Cellular Respiration Review Guide

Overview of Cellular Respiration: Cellular respiration is the process by which cells extract energy from glucose molecules and convert it into ATP (adenosine triphosphate), the primary energy currency of cells. It occurs in three main stages: glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation (electron transport chain and chemiosmosis).

1. Glycolysis:

• Occurs in the cytoplasm.
• Glucose (6-carbon) is broken down into two molecules of pyruvate (3-carbon).
• Produces a small amount of ATP and NADH (energy carrier).
• Doesn't require oxygen (anaerobic process).

2. Citric Acid Cycle (Krebs Cycle):

• Takes place in the mitochondrial matrix.
• Pyruvate is oxidized to produce carbon dioxide.
• Generates NADH and FADH2 (energy carriers).
• Produces a small amount of ATP.

3. Oxidative Phosphorylation:

• Consists of the electron transport chain (ETC) and chemiosmosis.
• Occurs in the inner mitochondrial membrane.
• NADH and FADH2 donate electrons to the ETC.
• Electrons pass through protein complexes, releasing energy.
• This energy is used to pump protons across the membrane, creating a proton gradient.
• Protons flow back through ATP synthase, driving ATP production (chemiosmosis).
• Oxygen is the final electron acceptor, forming water.
• Produces the majority of ATP in aerobic respiration.

Key Concepts:

• Aerobic respiration requires oxygen and occurs in the presence of oxygen, yielding a higher amount of ATP compared to anaerobic respiration.
• Anaerobic respiration, such as fermentation, occurs in the absence of oxygen and produces small amounts of ATP through glycolysis.
• Cellular respiration is essential for providing energy for various cellular processes, including muscle contraction, active transport, and biosynthesis.

Regulation and Significance:

• Enzymes play a crucial role in catalyzing the reactions in each stage of cellular respiration.
• Cellular respiration maintains the balance of energy and provides the necessary ATP for the survival and functioning of organisms.
• The efficiency of cellular respiration can be affected by factors such as substrate availability, enzyme activity, and oxygen availability.

Connections to Other Processes:

• Cellular respiration is closely related to photosynthesis as it uses the products (glucose and oxygen) produced during photosynthesis.
• The carbon dioxide produced during cellular respiration is utilized by plants during photosynthesis to produce glucose.

Summary: Cellular respiration is a complex series of biochemical reactions that extract energy from glucose molecules, generating ATP to power cellular activities, and is fundamental for the survival of living organisms.

Questions

1. Cellular respiration is the process by which cells extract _____ from glucose molecules to produce energy in the form of ATP.

2. Glycolysis occurs in the _____ and involves the breakdown of glucose into two molecules of _____ in the absence of oxygen.

3. The citric acid cycle, also known as the _____ cycle, takes place in the _____ of the mitochondria and produces carbon dioxide, NADH, FADH2, and a small amount of _____.

4. In _____ phosphorylation, NADH and FADH2 donate electrons to the electron transport chain (ETC) located in the _____ mitochondrial membrane.

5. The movement of electrons through the ETC creates a _____ gradient used to generate ATP through the process of _____. Oxygen acts as the final electron _____ in this process.

6. Anaerobic respiration, such as _____, occurs in the absence of oxygen and involves the regeneration of NAD+ from NADH produced during glycolysis.

7. Cellular respiration is essential for providing energy for various cellular processes, including _____ contraction, active transport, and biosynthesis.

8. The relationship between cellular respiration and _____ is complementary, as the products of one process (glucose and oxygen) are used as reactants in the other.

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Answers

1. energy 2. cytoplasm, pyruvate 3. Krebs, mitochondrial matrix, ATP 4. oxidative, inner 5. proton, chemiosmosis, acceptor 6. fermentation 7. muscle 8. photosynthesis