1. Section 3: Cell Organelles • The Nucleus: • Eukaryotic cells (plant and animal cells) have a nucleus • It is surrounded by a double membrane called the nuclear envelope • Holes in the nucleus called nuclear pores allow ribosomes to pass through and get out to the cell. • DNA is contained in the nucleus which contain hereditary information

2. Ribosomes and the Endoplasmic Reticulum (ER) • Proteins are made on ribosomes that are on the rough endoplasmic reticulum. • There are two types of endoplasmic reticulum: smooth and rough, smooth do not have ribosomes, rough do • Smooth endoplasmic reticulum have various functions such as making lipids and breaking down toxic substances

3. Packaging and distribution of proteins • The golgi apparatus is a set of flattened, membrane bound sacs that serve as the packaging and distribution center of the cell • Proteins received from the ER travel to the golgi apparatus where they are modified by enzymes, then packaged and exported from the cell in vescicles • Production, packaging, and distribution of proteins is starts in the rough ER , goes through the golgi apparatus, to the outside of the cell with the assistance of vesicles and lysosomes

4. mitochondria • An organelle that harvests energy from organic compounds, such as carbohydrates, to make ATP which can be used by the cell to make energy. • See p. 65 • The mitochondria has two membranes, inner and outer, the inner membrane is intricately folded • Cells with a high energy requirement, such as muscle cells, may contain thousands of mitochondria • Mitochondria have their own DNA and can make their own proteins which lends evidence that the first life on Earth were related to mitochondria

5. Plant cells • In addition to the organelles previously discussed, plant cells have: • A cell wall, composed of proteins and carbohydrates such as cellulose, it helps maintain and protect the cell • Chloroplasts, which use light energy to make carbohydrates during photosynthesis • Central vacuole, which is a large membrane-bound space which holds water and nutrients as well as wastes. When full it makes the cell rigid