bio/pls 210 jan smalle [email protected] website: smalle lab (jasmal3/) [email protected]
TRANSCRIPT
BIO/PLS 210
Jan Smalle
Website: Smalle Lab(http://www.uky.edu/~jasmal3/)
Syllabus
How to download the lectures?
http://www.uky.edu/~jasmal3/
TEACHING
PLS 210 Resources
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Quiz during the lecture
Results of the quiz discussed at the beginning of the next lecture
PLS/BIO210 Grades distribution over the past 7 years:
A: 21% (16-28%)
B: 21%
C: 28%
D: 22%
E: 8% (0-13%)
The Chemistry of LifeChapter 2
David Latimer and his bottle garden
Photosynthesis and Respiration
Photosynthesis:
6CO2 + 6H2O + energy C6H12O6 + 6O2
Respiration:
C6H12O6 + 6O2 6CO2 + 6H2O + energy
Atomic Particles
Particle Charge Mass Units Location
Proton + 1 Nucleus
NeutronNo
electrical charge
1 Nucleus
Electron -Negligible(0.0005 units)
Orbitals around nucleus
Twelve Most Common Elements in Living Organisms
Element Symbol Number of Protons
Hydrogen H 1
Carbon C 6
Nitrogen N 7
Oxygen O 8
Sodium Na 11
Magnesium Mg 12
Phosphorus P 15
Sulfur S 16
Chlorine Cl 17
Potassium K 19
Calcium Ca 20
Iron Fe 26
hydrogen
carbon
• Hydrogen has one proton and one electron located in one orbital surrounding the nucleus.
• Carbon has six protons and (thus) six electrons. One electron pair is located in the inner orbital. The other four are distributed over four outer orbitals organized in a tetrahedron structure.
hydrogen
carbon
• Carbon has six protons and (thus) six electrons. One electron pair is located in the inner orbital. The other four are distributed over four outer orbitals organized in a tetrahedron structure.
• Electrons of the Carbon atom are distributed over two energetically different electron shells.
Covalent Bonds
• Single bond– Atoms share two electrons– Represented by single line (-) in
structural formula
H - C - H
H
H
Methane
Overall Photosynthesis Reaction
6CO2 + 6H2O + energy C6H12O6 + 6O2
Carbon dioxide Water Glucose Oxygen
Overall Photosynthesis Reaction
6CO2 + 6H2O + energy C6H12O6 + 6O2
24 C-O bonds+
12 H-O bonds
36 covalent bonds
7 C-O bonds+
5 C-C bonds+
7 C-H bonds+
5 H-O bonds+
12 O-O bonds
36 covalent bonds
Overall Respiration Reaction
C6H12O6 + 6O2 6CO2 + 6H2O + energy
24 C-O bonds+
12 H-O bonds
36 covalent bonds
7 C-O bonds+
5 C-C bonds+
7 C-H bonds+
5 H-O bonds+
12 O-O bonds
36 covalent bonds
hydrogen
carbon
• Carbon has six protons and (thus) six electrons. One electron pair is located in the inner orbital. The other four are distributed over four outer orbitals organized in a tetrahedron structure.
• Electrons of the Carbon atom are distributed over two energetically different electron shells.
Electron energy levels
Carbon (C) Oxygen (O) Inner shell
(Low potential energy)
Outer shell
(high potential energy)
Nitrogen(N)
NucleusElectron
Carbon: six protons and six electrons
Nitrogen: seven protons and seven electrons
Oxygen: eight protons and eight electrons
Carbon (C) Carbon (C)
Inner shell
(Low potential energy)
Outer shell
(high potential energy)
C-C bond
Carbon (C) Carbon (C)
C-C bond
Electron energy levels
Carbon (C) Oxygen (O)
Inner shell
(Low potential energy)
Outer shell
(high potential energy)
Oxygen has 8 protons in its nucleus. The result is a higher positive charge that exerts a stronger attraction force on the electrons of the outer shell. On average, these electrons will be located closer to the nucleus (compared to Carbon).
Carbon (C) Oxygen (O)
Inner shell
(Low potential energy)
Outer shell
(high potential energy)
C-O bond
Carbon (C) Oxygen (O)
C-O bond?
No !
Yes !
C-O bond?
No !
Yes !
C O
- Oxygen has a higher electronegativity than Carbon (Oxygen nucleus has 8 protons compared to 6 in the carbon nucleus. The higher proton number results in a higher positive charge).
- Electron pair is pulled towards the O nucleus
- Bonding electron pair contains a lower level of potential energy compared to when it is in the middle between nuclei (see waterfall analogy).
High potential energy
Earth center
Gravitational force
Low potential energy
Waterfall analogy
LAKE
RIVER
C
O
C
C
High potential energy
Low potential energy
Electrical force
Electrical force
C
O
C
C
Carbon-Carbon bonds contain useful energy
Bonding electron pair of C-C contains more energy than C-O pair
Hydrogen (H) Carbon (C)
Inner shell
(Low potential energy)
Outer shell
(high potential energy)
H-C bond
Hydrogen (H) Carbon (C)
Inner shell
(Low potential energy)
Outer shell
(high potential energy)
The potential energy of the bonding electron pair of a H-C bond is defined by the distance to the C nucleus. The distance to the H nucleus is in this case irrelevant since the single electron orbital of the H atom already defines the lowest possible energy state of an electron (or electron pair).
H-C bond
The potential energy of the bonding electron pair of a H-C or H-O bond is defined by the distance to the C or O nucleus. The distance to the H nucleus is in this case irrelevant since the single electron orbital of the H atom already defines the lowest possible energy state of an electron (or electron pair).
H-O bond
H
O
H
C
Carbon-hydrogen bonds contain useful energy
Bonding electron pair of C-H contains more energy than H-O pair
C
C
Basis of photosynthesis:Light energy is used to transform C-O and H-O bonds into C-C and H-C bonds + Energy
C
O
+ Energy
Basis of respiration:Energy is liberated by transforming C-C and C-H bonds into C-O and H-O bonds
+ +
C
C
+ +
Increased potential energy
Decreased potential energy
H
C
H
C
H
O
C
O
H
O
Photosynthesis and Respiration
Photosynthesis:
6CO2 + 6H2O + energy C6H12O6 + 6O2
Respiration:
C6H12O6 + 6O2 6CO2 + 6H2O + energy