The Cell

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  1. What 3 elements are cells composed of?
    • Hydrogen
    • Nitrogen
    • Oxygen
    • (and some other trace elements)
  2. What does loss of cellular homeostasis result in?
    It underlies all diseases and problems ie. diabetes and DOMS
  3. What are the 2 main components of a cell?
    • Nucleus = a membrane bound structure that contains the genetic information
    • Cytoplasm = contains everything within the cell except the nucleus
  4. What is the purpose of the plasma membrane?
    Barrier between cytoplasm and the interstatial fluid (like soup!) in which the cell is suspended

    Will repair itself if punctured
  5. What are the two main classifications of membrane proteins and what do they do?
    • (1) Integral membrane proteins - allow transportation into and out of the cell
    • (2) Peripheral membrane proteins - sensing the environment and signalling?
  6. What are the 3 types of membranes with examples?
    • (1) Tight junctions - zipper action, tight, strong - form the lining of the gut
    • (2) Desmosomes - specialisations where there might be stress - skin
    • (3) Gap junctions - allow the flow of ions from point A to B - heart cells allow depolarisation
  7. How does the cell maintain homeostasis?
    Extracts what is requires from the interstitial fluid (like soup!) surrounding it

    Selective (differential) permeability = characteristic displayed by healthy cells to facilitate homeostasis - key to survival - if cell loses it, it will die.
  8. What are the 2 ways that substances are moved across the plasma membrane?
    • (1) Active diffusion - uses energy
    • (2) Passive diffusion
  9. What is passive diffusion?
    The tendency of molecules to disperse evenly in a given environment

    Molecules move along the concentration gradient
  10. What is facilitated diffusion?
    A protein carrier is used e.g. glucose won't move across the plasma membrane without being joined to a protein.
  11. What is filtration?
    Hydrostatic pressure - high concentration of water moves to a low concentration
  12. What is active transport?
    Similar to facilitated diffusion in that a carrier is used BUT does not adhere to the concentration gradient and does require ATP
  13. What is vesticular (bulk) transport?
    Large particles are transported via a vesticle (a small spherical sac) across the plasma membrane and also requires ATP
  14. What is the difference between exocytosis and endocytosis?
    Exocytosis = process of removing waste products out of the cell

    Endocytosis = process of bringing things into the cell - things needed but also viruses which bring problems - how viruses attack
  15. Where is the cytoplasm?
    Inside the plasma membrane but outside the nucleus
  16. What are the 3 major elements of the cytoplasm?
    • (1) Cytosol = viscous, semitransparent fluid in which a variety of fluids are suspended
    • (2) Organelles = metabolic machinery, each has its own specialised function
    • (3) Inclusions = non-functioning chemical substances, may or may not be present within the cell
  17. What is the function of the mitrochondria? (4 points)
    Majority of the ATP required by the cell is produced here

    Breaks down foodstuffs through cellular respiration

    Cells requiring more energy have more mitrochondria than less active cells for ATP production

    Can replicate themselves if more ATP needed
  18. What is the purpose of lysosomes?
    Contain enzymes that degrade intra and extracellular debris

    Join no longer functioning organelles, break them down, recycle parts still required, eliminate remaining waste from the cell
  19. What is the purpose of peroxisomes?
    Detoxify harmful substances

    Function = to render free radicals (by product of cellular metabolism) harmless
  20. What is Endoplasmic Reticulum (ER)?
    A network of membrane tubes continuing from the nuclear membrane
  21. What are the 3 functions of the Endoplasmic Reticulum?
    • (1) Storage
    • (2) Synthesis
    • (3) Transport
    • of biomolecules
  22. What are the 2 types of Endoplasmic Reticulum (ER)?
    • Rough ER
    • Smooth ER
  23. What is Golgi Apparatus and what is it's function?
    Principle director of protein traffic

    Function = to modify and package the proteins made in the rough ER, the proteins are then dispatched
  24. How many nuclei does a cell termed multinucleate have?
    Many i.e. skeletal cells
  25. How many nuclei does a cell termed anucleate have?
    1 but when the cell matures the nuclei are ejected. Without them the cell is unable to reproduce the proteins and structures required so it dies. I.e. red blood cells
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The Cell
The Cell
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