Isooctane
Methane
Acetylene
Butadiene
Benzene
59
Macromolecules giant molecules

• Formed by a process called polymerization

60
Monomers

• Smaller units

61
Polymers

• Linked up monomers

62
Carbohydrates

• Compounds made up of carbon, hydrogen, and oxygen
  atoms usually in a ratio of 121
• Main source of energy
• The monomers of starch are sugars

63

• Single sugar molecules are called monosaccharides
• The large macromolecules formed from
  monosaccharides are known as polysaccharides

64
(No Transcript)
65
Lipids

• Made mostly from carbon and hydrogen atoms
• Used to store energy

66
Lipid
Glycerol
Fatty Acids
67
Proteins

• Macromolecules that contain nitrogen as well as
  carbon, hydrogen, and oxygen
• Proteins are polymers of molecules called amino
  acids

68
Amino Acids
69

• More than 20 different amino acids, can join to
  any other amino acid
• The instructions for arranging amino acids into
  many different proteins are stored in DNA
• Each protein has a specific role
• The shape of proteins can be very important

70
Proteins
Amino Acids
71
Nucleic Acids

• Macromolecules containing hydrogen, oxygen,
  nitrogen, carbon, and phosphorus

Double Helix
72
Nucleotides

• Consists of 3 parts 5-carbon sugar, phosphate
  group and nitrogen base

Nitrogen Base
Phosphate group
5-Carbon Sugar
73
2 kinds of nucleic acids

• RNA (ribonucleic acids) contains sugar ribose
• DNA (deoxyribonucleic acid) contains sugar
  deoxyribose

74
Section 4 Chemical Reactions and Enzymes
75
Objectives

• What happens to chemical bonds during chemical
  reactions?
• How do energy changes affect whether a chemical
  reaction will occur?
• Why are enzymes important to living things?

76
The Big Idea

• Living things are made up of chemical compounds
• Everything that happens to an organism is based
  on chemical reactions

77
Chemical Reactions

• A process that changes or transforms one set of
  chemicals into another

78
Reactants

• Elements or compounds that enter into a reaction

79
Products

• Elements or compounds produced by a chemical
  reaction

80
Example Reaction Getting rid of carbon dioxide

• In the blood
• In the lungs

CO2 H20 ? H2CO3 (carbonic acid)
H2CO3 ? CO2 H2O
Released as you breathe
81
Energy in reactions
82
Activation Energy

• The energy that is needed to get a reaction
  started

83
(No Transcript)
84
Enzymes

• Some chemical reactions are too slow or have
  activation energies that are too high to make
  them practical for living tissue
• These chemical reactions are made possible by
  catalysts

85
Catalyst

• Substance that speeds up the rate of chemical
  reactions
• Work by lowering a reactions activation energy

86
Enzyme

• Biological catalysts
• Speed up reactions in cells
• Very specific
• Named for the reaction is catylzes
• Enzyme names always end in -ase

87
(No Transcript)
88
Substrates

• The reactants of enzyme catalyzed reactions
• The active site of the enzyme and the substrate
  have complementary shapes
• Fit like a lock and key

89
Enzyme Action
Enzyme substrate complex
90
Enzyme (hexokinase)
Glucose
ADP
Substrates
Products
ATP
Glucose-6- phosphate
Active site
Products are released
Substrates bind to enzyme
Enzyme-substrate complex
Substrates are converted into products
91
Regulation of Enzyme Activity

• Enzymes are affected by any variable that affects
  chemical reactions
• pH
• Temperature
• Concentration
• of enzyme

92
(No Transcript)