Chapter Review: Biochemistry and pH

Flashcards covering water properties, acid-base chemistry, pH/pOH, carbon, biomolecules, isomers, functional groups, and polarity from the chapter notes.

What is hydrogen bonding and is it a true bond or an interaction?

Hydrogen bonding is an interaction between a hydrogen atom covalently bonded to a highly electronegative atom (like N or O) and another electronegative atom; it is not a true covalent bond but an intermolecular interaction.

How does hydrogen bonding relate to water’s high specific heat?

Many hydrogen bonds between water molecules require a relatively large amount of energy to break, contributing to water’s high specific heat.

Define specific heat in the context of a substance like water.

The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree Celsius.

What does amphoteric mean in relation to water?

A substance that can act as either an acid or a base depending on what is dissolved in it (water can do this).

How is an acid defined in this lecture?

An acid donates a proton (H+) in water.

How is a base defined in this lecture?

A base accepts a proton (OH-) in water.

What does pH measure?

The negative logarithm of the hydrogen ion concentration, indicating how acidic or basic a solution is.

What does it mean for a solution to be neutral in terms of pH?

A neutral solution has equal concentrations of H+ and OH−, resulting in a pH of about 7.

How does changing [H+] affect pH and acidity?

Higher concentration [H+] yields a lower pH (more acidic); lower concentration [OH-] yields a higher pH (more basic).

What happens when hydrochloric acid (HCl) is placed in water?

HCl dissociates into H+ and Cl−, increasing the concentration of protons in solution.

Why is water considered amphoteric besides acids and bases?

Water can donate protons (act as an acid) or accept protons (act as a base), depending on what is present in the solution.

Why is CO2 related to acidity in rain and water bodies?

CO2 dissolves in water to form carbonic acid, making rain and water slightly acidic and affecting ecosystems.

Why is carbon described as tetravalent?

Carbon can form four covalent bonds, enabling complex, diverse organic structures.

What are hydrocarbons and why are they important in biology and energy?

Hydrocarbons are compounds composed of carbon and hydrogen; they are fuels and, when combusted with oxygen, produce CO2 and H2O and energy.

What are the four major biomolecule classes mentioned?

Proteins, carbohydrates, lipids, and nucleic acids.

What is the basic structure of an amino acid?

An alpha carbon attached to an amino group, a carboxyl group, a hydrogen, and a side chain (R group).

What is a functional group and why is it important?

A group of atoms responsible for characteristic chemical reactions and properties (e.g., solubility) of molecules.

What are isomers, and what are the three main types?

Isomers are molecules with the same formula but different arrangements; structural isomers, geometric isomers, and enantiomers.

What is an enantiomer?

A pair of molecules that are non-superimposable mirror images of each other.

How do polar and nonpolar functional groups differ in terms of solubility?

Polar groups containing O or N bonded to H (or to electronegative atoms) are typically water-soluble (hydrophilic); long sequences of C-C or C-H bonds are nonpolar and tend to be water-insoluble (hydrophobic).

What is the amino acid backbone, and what determines the identity of an amino acid?

Backbone consists of the alpha carbon, amino group, and carboxyl group; the side chain (R group) determines the specific amino acid.

How do polarity and hydrophobicity relate to amino acids with nonpolar vs polar side chains?

Nonpolar side chains (mostly C and H) are hydrophobic; polar side chains (containing O, N, or S with O-H or N-H groups) are hydrophilic and interact with water.

What is the role of carbon and its bonds in the formation of biomolecules?

Carbon’s ability to form four bonds allows the creation of complex biomolecules (carbohydrates, proteins, lipids, nucleic acids) via carbon–carbon and carbon–hydrogen chemistry.