Cell structure

• What type of cells are humans made up of?

  Eukaryotic cells
• What is the ultrastructure of eukaryotic cells?


  It refers to the detailed structure of cells obtained using a microscope
• What are the main components of the nucleus?


  • Double membrane called the envelope
  • ~3000 nuclear pores
  • Chromatin
  • Nucleolus (site of ribosome production)
  • Nucleoplasm (granular jelly-like material)
• What is the function of the rough endoplasmic reticulum (RER)?


  • Series of flattened sacs
  • Enclosed by a membrane with ribosomes
  • Folds and processes proteins made on ribosomes
• What is the function of the smooth endoplasmic reticulum (SER)?


  • System of membrane-bound sacs
  • Produces and processes lipids
• What is the function of the Golgi apparatus?


  • Series of fluid-filled, flattened, and curved sacs
  • Processes and packages proteins and lipids
  • Produces lysosomes
• What is the structure and function of mitochondria?


  • Oval-shaped, bound by a double membrane
  • Inner membrane folded into cristae
  • Contains enzymes needed for respiration
• What are centrioles and their function?


  • Hollow cylinders containing microtubules
  • Involved in producing spindle fibers for cell division
• What are ribosomes and their function?


  • Composed of two subunits
  • Site of protein production
• What are lysosomes and their function?


  • Vesicles containing digestive enzymes
  • Bound by a single membrane
• What are the main components of prokaryotic cells?


  • Cell wall (made of peptidoglycan)
  • Capsule (protective layer)
  • Plasmid (circular DNA)
  • Flagellum (tail-like structure)
  • Pili (hair-like structures)
  • Ribosomes (site of protein production)
  • Mesosomes (infoldings of the inner membrane)
• What are the characteristics of viruses?


  • Non-living structures
  • Consist of nucleic acid (DNA or RNA)
  • Enclosed in a protective protein coat (capsid)
  • Sometimes covered with a lipid layer (envelope)
• How are cells organized in multicellular organisms?


  • Cells form tissues
  • Tissues form organs
  • Organs form systems