Chapter 3 Notes: Cells, Membranes, and Homeostasis

Cell Theory

Core concepts stating that all organisms are made up of cells, the cell is the fundamental unit of life, and new cells arise from preexisting cells.

Robert Hooke

Scientist who studied cork tissue around 1665 and observed 'cells,' which were actually the cell walls of plant cork.

Prokaryotic Cells

Smallest cell type, lacking a nucleus and membrane-bound organelles; DNA is in the cytoplasm, and transcription/translation occur in the cytoplasm (e.g., bacteria, archaea).

Eukaryotic Cells

Larger cell type, containing a nucleus (housing DNA) and multiple membrane-bound organelles (e.g., mitochondria, endoplasmic reticulum); transcription occurs in the nucleus and translation in the cytoplasm (e.g., plants, animals, fungi).

Nucleus

A membrane-bound structure found in eukaryotic cells that houses the DNA.

Membrane-bound Organelles

Internal compartments within eukaryotic cells (e.g., mitochondria, Golgi apparatus) that perform specialized functions; absent in prokaryotes.

Cell Membrane

The surrounding layer of a cell that regulates the movement of molecules in and out, maintaining a stable internal environment (homeostasis).

Homeostasis

The ability of a cell to maintain a stable internal environment by controlling exchange with the external environment, primarily through the cell membrane.

Transcription

The biological process of synthesizing RNA from a DNA template.

Translation

The biological process of synthesizing protein from an RNA template.

Nerve Cells

Cells with very long projections (axons) adapted to facilitate communication and signaling over distances in the body.

Red Blood Cells (RBCs)

Cells with a biconcave shape that increases surface area, enhancing gas exchange (O2)