Campbell Biology Chapter 5: The Working Cell Flashcards

Vocabulary flashcards covering membrane structure, transport mechanisms, cell bioenergetics, and enzyme function based on Chapter 5 lecture notes.

Fluid mosaic model

A model describing plasma membrane structure as diverse protein molecules suspended in a fluid phospholipid bilayer.

Selective permeability

A property of biological membranes that allows some substances to cross more easily than others.

Transport proteins

Membrane proteins that allow specific ions or molecules to enter or exit the cell.

Attachment proteins

Membrane proteins that attach to the extracellular matrix (ECM) and cytoskeleton to help support the membrane and coordinate external and internal changes.

Receptor proteins

Membrane proteins bound by signaling molecules that relay messages by activating other molecules inside the cell.

Junction proteins

Membrane proteins that form intercellular junctions attaching adjacent cells.

Glycoproteins

Proteins with attached sugars that serve as ID tags recognized by membrane proteins of other cells.

Passive transport

The diffusion of particles across a cell membrane down their concentration gradient without requiring energy investment.

Diffusion

The tendency of particles to spread out evenly in an available space.

Osmosis

The diffusion of water across a selectively permeable membrane.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water.

Hypertonic solution

A solution with a higher solute concentration than the cell, causing animal and plant cells to lose water and shrink or plasmolyze.

Hypotonic solution

A solution with a lower solute concentration than the cell, causing cells to gain water, swell, and potentially lyse animal cells while making plant cells turgid.

Isotonic solution

A solution with an equal solute concentration relative to the cell, leaving animal cells normal and plant cells flaccid.

Facilitated diffusion

Passive transport of polar or charged substances across a membrane down their concentration gradient with the help of specific transport proteins.

Aquaporin

A protein channel that enables the very rapid diffusion of water into and out of certain cells.

Active transport

The movement of a solute across a cell membrane against its concentration gradient, requiring the expenditure of energy, typically supplied by ATP.

Sodium-potassium pump

An active transport mechanism that pushes $3\,Na^+$ out of the cell and brings $2\,K^+$ inside the cell using ATP.

Exocytosis

A cellular transport mechanism used to export bulky molecules, such as proteins or polysaccharides, out of a cell via vesicles that fuse with the plasma membrane.

Endocytosis

A transport process by which a cell takes in large molecules or particles by packaging them in vesicles derived from the plasma membrane.

Phagocytosis

A type of endocytosis where a cell engulfs a particle by wrapping its cell membrane around it, forming a food vacuole.

Receptor-mediated endocytosis

A type of endocytosis that uses membrane receptors to bind and take in specific solute molecules.

Energy

The capacity to cause change.

Kinetic energy

The energy of motion.

Potential energy

Energy stored in the location or structure of matter, including chemical energy.

Exergonic reaction

A chemical reaction that releases energy.

Endergonic reaction

A chemical reaction that requires an input of energy and yields products rich in potential energy.

Metabolism

The totality of a cell's chemical reactions.

Enzymes

Biological catalysts that decrease the activation energy barrier needed for a reaction to begin, without being consumed by the reaction.

Active site

The specific region of an enzyme where a substrate molecule fits and undergoes a catalytic cycle.

Competitive inhibitor

A molecule that reduces an enzyme's productivity by blocking substrate molecules from entering the active site.

Noncompetitive inhibitor

A molecule that binds to an enzyme at a site other than the active site, changing the enzyme's shape so that the active site no longer fits the substrate.

Feedback inhibition

A metabolic control method in which the final product of a pathway allosterically binds to and inhibits the enzyme catalyzing the first reaction in the pathway.

Metabolic pathway

A linked series of chemical reactions occurring within a cell, where each reaction is catalyzed by a specific enzyme and the product of one serves as the substrate for the next.