Unit 2 Vocabulary Flashcards

Vocabulary-style flashcards covering key cell biology terms from the lecture notes.

Active Transport

Energy-requiring transport of substances across the cell membrane via transport proteins or pumps.

Apoptosis

Programmed cell death.

Aquaporin

Channel protein that allows water to cross the membrane at a very high rate.

ATP

Adenosine triphosphate; the cell’s main energy currency.

Cell Membrane (Plasma Membrane)

Phospholipid bilayer that encloses the cell and regulates movement of substances.

Cell Wall

Protective layer external to the plasma membrane in plants, prokaryotes, fungi, and some protists.

Centrioles

Rod-like microtubule structures at the center of each animal cell centrosome.

Channel Protein

Membrane protein that forms a pore allowing a substance to pass through the membrane.

Chloroplast

Plant cell organelle that carries out photosynthesis.

Cholesterol

Lipid in the membrane that helps regulate fluidity in response to temperature.

Common Ancestry

Shared ancestral species from which two or more species evolved.

Compartmentalization

Division of a eukaryotic cell into distinct, membrane-bound organelles with specialized functions.

Concentration Gradient

Difference in concentration; area of high concentration adjacent to area of low concentration.

Cytoskeleton

Network of protein fibers that maintains cell shape, positions organelles, and enables movement.

Cytosol

Gel-like fluid of the cytoplasm in which cell structures are suspended.

Diffusion

Passive transport of low-molecular-weight material along its concentration gradient.

Double Membrane

A cellular organelle surrounded by two distinct lipid bilayer membranes.

Endocytosis

Active transport that moves substances into a cell via vesicles.

Endoplasmic Reticulum

Series of interconnected membranous structures that modify proteins and synthesize lipids.

Endosymbiosis

Relationship in which one organism lives inside the cells of another.

Endosymbiotic Theory

Mitochondria and plastids originated as prokaryotic cells engulfed by a host cell.

Eukaryotic Cell

Cell with a membrane-bound nucleus and other membrane-bound compartments.

Exocytosis

Process of bulk material exiting a cell.

Extracellular

Outside of the cell.

Facilitated Diffusion

Passive diffusion of molecules down their electrochemical gradient with help from transport proteins; no energy required.

Flagella

Long, tail-like structure used for cell movement.

Fluid Mosaic Model

Structure of the plasma membrane as a fluid mosaic of lipids, cholesterol, and proteins.

Glycolipid

Carbohydrates attached to lipids; involved in cell-to-cell recognition and adhesion.

Glycoprotein

Carbohydrates attached to proteins; involved in cell recognition and adhesion; may contribute to tissue strength.

Golgi Complex

Organelle that sorts, tags, and packages proteins and lipids for transport.

Heat Exchange

Transfer of thermal energy between parts of an organism or with the environment.

Homeostasis

Maintenance of stable internal conditions.

Hypertonic

Extracellular fluid has higher osmolarity than the cell interior; water moves out.

Hypotonic

Extracellular fluid has lower osmolarity than the cell interior; water moves in.

Integral Protein (Transmembrane Protein)

Protein that is embedded in the membrane and often spans it; removable only by detergents.

Intracellular

Inside the cell.

Ion Pump

Pumps ions against their concentration gradient, requiring energy (ATP).

Isotonic

Extracellular fluid has the same osmolarity as the cell interior; no net water movement.

Lysosome

Membrane-bound sac of hydrolytic enzymes found in animal cells and some protists.

Microscope

Instrument that magnifies small objects using lenses to bend light.

Mitochondria

Organelle responsible for cellular respiration and ATP production.

Necrosis

Uncontrolled cell death due to injury.

Nuclear Envelope

Double membrane surrounding the nucleus.

Nuclear Pores

Channels in the nuclear membrane that regulate transport between nucleoplasm and cytoplasm.

Nucleus

Cellular organelle that houses DNA and directs synthesis of ribosomes and proteins.

Organelle

A subcellular compartment with a specific function.

Osmolarity

Total solute concentration in a solution.

Osmoregulation

Regulation of solute concentrations and water balance by a cell or organism.

Osmosis

Movement of water across a semipermeable membrane down its water gradient due to solutes.

Passive Transport

Transport across a membrane that does not require energy.

Peripheral Protein

Protein located at the surface of the plasma membrane, on either the exterior or interior side.

Phagocytosis

Endocytosis that engulfs large particles; cell eating.

Phospholipid Bilayer

Two-layer arrangement forming the primary structure of a cell membrane; hydrophobic tails inward, hydrophilic heads outward.

Pinocytosis

Endocytosis that engulfs solutes and fluids; cell drinking.

Plasmodesmata

Channel between plant cell walls connecting adjacent cells, allowing transport of materials.

Plasmolysis

Detachment of the cell membrane from the cell wall and membrane constriction when a plant cell is in a hypertonic solution.

Pressure Potential

Component of water potential due to physical pressure; can be positive, zero, or negative.

Prokaryotic Cell

Cell that lacks a nucleus and other membrane-bound organelles.

Ribosome

Ribonucleoprotein complex that synthesizes proteins (composed of RNA and proteins).

Rough ER

Region of the endoplasmic reticulum studded with ribosomes; involved in protein modification and phospholipid synthesis.

SA:V Ratio

Surface area to volume ratio of a cell; affects exchange with the environment.

Selectively Permeable

Membrane that allows some substances to pass while restricting others.

Smooth ER

Region of the ER lacking ribosomes; synthesizes carbohydrates, lipids, and steroid hormones; detoxifies chemicals and stores calcium.

Sodium Potassium Pump

Ion pump that moves Na+ and K+ against their gradients, using ATP.

Solute

Substance dissolved in a solvent.

Solute Potential

Component of water potential related to solute concentration; can be zero or negative.

Solution

Homogeneous mixture of solute dissolved in solvent.

Solvent

The dissolving medium in a solution.

Subcellular Components

Individual organelles within a cell.

Tonicity

Overall solute concentration of a solution relative to another solution.

Turgor Pressure

Pressure exerted by water against the plant cell wall due to osmosis.

Vacuole

Membrane-bound sac for storage and transport; larger in plant cells.

Vesicle

Small membrane-bound sac that stores and transports materials; can fuse with membranes of ER and Golgi.

Water Potential

Potential energy of water in a solution relative to pure water under standard conditions.