General Biology 1 ATP and Photosynthesis Recap Quiz

The ATP-ADP Cycle

• ATP (adenosine triphosphate) is the primary energy currency of cells.
• The ATP-ADP cycle describes the continuous conversion of ATP to ADP (adenosine diphosphate) and back again.
• ATP releases energy when a phosphate group is removed, converting it to ADP.
• This energy is used to power cellular processes.
• ADP can then be re-phosphorylated to ATP using energy from various sources, like cellular respiration or photosynthesis.

Photosynthesis: Light-Dependent Reactions

• Chlorophyll and other pigments absorb light energy.
• This energy is used to excite electrons in the pigments.
• The excited electrons move through an electron transport chain, generating ATP and NADPH.
• Water is split, releasing oxygen as a byproduct.

Photosynthesis: Products of the Light-Dependent Reactions

• ATP (adenosine triphosphate) is a primary energy carrier used in the Calvin Cycle.
• NADPH (nicotinamide adenine dinucleotide phosphate) is a reducing agent used in the Calvin Cycle.
• Oxygen is a byproduct released into the atmosphere.

The Calvin Cycle

• The Calvin cycle is the light-independent stage of photosynthesis.
• It uses the energy from ATP and the reducing power of NADPH to convert carbon dioxide into sugar.

Discoverers of the Calvin Cycle

• Melvin Calvin and his team at the University of California, Berkeley, discovered the Calvin cycle.

Alternative Names for the Calvin Cycle

• The Calvin cycle is also known as the Calvin-Benson cycle or the C3 cycle.

Function of the Calvin Cycle

• The Calvin cycle is the main process by which plants fix carbon dioxide into organic compounds, specifically glucose.

G3P, a Product of the Calvin Cycle

• G3P (glyceraldehyde 3-phosphate) is a three-carbon sugar that is produced in the Calvin Cycle.
• It is used to synthesize other sugars and organic molecules.

Carbon Fixation

• The process of incorporating CO2 into an organic material is called carbon fixation.

RuBisCo

• Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) is an enzyme responsible for attaching CO2 to a five-carbon sugar molecule (ribulose bisphosphate) in the Calvin Cycle.

Six-Carbon Sugar: Fate after Carbon Fixation

• The resulting six-carbon sugar, an unstable intermediate, quickly breaks down into two molecules of 3-phosphoglycerate (3-PGA).

NADPH Role in the Calvin Cycle

• NADPH provides electrons to reduce 3-PGA into G3P, which is then used to synthesize glucose and other organic molecules.

G3P Fate: The Calvin Cycle

• Most of the G3P molecules produced by the Calvin Cycle are used to regenerate the five-carbon sugar (ribulose bisphosphate) to continue the cycle.
• A small portion of G3P is used to create glucose and other organic molecules, for plant growth and energy storage.

ADP and NADP+: Fate after the Calvin Cycle

• ADP and NADP+ formed during the Calvin Cycle return to the light-dependent reactions to be re-energized.
• This replenishes the energy carriers needed for continued carbon fixation.

Rubisco Function

• Rubisco is the most abundant enzyme on Earth and is essential for the Calvin Cycle.
• It has a dual role in fixing CO2 and oxygen.
• However, its affinity to oxygen can be a limiting factor in plant growth.

Product of Carbon Fixation

• The initial product of carbon fixation is an unstable six-carbon sugar that breaks down into two molecules of 3-phosphoglycerate (3-PGA).