Cell Structure

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  • Cell Structure
    • Ultrastructure
      • Plant Cell
        • cell wall
        • vacuole
        • chloroplasts
          • chloroplast envelope- double membrane, folded
            • controls entry and exit of substances in the chloroplast
      • Animal Cell
        • microtubule
        • vesicle
        • mitochondrion
          • double membrane
          • responsible for production of ATP
        • lysosome
        • golgi apparatus
          • occurs in almost all eukaryotic cells
          • acts as the cell's post office
        • cell membrane
        • ribosome
        • rough endoplasmic reticulum
        • smooth endoplasmic reticulum
        • nuleolus
          • nucleus
          • nuclear envelope
        • cytoplasm
        • centriole
    • Membranes
      • composed of a phospholipid bilayer
        • hydrophobic inner
        • hydrophilic inner
      • also include 2 major macromolecules
        • lipids
          • acts as a recognition site for specific chemicals
        • proteins
          • carbohydrate chains attached to extrinsic proteins
          • act as recognition sites for hormones and neurotransmitters
      • the fluid mosaic model shows the membrane structure
      • Transport
        • Facilitated diffusion
          • passive process, relying only on KE of the molecules
          • channel proteins
            • these allow water-soluble molecules, glucose and amino acids, to pass
            • channels are selective
          • carrier proteins
            • binds to a specific protein when present
              • which causes a change in shape
            • no use of external energy
          • from high concentration to low
          • doesn't use ATP
        • diffusion
          • example of passive transport
          • the motion is random
          • rate of diffusion is affected by
            • the area over which diffusion takes place
              • larger the area, the faster the rate of diffusion
            • the concentration gradient
              • the greater  the difference in the gradient, the faster the diffusion occurs
            • the distance over which diffusion occurs
              • shorter distance, the faster rate of diffusion
          • osmosis
            • special form of diffusion
            • passage of water from a region where it has a higher water potential to a region of lower water potential through a partially permeable membrane
            • water potential
              • measured in units of pressure
              • standard is 0
              • addition of a solute will reduce its water potential
              • the value must always be less than 0
            • solute potential
              • addition of a solute will reduce its water potential
              • the change in water potential as a consequence of solute molecules is called solute potential
            • pressure potential
              • resistance of the entry of water
      • cholesterol
        • stabilises the membrane, necessary in the absence of a cell wall
        • hydrophobic, so key in preventing leakages
        • pull together fatty acids, limiting their movement

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