Proteins and Nucleic Acids (Biomolecules)

Vocabulary flashcards covering key concepts related to proteins and nucleic acids from the lecture.

Amino acids

The 20 different monomer units that make up proteins; each contains an amino group, a carboxyl group, a central carbon, and a variable side chain (R group). They link to form proteins.

Peptide bond

The covalent bond formed by dehydration synthesis linking the carboxyl group of one amino acid to the amino group of the next, releasing a molecule of water.

Polypeptide

A chain of two or more amino acids linked by peptide bonds; the precursor polymer that folds to become a protein.

Primary structure

The linear sequence of amino acids in a polypeptide, which dictates higher-level folding and function.

Secondary structure

Local folding of the polypeptide backbone stabilized by hydrogen bonds, forming structures like alpha helices and beta pleated sheets.

Tertiary structure

The overall three-dimensional folding of a single polypeptide, due to interactions among R groups and the backbone.

Quaternary structure

The arrangement of multiple polypeptide subunits into a functional protein (e.g., hemoglobin).

Enzyme

A protein that acts as a catalyst to lower the activation energy of a chemical reaction and is not consumed in the reaction.

Active site

The region of an enzyme where substrates bind and catalysis occurs.

Substrates

The molecules that bind to an enzyme’s active site and undergo a chemical change during the reaction.

Saturation limit

When all enzyme active sites are occupied by substrates, increasing substrate does not increase the reaction rate.

Cofactors

Non-protein molecules (often inorganic) that assist enzyme activity.

Coenzymes

Organic cofactors that assist enzymes in catalysis.

Denaturation

Loss of enzyme (or protein) structure and function due to heat, extreme pH, or other factors; may be irreversible.

Glycoprotein

A protein bound to carbohydrate; common in mucus, membranes, and many secreted enzymes and antibodies.

Proteoglycan

A large polysaccharide bound to a polypeptide; increases viscosity of fluids and components of the extracellular matrix.

Nucleic acids

Large polymers that store and process genetic information; contain carbon, hydrogen, oxygen, nitrogen, and phosphorus.

Nucleotide

The monomer of nucleic acids; composed of a pentose sugar (ribose or deoxyribose), a phosphate group, and a nitrogenous base.

DNA

Deoxyribonucleic acid; double-stranded molecule that stores genetic information and directs protein synthesis.

RNA

Ribonucleic acid; usually single-stranded; involved in protein synthesis; contains uracil instead of thymine.

Nitrogenous bases

Bases in nucleotides: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U).

Purines

Two-ring bases: adenine (A) and guanine (G).

Pyrimidines

Single-ring bases: cytosine (C), thymine (T), and uracil (U).

Adenine

A purine base (A) that pairs with thymine in DNA and with uracil in RNA.

Guanine

A purine base (G) that pairs with cytosine in both DNA and RNA.

Cytosine

A pyrimidine base (C) that pairs with guanine in DNA and RNA.

Thymine

A pyrimidine base (T) that pairs with adenine in DNA (not present in RNA).

Uracil

A pyrimidine base (U) that pairs with adenine in RNA (replaces thymine in RNA).

Complementary base pairing (DNA)

In DNA, adenine pairs with thymine and cytosine pairs with guanine via hydrogen bonds, forming the double helix.

Complementary base pairing (RNA)

In RNA, adenine pairs with uracil and cytosine pairs with guanine; RNA is typically single-stranded.

Double helix

The characteristic two-stranded, helical structure of DNA formed by base pairing and a sugar–phosphate backbone.

ATP

Adenosine triphosphate; the primary high-energy currency of cells; hydrolysis releases energy that powers cellular processes; ATPase catalyzes phosphate removal.

ADP

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

AMP

Adenosine monophosphate; product after two phosphate removals; lower-energy nucleotide used in cellular energy mechanics.

High-energy compounds

Nucleotides with phosphate groups whose hydrolysis releases energy; includes ATP, ADP, and AMP.