Cell Structure and Function

Fluid mosaic model

The model describing cell membranes as fluid structures rather than static ones, featuring structural asymmetry and embedded transport proteins.

Membrane asymmetry

The structural property of a cell membrane where the outside-facing portion is structurally different from the inside-facing portion.

Transport proteins

Proteins embedded within the cell membrane that act like tunnels to allow substances through.

Plasma membrane

A phospholipid bilayer with embedded proteins that forms the cell's outer boundary, separates external and internal environments (cytoplasm), and controls what enters and exits all cells, including prokaryotes.

Cellulose cell wall

A protective structure made of cellulose embedded in lignin located outside the plasma membrane in plant cells only; it maintains cell shape, supports the whole plant, keeps cells from absorbing too much water and bursting, and contains channels connecting to other plant cells.

Nucleus

The organelle that holds genetic control of the cell and serves as DNA's protected office, allowing information to be communicated; surrounded by the nuclear envelope.

DNA

The genetic code for proteins that acts as the cellular "boss" and is found in all cells.

Ribosomes

Structures found in all cells that directly make proteins in the cytoplasm; they are not bound by a membrane (technically not an organelle) and can be suspended in fluid or attached to the ER.

Nucleolus

The region inside the cell where ribosome components are made.

Bacterial ribosomes

Ribosomes specific to bacteria that can be targeted and killed by antibiotics.

Endomembrane system

A system within the cell that manufactures and distributes cell products, consisting of the ER, transport vesicles, Golgi apparatus, secretory vesicles, lysosomes, vacuoles, and plasma membrane.

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