Biomolecules Lecture V'ocabulary: Proteins, Nucleic Acids, and Lipids

A set of vocabulary flashcards covering the key terms and definitions from the lecture notes on proteins, nucleic acids, and lipids.

Primary structure

The linear sequence of amino acids in a protein.

Secondary structure

Local folding patterns such as alpha helices and beta sheets stabilized by hydrogen bonds.

Tertiary structure

Three-dimensional shape of a single polypeptide, determined by interactions among side chains.

Quaternary structure

Assembly of multiple polypeptide subunits into a functional protein complex.

Denaturation

Loss of native protein structure and function due to heat or pH changes, breaking noncovalent bonds.

Globular protein

Water-soluble, roughly spherical proteins (e.g., enzymes, hemoglobin).

Fibrous protein

Long, thread-like proteins providing structural support (e.g., collagen, keratin).

Hemoglobin

Quaternary protein made of four subunits; carries oxygen in the blood.

Hydrogen bond

A weak, noncovalent interaction important for stabilizing protein structure and base pairing in nucleic acids.

Enzyme

Protein that acts as a biological catalyst to speed up chemical reactions.

Active site

Region of the enzyme where substrates bind and reaction occurs.

Substrate

Reactant(s) that bind to an enzyme's active site.

Specificity

Enzymes act on specific substrates or types of chemical reactions.

Activation energy

Minimum energy required to start a reaction; enzymes lower this barrier.

ATP

Adenosine triphosphate, the cell’s main energy currency; energy released by hydrolysis of its phosphate bonds.

ADP

Adenosine diphosphate; product of ATP hydrolysis; can be rephosphorylated to ATP.

ATPase

Enzyme that hydrolyzes ATP to release energy.

Creatine phosphate

High-energy phosphate donor in muscle that rapidly regenerates ATP from ADP.

Nucleotide

Monomer of nucleic acids: a sugar, a nitrogenous base, and a phosphate.

Nucleic acid

Polymers of nucleotides; include DNA and RNA.

DNA

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

RNA

Ribonucleic acid; usually single-stranded; sugar is ribose; bases A, C, G, U.

Purine

Two-ring nitrogenous bases: adenine and guanine.

Pyrimidine

Single-ring bases: cytosine, thymine (DNA), uracil (RNA).

Complementary base pairing

A pairs with T (DNA) or U (RNA); C pairs with G.

Double helix

DNA structure of two antiparallel strands wound into a helix with paired bases inside.

Backbone

Sugar–phosphate chain forming the exterior of DNA/RNA.

Phosphodiester bond

Bond linking nucleotides in DNA/RNA.

Phospholipid

Glycerol with two fatty acids and a phosphate group; amphipathic; forms membranes.

Glycolipid

Glycerol with two fatty acids and a carbohydrate; membrane component; amphipathic.

Triglyceride

Glycerol with three fatty acids; main long-term energy storage lipid.

Monoglyceride

Glycerol with one fatty acid.

Diglyceride

Glycerol with two fatty acids.

Saturated fat

Fatty acid chains with only single bonds; straight chains; solid at room temperature.

Unsaturated fat

Fatty acids with one or more carbon–carbon double bonds; kinked; usually liquid.

Essential fatty acids

Fatty acids the body cannot synthesize and must be obtained from the diet.

Acosanoids

Signaling lipids (e.g., prostaglandins, leukotrienes) derived from fatty acids; involved in inflammation and other processes.

Steroid

Lipids with a four-ring structure derived from cholesterol; includes steroid hormones.

Cholesterol

Sterol with four fused rings; component of cell membranes; precursor to steroid hormones.

Steroid hormone

Hormones derived from cholesterol (e.g., testosterone, estrogen, cortisol, aldosterone).

Vitamin D

Steroid hormone derived from cholesterol; important for calcium regulation.

Amphipathic

Molecule with both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

Phospholipid bilayer

Two-layer membrane formed by phospholipids; hydrophilic heads outward, hydrophobic tails inward.

Dehydration synthesis

Reaction that joins monomers with loss of water.

Hydrolysis

Reaction that breaks bonds by adding water.