Photosynthesis and Cellular Respiration Processes

Photosynthesis and Cellular Respiration

Key Biological Terms

• Photosynthesis: Only occurs in plants and some bacteria. It is the process in which autotrophs convert light energy into chemical energy.
• Respiration: The process in which cells make ATP by breaking down organic compounds. It occurs in both autotrophs (plants) and heterotrophs (animals).
• Autotrophs: An organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide, like plants, algae, and some bacteria. They are producers.
• Heterotrophs: Heterotrophs cannot make their own food, so they must eat or absorb it. For this reason, heterotrophs are also known as consumers. Consumers include all animals, fungi, and many protists and bacteria.
• Producers: Convert energy from the sun to food; they make their own food, like plants.
• Consumers: Cannot make their own food, like animals.
• Aerobic process: Occurs with oxygen.
• Anaerobic process: Occurs without oxygen.

Photosynthesis Deep Dive

Equation: 6H₂O + 6CO₂ + light => C₆H₁₂O₆ + 6O₂

Reactants: Water, CO₂, and light (6H₂O + 6CO₂ + light)

Products: Glucose and Oxygen (C₆H₁₂O₆ + 6O₂)

Cellular Respiration Deep Dive

Equation: C₆H₁₂O₆ + 6O₂ => 6H₂O + 6CO₂ + ATP

Reactants: Glucose and Oxygen (C₆H₁₂O₆ + 6O₂)

Products: Water, CO₂, and ATP energy (6H₂O + 6CO₂ + ATP)

Chemical Reactions and Electron Carriers

Oxidation: The process by which a substance loses one or more electrons.

Reduction: The process by which a substance gains one or more electrons.

Roles of NADH and FADH₂:

• NADH: Carries energy to the electron transport chain, where it is stored in ATP.
• FADH₂: An electron carrier (coenzyme) produced during the citric acid cycle.

Three Stages of Cellular Respiration

Cellular respiration produces a total of 32 ATPs across three main stages:

1. Glycolysis Stage

• Location: Cytoplasm
• What happens: Glucose is broken down into 2 molecules of pyruvate (two 3-carbon compounds).
• Reactant: 1 Glucose
• Products: 2 Pyruvates, NADH, and 4 ATP

2. Stage 2: Transition and Citric Acid Cycle

A. Prep (Transition Phase)

• Location: Mitochondria (occurs between Glycolysis and the Citric Acid Cycle)
• What happens: 2 pyruvates are chemically changed into Citric Acid (2 Acetyl CoA).
• Reactant: 2 Pyruvates
• Product: Citric Acid (2 Acetyl CoA)

B. Citric Acid Cycle (Krebs Cycle)

• Location: Mitochondria
• What happens: Completes the breakdown of carbon dioxide, makes small amounts of ATP, and generates electrons.
• Reactant: Citric Acid (2 Acetyl CoA)
• Produces: Electrons, NADH, FADH₂, CO₂, and 2 ATP

3. Electron Transport Chain (ETC)

• Location: Inner membrane
• What happens: NADH and FADH₂ are shuttled along the ETC to oxygen to produce water and release 28 ATP.
• Reactants: NADH, FADH₂, and CO₂
• Produces: H₂O and 28 ATP

Anaerobic ATP Production

What is the name of the process when organisms produce ATP in anaerobic environments? How does this process work?

The process is called Fermentation.

1. It is the production of energy in the absence of oxygen (which is harder).
2. It is a process that allows glycolysis to continue making ATP when oxygen isn't present.

During fermentation, NADH is converted back to NAD+ by adding the extra electrons in NADH to an organic molecule that acts as an electron acceptor.

There are two main pathways: alcoholic fermentation and lactic acid fermentation.