Biochemistry Basics

Study of how molecules in living things interact to maintain and perpetuate life.

Cells without a nucleus or membrane-bound organelles, generally simpler.

Cells with a nucleus and membrane-bound organelles, more complex.

The outermost layer of a bacterial cell that controls the passage of substances.

The process by which plants convert light energy into chemical energy.

The four most abundant elements in living organisms: hydrogen, oxygen, nitrogen, and carbon.

The ability of carbon to form single, double, and triple bonds with other elements, making it versatile for building diverse molecules.

Molecules with the same chemical bonds but different spatial arrangements of atoms, affecting their properties.

A type of interaction where molecules with partial charges attract each other. For example, water molecules form hydrogen bonds with each other.

A substance that dissolves other substances, like salt in water. Water is a good solvent for polar molecules and charged ions.

A molecule that attracts water molecules and readily dissolves in water. Think of sugar or salt dissolving in water.

A molecule that repels water and doesn't dissolve easily in water. Think of oil floating on water.

A region of water near a hydrophobic molecule becomes highly ordered, which lowers the entropy of the system. This is thermodynamically unfavorable, so nonpolar molecules tend to aggregate together to reduce the ordered water molecules.

Weak, non-covalent interactions that occur between all atoms, regardless of their polarity.

An attractive force between two atoms due to temporary fluctuations in their electron distribution.

A repulsive force that prevents atoms from getting too close to each other. It arises from the overlap of electron clouds.

A measure of the acidity or alkalinity of a solution, defined as the negative logarithm of the hydrogen ion concentration.

The product of the concentrations of hydrogen ions (H+) and hydroxide ions (OH-) in water at equilibrium.

A measure of the acidity of a weak acid, defined as the negative logarithm of the acid dissociation constant (Ka). A lower pKa indicates a stronger acid.

An equilibrium constant that indicates the strength of a weak acid. A higher Ka value means a stronger acid.

A solution that resists changes in pH upon the addition of small amounts of acid or base. It consists of a mixture of a weak acid and its conjugate base.

A pair of molecules or ions that are related by the gain or loss of a proton (H+).

Water's special properties arise from its bent molecular shape and strong dipole moment. This allows it to form hydrogen bonds, acting as both a donor and acceptor.

Individually weak but collectively strong, H-bonds are responsible for water's unusually high melting and boiling points and its high surface tension.

In ice, each water molecule forms four hydrogen bonds, creating a rigid, hexagonal lattice. This structure makes ice less dense than liquid water, allowing it to float.

Hydrogen bonds can occur between other molecules containing electronegative atoms like oxygen and nitrogen. These interactions contribute to the stability of biological molecules.

The arrangement of electron pairs around the oxygen atom gives water a bent shape, creating a partial negative charge on oxygen and partial positive charges on the hydrogens.

The difference in electronegativity between oxygen and hydrogen atoms creates a separation of charges within the water molecule.

Water makes up the majority of living organisms and plays a crucial role in biological processes, including transporting nutrients, regulating temperature, and providing a medium for reactions.

The strength of hydrogen bonds is key to their importance in biological systems. While weak individually, their collective effect is substantial, contributing to the stability and function of biomolecules and cellular processes.

Molecules with both polar (water-loving) and nonpolar (water-fearing) regions.

The rapid movement of protons (H+) through a network of hydrogen-bonded water molecules, facilitating proton transfer in solution.

A logarithmic scale that measures the acidity or alkalinity of a solution, defined as the negative logarithm of the hydrogen ion concentration.

A solution containing a weak acid and its conjugate base, which resists changes in pH by absorbing added H+ or OH-.

The fundamental building blocks of proteins, possessing properties that make them suitable for biological roles.

The ability of amino acids to link together to form long chains, creating the backbone of proteins.

The specific chemical group attached to each amino acid, responsible for its unique properties.

Use of UV light absorption to quantify and characterize aromatic amino acids, especially tryptophan and tyrosine.

The pH at which an amino acid has zero net charge, resulting in minimal solubility and absence of migration in an electric field.

Amino acids and peptides can act as buffers due to the presence of ionizable groups, such as amino and carboxyl groups. The pKa values of these groups determine their ionization state at different pH levels.