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Carbon and the Molecular Diversity of Life - Coggle Diagram
Carbon and the Molecular Diversity of Life
Organic Chemistry is Key to Origin of Life
Organic chemistry is the study of compounds that contain carbon, regardless of origin
Organic compounds range from simple molecules to colossal ones
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
The overall percentages of the major elements of life—C, H, O, N, S, and P—are quite uniform from one organism to another
Because carbon can form four bonds, these building blocks can be used to make an inexhaustible variety of organic molecules
The great diversity of organisms on the planet is due to the versatility of carbon
CONCEPT 4.2: Carbon atoms can form diverse molecules by bonding to four other atoms
Electron configuration is the key to an atom’s chemical characteristics
Electron configuration determines the kinds and number of bonds an atom will form with other atoms
The Formation of Bonds with Carbon
With four valence electrons, carbon can form four covalent bonds with a variety of atoms
This enables carbon to form large, complex molecules
In molecules with multiple carbons, each carbon bonded to four other atoms has a tetrahedral shape
However, when two carbon atoms are joined by a double bond, the atoms joined to the carbons are
in the same plane as the carbons
Carbon chains form the skeletons of most organic molecules
Carbon chains vary in length and shape
Hydrocarbons
Hydrocarbons are organic molecules consisting of only carbon and hydrogen
Many organic molecules, such as fats, have hydrocarbon components
Hydrocarbons can undergo reactions that release a large amount of energy
The number of unpaired electrons in the valence shell of an atom is generally equal to its valence, the number of covalent bonds it can form
The electron configuration of carbon gives it covalent compatibility with many different elements
The most frequent bonding partners of carbon are hydrogen, oxygen, and nitrogen
Carbon Atoms can form diverse molecules by bonding to four other atoms
A few chemical groups are key to molecular function
Distinctive properties of organic molecules depend on the carbon skeleton and the chemical groups attached to it
These groups help give each molecule its unique properties
The Chemical Groups Most Important in the Processes of Life
Estradiol and testosterone are both steroids with
a common carbon skeleton, in the form of four fused rings
These sex hormones differ only in the chemical groups attached to the rings of the carbon skeleton
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
The seven functional groups that are most important in the chemistry of life are the following:
Hydroxyl group
Carbonyl group
Carboxyl group
Amino group
Sulfhydryl group
Phosphate group
Methyl group
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 isomers (also called geometric isomers) have the same covalent bonds but differ in their spatial arrangements
Enantiomers are isomers that are mirror images of each other
ATP: An Important Source of Energy for Cellular Processes
The Chemical Elements of Life: A Review
The versatility of carbon makes possible the great diversity of organic molecules
Variation at the molecular level lies at the foundation of all biological diversity on our planet
An important organic phosphate is adenosine triphosphate (ATP)
ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups
ATP stores the potential to react with water
This reaction releases energy that can be used by the cell
Key Terms
Organic vs Inorganic
Organic: Compounds that contain carbon bonded to hydrogen (C–H bonds), often found in living organisms.
Inorganic: Compounds that generally do not contain C–H bonds (e.g., salts, metals, water).
Rule for # of Hydrogens per Carbons
General rule: Hydrocarbons follow CₙH₂ₙ₊₂ (alkanes) if all single bonds. Double/triple bonds reduce hydrogen count.
Alcohol
Organic compound containing a hydroxyl group (-OH) attached to a carbon.
Isomers
Compounds with the same molecular formula but different structures or properties.
Cis vs Trans (Geometric Isomers)
Cis: Substituents on the same side of a double bond.
Trans: Substituents on opposite sides of a double bond.
Effects of Double Bonds on Carbon Chains
Introduce rigidity (no free rotation), cause bends/kinks in chains, and influence molecule shape & function.
Structural Isomers
Isomers with different covalent arrangements of atoms.
Enantiomers
Definition: Mirror-image, non-superimposable isomers.
Example: L-glucose vs D-glucose (same formula, different handedness).
Methyl Group (-CH₃)
Definition: Functional group that affects activity and expression.
Example: DNA methylation → affects gene expression without changing sequence.
Amino Group (-NH₂)
Definition: Acts as a base; part of amino acids.
Example: Glycine (NH₂–CH₂–COOH), the simplest amino acid.
Carboxyl Group (-COOH)
Definition: Acidic group, donates H⁺.
Example: Acetic acid (CH₃COOH), main acid in vinegar.
Hydroxyl Group (-OH)
Definition: Polar group, makes molecules hydrophilic.
Example: Sugars like glucose have many -OH groups.
Hydroxyl Group (-OH)
Definition: Polar group, makes molecules hydrophilic.
Example: Sugars like glucose have many -OH groups.
ADP (Adenosine Diphosphate)
Definition: ATP after losing one phosphate; lower energy.
Example: ADP + P → ATP during cellular respiration.
