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The Chemical Context of Life
BIOL 101 General Biology I
Chapter 2
Rob Swatski Associate Professor of Biology
HACC - York Campus 1
2
3
4
Contains Mass
Occupies Space Matter
5
Matter is Made of…
Elements
Compounds
Sodium Chlorine Sodium chloride
6
7
The 4 Most Abundant
Elements of Life
O
C
H
N
8
The Next 4 Most
Abundant Elements of
Life
Ca
P
K
S
9
10
11
Atomic Structure
Nucleus
Protons (+)
Neutrons (0)
Electron Cloud
Electrons (-)
Electron Cloud
Nucleus
Electrons
12
13
14
How Are an Atom’s Electrons Organized?
3rd Shell
2nd Shell
1st Shell
Atomic Nucleus
15
Atomic Number
# of Protons
16
# of Neutrons
# of Protons
Atomic Mass
Electrons = Energy
17
18
# of Protons
# of Electrons
Electrically Neutral Atom
Electron-distribution diagrams
Hydrogen
1H
Lithium
3Li Beryllium
4Be Boron
5B Carbon
6C Nitrogen
7N Oxygen
8O Fluorine
9F Neon
10Ne
Helium
2He
Atomic number
Atomic mass
2 He
4.00 First shell
Second shell
Third shell
Sodium
11Na Magnesium
12Mg Aluminum
13Al Silicon
14Si Phosphorus
15P Sulfur
16S Chlorine
17Cl Argon
18Ar
19
20
Isotopes
Same # of protons
Different # of neutrons
21
Isotopes of carbon
22
Research Applications of Radioactive Isotopes
Dating fossils
Tracers in metabolism
studies
Diagnosing medical
disorders
23
Radioactive isotopes (tracers)
I-131 thyroid study
Various compounds + 3H radioactive tracer
Human cells
Incubators
1 2 3
4 5 6
7 8 9
50ºC 45ºC 40ºC
25ºC 30ºC 35ºC
15ºC 20ºC 10ºC
1
2
DNA (old and new)
TECHNIQUE
24
TECHNIQUE
The test tubes are placed in a scintillation counter. 3
25
RESULTS C
ou
nts
pe
r m
inu
te
( 1
,00
0)
0 10 20 30 40 50
10
20
30
Temperature (ºC)
Optimum temperature for DNA synthesis
26
27
Energy
Potential
Chemical Kinetic
28
29
30
31
32
How Are an Atom’s Electrons Organized?
3rd Shell
2nd Shell
1st Shell
Atomic Nucleus
33
34
1st
2nd
3rd
Energy absorbed
Energy lost
35
Valence
36
37
38
Stable Atoms
8 valence
e-
Unstable Atoms
< 8 valence
e-
39
40
41
1s orbital 2s orbital Three 2p orbitals
42 1s, 2s, and 2p orbitals
43
Covalent Bonds
Hydrogen molecule (H2)
44
Molecules
45
Covalent Bonds
Single Double Triple
46
H2
Molecular formula Structural formula
O2
H2O
CH4
(a) Hydrogen (H2)
Name and
Molecular
Formula
Electron
Distribution
Diagram
Lewis Dot
Structure and
Structural
Formula
Space-
Filling
Model
47
(b) Oxygen (O2)
Name and
Molecular
Formula
Electron
Distribution
Diagram
Lewis Dot
Structure and
Structural
Formula
Space-
Filling
Model
48
49
50 Electronegativity
51
Types of Covalent Bonds
Nonpolar
Polar
(d) Methane (CH4)
Name and
Molecular
Formula
Electron
Distribution
Diagram
Lewis Dot
Structure and
Structural
Formula
Space-
Filling
Model
52
Name and
Molecular
Formula
Electron
Distribution
Diagram
Lewis Dot
Structure and
Structural
Formula
Space-
Filling
Model
(c) Water (H2O)
53
–
+ + H H
O
54
55
Ions
Anions
(-)
Cations
(+)
Gain e- Lose e-
Na Cl Na Cl
56
Ionic Bonds
57
Ionic Compounds
+
+
+
+
+
58
Hydrogen Bonds
59
60
Van der Waals Interactions
61
62
Substrates
Active Site
Enzyme
63
Enzymes = Catalysts
64
Natural endorphin
Morphine
Carbon
Hydrogen
Nitrogen
Sulfur
Oxygen
(a) Structures of endorphin and morphine
(b) Binding to endorphin receptors
Brain cell
Morphine Natural
endorphin
Endorphin
receptors
65
Reactants Products
2 H2 O2 2 H2O
66
Chemical Reactions
A B AB
67
Synthesis (Anabolism)
68
69
6 CO2 + 6 H20 →
C6H12O6 + 6 O2
Photosynthesis
70
AB A B
Decomposition (Catabolism)
71
72
A B AB
Reversible
73
74
Chemical Equilibrium