Chapter 2: The Chemistry of Life

Vocabulary flashcards covering key concepts, terms, and definitions from the notes on the chemistry of life.

Major Elements

Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N) make up about 96% of the body’s mass (O 65%, C 18%, H 10%, N 3%).

Oxygen (O)

65% of body mass; a major element in life.

Carbon (C)

18% of body mass; key element in organic compounds.

Hydrogen (H)

10% of body mass; abundant in water and organic molecules.

Nitrogen (N)

3% of body mass; essential in amino acids and nucleic acids.

Mineral Elements

Seven minerals that make up less than 4% of body mass: Na, K, Ca, Cl, Mg, P, S.

Sodium (Na)

Key extracellular cation; helps maintain osmotic balance.

Potassium (K)

Key intracellular cation; essential for nerve impulses and muscle function.

Calcium (Ca)

Structural in bones; important in signaling and muscle contraction.

Chlorine (Cl)

Major extracellular anion; helps maintain osmotic balance.

Magnesium (Mg)

Cofactor for many enzymes; stabilizes ATP.

Phosphorus (P)

Component of nucleotides, DNA, RNA, and ATP; part of bone.

Sulfur (S)

Found in certain amino acids (cysteine, methionine).

Trace Elements

Thirteen essential elements in small amounts (includes Fe, Cu, I, Zn).

Iron (Fe)

Key for oxygen transport (hemoglobin, myoglobin) and enzyme cofactors.

Copper (Cu)

Cofactor for enzymes; involved in iron metabolism.

Iodine (I)

Essential for thyroid hormone production.

Zinc (Zn)

Important for many enzymes and gene expression.

Atomic Structure

Atoms consist of protons and neutrons in the nucleus and electrons in orbitals.

Ionic Bond

Electrical attraction between oppositely charged ions formed by transfer of electrons.

Covalent Bond

Bond formed by sharing electrons between atoms.

Hydrogen Bond

Weak attraction between polar molecules; important in water and proteins.

Properties of Water

Water is a universal solvent with high heat capacity and cohesive properties essential for life.

Acids and Bases

Acids donate protons; bases accept protons; salts and electrolytes conduct electricity in solution.

Catabolic Reactions

Larger substances are broken down into smaller ones (AB → A + B).

Exchange Reactions

Atoms/electrons transferred between reactants (AB + CD → AD + BC).

Anabolic Reactions

Form new chemical bonds; build larger molecules (A + B → AB).

Enzyme

Biological catalyst that speeds up reactions; highly specific for substrates.

Active Site

Region of an enzyme where the substrate binds; not permanently altered after reaction.

Tay-Sachs Disease

Deficiency of hexosaminidase; accumulation of gangliosides in brain; often fatal by age ~3.

SCID (Severe Combined Immunodeficiency)

Severe immune system deficiency; ADA deficiency; requires sterile environment or gene therapy.

Phenylketonuria (PKU)

Deficiency of phenylalanine hydroxylase; buildup of phenylalanine; seizures; managed by diet.

Dehydration Synthesis

Links two monomers by removing a water molecule.

Hydrolysis

Splits a polymer by adding a water molecule.

Monomer

Single subunit that can be joined to build larger structures.

Polymer

Large molecule composed of many monomers linked together.

Monosaccharide

Simple sugar; 3–7 carbon atoms; examples include glucose, fructose, galactose; also ribose and deoxyribose.

Disaccharide

Two monosaccharides linked by dehydration synthesis; examples: sucrose, lactose.

Polysaccharide

Long chains of monosaccharides; plants store starch; animals store glycogen.

Glycoprotein

Carbohydrate attached to a protein; helps cell recognition and communication.

Glycolipid

Carbohydrate attached to a lipid; involved in cell recognition.

Glucose

Primary monosaccharide fuel for cells (C6H12O6).

Lipids

Compounds mainly of carbon, hydrogen (and some oxygen); include fats, phospholipids, steroids; used as fuel and membrane components.

Fatty Acids

Hydrocarbon chain with a carboxyl group; can be saturated or unsaturated.

Saturated Fat

No double bonds between carbons; typically solid at room temperature; animal fats.

Monounsaturated Fat

One double bond between carbons; usually liquid at room temperature (plant oils).

Polyunsaturated Fat

Two or more double bonds; generally liquid at room temperature (plant and fish oils).

Omega-3 Fats

Essential fatty acids; found in flaxseed oil and fish oil; beneficial for heart health.

Trans-Fats

Hydrogenated unsaturated fats; no safe consumption level; raises heart disease risk.

Triglycerides

Three fatty acids linked to glycerol; main storage form of fats.

Phospholipids

Glycerol backbone, two fatty acids, and a phosphate; amphipathic; main component of cell membranes.

Amphiphilic

Molecules with both polar (hydrophilic) and nonpolar (hydrophobic) parts.

Cholesterol

Steroid nucleus; precursor to bile acids and steroid hormones; part of membranes.

Steroids

Lipids with a four-ring structure (includes cholesterol derivatives and hormones).

Proteins

Polymers of amino acids; essential for structure, enzymes, signaling, and more; about 20% of body mass.

Amino Acids

21 standard amino acids; central carbon bonded to H, amino group, carboxyl group, and an R group.

Peptide

Bonded amino acids forming dipeptides, tripeptides, and polypeptides (via peptide bonds).

Peptide Bond

Covalent bond joining amino acids.

Globular Protein

Compact, generally water-soluble proteins (enzymes, hormones, messengers).

Fibrous Protein

Long, insoluble proteins; structural roles (hair, nails, tendons, bones).

Protein Denaturation

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

DNA

Deoxyribonucleic acid; double helix; sugar is deoxyribose; bases A, G, C, T; stores genetic code.

RNA

Ribonucleic acid; single strand; sugar is ribose; bases A, G, C, U; transports genetic information for protein synthesis.

Purines

Double-ring bases: Adenine (A) and Guanine (G).

Adenine

Purine base; pairs with Thymine in DNA and with Uracil in RNA.

Guanine

Purine base; pairs with Cytosine in DNA and RNA.

Pyrimidines

Single-ring bases: Cytosine (C), Thymine (T), Uracil (U).

Cytosine

Pyrimidine base; pairs with Guanine.

Thymine

Pyrimidine base in DNA; pairs with Adenine.

Uracil

Pyrimidine base in RNA; replaces Thymine.

Nucleotides

Monomers of nucleic acids; a nitrogenous base, a five-carbon sugar, and a phosphate group.

Adenosine Triphosphate (ATP)

Primary energy currency of the cell; formed from ADP and Pi; energy released by hydrolysis; replenished with oxygen.

ADP (Adenosine Diphosphate)

Precursor to ATP; combines with Pi to form ATP.

Deoxyribose

Five-carbon sugar in DNA.

Ribose

Five-carbon sugar in RNA.