Biochemistry: Energy Pathway and Properties of Water

Flashcards covering the fundamentals of biochemistry, the unique properties of water, pH concepts, and biological buffer systems based on the lecture notes.

Biochemistry

The branch of science that combines biology and chemistry to study the chemical substances and processes that occur in living organisms, focusing on molecules like proteins, carbohydrates, lipids, and nucleic acids.

Polarity

A property of water where oxygen attracts shared electrons more strongly than hydrogen, creating a partial negative charge on oxygen and partial positive charges on hydrogen.

Hydrogen Bonding

Transient bonds formed between water molecules due to polarity; each water molecule can form bonds with up to four neighboring molecules.

Cohesion

The attraction of water molecules to one another through hydrogen bonds, which helps create surface tension.

Adhesion

The attraction of water molecules to other polar surfaces, which works with cohesion to contribute to capillary action.

Capillary Action

The ability of a liquid to move upward or through narrow spaces without the help of gravity, driven by the combined effects of adhesion and cohesion.

High Specific Heat

The ability of water to absorb a large amount of heat with only a small increase in temperature, helping organisms maintain stable internal environments.

High Heat of Vaporization

The property requiring significant energy ($2,260\,J/g$ at boiling point) to change water from liquid to gas, which enables evaporative cooling.

Density Anomaly

The unique behavior of water where the solid phase (ice) is less dense than the liquid phase, cause by an open hexagonal crystal lattice that forms during freezing.

Ice Density

The mass per unit volume of frozen water, which is approximately $0.92\,g/cm^3$ compared to liquid water's $1.00\,g/cm^3$ at $4\,^\circ\text{C}$.

Universal Solvent

A nickname for water describing its proficiency at dissolving many ionic compounds and polar macromolecules due to its strong dipole moment.

Hydrolysis

A chemical reaction in which water is used to break chemical bonds.

Amphoteric Property

The characteristic of water that allows it to act as either an acid or a base depending on the chemical reaction.

Solute

The solid substance that fully dissolves into a liquid to create a solution, such as salt.

Solvent

The liquid used to dissolve a solid, such as water.

pH scale

A logarithmic scale typically ranging from $0$ to $14$ used to measure the hydrogen ion concentration ($H^+$) of a solution, where $pH = -\log_{10}[H^+]$.

Acid

A substance that donates hydrogen ions ($H^+$) or increases the $H^+$ concentration of a solution, resulting in a pH below $7$.

Base

A substance that accepts hydrogen ions ($H^+$) or increases the concentration of hydroxide ions ($OH^-$), resulting in a pH above $7$.

Acid-Base Homeostasis

The body's ability to maintain a stable arterial blood pH between $7.35$ and $7.45$ despite metabolic acid and base production.

Acidosis

A clinical condition where the arterial blood pH falls below $7.35$.

Alkalosis

A clinical condition where the arterial blood pH rises above $7.45$.

Buffer

A system that resists sudden changes in pH when small amounts of acid or base are added, typically consisting of a weak acid and its conjugate base.

Conjugate Base

The particle that remains after an acid donates a hydrogen ion ($H^+$), which is capable of accepting a proton to reform the original acid.

Bicarbonate Buffer System

The primary extracellular buffer system in the blood involving the equilibrium between carbonic acid ($H_2CO_3$) and bicarbonate ($HCO_3^-$).

Phosphate Buffer System

An important buffer system inside cells and in the kidneys consisting of dihydrogen phosphate ($H_2PO_4^-$) and hydrogen phosphate ($HPO_4^{2-}$).

Protein Buffer System

A buffering mechanism where amino acid side chains accept or donate $H^+$ions; hemoglobin is a major example in red blood cells.