Unit 2 Vocabulary

Comprehensive vocabulary flashcards defining essential terms related to cell structure, cellular transport, and cell biology for Unit 2.

Active Transport

The movement of molecules across a cell membrane from a region of lower concentration to higher concentration against the concentration gradient, requiring cellular energy (such as ATP).

Centrosome

A cellular structure that functions as the main microtubule-organizing center in animal cells and plays a critical role in coordinating the mitotic spindle during cell division.

Compartmentalization

The organization of a eukaryotic cell's interior into distinct, membrane-bound organelles, allowing specialized metabolic processes to occur efficiently in isolated environments.

Diffusion

The passive net movement of particles or solutes from an area of higher concentration to an area of lower concentration down a concentration gradient.

Endosymbiosis

The evolutionary theory proposing that eukaryotic organelles, such as mitochondria and chloroplasts, originated as free-living prokaryotes that were engulfed by an ancestral host cell.

Facilitated Diffusion

The passive transport of specific molecules or ions across a biological membrane via transmembrane transport proteins, moving down a concentration gradient without energy expenditure.

Hydrolytic Enzymes

Enzymes that break chemical bonds within macromolecules by the addition of water (hydrolysis), commonly packaged inside lysosomes to degrade waste and foreign materials.

Hypertonic

A solution that has a higher concentration of solutes (and lower water potential) compared to another solution or the internal environment of a cell, causing water to exit the cell.

Hypotonic

A solution that has a lower concentration of solutes (and higher water potential) compared to another solution or the internal environment of a cell, causing water to enter the cell.

Nucleoid

The irregularly shaped, non-membrane-enclosed region within a prokaryotic cell where the primary genetic material (DNA) is concentrated.

Osmosis

The net diffusion of water molecules across a selectively permeable membrane from a region of higher water potential (lower solute concentration) to a region of lower water potential (higher solute concentration).

Plasmodesmata

Microscopic open channels traversing the cell walls of adjacent plant cells that enable the direct transport of substances and communication between their cytoplasms.

Surface Area:Volume

The mathematical relationship between a cell's outer surface area and its internal volume, which constrains maximum cell size and influences the efficiency of nutrient and waste exchange.

Thylakoid

A flattened, membrane-bound sac inside a chloroplast that contains photosynthetic pigments (such as chlorophyll) and serves as the site for the light-dependent reactions of photosynthesis.

Water Potential

The physical property that predicts the direction of water movement, determined by solute concentration and physical pressure, with water moving spontaneously from higher to lower potential.