Chapter 4 - Carbon and the Molecular Diversity of Life Flashcards
Living organisms consist mostly of ______-_____ compounds.
- carbon-based Proteins
- DNA
- carbohydrates
- molecules that distinguish living matter are all composed of carbon compounds.
Organic chemistry
the study of compounds that contain carbon.
Most organic compounds contain ________ atoms in addition to carbon atoms.
hydrogen
Vitalism
the idea that organic compounds arise only in organisms, was disproved when chemists synthesized these compounds. Stanley Miller’s classic experiment demonstrated the abiotic synthesis of organic compounds.
Mechanism
the view that all natural phenomena are governed by physical and chemical laws
With four valence electrons, carbon can form ____ covalent bonds with a variety of atoms.
four. Carbon is unparalleled in its ability to form large, complex, and diverse molecules.
In molecules with multiple carbons, each carbon bonded to four other atoms has a ____________ shape.
tetrahedral 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. They can vary by:
- Length
- Branching
- Double bond position
- Presense of rings
Hydrocarbons
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.
Isomers
compounds with the same molecular formula but different structures and properties.
Structural isomers
Isomers that have different covalent arrangements of their atoms.

Cis-trans isomers (Geometric Isomers)
Isomers that have the same covalent bonds but differ in spatial arrangements. (On different sides than before)
- Cis isomer: The two Xs
are on the same side. - Trans isomer: The two Xs
are on opposite sides.

Enantiomers
are isomers that are mirror images of each other. Usually only one isomer is biologically active. Differing effects of enantiomers demonstrate that organisms are sensitive to even subtle variations in molecules.
Functional groups
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:
- Hydroxyl group
- Carbonyl group
- Carboxyl group
- Amino group
- Sulfhydryl group
- Phosphate group
- Methyl group
Hydroxyl
- Name of Compound: Alcohols (names usually end in -ol)
- Functional Properties:
- 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

Carbonyl
- Name of Compound:
- Ketones if the carbonyl group is within a carbon skeleton.
- Aldehydes if the carbonyl group is at the end of the carbon skeleton.
- Functional properties:
- A keytone and an aldehyde may be structural isomers with different properties, as in the case for acetone and propanal.
- Keytone 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)

Carboxyl
- Name of compound: Carboxlic acids, or organic acids
- Functional properties:
- Acts as an acid; can donate an H+ because the covalent bond between oxygen and hydrogen is so polar.
- Found in cells in the ionized form with a charge of 1- and called a carboxylate ion.

Amino
- Name of compound: Amines
- Functional properties:
- Acts as a base; can pick up an H+ from the surrounding solution (water, in living organisms).
- Found in cells in the ionized from with a charge of 1+

Sulfhydryl
- Name of compound: Thiols
- Functional properties:
- Two sulfhydryl groups can react, forming a covalent bond. This “cross-linking” helps stabilize protein structure.
- Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair.

Phosphate
- Name of compound: Organic phosphates
- Functional properties:
- Contributes negative charge to the molecules of which it is a part (2- when at the end of a molecule and 1- when located internally in a chain of phosphates.
- Molecules containing phosphate groups have the potential to react with water, releasing energy.

Methyl
- Name of compound: Methylated compounds
- Functional properties:
- Addition of a methyl group to DNA, or to molecules bound to DNA, affects the expression of genes
- Arrangement of methyl groups in male and female sex hormones affects their shape and function

adenosine triphosphate (ATP)
- A phosphate molecule that is the the primary energy-transferring molecule in the cell
- consists of an organic molecule called adenosine attached to a string of three phosphate groups
