Essential Cell Biology: Protein Structure and Function

Vocabulary practice flashcards covering fundamental protein structure and function concepts from Chapter 4 of Essential Cell Biology.

Enzymes

Proteins that catalyze covalent bond breakage or formation to accelerate chemical reactions in cells.

Structural Proteins

Proteins that provide mechanical support to cells and tissues.

Transport Proteins

Proteins that carry small molecules or ions across cell membranes or throughout organisms.

Motor Proteins

Proteins that generate mechanical movement in cells and tissues, such as muscle contraction and organelle transport.

Storage Proteins

Proteins whose primary function is to store amino acids or ions for later cellular use.

Signal Proteins

Proteins that carry extracellular signals from cell to cell to coordinate cellular responses.

Receptor Proteins

Proteins that detect signals outside the cell and transmit them inward to the cell's response machinery.

Transcription Regulators

Proteins that bind directly to DNA to switch specific genes on or off.

Peptide

A short polymer chain composed of amino acids, usually containing fewer than approximately 50 amino acid residues.

Side Chain (R-Group)

The variable chemical group attached to the alpha-carbon of an amino acid that determines its identity and unique chemical properties.

Peptide Bond

The covalent chemical bond formed between the carboxyl group of one amino acid and the amino group of another via a condensation reaction with the removal of water.

Nonpolar Amino Acids

Hydrophobic amino acids with nonpolar side chains that tend to be packed into the interior hydrophobic core of folded proteins.

Polar Amino Acids

Hydrophilic amino acids with uncharged or charged side chains that tend to arrange on the exterior surface of folded proteins in aqueous environments.

Urea

A chemical denaturing agent with a carbonyl C=O group that acts as an excellent hydrogen bond acceptor, disrupting the hydrogen bonds stabilizing protein structure.

Chaperone Proteins

Specialized helper proteins that assist newly synthesized or partially folded polypeptides in folding correctly along energetically favorable pathways.

Alpha Helix

A common secondary structure formed when the backbone N-H of every peptide bond is hydrogen-bonded to the backbone C=O four residues away, completing a full turn every 3.6 amino acids.

Coiled-Coil Domain

A structural motif formed when two or more alpha helices wrap around one another to bury their hydrophobic side chains away from water.

Beta Sheet

A common secondary structure formed by hydrogen bonding between backbone N-H and C=O groups on adjacent segments or strands of a polypeptide chain.

Amyloid Structure

Insoluble, highly ordered protein aggregates composed of stacked beta sheets that can cause cell damage and neurodegenerative disease.

Quaternary Structure

The multi-subunit protein structure formed by the noncovalent association of two or more individual polypeptide chains.

Disulfide Bonds

Covalent sulfur-sulfur linkages formed by oxidation between cysteine residues that stabilize the conformations of extracellular proteins.

Protein Domain

A segment of a polypeptide chain that can fold independently into a compact, stable, and functionally distinct structure.

Intrinsically Disordered Regions

Unstructured polypeptide segments lacking a fixed 3D shape that flex dynamically to facilitate rapid thermal collisions and protein complex formation.

Ligand

Any molecule that binds specifically and non-covalently to a protein at a specialized binding site.

Antibodies

Y-shaped immunoglobulin proteins produced by B cells that bind with high specificity to target foreign antigens.

B Lymphocytes (B Cells)

White blood cells that present membrane-bound surface antibodies and proliferate to secrete soluble antibodies upon antigen recognition.

Monoclonal Antibodies

Identical antibody molecules produced continuously by hybridoma cells created from the fusion of an antibody-secreting B cell and a tumor cell.