Chapter 2 – Chemistry of Life

Question-and-answer flashcards covering atoms, water properties, macromolecules, metabolism, enzymes, pH, and other chemistry of life topics for Chapter 2.

What is the smallest stable unit of matter?

An atom.

How does an ion differ from a neutral atom?

Ions are charged (electron gain/loss); neutral atoms have equal protons/electrons.

Define an element.

Pure substance, one atom type.

What is a molecule?

Atoms held by covalent bonds.

What distinguishes a compound from a molecule?

A molecule of two or more different elements.

List the four important properties of water for the human body.

Lubrication, solvent, high heat capacity, and chemical reactant.

Name the four basic categories of biological macromolecules.

Carbohydrates, lipids, proteins, and nucleic acids.

What is metabolism?

All chemical reactions in the body.

Why are enzymes crucial to metabolism?

Specific catalysts that speed up metabolic reactions.

Arrange the levels of structural organization in the human body from simplest to most complex.

Chemical, cellular, tissue, organ, organ system, organism.

Matter has mass and occupies space. What are its three physical states?

Solid, liquid, and gas.

Which subatomic particles are found in an atom’s nucleus?

Protons and neutrons.

How many natural elements exist, and how many total elements are listed in the periodic table?

92 naturally; 118 total.

Which four elements are most abundant in human body tissues?

Oxygen, carbon, hydrogen, and nitrogen.

What is an electrolyte?

Inorganic substance dissolved ions conduct electricity.

Give an example of a biologically important electrolyte.

Sodium chloride (NaCl).

How is a cation formed?

Atom loses electrons; gains positive charge.

How is an anion formed?

By an atom gaining one or more electrons, resulting in a negative charge.

What is a non-polar molecule?

Equal electron sharing, no charge separation.

Describe a polar molecule.

Unequal electron sharing, creates poles.

What does amphipathic mean?

Both polar and non-polar regions.

Define an acid in aqueous solution.

Releases H+, lowering pH.

Define a base in aqueous solution.

removes hydrogen ions, often releasing hydroxide ions (OH-), raising pH.

What pH value is considered neutral?

pH 7.

What is the function of a buffer system in the body?

To resist changes in pH by absorbing excess H+ or OH- ions.

Differentiate metabolites from nutrients.

Metabolites: broken down in the body, nutrients: obtained from the diet.

State the key difference between inorganic and organic molecules.

Organic contain carbon and hydrogen; inorganic do not.

What reaction links monomers to form polymers?

Dehydration synthesis.

What reaction breaks polymers into monomers?

Hydrolysis.

Match each monomer with its macromolecule: monosaccharide, fatty acid, amino acid, nucleotide.

Monosaccharide → carbohydrate; fatty acid → lipid; amino acid → protein; nucleotide → nucleic acid.

What is the elemental ratio for carbohydrates?

Carbon, hydrogen, and oxygen in a 1:2:1 ratio.

Which monosaccharide is the primary metabolic fuel in humans?

Glucose.

What polysaccharide do humans store in muscle and liver as an energy reserve?

Glycogen.

List three major functions of lipids in the body.

Energy storage, structural components of cell membranes, and chemical messengers.

Name the lipid class that includes triglycerides, diglycerides, and monoglycerides.

Glycerides.

What lipid type forms the structural framework of cell membranes along with proteins?

Phospholipids (and glycolipids).

Approximately what percentage of an adult’s body weight is protein?

About 20 percent.

How many different amino acids build human proteins?

Twenty.

Name the four levels of protein structure in order.

Primary, secondary, tertiary, quaternary.

What feature gives enzymes their specificity?

shape of the active site that binds to substrates.

What are the two types of nucleic acids?

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

Which sugar is found in DNA and which in RNA?

DNA contains deoxyribose; RNA contains ribose.

Which nitrogenous base is present in RNA but not in DNA?

Uracil.

What is the primary function of DNA?

To store genetic information that controls protein synthesis.

What is the role of RNA in the cell?

To perform protein synthesis as directed by DNA.

Proteins are polymers made up of what monomers?

Amino acids.

All organic compounds in the body contain carbon, hydrogen, and oxygen. Which element listed in the quiz is NOT common to all?

Calcium.

How are phospholipids best described with respect to polarity?

Amphipathic molecules.

Identify the molecule that is NOT organic: protein, water, glucose, cholesterol, or DNA.

Water.