Unit 2: Cell Structure and Function

Cell

The basic unit of structure and function in living things.

Surface area-to-volume ratio

The ratio of the surface area of a cell or organism to its volume, which affects the efficiency of material exchange.

Prokaryotic cell

A small and simple type of cell without a nucleus or membrane-bound organelles, found in bacteria and archaea.

Eukaryotic cell

A more complex type of cell with a nucleus and membrane-bound organelles, found in fungi, protists, plants, and animals.

Plasma membrane

The outer envelope of a cell made up of phospholipids and proteins, regulating the movement of substances into and out of the cell.

Nucleus

The largest organelle in a cell, responsible for directing cell activities and containing the genetic material (DNA).

Ribosomes

Sites of protein synthesis in a cell, composed of ribosomal RNA (rRNA) and proteins.

Endoplasmic reticulum (ER)

A continuous channel in the cytoplasm that provides mechanical support and transportation, with rough ER involved in protein synthesis and smooth ER involved in lipid synthesis.

Golgi complex

Modifies, processes, and sorts proteins synthesized by the ribosomes on the rough ER, packaging them into vesicles for distribution.

Mitochondria

Power stations of the cell, responsible for converting energy from organic molecules into ATP.

Lysosomes

Sac-like organelles containing digestive enzymes used to break down old organelles, debris, or large particles.

Vacuoles

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

Peroxisomes

Organelles that detoxify substances and break down hydrogen peroxide into oxygen and water.

Cytoskeleton

A network of protein fibers that determine the shape of a cell and are involved in cellular division and movement.

Cilia and Flagella

Structures with locomotive properties in single-celled organisms, allowing movement.

Plant cells

Cells with a cell wall made of cellulose, chloroplasts for photosynthesis, and a large central vacuole.

Animal cells

Cells without a cell wall, lacking chloroplasts, and containing centrioles.

Passive transport

The movement of molecules across the cell membrane without the use of energy.

Active transport

The movement of molecules against the concentration gradient, requiring the use of energy (ATP).

Endocytosis

The process by which a cell engulfs large particles or substances by forming a vesicle from the cell membrane.

Exocytosis

The process by which a cell releases waste products or specific secretion products by fusing a vesicle with the plasma membrane.