Cellular Respiration and Cell Cycle: Key Concepts and Processes

Cellular Respiration

1. Definition and Chemical Equation

Cellular respiration is the chemical reaction in which glucose and oxygen are converted into water, carbon dioxide, and energy (ATP). The balanced chemical equation for cellular respiration is: C₆H₁₂O₆ + 6 O₂ --> 6 CO₂ + 6 H₂O + ATP

2. Location of Respiration

Cellular respiration takes place in the mitochondria of living cells.

3. Phases of Respiration and ATP Production

Cellular respiration occurs in three stages: glycolysis, the Krebs cycle, and electron transport. Glycolysis takes place in the cytoplasm and results in a net gain of two ATP molecules.

4. ATP and Energy Production

ATP provides energy to the cell when it is broken down into ADP (adenosine diphosphate) and inorganic phosphate, releasing energy.

5. Anaerobic Phase of Respiration

Glycolysis, the first step in cellular respiration, is anaerobic and does not require oxygen.

7. Comparison of Photosynthesis and Cellular Respiration

Photosynthesis occurs in the chloroplasts of cells and provides energy to all living organisms. Cellular respiration, on the other hand, converts oxygen and glucose into carbon dioxide and water, releasing energy.

Cell Cycle

1. Definition

The cell cycle is the series of events that occur in a cell leading to the duplication of its DNA (DNA replication) and division of cytoplasm and organelles to produce two daughter cells.

2. Stages

• Gap 0 (G0): Cells may leave the cycle and stop dividing, either temporarily or permanently.
• Gap 1 (G1): Cells increase in size, produce RNA, and synthesize proteins. A cell cycle control mechanism (G1 Checkpoint) ensures readiness for DNA synthesis.
• Synthesis Phase (S): DNA replication occurs, duplicating the cell's DNA instructions.
• Gap 2 (G2): Cells continue to grow and produce proteins. Another control checkpoint (G2 Checkpoint) determines readiness for mitosis.
• Mitosis (M Phase): Cell growth and protein production stop, and the cell focuses on dividing into two similar daughter cells. A Checkpoint (Metaphase Checkpoint) ensures readiness for cell division completion.

4. Cell Cycle and Cancer

In normal cells, the cell cycle is controlled by signaling pathways that ensure proper growth, DNA replication, and division. In cancer, genetic mutations disrupt this process, leading to uncontrolled cell proliferation.

5. Mitosis: Stages, Importance, and Purpose

Mitosis is the process of cell division that results in two identical daughter cells. It is important for growth, tissue repair, and asexual reproduction. The stages of mitosis include prophase, metaphase, anaphase, and telophase.