2.2 Organelles

• The Nucleus


  • control centre
  • contains DNA: genetic material
  • most cells have one apart from:
  • skeletal cells (many)
  • RBCs (none)

  
• Structure of the nucleus

  • nucleus
  • largest organelle
  • nuclear envelope
  • double membrane, connected to ER, controls what goes in and out
  • nuclear pores with regulator proteins
  • control exchange of materials between nucleus & cytoplasm
• Within the nucleus

  -nucleoplasm

  -nucleoli
• Nucleoplasm


  contains ions, enzymes, DNA, RNA and nucleoli
• Nucleoli


  site of rRNA synthesis
• Mitochondrion structure


  • rod shaped
  • double membrane
  • outer=smooth
  • inner=folded into cristae
  • centre=matrix
  • semi autonomous: makes own DNA

  
• Mitochondria function


  -aerobic respiration

  -takes energy from glucose, hydrolyses it and converts ADP to ATP

  -supplies most of the cell's energy

  -can replicate independently from cell: have their own DNA
• Chloroplasts

  -plastids family

  -double membrane

  -chlorophyll

  -enzymes for photosynthesis

  
• Chloroplast structure


  -thylakoids

  -stroma
• thylakoids


  membranous sacs, stacked to form a granum

  
• stroma


  fluid portion of the chloroplast; outside of the thylakoids

  
• Endoplasmic Reticulum


  -attached to nuclear envelope

  -2 types: rough and smooth

  
• function of endoplasmic reticulum


  • synthesis of proteins, carbs and lipids
  • storage of synthesised molecules and materials
  • transport of materials within the ER
  • detoxification of drugs or toxins
• Smooth endoplasmic reticulum


  -no ribosomes

  -tubular membrane

  
• rough endoplasmic reticulum


  surface covered in ribosomes

  
• Functions of rough endoplasmic reticulum


  -modify proteins

  -provide pathways for materials to be transported
• Golgi apparatus


  • stack of cisternae with associated transport vesicles
  • near nucleus, not attached

  
• function of golgi apparatus

  Modify, sorts and packages proteins and other materials from the ER for storage in the cell or secretion outside the cell
• Lysosomes


  • digests large molecules and structures
  • contains lysozymes and hydrolytic enzymes

  
• endocytosis


  process by which a cell takes material into the cell by infolding of the cell membrane

  
• exocytosis


  Process by which a cell releases large amounts of material

  
• function of lysosome

  "Clean up the mess" (Used in catabolic processes)

  -break down large molecules, attack bacteria, recycle damaged organelles, ejects waste by exocytosis
• Centrioles


  form spindle apparatus during cell division

  
• cilia and flagella


  hairlike structures that extend from the surface of the cell, where they assist in movement. contain microtubule core with cytoplasm covered in plasma membrane

  
• cilia


  -short

  -numerous

  
• function of cilia


  sweep materials across a surface
• flagella


  -long

  -singular

  
• function of flagella


  propels the cell
• ribosomes


  makes proteins

  
• cell wall


  -microfibrils of cellulose

  -adds strength to plant cell

  -prevents it bursting under pressure

  
• vacuoles


  Cell organelle that stores materials such as water, salts, proteins, and carbohydrates