Cell Biology Vocabulary Review

A comprehensive set of flashcards covering key vocabulary terms related to cell biology, transport mechanisms, and energy metabolism.

Cell theory

A fundamental concept in biology that states all living organisms are composed of cells.

Cell membrane

A biological membrane that separates and protects the interior of all cells from the outside environment.

Phospholipid

A type of lipid molecule that is a major component of cell membranes.

Micelle

An aggregate of surfactant molecules dispersed in a liquid colloid.

Bilayer

A thin polar membrane made of two layers of lipid molecules.

Liposome

A spherical vesicle composed of lipid bilayers.

Cholesterol

A type of sterol that is an essential molecule in cell membrane structure.

Membrane protein

Proteins that interact with, or are part of, biological membranes.

Transporter protein

A protein that moves substances across a cell membrane.

Passive transport

The movement of molecules across a cell membrane without the need for energy.

Active transport

The movement of molecules across a cell membrane using energy.

Receptor protein

A protein that binds to signaling molecules, initiating a cellular response.

Enzyme

A biological catalyst that speeds up chemical reactions in cells.

Anchor protein

A protein that helps to attach the membrane to its surroundings.

Extracellular matrix

A network of proteins and carbohydrates outside of a cell.

Integral membrane protein

A type of protein that is permanently attached to the membrane.

Peripheral membrane protein

A protein that is temporarily attached to the membrane.

Fluid-mosaic model

The model that describes the structure of cell membranes.

Semipermeable

A characteristic of membranes that allows some substances to pass while blocking others.

Diffusion

The passive transport of molecules from an area of high concentration to an area of low concentration.

Solute

A substance that is dissolved in a solution.

Simple diffusion

The process by which solutes move down their concentration gradient through a membrane.

Facilitated diffusion

The process of spontaneous passive transport of molecules across a biological membrane via specific transmembrane integral proteins.

Channel

A protein that forms a pore across the membrane allowing ions or molecules to pass.

Carrier

A protein that binds to molecules and changes shape to shuttle them across the membrane.

Primary active transport

The transport of solutes against their concentration gradient using ATP.

Secondary active transport

The transport of solutes against their gradient by using energy from another gradient.

Antiporter

A type of transporter protein that moves two substances in opposite directions.

Symporter

A transporter protein that moves two substances in the same direction across a membrane.

Sodium-potassium pump

A membrane protein that pumps sodium ions out of and potassium ions into a cell.

Isotonic

A solution with the same solute concentration as another solution.

Hypertonic

A solution that has a higher concentration of solutes compared to another solution.

Hypotonic

A solution that has a lower concentration of solutes compared to another solution.

Turgor pressure

The pressure exerted by fluid in a plant cell's central vacuole against the cell wall.

Endoplasmic reticulum

An organelle that helps in the synthesis of proteins and lipids.

Endomembrane system

A series of membranes within a cell including the nuclear envelope, endoplasmic reticulum, and Golgi apparatus.

Protein sorting

The process by which proteins are directed to their proper destinations in a cell.

Signal sequence

A short peptide present at the N-terminus of the protein that directs the protein to its specific location.

Amino-terminal signal sequence

A type of signal sequence located at the beginning of the protein.

Internal signal sequence

A signal sequence located within the protein that targets it to certain locations within the cell.

Nuclear envelope

A double membrane that surrounds the nucleus in eukaryotic cells.

Nuclear pore

A large protein complex that allows molecules to pass in and out of the nucleus.

Nuclear localization signal

A signal that directs proteins to the nucleus.

Nuclear import receptor

A protein that binds to the nuclear localization signal and facilitates transport into the nucleus.

Protein translocator

A protein complex that facilitates the transport of proteins across a membrane.

Vesicle

A small, membrane-bound sac that transports substances within or outside the cell.

Golgi apparatus

An organelle that modifies, sorts, and packages proteins and lipids for secretion.

Signal recognition particle (SRP)

A ribonucleoprotein that recognizes and targets specific proteins to the membrane.

SRP receptor

A protein that binds to the signal recognition particle at the membrane.

Protease

An enzyme that breaks down proteins by cleaving their peptide bonds.

Signal anchor sequence

A sequence that anchors a protein to a membrane.

Exocytosis

The process of vesicles fusing with the plasma membrane to release their contents outside the cell.

Endocytosis

The process by which cells internalize substances from their external environment.

Phagocytosis

A form of endocytosis where cells engulf large particles.

Pinocytosis

A form of endocytosis where cells ingest liquid and small molecules.

Lysosome

An organelle containing enzymes that break down waste materials.

Endosome

A membrane-bound compartment within the cell that processes material taken up by the cell.

Early endosome

An endosome that is formed shortly after the internalization of material.

Late endosome

An endosome that is involved in the sorting of materials for degradation.

Mitochondria

Organelles known as the powerhouses of the cell that generate ATP.

Catabolism

The breakdown of complex molecules into simpler ones, releasing energy.

Anabolism

The synthesis of complex molecules from simpler ones, requiring energy.

Cellular respiration

The process by which cells convert glucose and oxygen into energy.

Oxidation-reduction (redox)

A chemical reaction that involves the transfer of electrons.

Oxidizing agent

A substance that gains electrons in a redox reaction.

Reducing agent

A substance that loses electrons in a redox reaction.

Substrate-level phosphorylation

The direct synthesis of ATP from ADP during a chemical reaction.

Oxidative phosphorylation

The production of ATP using energy derived from electron transport and the proton gradient.

Electron carriers

Molecules that transport electrons in cellular respiration.

Glycolysis

The metabolic pathway that converts glucose into pyruvate.

Pyruvate oxidation

The process that converts pyruvate into acetyl CoA.

Citric acid cycle

A series of chemical reactions used by all aerobic organisms to generate energy.

Electron transport chain

A series of protein complexes that transfer electrons through redox reactions.

Glucose

A simple sugar that is an important energy source.

Pyruvate

The end product of glycolysis that enters the citric acid cycle.

NADH

An electron carrier that plays a crucial role in cellular respiration.

Fermentation (anaerobic respiration)

A metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen.

Pyruvate dehydrogenase complex

A multi-enzyme complex that converts pyruvate to acetyl CoA.

Acetyl CoA

A key metabolic intermediate that enters the citric acid cycle.

FADH2

An electron carrier produced in the citric acid cycle.

Mitochondrial matrix

The space within the inner membrane of a mitochondrion.

Intermembrane space

The space between the inner and outer membranes of a mitochondrion.

Chemiosmotic coupling

The process of using an electrochemical gradient to drive ATP synthesis.

Complex I (NADH dehydrogenase)

A large enzyme complex that oxidizes NADH and pumps protons into the intermembrane space.

Complex II (succinate reductase)

An enzyme complex in the electron transport chain that oxidizes succinate.

Complex III (cytochrome c reductase)

A protein complex that transfers electrons from ubiquinol to cytochrome c.

Complex IV (cytochrome c oxidase)

The enzyme that transfers electrons from cytochrome c to oxygen.

Final electron acceptor

The molecule that receives electrons at the end of the electron transport chain.

ATP synthase

An enzyme that creates ATP from ADP and inorganic phosphate.

Photosynthesis

The process by which green plants and some other organisms use sunlight to synthesize foods.

Chloroplast

An organelle found in plant cells where photosynthesis occurs.

Thylakoid membrane

Membrane-bound compartments inside chloroplasts and cyanobacteria.

Grana

Stacked thylakoid membranes within chloroplasts.

Stroma

The fluid-filled space surrounding the thylakoids in chloroplasts.

Light dependent

Reactions of photosynthesis that require light energy.

Light independent

Reactions of photosynthesis that do not require light energy.

Chlorophyll

A green pigment found in plants that absorbs light energy.

Photosystem I

A protein complex that absorbs light at 700 nm and facilitates the transfer of electrons.

Photosystem II

A protein complex that absorbs light at 680 nm and initiates the electron transport chain.

NADPH

An electron carrier produced during the light-dependent reactions of photosynthesis.