Unit 2: Cell Structure and Function (copy)

Cell

Life's basic unit of structure and function.

Surface area-to-volume ratio

As cells or organisms increase in size, this ratio decreases, affecting efficiency of material exchange.

Light microscope

Used to study stained or living cells, magnifying them up to 1,000 times.

Electron microscope

Used for studying detailed structures of cells, not visible with light microscopy.

Prokaryotic cell

A simpler, smaller type of cell without membrane-bound organelles, found in bacteria and archaea.

Eukaryotic cell

More complex cells containing organelles, found in fungi, protists, plants, and animals.

Plasma membrane

Outer envelope of the cell made up of phospholipids and proteins; regulates movement of substances.

Nucleus

Largest organelle, directing cell activities and containing hereditary information (DNA).

Ribosomes

Sites of protein synthesis, composed of rRNA and proteins.

Endoplasmic Reticulum (ER)

Continuous channel providing support and transport; rough ER has ribosomes, smooth ER does not.

Golgi complex

Packaging and distribution centers for materials to be sent out of the cell.

Mitochondria

Power stations converting energy from organic molecules into ATP.

Lysosomes

Sacs carrying digestive enzymes to break down old organelles and particles.

Vacuoles

Fluid-filled sacs that store water, food, wastes, salts, or pigments.

Peroxisomes

Organelles that detoxify substances and convert hydrogen peroxide into water and oxygen.

Cytoskeleton

Network of protein fibers determining cell shape; includes microtubules and microfilaments.

Passive transport

Movement of substances across the membrane without the need for energy.

Diffusion

Movement of molecules from an area of high concentration to low concentration.

Facilitated diffusion

Diffusion that requires the help of channel-type proteins.

Osmosis

Diffusion of water across a selectively permeable membrane.

Tonicity

Describes osmotic gradients (isotonic, hypertonic, hypotonic) relative to a cell.

Active transport

Movement of substances against their concentration gradient, requiring energy (ATP).

Endocytosis

Process where the cell membrane engulfs particles to bring them into the cell.

Pinocytosis

Type of endocytosis where the cell ingests liquids.

Phagocytosis

Type of endocytosis where the cell takes in solids.

Exocytosis

Process where a cell ejects waste or secretion products by fusing a vesicle with the plasma membrane.