2b

• Eukaryote cell


  • Much more complex than prokaryotic cells
• Differences between Plants and Animals

  • Plants: Chloroplasts, Cell wall, Central vacuole
  • Animals: Lysosomes, Motility
• Nucleus


  • Contains chromatin, long fibres of DNA, coils up into structures called chromosomes during cell division, Ribosomes produced in nucleolus, Nuclear membrane is a double membrane with pores, Some organelle membranes are continuous, Others exchange sacs of membrane via budding and fusion of vesicles
• Organelles of the endomembrane system

  • Nuclear membrane, Endoplasmic reticulum, Golgi apparatus, Lysosomes, Vacuoles
• Ribosomes are made in the nucleus, exported via the nuclear pores, participate in translation (protein production), exist free in the cytoplasm or bound to the endoplasmic reticulum, cells with high rates of protein synthesis will tend to contain many ribosomes
• Rough Endoplasmic Reticulum (Rough ER)

  • Studded with ribosomes, the site of synthesis of membrane-bound proteins and secreted proteins, continuous with the nuclear envelope
• Smooth Endoplasmic Reticulum (Smooth ER)


  • Tubular structure that is continuous with the Rough ER, the site of new membrane (lipid) synthesis, cell type specific functions: Endocrine cells = site of synthesis of steroid hormones, Liver cells = drug detoxification, Muscle cells = stores calcium
• Golgi Apparatus


  • Stacks are not interconnected, modifies the sugars on proteins, forms transport vesicles, consists of a stack of flattened membranous sacs, the Golgi stack has two sides: the receiving side accepts transport vesicles from the rough ER, the shipping side sends out transport vesicles to plasma membrane or other organelle, cells actively secreting protein have extensive Golgi stacks
• Lysosomes


  • Diverse forms of a membranous organelle containing digestive enzymes, Functions: Food vacuoles take up nutrients then fuse with lysosomes to di
• The shipping side


  Sends out transport vesicles to plasma membrane or other organelle
• Cells actively secreting protein

  • Have extensive Golgi stacks
• Forms of a membranous organelle containing digestive enzymes

  • Food vacuoles take up nutrients then fuse with lysosomes to digest the food
  • Destruction of engulfed bacteria in white blood cells
  • Recycle worn out organelles or cell macromolecules
• Lysosomal storage diseases


  • Pompe’s disease (glycogen storage)
  • Tay-Sachs disease (lipid disorder)
• Central Vacuole of plant cell

  • Functions: Growth - expansion of the central vacuole reduces the volume of the cytoplasm allowing plant cells to grow, Storage - Seed nutrients, Flower pigments, Toxic metabolic waste products, Chemical defences (poisons)
• Chloroplasts and Mitochondria


  • Key structures for energy transformation in eukaryotes, Have their own DNA and ribosomes, Believed to have evolved from endosymbiosis of prokaryotes, Thought to have previously been free-living organisms, Engulfed by larger cells during endosymbiosis, Provide energy to cells
• Chloroplasts


  Site of photosynthesis, Composed of 3 internal compartments, Inter-membrane system, Stroma - thick fluid, Granum - stacks of tubes and discs called thylakoids that contain chlorophyll
• Mitochondria


  Harvest chemical energy from food by the process of cellular respiration, Produces ATP - energy currency of the cell, 2 membranes - the inner membrane is folded into cristae, 2 compartments - inter-membrane space and the matrix
• How do chloroplasts and mitochondria divide?

  Bacteria divide by binary fission.... so do chloroplasts, but not all mitochondria
• Bacteria divide by binary fission