AP Biology Unit 2 Vocabulary and Concepts

Vocabulary flashcards generated from AP Biology Unit 2 study notes, covering organelles, membrane structure, cell transport mechanisms, and water potential principles.

Active Transport

Method of transporting material that requires energy.

Apoptosis

Programmed cell death.

Aquaporin

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

Cell Wall

A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists.

Centrioles

Rod-like structure consisting of microtubules at the center of each animal cell centrosome.

Channel Protein

Membrane protein that allows a substance to pass through its hollow core across the plasma membrane.

Chloroplast

Plant cell organelle that carries out photosynthesis.

Cholesterol

Regulates membrane fluidity in response to temperature changes.

Common Ancestry

An organism that is the shared ancestral species from which two or more different species evolved.

Compartmentalization

The division of a eukaryotic cell into distinct, membrane-bound organelles, each with specialized functions, allowing different cellular processes to occur simultaneously in separate environments within the cell.

Concentration Gradient

Area of high concentration adjacent to an area of low concentration.

Cytoskeleton

Network of protein fibers that collectively maintain the shape of the cell, secure some organelles in specific positions, allow cytoplasm and vesicles to move within the cell, and enable unicellular organisms to move independently.

Cytosol

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

Diffusion

Passive process of transport of low-molecular weight material according to its concentration gradient.

Double Membrane

A cellular organelle that is surrounded by two distinct lipid bilayer membranes.

Endocytosis

Type of active transport that moves substances, including fluids and particles into a cell.

Endoplasmic Reticulum

Series of interconnected membranous structures within eukaryotic cells that collectively modify proteins and synthesize lipids.

Endosymbiosis

A relationship between two species in which one organism lives inside the cell or cells of another organism.

Endosymbiotic Theory

The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by a host cell, which then evolved into a single organism.

Eukaryotic Cell

Cell that has a membrane-bound nucleus and several other membrane-bound compartments or sacs.

Exocytosis

Process of passing bulk material out of a cell.

Extracellular

Outside of the cell.

Facilitated Diffusion

The passage of molecules or ions down their electrochemical gradient across a membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure.

Flagella

Long hair-like structure that extends from the plasma membrane and is used to move the cell.

Fluid Mosaic Model

Describes the structure of plasma membrane as a mosaic of components including phospholipids, cholesterol, proteins, glycoproteins, and glycolipids (sugar chains attached to proteins or lipids) resulting in a fluid character (fluidity).

Glycolipid

Combination of carbohydrates and lipids; facilitate cell-to-cell recognition and adhesion.

Glycoprotein

Combination of carbohydrates and proteins; allows for cross linking of cells, which gives tissues strength.

Golgi Complex

Eukaryotic organelle made up of a series of stacked membranes that sorts, tags, and packages proteins and lipids for distribution.

Heat Exchange

The transfer of thermal energy between different parts of an organism or between an organism and its environment.

Homeostasis

Ability to maintain equilibrium of appropriate bodily or cellular functions and consistent internal conditions.

Hypertonic

Situation in which extracellular fluid has a higher osmolarity than the fluid inside the cell, resulting in water moving out of the cell.

Hypotonic

Situation in which extracellular fluid has a lower osmolarity than the fluid inside the cell, resulting in water moving into the cell.

Integral Protein (Transmembrane Protein)

Protein integrated into the membrane structure that interacts extensively with the hydrocarbon chains of membrane lipids and often spans the membrane; these proteins can be removed only by the disruption of the membrane by detergents.

Intracellular

Inside of the cell.

Ion Pump

Transports ions against a concentration gradient, requiring the use of energy or ATP.

Isotonic

Situation in which the extracellular fluid has the same osmolarity as the fluid inside the cell, resulting in no net movement of water into or out of the cell.

Lysosome

A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists.

Microscope

A laboratory instrument that allows scientists to observe objects too small to be seen by the naked eye, by magnifying the image using lenses to bend light and make the object appear larger.

Mitochondria

Cellular organelles responsible for carrying out cellular respiration, resulting in the production of ATP, the cell’s main energy-carrying molecule.

Nuclear Envelope

Double-membrane structure that constitutes the outermost portion of the nucleus.

Nuclear Pores

Small channels in the nuclear membrane that facilitate the selective and directional transport of RNA and proteins between the nucleoplasm and the cytoplasm of the cell.

Nucleus

Cell organelle that houses the cell’s DNA and directs the synthesis of ribosomes and proteins.

Organelle

Compartment or sac within a cell.

Osmolarity

Total amount of solutes dissolved in a specific amount of solution; concentration.

Osmoregulation

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

Osmosis

Transport of water through a semi-permeable membrane according to the concentration gradient of water across the membrane that results from the presence of solute that cannot pass through the membrane.

Passive Transport

Method of transporting material through a membrane that does not require energy.

Peripheral Protein

Protein found at the surface of a plasma membrane either on its exterior or interior side.

Phagocytosis

Form of endocytosis that involves the intake of large particles (microorganisms or dead cells) from the extracellular fluid; also known as "cell eating".

Phospholipid Bilayer

Double layer of phospholipid molecules that form the primary structure of a cell membrane, where hydrophobic tails face inwards and hydrophilic heads face outwards, separating the cell's interior from its external environment.

Pinocytosis

Form of endocytosis that involves the intake of solutes and fluid from the extracellular fluid; also known as "cell drinking".

Plasmodesmata

Channel that passes between the cell walls of adjacent plant cells, connects their cytoplasm, and allows materials to be transported from cell to cell.

Plasmolysis

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

Pressure Potential

A component of water potential that consists of the physical pressure on a solution, which can be positive, zero, or negative.

Prokaryotic Cell

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

Ribosome

Cellular structure that carries out protein synthesis, composed of rRNA.

Rough ER

Region of the endoplasmic reticulum that is studded with ribosomes and engages in protein modification and phospholipid synthesis.

SA:V Ratio

The mathematical calculation of a cell's surface area divided by its volume.

Selectively Permeable

Characteristic of a membrane that allows some substances through but not others (also known as semi-permeable).

Smooth ER

Region of the endoplasmic reticulum that has few or no ribosomes on its cytoplasmic surface and synthesizes carbohydrates, lipids, and steroid hormones; detoxifies certain chemicals and stores calcium ions.

Solute Potential

A component of water potential that is proportional to the molarity of a solution and measures the effect of solutes on the direction of water movement; can be zero or negative.

Subcellular Components

The individual structures within a cell, like organelles, that perform specific functions.

Tonicity

Amount of solute in a solution.

Turgor Pressure

The force directed against a plant cell wall after the influx of water and swelling of the cell due to osmosis.

Vacuole

Membrane-bound sac, somewhat larger than a vesicle, which functions in cellular storage and transport.

Vesicle

Small membrane-bound sac that functions in cellular storage and transport; its membrane is capable of fusing with the plasma membrane of the endoplasmic reticulum and Golgi apparatus.

Water Potential

The potential energy of a water solution per unit volume in relation to pure water at atmospheric pressure and ambient temperature.

Inner Membrane Folds

Structural adaptation of cellular organelles that increases the surface area available for cellular processes.

Cell Size and Transport Efficiency

Smaller cells are more efficient at transporting materials because all organelles are closer together due to a higher surface area to volume ratio.