Viewing 4 reply threads
  • Author
    Posts
    • #1627
      *susie*
      Participant

      i have an exam paper to do and i am stuck on the following question:

      two sets of plants of the same spechies were grown under identical conditions except for ambient temperature. describe and explain the differences you would expect to see, in the lipid composition of the membranes, between the plants grown at 10degrees and those grown at 25degrees. (9 marks)

      could anyone help me with the answer….PLEASE 🙂 im really stuck as i know what temperature does to lipid membranes, just dont know how the composition of lipids is affected in growth at the different temperatures.

      thank-you 😀

    • #28209
      fabienne
      Participant

      if you compare plant at ambiant temperature to plant at 10 degrees, plant at 10 degrees are going to be smaller because of stress caused by cold whitch involve regulation of growing, regulation of genetic program to be able to survive to cold temperature. exemples of this regulation are to permit synthesis of proteins and sugar who are cryoprotectant (chaperonin, ….), to change the membrane fluidity

      membranes are sensitive to low temperature, because low temperatures reduce membrane fluidity. this reduction of the fluidity willl reduce
      -plasticity of membrane ( involved in trafficing between cells, shape and size changes during growth, ability to include new proteins in the membrane…)
      -capacity not to “break” because of ice in the cell

      Fluidity is determined by lipid composition and temperature

      longer fatty acids in the lipids=higher melting temp
      addition of double bonds in fatty acids=lower melting temp

      plants can be classified as “chilling tolerant” or “chilling sensitive” (chilling is not freezing); chilling tolerant plants have a higher % of unsaturated fatty acids in membranes to maintain fluidity

      this reorganisation of membrane is the result of changes in genetics programs what allow synthesis of enzymes or modification of the activity of proteins, involved in the composition of the membrane

      good luck!

    • #28349
      mothorc
      Participant

      I don’t agree with fabien’s explain because the concentration of lipit can be change but the structure is always const.(FAME’s principle)
      I think the question is more intersting if degree temperature mean degree in rotation. 😉

    • #28722
      har0bed1813
      Participant

      you people are smart 💡 😉

    • #28727
      mith
      Participant

      I think he did mean the different concentrations of lipids

Viewing 4 reply threads
  • You must be logged in to reply to this topic.