Cell Organelles Overview

Cell Organelles

• The endoplasmic reticulum (ER) is a network of membranes within the cytoplasm.
  • Rough ER is coated with ribosomes and is involved in protein modification, folding, and sorting.
  • Smooth ER synthesizes lipids and breaks down nutrients and toxins.
• Ribosomes are small bodies found in the cytoplasm or attached to the ER.
  • Composed of RNA and protein, they manufacture proteins.
• The Golgi apparatus is a series of layered membranes that further modifies proteins.
  • It sorts and prepares proteins for transport to other parts of the cell or out of the cell.
• Mitochondria are large organelles with internal folded membranes.
  • They convert energy from nutrients into ATP.
  • Cells with high energy demands, like liver and kidney cells, have more mitochondria than cells with low energy demands, like bone and tendon cells.
  • Mitochondria have their own DNA. Their structure resembles elongated bacteria.
  • Composed of an outer smooth membrane and an inner membrane with folds called cristae.
  • The fluid inside the inner membrane is called the matrix and contains ribosomes, DNA, and enzymes.
• Lysosomes are small sacs of digestive enzymes that rid the body of worn-out parts.
• Peroxisomes are membrane-enclosed organelles containing enzymes.
  • They break down harmful substances like alcohol and other cellular toxins.
  • They target free radicals.
• Proteasomes are barrel-shaped structures composed of protein.
  • They capture and degrade proteins that are no longer required by the cell.
• Vesicles are small membrane-bound sacs in the cytoplasm.
  • They store materials and move materials into or out of the cell in bulk.
• Centrioles are rod-shaped bodies (usually two) near the nucleus.
  • They help separate the chromosomes during cell division.

Tissues of the Body

• There are four basic tissue types: epithelial tissue, connective tissue, muscle tissue, and nervous tissue.
• Epithelial tissue forms protective boundaries and is involved in the diffusion of ions and molecules.
• Connective tissue underlies and supports other tissue types.
• Muscle tissue contracts to initiate movement in the body.
• Nervous tissue transmits and integrates information through the central and peripheral nervous systems.