Required Practical 4 Flashcards

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1
Q

How do you calculate percentage uncertainties?

A

percentage uncertainty = uncertainty/mean value x 100%

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2
Q

Which part of the phospholipid is affected if temperature changes?

A

The fatty acid tails

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3
Q

What happens if the temperature is very high?

A
  • The fatty acid tails gain kinetic energy
  • They become less rigid and more fluid
  • They gain enough energy to break the hydrogen bonds holding the bilayer together
  • Permeability and fluidity of the membrane is increased
  • More substances can exit and enter the cell
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3
Q

What happens if the temperature is much too high?

A
  • The integral and peripheral proteins can denature completely
  • Membrane becomes so fluid that dangerous substances can exit and enter the cell
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4
Q

What happens if the temperature is very low?

A
  • The fatty acid tails lose kinetic energy
  • More rigid and close together
  • Less gaps in the bilayer, preventing more substances than usual to enter the cell
  • Includes essential substances like oxygen and glucose
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5
Q

What happens if the temperature is much too low?

A
  • The liquid inside the cells can freeze
  • Creates crystals that can pierce the membrane and kill the cell
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6
Q

What is the optimum temperature for most cells?

A

37.5°C

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7
Q

What is a colorimeter?

A

A light-sensing device that is used to measure the absorbance of light as it moves through a sample of liquid.

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8
Q

Why is red cabbage used in the required practical?

A

Red cabbage has a red dye inside its cells which will leak out if the cell membrane becomes permeable

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