This document summarizes the key components of plant and animal cells. It describes the cell membrane as the outer boundary that protects the cell and controls what enters and leaves. It notes that plant cells also contain a cell wall made of cellulose that provides protection and support. The nucleus controls most cell activities and contains DNA. The cytoplasm and organelles like the endoplasmic reticulum, Golgi complex, mitochondria, vacuoles, lysosomes, and chloroplasts carry out specialized functions like protein production, packaging and transport of materials, energy production, storage, and waste digestion.