Chapter 3: Cells

Cells

Smallest unit of life; all organisms are made of one or more cells.

Extracellular Material

Surrounds cells and contains various substances; includes extracellular fluid and matrix.

Plasma Membrane

Semi-permeable barrier that separates intracellular fluid from extracellular fluid.

Cytoplasm

Intracellular fluid containing organelles; location of most cellular activities.

Nucleus

Organelle that controls cellular activities; contains genetic material.

Membrane Lipids

Phospholipids form the bilayer structure of the plasma membrane; hydrophobic tails and hydrophilic heads.

Membrane Proteins

Facilitate communication and specialized functions of the cell membrane.

Cell Junctions

Join plasma membranes of adjacent cells; include tight junctions, desmosomes, and gap junctions.

Passive Transport

Movement of substances across the membrane without added energy; includes simple diffusion, facilitated diffusion, and osmosis.

Active Transport

Requires energy (ATP) to move substances against their concentration gradient.

Endocytosis

Process of transporting substances into the cell via vesicles; includes phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Exocytosis

Process of transporting substances out of the cell using vesicles.

Resting Membrane Potential (RMP)

Potential energy produced by separation of charged particles across the plasma membrane in excitable cells.

Cytoskeleton

Provides structural support and shape to the cell; includes microfilaments, intermediate filaments, and microtubules.

Organelles

Specialized structures within the cell that perform specific functions; includes mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, and peroxisomes.

Mitosis

Process of cell division that results in two daughter cells; includes phases:prophase, metaphase, anaphase, and telophase.

Gene

Segment of DNA that carries instructions for protein synthesis.

Protein Synthesis

Process of creating proteins from amino acids; involves transcription and translation.

Autophagy

Process of self-digestion where cells recycle components; important for cell maintenance and survival.

Apoptosis

Programmed cell death; eliminates damaged or unnecessary cells.