Chapter 3: Molecules of Life - Vocabulary Flashcards

Key vocabulary from the notes on carbohydrates, lipids, proteins, and nucleic acids, including structures, components, and functions.

Macromolecule

A large biological molecule such as carbohydrates, lipids, proteins, or nucleic acids; built from smaller subunits.

Carbohydrate

A macromolecule that provides energy and structural support; composed of monosaccharides; primary fuel source for cells.

Monosaccharide

A simple sugar; examples include glucose, fructose, and galactose.

Glucose

A six-carbon monosaccharide (C6H12O6); primary energy source for cells.

Fructose

A six-carbon monosaccharide found in fruits; isomer of glucose.

Galactose

A six-carbon monosaccharide; component of lactose.

Disaccharide

Two monosaccharides linked together (via a glycosidic bond); examples include sucrose, lactose, maltose.

Sucrose

Table sugar; disaccharide composed of glucose and fructose.

Polysaccharide

A carbohydrate polymer composed of many monosaccharide units; examples include starch, cellulose, and glycogen.

Starch

Plant storage polysaccharide made of many glucose units; energy storage in plants.

Cellulose

Structural polysaccharide in plants; provides rigidity; indigestible by humans.

Glycogen

Animal storage polysaccharide; highly branched polymer of glucose.

Fiber

Indigestible carbohydrate that aids digestion and contributes to health; roughage.

Lipid

Nonpolar macromolecule; not soluble in water; major energy storage and components of membranes; includes fats, phospholipids, and sterols.

Triglyceride

Glycerol molecule bound to three fatty acids; primary form of stored fat in animals.

Glycerol

A three-carbon alcohol that forms the backbone of triglycerides.

Fatty acid

Hydrocarbon chains with a carboxyl group; components of triglycerides and phospholipids.

Saturated fat

Fatty acids with no double bonds (fully hydrogenated); straight chains; typically solid at room temperature.

Unsaturated fat

Fatty acids containing one or more double bonds; kinked chains; typically liquid at room temperature.

Trans fat

Hydrogenated fats with trans double bonds; associated with increased heart disease risk.

Phospholipid

Lipid with two fatty acids, a glycerol backbone, and a phosphate group; hydrophilic head and hydrophobic tails; form cell membranes.

Hydrophilic

Water-loving; polar or charged regions that interact with water.

Hydrophobic

Water-fearing; nonpolar regions that do not interact with water.

Sterol

A type of lipid with a four-ring structure; includes cholesterol; precursor for steroid hormones.

Cholesterol

Sterol essential for cell membranes; can contribute to arterial plaque when levels are high.

Steroid hormones

Cholesterol-derived hormones that regulate development, maturation, and metabolism (e.g., estrogen, testosterone).

Estrogen

A steroid hormone that influences sexual development, memory, and mood.

Testosterone

A steroid hormone that stimulates muscle growth and male development.

Amino acid

Organic compounds that are the building blocks of proteins; 20 standard amino acids; 9 are essential.

Peptide bond

Covalent bond linking amino acids in a polypeptide chain.

Essential amino acid

Nine amino acids that must be obtained from the diet because the body cannot synthesize them.

Nonessential amino acid

Amino acids that can be synthesized by the body.

Protein

Macromolecule made of amino acids; diverse functions including structural support, protection, regulation, contraction, and transport.

Primary structure

The linear sequence of amino acids in a polypeptide.

Secondary structure

Local folded structures (α-helix and β-pleated sheet) formed by hydrogen bonds between amino acids.

Tertiary structure

Three-dimensional folding of a single polypeptide; determined by side-chain interactions and solvent.

Quaternary structure

Two or more polypeptide chains held together by interactions between chains.

Denaturation

Loss of a protein's shape and function due to heat, pH change, or other factors.

Nucleic acid

Macromolecule that stores genetic information; includes DNA and RNA; composed of nucleotides.

DNA (Deoxyribonucleic acid)

Nucleic acid with deoxyribose sugar; typically double-stranded; stores genetic information; uses thymine.

RNA (Ribonucleic acid)

Nucleic acid with ribose sugar; usually single-stranded; uses uracil instead of thymine; involved in protein synthesis.

Nucleotide

Nucleic acid subunit consisting of a phosphate group, a sugar, and a nitrogenous base.

Sugar-phosphate backbone

The repeating pattern of sugar and phosphate groups forming the structural framework of DNA and RNA.

Adenine

Purine base; pairs with thymine in DNA and with uracil in RNA.

Thymine

Pyrimidine base; pairs with adenine in DNA.

Guanine

Purine base; pairs with cytosine.

Cytosine

Pyrimidine base; pairs with guanine.

Uracil

Pyrimidine base used in RNA in place of thymine.

Base pair

A complementary pair of nitrogenous bases (A with T or U, and G with C) in nucleic acids.

A-T pairing

Adenine pairs with thymine in DNA (two hydrogen bonds) during base pairing.

RNA function

Acts as a messenger and adaptor, taking genetic instructions from DNA to the ribosome to synthesize proteins.

Food Guide Pyramid

Nutritional guide showing major food groups: grains, vegetables, fruits, milk, meat & beans; approximate daily energy distribution (60% carbs, 15% lipids, 25% proteins).