Lecture14_PostClass

Conditions Affecting Enzymatic Activity

  • Factors Influencing Enzyme Function:

    • Presence of inhibitors or activators

    • Concentration of enzymes

    • Concentration of substrates

    • Temperature

    • pH, which influences protein folding.

Rate of Reaction

  • Enzyme and Substrate Concentration:

    • Rate of reaction as a function of enzyme concentration with substrate at high concentration.

    • Rate of reaction as a function of substrate concentration with enzyme amount constant.

    • Key Points:

      • Increasing enzyme concentration generally increases the reaction rate until saturation is reached.

      • The rate also depends on substrate availability.

Enzyme Activity

  • Effect of pH:

    • Different enzymes have optimal pH ranges for maximum activity.

      • Example: Pepsin functions best in acidic conditions, while trypsin is optimal at basic pH.

      • Most cellular enzymes operate close to neutral pH.

Temperature Effects on Enzyme Activity

  • Temperature vs. Reaction Rate:

    • As temperature increases, enzyme activity generally increases until it reaches a peak (optimal temperature).

    • Subsequent temperature rises can denature the enzyme leading to loss of activity.

Practice Questions

  • Understanding Cellular Pathways:

    • GLUT proteins are synthesized in the RER, then travel through the Golgi apparatus to reach the plasma membrane (PM).

    • Transport vesicles are essential in this pathway, connecting the RER and Golgi.

Organelle Function in Lipid Production

  • Gangliosides:

    • Found in neuron membranes, gangliosides are primarily produced in the Golgi apparatus.

Enzyme Function: Breakdown of Gangliosides

  • Hexosaminidase:

    • This enzyme, essential for breaking down gangliosides, is located in lysosomes.

Oxidation-Reduction Reactions (Redox)

  • Definitions and Process:

    • Oxidation: Loss of electrons; associated with an increase in C-O bonds.

    • Reduction: Gain of electrons; associated with a decrease in C-O bonds.

    • Redox reactions must occur in pairs, illustrating the principle of OIL RIG (Oxidation Is Loss, Reduction Is Gain).

Characteristics of Chemical Bonds

  • Energy Rich Bonds:

    • C-H bonds are typically energy-rich compared to C-O bonds. Energy release occurs when chemical bonds break, facilitating cellular energy needs.

  • Potential Energy in Chemical Reactions:

    • High-energy molecules can release energy through redox reactions, contributing to overall metabolic processes.

Free Energy Changes in Reactions

  • Exergonic vs. Endergonic Reactions:

    • Exergonic Reactions: Release heat and light energy, like the combustion of hydrogen.

    • Cellular Respiration: A controlled progression that captures energy from food to produce ATP, emphasizing the difference between uncontrolled and metabolic processes.