Cellular Respiration Flashcards

Interaction and Interdependence: Molecules / Cell Respiration

Understanding Cell Respiration

Production of ATP

• Cell respiration is the primary process for providing energy to cells.
• Organisms must obtain molecules for cell respiration through production or absorption.
• Respiratory substrate: Any molecule broken down in respiration to release energy.
• Glucose is the main respiratory substrate for most cells.
• If glucose is depleted, cells use lipids and fatty acids.
• Cells may use different sugars and carbohydrates.
• Proteins and amino acids are used as a last resort due to their other important functions.
• Cell respiration is a series of metabolic pathways breaking down carbon compounds, releasing energy for ATP production.

Learning Outcomes

• Describe cell respiration as the process that produces ATP using energy from carbon compounds.
• Distinguish between cell respiration and gas exchange.
• Distinguish between aerobic and anaerobic respiration.
• Describe the variables that affect the rate of cell respiration and be able to calculate the rate of respiration.

Cell Respiration vs. Gas Exchange

• Cell respiration should not be confused with gas exchange in the alveoli of the lungs.
• Gas exchange involves the movement of oxygen into the blood and carbon dioxide out of the blood.

Comparing Anaerobic and Aerobic Cell Respiration

Types of Cell Respiration

• Aerobic respiration: Occurs in the presence of oxygen.
  • Begins in the cytoplasm, most steps in the mitochondria.
  • Can use any respiratory substrates.
  • ATP yield: Approximately 36–38 molecules.
  • Waste products: Carbon dioxide and water.
• Anaerobic respiration: Occurs in the absence of oxygen.
  • Occurs only in the cytoplasm.
  • Respiratory substrates: Only glucose and other carbohydrates.
  • ATP yield: Net gain of two molecules.
  • Waste product: Lactate (lactic acid).

Differences Between Aerobic and Anaerobic Respiration in Humans

• Table summarizing key differences:
  • Oxygen:
    • Aerobic: With oxygen
    • Anaerobic: Without oxygen
  • Location:
    • Aerobic: Cytoplasm and mitochondria
    • Anaerobic: Cytoplasm only
  • Respiratory substrates:
    • Aerobic: All (glucose, lipids, proteins)
    • Anaerobic: Carbohydrates only
  • ATP yield:
    • Aerobic: High (36-38 ATP)
    • Anaerobic: Low (2 ATP)
  • Waste products:
    • Aerobic: Carbon dioxide and water
    • Anaerobic: Lactate/lactic acid

Word Equations for Aerobic and Anaerobic Respiration

• Aerobic respiration: glucose + oxygen \rightarrow carbon dioxide + water (+ATP)
• Anaerobic respiration: glucose \rightarrow lactate (+ATP)

Variables Affecting the Rate of Cell Respiration

Factors Influencing Respiration Rate

• Temperature
• pH
• Substrate concentration
• Oxygen concentration
• Respiration is a series of enzyme-controlled reactions, so factors affecting enzymes also affect respiration.

Respirometer

• A respirometer measures the rate of respiration by measuring the consumption of oxygen.
• Setup includes:
  • Tube A: Contains organisms to be tested (e.g., insects, germinating seeds).
    • The alkaline solution absorbs CO_2, reducing gas volume equivalent to oxygen absorbed.
  • Tube B: Control tube (no living organism).
  • Capillary connecting the tubes (manometer).
• The reduction in oxygen in Tube A reduces pressure, moving the colored liquid in the manometer towards Tube A.
• This measures oxygen consumption, used to calculate the respiration rate.

Ethical Considerations

• The use of animals in scientific experimentation has ethical implications.
• IB has strict guidelines for animal experimentation.
• Respect of the IB animal experimentation policy is crucial.

Calculations

• Volume of a cylinder: V = \pi r^2 h
• Rate: Rate = \frac{volume}{time}
• Mean rate: Mean = \frac{sum \space of \space values}{number \space of \space trials}

Worked Examples

1. Volume of a cylinder with diameter 5 cm and height 10 cm:
   • V = \pi r^2 h
   • V = \pi \times (\frac{5}{2})^2 \times 10
   • V = 196.35 \space cm^3
2. Rate of oxygen consumption if 50 cm3 was consumed over 5 minutes:
   • Rate = \frac{volume}{time}
   • Rate = \frac{50 \space cm^3}{5 \space min}
   • Rate = 10 \space cm^3/min
3. Mean rate of oxygen consumption for trials with rates: 12, 14, 15, 13, 15 cm3/min:
   • Mean = \frac{sum \space of \space values}{number \space of \space trials}
   • Mean = \frac{(12 + 14 + 15 + 13 + 15)}{5}
   • Mean = 13.8 \space cm^3/min

Activity: Analyzing the effect of temperature on the rate of cell respiration

Task

1. Calculate the volume of oxygen consumed for each measurement.
2. Calculate the mean volume of oxygen consumed for each temperature.
3. Calculate the mean rate of oxygen consumption for each temperature.
4. Graph the mean rates of oxygen consumption against the temperatures.
5. Describe and explain the results using the graph and specific data.The diameter of the manometer tubing is 1 mm.