Cellular Organelles

• What is the structure of a nucleus?

  • Largest organelle
  • Spherical
  • Dark patches = Chromatin
  • Surrounded by nuclear envelope
  • Composed of two fluid-filled membranes
  • Has nuclear pores two allow large molecules through
  • Nucleolus inside
• What is the function of a Nucleus?

  • Contains genetic material
  • Chromatin consists of DNA and proteins
  • Contains instructions for protein synthesis
  • When cell divides, Chromatin condenses and forms visible chromosomes
  • Nucleolus makes RNA and ribosomes
• What is the structure of an Endoplasmic Reticulum?

  • Consists of flattened membrane-bound sacs
  • Cisternae which are continuous around the outer nuclear membrane
• What kind of Endoplasmic Reticulum contains ribosomes?

  Rough
• What is the function of an Endoplasmic Reticulum?

  • Smooth ER - Involved in making lipids
  • Rough ER - Transports proteins made on attached ribosomes
• What is the structure of a Golgi Apparatus?

  Stack of membrane-bound flattened sacs
• What is the function of a Golgi Apparatus?

  • Receives proteins from the ER
  • Modifies them (adds sugar)
  • Packages proteins into vesicles to transported inside the cell or outside
• What is the structure of Mitochondria?

  • 2 membranes separated by a fluid-filled space
  • The inner membrane is folded to form a Cristae
  • The central part is called a Matrix
• What is the function of Mitochondria?

  Site where ATP is produced during respiration
• What is the structure of a Chloroplast?

  • 2 membranes separated by a fluid-filled space
  • Inner membrane is continuous with a network of thylakoids
  • A stack of thylakoids is called a granum
  • Chlorophyll molecules are present on these membranes
• What is the function of a Chloroplast?

  • Site of Photosynthesis
  • Light energy is used to derive carbohydrate molecules from carbon dioxide
• What is the structure of a Lysome?

  Spherical sacs surrounded by a single membrane
• What is the function of a Lysosome?

  Contains digestive enzymes to break down materials such as cell organelles, or even whole cells
• What is a specialised use of Lysosomes?

  In sperm cells, the tip contains specialised Lysosomes called Acrosomes, which allows them to penetrate the egg
• What organelles are not membrane bound?

  Ribosomes and Centrioles
• What is the structure of a Ribosome?

  • Very small organelles in Cytoplasm and bound to Rough ER
  • Consists of 2 subunits
• What is the function of a Ribosome?

  Site of protein synthesis and acts as an assembly line for mRNA to assemble proteins
• What is the structure of the Centrioles?

  Small protein tubes of microtubules
• What is the function of a Centriole?

  Form fibres in cell division known as spindles which separate chromosomes