Lecture Cycle 5

• How would you measure respiration in isolated mitochondria and using what?

  measure change in oxygen using an oxygen electrode chamber
• What are the steps of measuring cellular respiration?

  1. grind up chlamy cells

  2. purify intact mitochondria

  3. wash mitochondria

  4. incubate in a buffer
• How does respiration rate (oxygen consumption) change when NADH is added?

  increases
• How does respiration rate (oxygen consumption) change when ADP and Pi is added?

  consumption increases more steeply
• How does respiration rate (oxygen consumption) change when uncoupler is added?

  highest rate of consumption
• What is respiratory control, how does it work?

  rate of elctron transport which adjusts based on the availability of ADP and Pi
• How do chloroplasts and cellular respiration work together in autotrophic metabolism?

  G3P from the calvin cycle is used to make glucose and pyruvate which is used in the citric acid cycle
• What are two of the specific roles of G3P?

  -intermediate of glycolosis (regenerate RuBP)

  -carbon backbone for biosynthetic reactions (make glucose)
• Can chlamy grow in the dark?

  yes
• What can't chlamy grow in the dark with glucose?

  because glycolosis is present in the chloroplast
• What does it mean to have a mixotrophic metabolism?

  both autotrophic and heterotrophic growth
• What metabolism has the fastest rate of growth? Why?

  mixotrophic growth, because it utilizes both autotrophic and heterotrophic growth
• Does respiration produce or consume O2 and CO2?

  -consumes: O2

  -produces: CO2
• Does photosynthesis produce or consume O2 and CO2?

  -consumes: CO2

  -produces: O2
• Why does the measurement of O2 production and CO2 fixation both underestimate the actual rate?

  the reactions is ongoing when being measured, both are still being used and produced
• How would you measure photosynthesis using gas exchange?

  measure CO2 fixation
• What are the units of carbon fixation?

  micromol CO2 consumed/minute/cell
• What is a light response curve representing?

  how the rate of photosynthesis changes with light intensity
• What are the different segments of a light response curve, what is happening at each segment?

  -light limited: CO2 fixation is increasing

  -light saturated: CO2 fixation levels out
• How could the light saturated rate be increased?

  1. increase rubisco

  2. enrich air with CO2
• How could one determine the rate of respiration if a chloroplast is present?


  place in the dark
• What is a light compensation point? What would be an example of this?

  light intensity needed for equilibrium between rate of photosynthesis and rate of respiration
• At what point does a plant grow?


  when there is more CO2 in than out, at or beyond light compensation point
• What would you do with the enzyme concentration if there were low temperatures?

  increase concentration
• What does the Rate of Reaction vs Enzyme concentration graph look like? What is constant?

  -linear

  -substrate is constant
• What does a Rate of Reaction vs Substrate Concentration curve look like? Why does it plateau?

  - increasing then plateau

  - enzyme constant

  - plateau because maximum catalytic speed is reached
• What is a saturation level? Why does this happen?

  -Vmax

  -maximum amount of substrate the enzyme can catalyse
• What is Vmax on an enzyme kinetic curve?

  maximum reaction rate
• What Km on an enzyme kinetic curve?

  affinity between enzyme and Vmax (amount to get to 1/2 Vmax)
• What is a competitive inhibitor? Does it change Vmax or Km?

  -competes with substrate for active site

  - changes Km
• What is an allosteric inhibitor?

  alters the shape of the active site so that substrate cannot bind (decreasing the amount of enzyme that can be active)
• What are the two types of non-competitive inhibition? How do they work?

  -allosteric activation: activates the enzymes

  -allosteric inhibitor: changes active site
• How do non-competitive inhibitors affect rate of reaction (V)? Does it change Vmax or Km?


  Vmax changes, slowing reaction rate
• Would it be more or less beneficial to regulate enzyme activity at the level of enzyme activity or at transcription/translation.

  more beneficial to regulate at level of enzyme activity, because processes can be sped up