The Chemistry of Life (Chapter 2)

Flashcards cover key concepts from Chapter 2: The Chemistry of Life, including atomic structure, bonds, water properties, mixtures, biomolecules, metabolism, and nucleic acids.

What are the four major biochemistry macromolecules studied in life sciences?

Carbohydrates, lipids, proteins, and nucleic acids.

What is biochemistry useful for?

Understanding cellular structures, basic physiology, nutrition, and health.

How is a chemical element identified?

By its atomic number, which equals the number of protons in the nucleus.

How are elements arranged in the periodic table?

By atomic number; symbols are 1–2 letters.

What does atomic mass roughly equal?

The total number of protons and neutrons in the nucleus.

What are the three basic subatomic particles?

Protons, neutrons, and electrons.

What determines an atom's chemical bonding properties?

Valence electrons in the outermost shell.

What is the nucleus composed of?

Protons and neutrons.

What does it mean for an atom to be electrically neutral?

The number of electrons equals the number of protons.

What is the Bohr planetary model primarily used for?

A schematic of energy levels and electron arrangement; not a fully accurate structure.

Which shell is the valence shell?

The outermost energy level of an atom.

What is an isotope?

An element variant differing in the number of neutrons.

Do isotopes have the same chemical behavior?

Yes; they have the same chemical behavior but different masses.

What is radioactivity?

Unstable isotopes that decay and emit radiation.

What is the standard unit of radiation dose?

The sievert (Sv).

Name a pioneer who coined 'radioactivity' and studied polonium and radium.

Marie Curie.

What is an ion?

A charged particle with unequal numbers of protons and electrons.

What is the Octet Rule?

Atoms tend to have eight electrons in their valence shell.

What is an anion?

An atom that gains electrons, resulting in a negative charge.

What is a cation?

An atom that loses electrons, resulting in a positive charge.

What happens in the formation of NaCl?

Sodium donates an electron to chlorine, forming Na+ and Cl−.

Where are cations and anions located on the periodic table?

Cations are on the left; anions on the right of the staircase line.

What is an electrolyte?

A substance that ionizes in water and conducts electric current.

Give an example of an electrolyte.

Sodium chloride (NaCl) or calcium chloride (CaCl2).

What are free radicals?

Unstable, highly reactive particles with unpaired electrons.

What enzyme converts superoxide to oxygen and hydrogen peroxide?

Superoxide dismutase (SOD).

What is an ionic bond?

Attraction between a cation and an anion with electron transfer.

What is a covalent bond?

Atoms share one or more pairs of electrons.

What is a nonpolar covalent bond?

Electrons are shared equally.

What is a polar covalent bond?

Electrons are shared unequally, creating partial charges.

What is electronegativity?

An atom's tendency to attract bonded electrons; increases with more protons.

How does electronegativity change down a group?

It decreases due to more electron shells and greater distance from the nucleus.

What are Van der Waals forces?

Weak, brief attractions between neutral atoms; important in physiology (e.g., protein folding, hydrogen bonds).

What are hydrogen bonds?

A weak attraction between a slightly positive hydrogen and a slightly negative atom (O or N) in another molecule.

What are the key properties of water?

Solvency, adhesion, cohesion, chemical reactivity, and thermal stability.

Why is water called the universal solvent?

Because it dissolves more substances than any other solvent.

What are hydration spheres?

Water shells around ions that facilitate dissolution.

What is adhesion?

Tendency of water to cling to other substances (e.g., membranes).

What is cohesion?

Tendency of water molecules to cling to each other via hydrogen bonds.

What is chemical reactivity in water?

Water ionizes into H+ and OH− and participates in hydrolysis and dehydration synthesis.

What is water's thermal stability?

Water resists temperature changes due to hydrogen bonding and high heat capacity.

What is a solution?

A mixture where solute particles are <1 nm, do not scatter light, pass through membranes, and do not separate on standing.

What is a colloid?

A mixture with particles 1–100 nm; scatters light and appears cloudy; does not pass through membranes.

What is a suspension?

A mixture with particles >100 nm; cloudy and separates on standing.

What is an emulsion?

Suspension of one liquid in another that tends to separate.

What does molarity measure?

Number of moles of solute per liter of solution.

What units are common for body fluids?

Millimolar (mM) and milliequivalents per liter (mEq/L).

What is pH?

The negative logarithm of the hydrogen ion concentration.

What is neutral pH?

pH 7.0.

What is the normal blood pH range?

Approximately 7.35 to 7.45.

What are buffers?

Solutions that resist changes in pH.

What is metabolism?

All chemical reactions in the body; includes catabolism and anabolism.

What is catabolism?

Energy-releasing decomposition reactions that break covalent bonds.

What is anabolism?

Energy-storing synthesis reactions that build larger molecules.

What is oxidation?

Loss of electrons; part of redox reactions.

What is reduction?

Gain of electrons; part of redox reactions.

What are organic macromolecules?

Carbohydrates, lipids, proteins, nucleic acids.

Why is carbon versatile?

Carbon has four valence electrons and can form four covalent bonds, creating diverse structures.

What are functional groups?

Groups such as hydroxyl, amino, carboxyl, phosphate, and methyl that impart properties to molecules.

What are monomers and polymers?

Monomers are small units that join to form polymers; polymerization often via dehydration synthesis.

What does dehydration synthesis produce?

Water is produced when monomers join to form polymers.

What is hydrolysis?

Splitting a polymer into monomers by the addition of water.

What are the three important monosaccharides?

Glucose, galactose, and fructose; all have formula C6H12O6.

Which sugars are components of RNA and DNA?

Ribose (RNA) and deoxyribose (DNA).

What are disaccharides and examples?

Sugars formed from two monosaccharides; examples: sucrose (glucose+fructose), lactose (glucose+galactose), maltose (glucose+glucose).

What are polysaccharides and examples?

Long chains of monosaccharides; glycogen, starch, cellulose.

What are the five primary lipid types in the body?

Fatty acids, triglycerides, phospholipids, eicosanoids, steroids.

What is a triglyceride?

Three fatty acids linked to glycerol; main energy storage lipid.

What makes phospholipids amphipathic?

Two hydrophobic fatty acid tails and a hydrophilic phosphate head.

What are eicosanoids?

20-carbon signaling molecules derived from arachidonic acid, including prostaglandins.

What is cholesterol's role in biology?

A steroid precursor essential for membranes and nervous system function; largely synthesized in liver.

What is HDL?

High-density lipoprotein; 'good' cholesterol; lower lipid-to-protein ratio.

What is LDL?

Low-density lipoprotein; 'bad' cholesterol; higher lipid-to-protein ratio.

What are the four levels of protein structure?

Primary, secondary, tertiary, and quaternary structures.

What stabilizes protein tertiary structure?

Hydrophobic/hydrophilic interactions and disulfide bridges between cysteine residues.

What is denaturation?

Extreme conformational change that destroys protein function (often reversible with mild conditions but can be irreversible with heat/pH).

What is a conjugated protein?

A protein bound to a non-amino acid prosthetic group (e.g., heme in hemoglobin).

What is an enzyme?

A protein that acts as a biological catalyst by lowering activation energy.

What is the active site?

The region of the enzyme where the substrate binds.

What is the induced fit model?

Enzyme and substrate binding induces conformational changes to improve the fit.

What is a cofactor?

Nonprotein partner required for some enzymes; can be inorganic ions or organic coenzymes.

What is NAD+ used for?

Cofactor that accepts electrons during glycolysis and aerobic respiration.

What is ATP?

Adenosine triphosphate; the body's primary energy-transfer molecule.

What happens when ATP is hydrolyzed?

ATP → ADP + Pi + energy; energy used for cellular work.

What is glycolysis?

First stage of glucose oxidation producing two pyruvate and a small amount of ATP.

What determines whether pyruvate becomes lactate or enters aerobic respiration?

Oxygen availability.

What are nucleic acids?

Polymers of nucleotides; include DNA and RNA.

What are DNA and RNA base-pairing rules?

DNA: A pairs with T (two hydrogen bonds); C pairs with G (three hydrogen bonds). RNA uses A–U pairing.

What sugar is in DNA and RNA?

DNA uses deoxyribose; RNA uses ribose.