Lecture 2 - The Chemistry of Life (Test Prep)

What is matter?

Anything that takes up space and has mass; composed of elements.

Define mass and weight.

Mass = amount of matter; Weight = heaviness due to gravity on mass.

What is chemistry?

The study of composition, properties, and interactions of matter.

What is biochemistry?

The study of chemical processes in living organisms and disease.

What is an element?

The simplest form of matter with unique chemical properties (e.g., O, H).

What is a compound?

A chemical combination of two or more different elements.

What is an atom?

The smallest unit of an element that retains its properties.

What are bulk, trace, and ultratrace elements?

Bulk: Needed in large amounts (C, H, O, N, S, P)

Trace: Needed in small amounts (Fe, I)

Ultratrace: Needed in minute amounts (As)

Name the subatomic particles and their charges.

Proton: +1 charge

Neutron: neutral

Electron: −1 charge

What makes an atom electrically neutral?

Equal numbers of protons and electrons.

Define atomic number and mass number.

Atomic number = # of protons

Mass number = protons + neutrons

What are isotopes?

Variants of the same element with different numbers of neutrons.

What are radioisotopes?

Unstable isotopes that emit radiation as they decay.

Give examples of radiation types.

Alpha particles, beta particles, gamma rays, X-rays, UV radiation.

Define molecule and compound.

Molecule = 2+ atoms chemically bonded

Compound = atoms of different elements bonded

What are the 3 types of chemical bonds?

Ionic, covalent, and hydrogen bonds.

What is an ionic bond?

Attraction between oppositely charged ions.

Define cation and anion.

Cation = positive ion (loses electrons)

Anion = negative ion (gains electrons)

What is a covalent bond?

Bond formed by sharing electrons between atoms.

Differentiate between polar and nonpolar covalent bonds.

Nonpolar: Electrons shared equally (H₂).

Polar: Electrons shared unequally (H₂O).

What is a hydrogen bond?

Weak attraction between slightly positive H and slightly negative O/N in nearby molecules.

What are mixtures?

Substances physically blended but not chemically combined.

Name the three types of mixtures.

Solution: Solute dissolved in solvent (e.g., salt water).

Colloid: Cloudy, protein–water mixture (e.g., cytoplasm).

Suspension: Particles settle on standing (e.g., blood cells in plasma).

What is the universal solvent?

Water.

What are reactants and products?

Reactants: Starting materials

Products: Substances formed after reaction

Name the 4 types of chemical reactions.

Synthesis (A + B → AB)

Decomposition (AB → A + B)

Exchange (AB + CD → AD + CB)

Reversible (A + B ↔ AB)

What are electrolytes?

Substances that release ions in water and conduct electricity.

Define acids, bases, and salts.

Acids: Release H⁺ in water.

Bases: Combine with H⁺ or release OH⁻.

Salts: Formed by reaction between acid and base.

What is the pH scale?

Measures hydrogen ion concentration from 0–14.

What pH values are acidic, neutral, and basic?

Acidic: <7

Neutral: 7

Basic: >7

What is a buffer?

A solution that resists pH changes.

What is the normal blood pH?

7.35–7.45

Define acidemia and alkalemia.

Acidemia: pH 7.0–7.3 (fatigue, confusion)

Alkalemia: pH 7.5–7.8 (dizziness, agitation)

What makes a molecule organic?

Contains carbon and hydrogen.

What are examples of inorganic molecules?

Water, oxygen, carbon dioxide, salts.

Why is water important?

It’s the most abundant compound in the body and medium for metabolic reactions.

What are carbohydrates used for?

Main source of energy and building materials.

What elements do carbohydrates contain?

C, H, and O (ratio 2:1 for H:O).

Name 3 types of carbohydrates.

Monosaccharides: Glucose, fructose

Disaccharides: Sucrose, lactose

Polysaccharides: Glycogen, starch, cellulose

What are lipids and their properties?

Hydrophobic molecules that store energy and make up membranes.

What are triglycerides made of?

1 glycerol + 3 fatty acids.

What are phospholipids made of?

Glycerol, 2 fatty acids, and a phosphate group.

What is the main steroid in the body?

Cholesterol.

Difference between saturated and unsaturated fats?

Saturated: Single bonds, solid, animal origin.

Unsaturated: Double bonds, liquid, plant origin.

What are proteins made of?

Amino acids linked by peptide bonds.

What are peptide bonds?

Bonds between amino and carboxyl groups of amino acids.

What are the four levels of protein structure?

Primary – amino acid sequence

Secondary – coils/sheets via H bonds

Tertiary – 3D shape

Quaternary – multiple polypeptides together

What is denaturation?

Loss of protein shape (and function) due to heat, pH, or chemicals.

What are the building blocks of nucleic acids?

Nucleotides (sugar + phosphate + base).

What are the two types of nucleic acids?

DNA and RNA.

What is metabolism?

The sum of all chemical reactions in the body.

Define anabolism and catabolism.

Anabolism: Builds molecules; requires energy.
Catabolism: Breaks molecules; releases energy.

What is dehydration synthesis?

Joins molecules by removing water.

What is hydrolysis?

Breaks molecules using water.

What is an enzyme?

A protein catalyst that speeds up reactions without being consumed.

What is the enzyme–substrate complex?

The temporary binding of enzyme and substrate during a reaction.

What are cofactors and coenzymes?

Cofactor: Non-protein activator (ions or molecules).

Coenzyme: Organic cofactors (often vitamins).

What is enzyme denaturation?

Enzyme loses shape and cannot function due to heat or pH change.