AP Biology Unit 2 Review

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

apoptosis

programmed cell death

aquaporin

A transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane

carrier protein

Transport protein that changes shape when a particle binds with it

cell wall

A rigid layer of nonliving material that surrounds the cells of plants and some other organisms.

centrioles

a minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division.

channel protein

protein that forms a channel to allow a particular molecule or ion to cross the plasma membrane

chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

concentration gradient

difference in the concentration of a substance from one location to another

cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

endocytosis

A process in which a cell engulfs extracellular material through an inward folding of its plasma membrane.

Golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell

hypertonic

when comparing two solutions, the solution with the greater concentration of solutes

hypotonic

when comparing two solutions, the solution with the lesser concentration of solutes

isotonic

when the concentration of two solutions is the same

lysosome

cell organelle filled with enzymes needed to break down certain materials in the cell

nuclear envelope

A double membrane that surrounds the nucleus in the cell

phospholipid

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells

plasmolysis

Collapse of a walled cell's cytoplasm due to a lack of water

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea.

ribosome

site of protein synthesis

rough ER

ER that is dotted with ribosomes

selectively permeable

a property of cell membranes that allows some substances to pass through, while others cannot

smooth ER

ER that has no ribosomes

exocytosis

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

eukaryotic cell

cell that has a nucleus and other membrane-bound organelles

facilitated diffusion

Movement of specific molecules across cell membranes through protein channels

flagella

A long, whip-like filament that helps in cell motility.

fluid mosaic model

Structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer.

nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

organelles

A tiny cell structure that carries out a specific function within the cell

osmosis

Diffusion of water through a selectively permeable membrane

passive transport

the movement of substances across a cell membrane without the use of energy by the cell

phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells

surface area: volume ratio

a variable that decreases as cells grow, so that it sets a limit to the size of cells.

transmembrane protein

integral membrane protein that spans the entire width of a cell membrane

vacuole

Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

endoplasmic reticulum

A cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another.

vesicle

Small membrane-bound sac that functions in moving products into, out of, and within a cell.

endomembrane system

The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.

mitochondria

organelle that is the site of ATP (energy) production; contains a double membrane as well as its own DNA and ribosomes

cholesterol

a lipid that prevents the membrane from becoming too flexible as well as from crystalizing

glycoprotein

A protein with one or more carbohydrates covalently attached to it; found on the exterior portion of the cell membrane for cell signaling

glycolipid

a lipid with one or more covalently attached carbohydrates; found on the exterior portion of the cell membrane for cell signaling

integral protein

a type of membrane protein that is permanently attached to the biological membrane.

peripheral protein

A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer.