Cell Structure Overview

Overview

This lecture introduces the basic structures and functions of a typical cell, focusing on the cell membrane, cytoplasm, and key organelles.

The cell membrane forms the outer boundary of the cell.
It is composed of a double phospholipid layer, creating a barrier between the inside and outside of the cell.
The membrane contains channels that regulate entry and exit of substances.

Cytoplasm refers to everything inside the cell membrane but outside the nucleus.
Cytoplasm includes both the cytosol (liquid part) and cell organelles.
Cytosol is purely the aqueous, liquid portion of the cytoplasm.

Organelles are specialized "little organs" within the cytoplasm, each with different functions.
The nucleus acts as the brain of the cell and contains DNA.
Mitochondria are called the powerhouse of the cell because they produce ATP (energy).
Rough endoplasmic reticulum (RER) has ribosomes on its surface and synthesizes proteins.
Smooth endoplasmic reticulum (SER) lacks ribosomes and assists in transport within the cell.
The Golgi body (or Golgi apparatus) packages and distributes substances throughout the cell.
Lysosomes are filled with enzymes and break down cellular waste.

Cell membrane — double-layered barrier separating interior and exterior of the cell.
Phospholipid — molecule forming the main structure of cell membranes.
Cytoplasm — all contents within the cell membrane except the nucleus.
Cytosol — the liquid component of the cytoplasm.
Organelle — specialized structures within a cell performing distinct functions.
Nucleus — organelle containing DNA; directs cell activities.
Mitochondria — organelle that produces energy (ATP) for the cell.
Endoplasmic reticulum (ER) — network for transport and synthesis; rough ER has ribosomes, smooth ER does not.
Ribosome — small structure that makes proteins.
Golgi body/apparatus — organelle that packages and ships materials within the cell.
Lysosome — organelle with enzymes for breaking down waste.