AP Biology Unit 2: Cell Structure and Function

30 vocabulary flashcards covering cell structure, organelles, membranes, and transport based on the Unit 2 lecture notes.

Prokaryotic cells

Cells belonging to Bacteria and Archaea that are generally smaller and lack membrane-bound organelles.

Peptidoglycan

The material that composes the cell wall in most bacteria.

Nucleoid

The region in a prokaryotic cell where the continuous, circular DNA molecule is found, not enclosed by a nucleus.

Compartmentalization

The use of internal membranes in eukaryotic cells to create regions with distinct conditions such as pH, enzymes, and ion concentrations.

Nucleolus

The visible structure inside the nucleus where rRNA is produced and ribosome subunits begin assembly.

Bound ribosomes

Ribosomes attached to the rough ER that often make proteins destined for secretion, membranes, or certain organelles.

Rough ER (RER)

A portion of the endoplasmic reticulum studded with ribosomes that serves as a major site for synthesizing, folding, and modifying proteins.

Smooth ER (SER)

A portion of the endoplasmic reticulum that lacks ribosomes and synthesizes lipids, metabolizes carbohydrates, detoxifies drugs, and stores calcium ions.

Golgi apparatus

An organelle that modifies, processes, and sorts products from the ER and distributes them into vesicles for specific destinations.

Lysosomes

Membrane-bound sacs containing digestive enzymes that break down debris or old organelles and work best in an acidic interior.

Turgor pressure

The physical pressure generated by the plant cell's central vacuole against the cell wall to support the plant and aid growth.

Cristae

The folds of the inner mitochondrial membrane that create internal regions for energy conversion into ATP.

Thylakoids

Internal membranes in chloroplasts, often stacked as grana, that perform photosynthesis.

Peroxisomes

Specialized compartments that break down fatty acids and detoxify substances, converting byproduct $H_2O_2$ into water and oxygen.

Microtubules

Hollow tubes made of tubulin that are important in cell division, intracellular transport, and the structure of cilia and flagella.

Microfilaments

Thin rods made of actin that allow for cell movement, muscle contraction, and changes in cell shape.

Plasmodesmata

Channels in plant cell walls that connect neighboring cells and allow for communication and transport.

Surface area-to-volume ratio (SA:V)

A ratio that decreases as a cell's volume grows faster than its surface area, limiting the efficiency of material exchange.

Amphipathic

A property of molecules, such as phospholipids, having both a hydrophilic head and a hydrophobic tail.

Fluid mosaic model

A description of the plasma membrane as a patchwork of lipids, proteins, and carbohydrates where parts can move laterally.

Transmembrane proteins

Integral proteins that span the entire lipid bilayer of the plasma membrane.

Cholesterol

A lipid in animal cells that buffers membrane fluidity across varying temperatures.

Facilitated diffusion

A form of passive transport where membrane proteins help move substances down their concentration gradient without using energy.

Aquaporins

Water-specific channel proteins that increase the permeability of the plasma membrane to water.

Plasmolysis

The process where the plasma membrane pulls away from the cell wall in a plant cell due to water loss in a hypertonic environment.

Water potential ($\Psi$)

A quantitative measure of the potential energy of water compared with pure water, influenced by solute concentration and pressure.

Solute potential ($\Psi_s = -iCRT$)

A component of water potential that decreases (becomes more negative) as solute concentration increases.

Secondary active transport

The movement of a substance against its gradient using energy stored in an ion gradient created by primary active transport.

Receptor-mediated endocytosis

The specific uptake of material using clathrin-lined pits that invaginate when a ligand binds to its receptor.

Endosymbiotic theory

The theory that mitochondria and chloroplasts originated as prokaryotes that formed a mutualistic relationship within a host cell.