Unit 15.16 C 1.2 Cell Respiration.SL

C 1.2 Cell Respiration

• Roles of Hydrogen and Oxygen in Energy Release

  • Hydrogen atoms are integral in the chemical reactions during cellular respiration, aiding in the transfer of high-energy electrons.

  • Oxygen acts as the final electron acceptor in aerobic respiration, allowing the release of energy stored in nutrients.

• Energy Distribution and Usage Inside Cells

  • Energy is distributed primarily through ATP (adenosine triphosphate), known as the energy currency of the cell, facilitating various cellular processes.

C1.2.1 ATP as Energy Distributor

• ATP (Adenosine Triphosphate) is a nucleotide that provides energy through the hydrolysis of its phosphate bonds.

• Key Properties of ATP:

  • Can release energy in manageable amounts.

  • Highly reactive, enabling it to fuel biological reactions.

  • Small size allows easy transport within cells.

C1.2.2 Life Processes Powered by ATP

• ATP supplies energy for various processes:

  • Active Transport: Movement of molecules across cell membranes against concentration gradients.

  • Synthesis of Macromolecules: Energy is used in anabolic reactions to form complex molecules from simpler ones.

  • Cell Movement: ATP facilitates the movement of cells and cellular components (e.g., chromosome movement during cell division).

C1.2.3 Energy Transfer in ATP/ADP Interconversion

• Energy is released when ATP hydrolyzes to ADP (Adenosine Diphosphate) and a phosphate group, crucial for powering cellular processes.

• ATP Synthesis: Requires energy input from food during metabolic processes.

• Students should grasp the significance of energy output without needing specific kilojoule values.

C1.2.4 Cellular Respiration and ATP Production

• Cellular respiration utilizes energy from food, mainly glucose and fatty acids, to produce ATP.

• Key Points to Distinguish:

  • Cell Respiration vs. Gas Exchange: Cell respiration involves ATP production, while gas exchange pertains to the intake of O2 and release of CO2.

C1.2.5 Anaerobic vs. Aerobic Respiration in Humans

• Anaerobic Respiration:

  • Does not require oxygen, results in lactic acid production from pyruvate, and yields less ATP.

• Aerobic Respiration:

  • Requires oxygen, yields more ATP, occurs mainly in mitochondria, and produces CO2 and water as by-products.

• Students should be capable of writing simple word equations for both aerobic and anaerobic respiration.

C1.2.6 Factors Affecting Rate of Cell Respiration

• Students should learn to measure and analyze the rate of cellular respiration through practical experimentation.

Cellular Respiration Overview

• Cells require energy in the form of ATP, obtained via cell respiration as organic compounds (nutrients) are broken down using enzymes into CO2, H2O, and ATP.

• Understanding of Organic Compounds:

  • Contains carbon-hydrogen and carbon-carbon bonds (e.g., glucose, fatty acids).

Organic Compound Sources

• Foods provide organic compounds, specifically carbohydrates, lipids, and even proteins, for energy through cellular respiration.

• ATP production occurs by adding a phosphate group to ADP, a process that requires energy from food.

Distinction: Cellular Respiration vs. Breathing

• Cellular respiration refers to the controlled energy release from organic compounds producing ATP, while breathing involves the exchange of gases (O2 intake and CO2 expulsion).

Energy Transfer and ATP

• Controlled Energy Release:

  • Energy is released in small amounts during cellular respiration to prevent excessive heat loss.

Energy Conversion Using ATP

• Produced ATP can be converted into different energy forms such as electrical energy (nerve impulses), kinetic energy (muscle contraction), and even light energy (bioluminescence).

Anaerobic and Aerobic Respiration Differences

• Aerobic Respiration: Takes place with oxygen present, producing a high ATP yield through gradual substrate reduction.

• Anaerobic Respiration: Conducted without oxygen, yielding less ATP and resulting in lactic acid in humans.

Measurement of Cellular Respiration

• Utilizing tools like respirometers to measure respiration rate by assessing CO2 production and O2 consumption.

  • Components include a gas-absorbing substance (e.g., KOH), a capillary tube for pressure monitoring, and a sealed container for the test organism.

Experimental Design for Measuring Respiration Rate

• Set specific controlled variables when designing experiments, assess effects of varying temperatures, and ensure ethical considerations when using living organisms for experiments.

Data Analysis for Respiration Studies

• Investigate mass changes in yeast during fermentation processes and understand environmental impacts on cellular respiration rates.