Choristry of Life: Lipids, Cell Membranes, Proteins, Nucleic Acids, and Cellular Processes

A comprehensive set of vocabulary flashcards covering lipids, membranes, proteins, nucleic acids, ATP, and major organelles and processes described in the lecture notes.

Lipids

Large, diverse group of insoluble organic molecules (in water) including fats, phospholipids, and steroids; roles in energy storage, protection, and insulation.

Triglycerides

Most abundant lipid; consists of glycerol backbone with three fatty acid chains; primary energy storage molecule.

Glycerol

Three-carbon backbone for fatty acids in triglycerides.

Fat

Lipid that is solid at room temperature; saturated fats have only single bonds and are from animal sources; unsaturated fats have double bonds and are from plant sources.

Unsaturated fatty acid

Fatty acid with at least one carbon–carbon double bond; typically bent and liquid at room temperature. ex: olive oil

Saturated fatty acid

Fatty acid with only single bonds between carbons; straight chains and typically solid at room temperature. ex: cheese

Phospholipid

Structural unit of cell membranes with a glycerol backbone, two fatty acids, and a phosphate group; polar hydrophilic head and nonpolar hydrophobic tails.

Phospholipid bilayer

Two-layer membrane with polar heads facing water and nonpolar tails inward; forms the cell membrane.

Polar head

Hydrophilic region of a phospholipid that faces aqueous environments.

Nonpolar tail

Hydrophobic region of a phospholipid that faces inward, away from water.

Cholesterol

Steroid molecule interspersed among phospholipids; regulates membrane fluidity and serves as a precursor for steroid hormones.

Steroids

Lipids with a ring structure including cholesterol, bile salts, estrogen, and testosterone; regulators and membrane components.

Protein

Large biomolecule with specific structure and function; built from amino acids; 20 standard amino acids with 9 essential ones.

Amino acid

Building block of proteins; contains amino group, carboxyl group, and a variable side chain (R).

Peptide bond

Covalent bond linking amino acids during protein synthesis.

Nucleic acids

Polymers of nucleotides; contain a five-carbon sugar, nitrogenous bases, and a phosphate group; include DNA and RNA.

ATP (Adenosine Triphosphate)

Energy currency of the cell; fuels endergonic reactions and drives cellular processes.

Adenosine

Nucleoside component of ATP (adenine + ribose) involved in energy transfer.

Ribose

Five-carbon sugar found in RNA and in ATP's ribose portion.

Plasma membrane

Membrane surrounding the cell; defines boundaries and regulates molecule passage; embedded proteins and lipids form a phospholipid bilayer.

Glycocalyx

Carbohydrate-rich outer surface formed by glycolipids and glycoproteins; involved in cell recognition.

Fluid mosaic model

Model of the cell membrane as a dynamic, fluid structure with diverse proteins floating in a phospholipid bilayer.

Semipermeable

Membrane property that allows some substances to pass while restricting others.

Phospholipids

Major membrane component; amphipathic molecules with polar heads and nonpolar tails.

Glycolipid

carbohydrate attached to a phospholipid; part of the glycocalyx and cell recognition.

Glycoprotein

Carbohydrate attached to a membrane protein; part of the glycocalyx and cell signaling.

Marker molecules

Glycoproteins and glycolipids that identify cells and mediate recognition and communication.

Cadherins

Attachment proteins that connect cells to other cells.

Integrins

Integral proteins that attach cells to extracellular molecules; participate in cell signaling.

Passive transport

Membrane transport that does not require ATP; follows concentration gradient; includes diffusion and osmosis.

Osmosis

Diffusion of water across a semipermeable membrane from high to low water potential.

Diffusion

Movement of molecules from high to low concentration; may occur with or without a membrane.

Facilitated diffusion

Diffusion aided by transport proteins (channel or carrier); may involve gating and specificity.

Channel protein

Membrane protein forming a pore for ion passage; can be gated (ligand, voltage, mechanical) or nongated.

Ligand-gated channel

Channel opens in response to binding of a specific molecule (ligand).

Voltage-gated channel

Channel opens in response to changes in membrane potential.

Mechanically-gated channel

Channel opens in response to mechanical stretch or pressure.

Carrier proteins

Transport proteins that change shape to move substances across the membrane; include uniporters, symporters, and antiporters.

Uniporter

Carrier that transports a single type of particle across the membrane.

Symporter

Carrier that moves two different substances in the same direction.

Antiporter

Carrier that moves two substances in opposite directions.

Cytoplasm

Cellular material inside the cell membrane but outside the nucleus; includes cytosol, cytoskeleton, and organelles.

Cytosol

Fluid portion of cytoplasm; dissolves ions and small molecules.

Cytoskeleton

Network of protein filaments (microtubules, microfilaments, intermediate filaments) supporting cell shape and movement.

Microtubules

Hollow tubules made of tubulin; internal scaffold and tracks for transport and cell division.

Microfilaments

Actin filaments; provide shape and enable movement; support microvilli.

Intermediate filaments

Filaments providing mechanical strength to cells.

Nucleus

membrane-bound organelle containing DNA; includes nuclear envelope, nucleolus, and nucleoplasm; regulates gene expression.

Nucleolus

Nuclear region where ribosomal RNA synthesis and ribosome assembly begin.

Nuclear pores

Openings in the nuclear envelope regulating transport between nucleus and cytoplasm.

Chromosome

DNA-protein structure; 46 chromosomes in humans (23 pairs); chromatin condenses into chromosomes during division; centromere links sister chromatids.

Chromatin

DNA wrapped around proteins; less condensed form of genetic material in the nucleus.

Ribosome

Ribonucleoprotein complex that synthesizes proteins; consists of large and small subunits; can be free or attached to rough ER.

Endoplasmic reticulum (ER)

Membrane network; rough ER has ribosomes for protein synthesis; smooth ER synthesizes lipids, carbohydrates, and detoxification.

Golgi apparatus

Flatted membrane sacs that modify, package, and direct proteins and lipids to their destinations.

Secretory vesicles

Vesicles that carry and release substances outside the cell via exocytosis.

Lysosome

Digestive organelle formed from secretory vesicles; contains enzymes for waste processing.

Mitochondrion

Site of cellular respiration and ATP production; double membrane with cristae and matrix; contains own DNA and replicates independently.

Cristae

Folds of the inner mitochondrial membrane that increase surface area for respiration.

Matrix

Fluid inside the mitochondrion where metabolic reactions occur.

Cilia

Short, hair-like projections that move substances across cell surfaces (e.g., in respiratory tract). Beat with power and recovery strokes.

Flagella

Long, whip-like projection used to propel cells (one per cell in humans, e.g., sperm).

Sodium-Potassium Pump (Na+/K+ ATPase)

Active transporter that pumps Na+ out and K+ in; maintains cell membrane potential.

Endocytosis

Process of taking substances into the cell by engulfing them with the plasma membrane; includes phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Exocytosis

Process of vesicles fusing with the plasma membrane to release contents outside the cell.

Phagocytosis

Cell eating; ingestion of large particles via endocytosis.

Pinocytosis

Cell drinking; uptake of extracellular fluid and dissolved solutes via endocytosis.

Receptor-mediated endocytosis

Endocytosis triggered by specific receptors binding to ligands, enabling selective uptake.

Transcription

Synthesis of RNA from a DNA template; RNA polymerase creates mRNA; ends at a terminator sequence.

Translation

Synthesis of a polypeptide on a ribosome using mRNA as the template and tRNA as amino acid carriers.

mRNA

Messenger RNA; carries genetic code from DNA to ribosome for protein synthesis.

tRNA

Transfer RNA; delivers specific amino acids to the ribosome during translation and contains an anticodon.

Central dogma

Flow of genetic information: DNA -> RNA -> Protein.

Replication (semiconservative)

DNA duplication in which each new double helix contains one old strand and one new strand.

Nucleoplasm

Fluid inside the nucleus surrounding the chromatin and nucleolus.