section 4

• The nucleus directs cell activities and stores DNA.
• The nucleus is surrounded by the nuclear membrane or nuclear envelope which is a lipid bi-layer.
• Organelles involved in protein production, packaging and distribution are: endoplasmic reticulum(ER), ribosomes, vesicles, golgi apparatus, and lysosome.
• Endoplasmic reticulum(ER) is an extensive system of internal membranes and moves proteins and other substances.
• Ribosomes produce proteins in 2 places rough ER and in cytoplasm.
• Vesicles are a small membrane bound sac that transports substances in the cell. It is formed by pinching off the ER or Golgi Apparatus.
• Golgi apparatus is a set of flattened sacs. It serves as the packaging and distribution center of the cell.
• Lysosome is a small spherical organelle that contains digestive enzymes. The enzymes digest worn out cell components into lipids, proteins, carbohydrates, and nucleic acids and recycles them within the cell.
• The mitochondria harvests energy from organic compounds to make adenosine triphosphate(ATP) which is cellular respiration.
• The mitochondria has a higher folded inner membrane to increase surface area for more chemical reactions to occur on. It also contains its own DNA and ribosomes.
• The nucleolus or nucleoli is a dense structure in the nucleus that produces ribosomal sub units and aids in making proteins.
• Substances pass in and out of nuclear membrane through nuclear pores.
• Mitochondria is found in all eukaryote cells and muscle cells may contain 100's to 1000's due to high energy requirement.