Chapter 2: The Chemistry of Life

A set of practice flashcards covering the key concepts from Chapter 2: The Chemistry of Life, including atomic structure, chemical bonds, mixtures, pH and buffers, organic macromolecules, energy, and basic metabolic processes.

What are the four major elements found in the human body?

Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N).

Describe the charge, mass, and relative location of electrons, protons, and neutrons.

Protons are positively charged and reside in the nucleus; neutrons are neutral and in the nucleus; electrons are negatively charged with negligible mass and orbit the nucleus in the electron cloud.

What is the nucleus of an atom composed of?

Protons and neutrons.

What is the atomic number?

The number of protons in an atom; it equals the number of electrons in a neutral atom and determines the element’s identity.

What is the mass number?

The sum of protons and neutrons in the nucleus.

How are isotopes defined?

Forms of the same element that have the same number of protons and electrons but different numbers of neutrons.

What is a radioisotope?

An unstable isotope that decays to a more stable form by emitting radiation.

Differentiate between a solution, a suspension, and a colloid.

Solution: uniform distribution; solute dissolved in solvent. Suspension: large particles that settle out. Colloid: small particles that remain dispersed and do not settle.

Define solvent and solute.

Solvent is the substance that dissolves the solute; solute is the substance being dissolved.

What does solubility mean?

The ability of one substance to dissolve in another.

What is concentration? Give examples.

The amount of solute in a solution; expressed as percent, mg/dL, molarity, etc. Examples: 5% dextrose (D5W), 70% ethanol, 8.5 g NaCl per liter of solution.

Describe an ionic bond.

A bond formed by transfer of electrons from one atom to another, creating oppositely charged ions (e.g., NaCl).

Name the main types of covalent bonds.

Nonpolar covalent (equal sharing of electrons), Polar covalent (unequal sharing), Hydrogen bonds (weak intermolecular forces), Van der Waals forces (weak transient attractions).

What is a hydrogen bond and why is it important?

A weak attraction between a slightly positive hydrogen atom and a slightly negative atom (usually O or N); crucial for water properties and three-dimensional folding of large molecules like DNA and proteins.

What is a macromolecule?

A very large molecule composed of many monomers linked by covalent bonds.

Name the four main types of biological macromolecules and their monomers.

Carbohydrates (monosaccharides), Lipids (fatty acids and glycerol), Proteins (amino acids), Nucleic acids (nucleotides).

What are the major classes and functions of carbohydrates?

Carbohydrates provide energy and can be stored as glycogen; they are hydrophilic due to polar C–O bonds.

What are the major lipid classes and their roles?

Triglycerides (energy storage, protection, insulation), Phospholipids (membrane structure), Steroids (hormones and membrane components), Cholesterol (membrane fluidity and precursor to steroids).

What are amino acids, and why are proteins diverse in function?

Amino acids are the monomers of proteins; their R groups determine properties and protein shape, leading to diverse functions like catalysis, transport, and defense.

What are nucleotides and nucleic acids?

Nucleotides are the monomers; nucleic acids (DNA and RNA) store and transmit genetic information and direct protein synthesis.

What is the difference between DNA and RNA bases?

DNA uses adenine, thymine, cytosine, and guanine; RNA uses adenine, uracil, cytosine, and guanine.

What is ATP and why is it important?

Adenosine triphosphate (ATP) is the primary energy currency of the cell; ATP hydrolysis provides energy for cellular work.

What is dehydration synthesis and hydrolysis?

Dehydration synthesis links monomers by removing a water molecule to form a polymer; hydrolysis breaks polymers by adding water, splitting into monomers.

What are enzymes and cofactors?

Enzymes are proteins that speed up reactions by lowering activation energy and are highly specific; cofactors (inorganic ions or organic molecules) assist enzyme activity.

What is the effect of pH on biological systems and what does a buffer do?

pH measures acidity; physiologic pH is ~7.40. Buffers resist pH changes by neutralizing excess acids or bases (e.g., bicarbonate, phosphate, proteins).

What are electrolytes and why are they important?

Electrolytes are dissociated cations and anions in water that conduct electricity and are essential for nerve, muscle function, and fluid balance.

What is the difference between a solvent and a solute in a solution?

The solvent dissolves the solute; the solute is what is dissolved.

Explain the concept of 'Like dissolves like' in water chemistry.

Water (a polar solvent) dissolves solutes that are hydrophilic or polar; hydrophobic substances do not readily dissolve.

What are the three types of chemical reactions described, and what do they do?

Synthesis (anabolism) forms bonds to create larger molecules; Decomposition (catabolism) breaks bonds to form smaller pieces; Exchange reactions involve transfer of atoms or electrons between reactants; oxidation-reduction reactions involve electron transfer.

What is the role of oxidation-reduction reactions in metabolism?

They generally release energy as electrons are transferred from one substance to another.

What are the levels of protein structure and why is shape important?

Primary (amino acid sequence), Secondary (alpha helix or beta-pleated sheet via H bonds), Tertiary (3D folding), Quaternary (assembly of multiple polypeptides). Shape determines function.

What is complementary base pairing in DNA?

A pairs with T, and C pairs with G.

Where are DNA and RNA located and what is their general function?

DNA stores genetic information; RNA interprets and helps build proteins; both are found in the nucleus and cytosol.

Where is glycogen stored and what is its function?

Glycogen is stored mainly in the liver and skeletal muscles and serves as a rapid energy reserve.