Lecture 7 Cellular Respiration 2025

ATP Synthase: Key enzyme responsible for synthesizing ATP from ADP and inorganic phosphate using energy from a proton gradient.
Role in Cellular Work: ATP is considered the energy currency of the cell; it powers various cellular processes such as muscle contraction and biochemical reactions.

Describe the processes involved in the generation of ATP from the breakdown of a glucose molecule, including an overall description of the processes, where those processes occur and the net number of ATP molecules produced per glucose molecule broken down
Understand the difference between substrate level phosphorylation and oxidative phosphorylation and how the electron transport chain builds a proton gradient across the inner mitochondrial membrane to generate ATP
Be able to describe the roles of insulin and glucagon in the body, and how these contribute to blood sugar levels
describe the fundamental pathology of Diabetes Mellitus

Hydrolysis Reaction: Conversion of ATP to ADP and inorganic phosphate, releasing energy utilized for cellular functions.
Location: Occurs in mitochondria, dubbed the "ATP factory" of the cell.

Ciliary Movement: An example of ATP-powered cell movement.
ATP Cycle: Describes the transfer of energy through complex to simple molecules and simple molecules to complex molecules, with ATP mediating this process. Energy needs for cellular activities are not spontaneous; thus, ATP is crucial.

Carbohydrates: Broken down into simple sugars.
Proteins: Decomposed into amino acids.
Fats: Metabolized into fatty acids.
Cellular Respiration: Process utilizing oxygen and dietary foods (like glucose) to produce water, carbon dioxide, and ATP.

The process of glucose going from the blood stream to a cell is facilitated by isnulin and once in the cell it can either be used straight for cellular respiration or stored away where it becomes Glycogen
The breakdown of glycogen so it can be used and be transported back into bloodstream is facilitated by Glucagon

Glycolysis:
- Converts glucose to 2 pyruvate molecules, occurs in cytosol
- Generates a net gain of 2 ATP and 2 NADH (4 overall ATP produced), and 2 ATP are invested
Pyruvate Oxidation:
- Converts pyruvate to Acetyl CoA, producing NADH per pyruvate/2 per glucose and 1 CO2
- Produces no ATP
- Occurs in the mitochondrial matrix.
Citric Acid Cycle (Krebs Cycle):
- Occurs in mitochondrial matrix
- Produces 2 ATP, 6 NADH, 2 FADH2, 4 CO2 (Per glucose molecule)
- NADH, and FADH2 act as electron donors in the electron transport chain
- This step requires oxygen
- Citric acid cycle completes the extraction of energy from glucose
Oxidative Phosphorylation:
- Accounts for most ATP production (26-28 ATP per glucose) from NADH and FADH2 by utilising complex 1, 2, 3, and 4 on the electron transport chain (ETC) and chemiosmosis.
- Oxygen serves as the final electron acceptor.
- Occurs across the inner membrane

Oxygen is critical as it acts as the final acceptor for electrons, and without it, cellular respiration halts.
Electrons from NADH and FADH2 move through a series of proteins, powering proton pumps that move H+ ions across the inner membrane, creating a gradient.

Protons (Hydrogen ions) flow back through ATP synthase, driving the phosphorylation of ADP to ATP.
This process underlines oxidative phosphorylation's efficiency compared to substrate-level phosphorylation.

Phosphofructokinase: Regulates glycolysis, is inhibited by Citrate and ATP, and is stimulated by AMP

Diabetes: Failure of insulin production or response to insulin leads to high blood glucose levels, marked symptoms include increased hunger and weight loss despite food intake.
Type 1: Body doesn’t produce insulin, often genetic, beta cells are destroyed
Type 2: Body produces insulin, but receptors are non functional (insulin resistance)

Formula for cellular respiration summarized: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy.
Versatility: Cellular respiration can utilize fats and proteins as energy sources beyond glucose.