Chapter 3 Flashcards
Cell membrane
The thin covering that forms the outer boundary of a cell and that is composed primarily of phospholipids and proteins; see also fluid mosaic model.
Selectively permeable membrane
A membrane that only
certain molecules can pass through.
Passive transport
The movement of substances across a
cell membrane without the use of cellular energy.
Diffusion
A form of passive transport in which molecules move from an area of higher concentration to an area of lower concentration.
Osmosis
The diffusion of water through a selectively permeable membrane.
Active transport
The movement of molecules across a cell
membrane, requiring the use of cellular energy.
Cell wall
A rigid structure manufactured by cells of plants, fungi, algae, and most bacteria to surround the cell membrane.
Cytoplasm
The thick fluid inside a cell that contains
organelles; all the material inside a cell except the nucleus.
Organelle
One of the cellular structures found in the cy-
toplasm that perform the functions needed to keep the cell
alive.
Mitochondrion
The organelles in which aerobic respiration occurs to release usable energy from food.
Endoplasmic reticulum
An organelle consisting of a net- work of membranes that enable substances to be transported throughout the cell.
Ribosome
A non-membrane-bound organelle that directs
the assembling of proteins.
Golgi apparatus
An organelle that collects chemicals
from the cytoplasm, processes them, and secretes them.
Vacuole
A membrane-bound sac that stores various substances, such as water, food, or wastes, within a cell.
Lysosome
An organelle that contains digestive enzymes for disposing of foreign particles and worn-out cellular structures.
