Dehydrogenase Activity In Chloroplasts R8 Flashcards
What is the title for this experiment?
Investigating the rate of dehydrogenase activity in extracts of chloroplasts
What is the aim of this study?
To investigate the effect the addition of a variable has on the rate of dehydrogenase enzyme in chloroplasts
What is the function of dehydrogenase in chloroplasts?
Dehydrogenase catalyses reactions involving NADP accepting electrons in the light dependent reaction
What is the purpose of DCPIP?
DCPIP is a redox indicators dye that acts as an alternate electron acceptor instead of NADP.
It turns blue to colourless when reduced
Why is ammonium hydroxide added to one of the experimental tubes alongside DCPIP?
Ammonium hydroxide denatures dehydrogenase and also acts as an electron acceptor. As a result it prevents dehydrogenase from picking up electrons.
What is the hypothesis of this experiment?
The rate of reaction will decrease with the addition of ammonium hydroxide
Why is the plant extract chilled in an ice water bath?
The plant extract is chilled to lower the activity of enzymes to prevent them from breaking down the chloroplasts
How is the control (standard) set up? What is its purpose?
A cuvette is filled with chloroplast extract and distilled water. This is done so there is a standard to coarse with the experiment test tubes to identify de colourisation end point
How is light intensity controlled?
The distance of the lamp is set up from the beginning. Additionally by performing the experiment in a dark room, the lamp can act as the only light source
Why filter out the blended spinach? What is the function of the muslin cloth in this process?
The blended spinach is filtered to remove larger pieces of cell debris and other organelles. The muslin cloth helps filter out any debris in the leaf mixture but allows chloroplasts to pass through
Why are the stalks of the leaves removed before grinding?
The stalks do not contain many chloroplast so do not need to be added
Why must the isolation medium be an isotonic solution?
Isotonic means the solution has the same water potential as the chloroplasts, therefore preventing the chloroplast from swelling or bursting
Ammonium hydroxide and other electron accepting chemicals are used as weed killers. Suggest how these may kill weeds?
Ammonium hydroxide slows the light independent reaction and results in slow ATP and NADPH production. Without ATP and NADPH the light independent reaction will stop and organic substances will not be made in the weeds
What does the removal of a light source and chloroplast suspension in the control experiments do?
To prove that without one thing the experiment would not work.
