Comprehensive Biology 1330 Study Guide: Cell Biology, Chemistry, Lipids, and Membrane Dynamics

Foundational Principle 1 of Cell Theory

All living organisms are composed of one or more cells.

Foundational Principle 2 of Cell Theory

The cell is the fundamental, structural, and functional unit of life.

Foundational Principle 3 of Cell Theory

All cells arise only from pre-existing cells through cell division.

Molecule

Two or more atoms held together by chemical bonds.

Electronegativity

An atom's inherent capacity to attract shared electrons toward itself within a chemical bond.

Single Covalent Bond

Formed when atoms share exactly 1 pair of electrons (2 total electrons).

Nonpolar Covalent Bond

Formed between two atoms with equal or nearly equal electronegativity; electrons are shared equally between the nuclei.

Polar Covalent Bond

Formed between atoms with significantly different electronegativities; electrons are shared unequally, resulting in partial positive (δ+) and partial negative (δ−) charges.

Ionic Bond

Formed when an atom with high electronegativity completely steals one or more electrons from an atom with low electronegativity, generating oppositely charged ions that attract each other.

Hydrogen Bond

A weak electrostatic attraction between a hydrogen atom covalently bound to a highly electronegative atom (like O or N) and another nearby electronegative atom.

Nonpolar Covalent Bond

Formed between two atoms with equal or nearly equal electronegativity; electrons are shared equally between the nuclei.

Polar Covalent Bond

Formed between atoms with significantly different electronegativities; electrons are shared unequally, resulting in partial positive (δ+) and partial negative (δ−) charges.

Ionic Bond

Formed when an atom with high electronegativity completely steals one or more electrons from an atom with low electronegativity, generating oppositely charged ions that attract each other.

Hydrogen Bond

A weak electrostatic attraction between a hydrogen atom covalently bound to a highly electronegative atom (like O or N) and another nearby electronegative atom.

Valence Electron

An electron occupying the outermost shell of an atom that participates in chemical bonding.

Cation

A positively charged ion created when an atom loses one or more valence electrons.

Anion

A negatively charged ion created when an atom gains one or more valence electrons.

Molecule

Two or more atoms held together by chemical bonds.

Electronegativity

An atom's inherent capacity to attract shared electrons toward itself within a chemical bond.

Single Covalent Bond

Formed when atoms share exactly 1 pair of electrons (2 total electrons).

• Hydrophilic

• : Polar or charged substances that form hydrogen bonds with water and dissolve readily in aqueous solvents

• Hydrophobic

• Nonpolar, uncharged molecules that cannot form hydrogen bonds with water; they coalesce and separate from polar solvents.

• Organic Molecules:

• Must contain both Carbon ($C$) and Hydrogen ($H$) atoms.

• Saturated Fatty Acids:

• Unsaturated Fatty Acids:

• Contain one or more double bonds ($C=C$), introducing double-bond kinks that prevent dense packing, making them liquids (oils) at room temperature.

• Dehydrogenation

• The chemical removal of hydrogen atoms from a lipid, which introduces double bonds (converting a saturated lipid into an unsaturated structure) and alters its physical state at room temperature.

• Structure

• Characterized by a carbon skeleton composed of four fused rings.

• Functions

• Functions: Regulates cell membrane fluidity (cholesterol) and acts as signaling hormones (e.g., estrogen, testosterone).

• Phospholipid

• Composed of one glycerol molecule attached to two fatty acid tails and one negatively charged phosphate group. Unlike neutral fats, phospholipids are amphipathic.