BIOL 101 Chp 4: Carbon and the Molecular Diversity of Life
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Transcript of BIOL 101 Chp 4: Carbon and the Molecular Diversity of Life
BIOL 101 General Biology I
Chapter 4
Carbon & the Molecular Diversity of Life
Rob Swatski
Associate Professor of Biology
HACC – York Campus 1
Carbon: The Backbone of Life
• Living organisms consist mostly of carbon-based compounds
• Carbon is unparalleled in its ability to form large, complex, and diverse molecules
• Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds
2
Carbon: Life’s Backbone
3
Organic Chemistry
C
H
O
N
4
Vitalism
5
the idea that
organic compounds
arise only in
organisms
- was disproved when
chemists synthesized
these compounds
Mechanism
6
the view that all natural phenomena are governed
by physical and chemical laws
Organic Molecules and the Origin of Life on Earth
• Stanley Miller’s classic experiment demonstrated the abiotic synthesis of organic compounds
• Experiments support the idea that abiotic synthesis of organic compounds, perhaps near volcanoes, could have been a stage in the origin of life
7
Water vapor
“Atmosphere”
Electrode
Condenser
Cold water
Cooled water containing organic molecules
Sample for chemical analysis
H2O “sea”
EXPERIMENT
CH4
8
Electron Configuration
9
Valence
Hydrogen valence = 1
Oxygen valence = 2
Nitrogen valence = 3
Carbon valence = 4
H O N C
10
4 valence
electrons
4 covalent
bonds
Tetravalence
11
Valence Electrons of Carbon
Tetrahedral 12
Name and Comment
Molecular
Formula
(a) Methane
(b) Ethane
•CH4
Ball-and-
Stick Model
Space-Filling
Model
(c) Ethene (ethylene)
•C2H6
•C2H4
Structural
Formula
13
Carbon dioxide CO2
Urea CO(NH2)2
O = C = O
14
Carbon Skeletons & Molecular Diversity
15
Ethane Propane 1-Butene 2-Butene
Double bonds
Rings
Cyclohexane Benzene Butane 2-Methylpropane
(isobutane)
Branching
Length
16
Hydrocarbons
17
•Nucleus
•Fat droplets
(b) A fat molecule (a) Part of a human adipose cell
•10 m
18
Isomers
Structural
Cis-Trans
(Geometric) Enantiomers
19
Isomers
• Isomers are compounds with the same molecular formula but different structures and properties
– Structural isomers have different covalent arrangements of their atoms
– Cis-trans (Geometric) isomers have the same covalent bonds but differ in spatial arrangements
– Enantiomers are isomers that are mirror images of each other
20
Pentane
Structural isomers
Cis-Trans (Geometric)
isomers
2-methyl butane
cis isomer same
trans isomer across
Enantiomers
L isomer D isomer
21
• Enantiomers are important in the pharmaceutical industry
• Two enantiomers of a drug may have different effects
• Usually only one isomer is biologically active
• Differing effects of enantiomers demonstrate that organisms are sensitive to even subtle variations in molecules
22
Dr. George Cotzias 1967
23
Enantiomers
L-dopa D-dopa inactive active
24
Drug
Ibuprofen
Albuterol
Condition
Pain, inflammation
Asthma
Effective Enantiomer
S-Ibuprofen
R-Albuterol
R-Ibuprofen
S-Albuterol
Ineffective Enantiomer
25
The Chemical Groups Most Important in the Processes of Life
• Functional groups are the components of organic molecules that are most commonly involved in chemical reactions
• The number and arrangement of functional groups give each molecule its unique properties
26
Functional groups
Estradiol Testosterone
27
Na+ Na+
Na+
Ca++ Ca++
Ca++
Ca++
28
7 Major Functional Groups
Hydroxyl group
Carbonyl group
Carboxyl group
Amino group
Sulfhydryl group
Phosphate group
Methyl group
29
STRUCTURE
EXAMPLE
Alcohols
-Their specific names usually
end in -ol. (may be written
HO—)
Ethanol
Is polar as a result
of the electrons
spending more
time near the
electronegative
oxygen atom.
Can form hydrogen
bonds with water
molecules, helping
dissolve organic
compounds such
as sugars.
Hydroxyl
30
Carbonyl STRUCTURE
EXAMPLE
Ketones if the carbonyl
group is within a
carbon skeleton
Aldehydes if the carbonyl
group is at the end of the
carbon skeleton
A ketone and an aldehyde may be structural
isomers with different properties, as is the
case for acetone and propanal.
Acetone
Propanal
Ketone and aldehyde groups are also found
in sugars, giving rise to two major groups of
sugars: ketoses (containing ketone groups)
and aldoses (containing aldehyde groups).
31
Carboxyl
Acetic acid
Carboxylic acids (organic acids)
Polar covalent bond
Carboxylate ion (-1)
Acetic acid Acetate ion
32
Amino
Amino acid
Amines
+1 Base
(ionized)
(nonionized)
Glycine
33
Sulfhydryl
Cysteine
S-containing amino acid
Thiols
Cross-linking covalent bonds
Protein shape
34
Phosphate
Chemical reactions
Phospholipid backbone
Glycerol phosphate
Organic phosphates
-2 or -1 charge
35
Methyl
DNA structure
5-Methyl cytidine
Methylated compounds
Gene expression
Hormone function
36
ATP: An Important Source of Energy for Cellular Processes
• One phosphate molecule, adenosine triphosphate (ATP), is the primary energy-transferring molecule in the cell
• ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups
37
ATP
Adenosine triphosphate
Adenosine
38
Adenosine Triphosphate (ATP)
Primary source of chemical potential energy
Powers muscle
contraction, chemical transport, organelle
movement
Adenine, ribose, and 3
phosphate groups
39
40
•Energy P P P P i P P Adenosine Adenosine
ADP ATP
Reacts with H2O
•Energy
41
ATP Cycle
P i ADP +
H2O ATP + ATP
ATP hydrolysis
ATP synthesis
42
43
44