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