Biology U3O2 - Photosynthesis & Cellular Respiration

Where does light dependent stage happen?

In Thylakoid’s membrane in the Chloroplast

Where does light Independent stage happen?

In Stroma in the Chloroplast

Inputs for light dependent stage?

• ADP+Pi

• H2O

• NADP+

Outputs for light dependent stage?

• ATP

• NADPH

• O2 (byproduct)

Inputs for light independent stage?

• ATP

• NADPH

• CO2

Outputs for light independent stage?

• Glucose (C6H12O6)

• H2O (byproduct)

Inputs for Glycolysis (Cellular Respiration)

• 2 (net) ADP+Pi

• NAD+

• Glucose (C6H12O6)

Outputs for Glycolysis (Cellular Respiration)

• 2 (net) ATP

• NADH+

• Pyruvate

ATP Yield for Glycolysis?

2 (net) ATP

Inputs for Kreb’s Cycle + Pyruvate Oxidation

• 2 Acetyl CoA

• NAD+

• FAD

• ADP+Pi

Outputs for Kreb’s Cycle + Pyruvate Oxidation

• NADH

• FADH2

• ATP

• CO2

Kreb’s Cycle + Pyruvate Oxidation’s ATP Yield?

2 ATP

Inputs for Electron Transport Chain (ETC)

• 6O2

• NADH

• FADH2

• ADP+Pi

Outputs for Electron Transport Chain (ETC)

• 6H2O

• NAD+

• FAD+

• ATP

Electron Transport Chain (ETC)’s ATP Yield?

26 or 28 ATP

Where does Glycolysis happen?

Cytosol

Where does Kreb’s Cycle + Pyruvate Oxidation happen?

Mitochondria’s Matrix

Where does Electron Transport Chain (ETC) happen?

Mitochondria’s Cristae

Parts of the Chloroplast?

• Thylakoid/ Thylakoid membrane

• Granum (pl. Granum)

• Stroma

• Lumen

• Inner membrane

• Outer membrane

Parts of the Mitochondria?

• Outer membrane

• Inner membrane

• Intermembrane

• Matrix

• Cristae

What is a loaded co-enzyme and examples?

• A co-enzyme carries electrons, protons and chemical products needed for anabolic reaction.

• They temporarily bind onto the enzyme’s active site and enable it to catalyze.

• They transfer atoms/electrons during chemical reactions

• Examples: ATP, NADPH, FADH2, NADH, Acetyl CoA

What are co-factors and examples?

• inorganic molecules that tightly bind near the enzyme’s active site and conform its shape.

• They are used to change an enzyme’s shape and/or functionality.

  • Examples: Zn, Mg, Fe

Examples of unloaded coenzymes

NAD+, NADP+, FAD+, ADP+Pi

C4 Plants

• Plants in hotter climates

• Light dependent stage happens in Mesophyll cells (nearer to Stomata)

• Light independent stage happens in Bundle Sheath cells (deeper in the leaf)

• The benefits for reduced photorespiration outweigh the sacrifice needed to exert more energy for transportation around cells.

• Separated spatially

1. The enzyme PEP Carboxylase fixes CO2 and Oxaloacetate together to form Malate/Malic acid.

2. Malate is then transported to Bundle Sheath cell, it breaks back into CO2 and undergoes Calvin Cycle to create Glucose.

CAM Plants

• Plants in arid/drier environments

• Light dependent and independent stage happens in the Mesophyll cell

• Separated over time

• Stomata are opened at night for gas exchange to minimize water in plants being evaporated

1. At night, the stomata open up to collect CO2

2. PEP Carboxylase fixes CO2 and Oxaloacetate together to form Malate/Malic acid.

3. Malate is then stored in Vacuoles

4. When day time comes, light dependent stage then occurs, creating ATP and NADPH along with O2 as a byproduct

5. Calvin Cycle then happens with the CO2 stored overnight.

What happens when climate becomes too hot for plants?

• RuBisCO starts to conform and lose its 3D shape, having a more complementary shape to Oxygen.

• It’s affinity for CO2 decreases and for Oxygen, it increases

• Leading to Photorespiration occurring more rather then Carbon Fixation, which is not desirable because it doesn’t produce Glucose

When does Anaerobic Respiration occur? And what doesn’t occur and why?

• When Oxygen isn’t present in the cell

• Kreb’s Cycle and ETC won’t happen because they’re Aerobic respirations, meaning they require Oxygens to happen

What does Pyruvate convert into in animals and plants during Anaerobic Respiration?

• Animal: Pyruvate → Lactic acid

  • Called Lactic Acid Fermentation

• Plant: Pyruvate → Alcohol (Ethanol) and CO2

  • Called Alcohol Fermentation

Pro and Cons about Anaerobic Respiration/Fermentation compared to Aerobic Respiration?

Pros

• Rate of anaerobic fermentation is much more faster than aerobic respiration, which becomes useful when quick energy to the cell is needed.

Cons

• Anaerobic fermentation isn’t sustainable and cannot be used for a long time because Lactic acid is toxic to the cells that produce them.

• Aerobic Respiration is more efficient because it produces 30 or 32 ATP, while Anaerobic Respiration only produces 2 ATP.

Chemically, how does Pyruvate convert into Lactic acid or Alcohol & CO2 in Anaerobic Fermentation?

NADH unloading H+ ion produces enough energy for the conversion of Pyruvate to Lactic acid or Alcohol & CO2