University:
University of Phoenix
Course:
BIO 350 | General Biology I
Academic year:

2022
Views:

192

Pages:

10
Author:

winddeviant51w

Cell Fractionation (Unit 2): Definition: A process that allows different parts of a cell to be separated using centrifugation or other methods. Purpose: Used in biological analysis to study the structure, chemical composition, and functions of cellular constituents. Steps of Cell Fractionation: Extraction Homogenization Centrifugation Separation Homogenization: Process: Cells are suspended in an appropriate pH and isotonic salt or sucrose solution. Method: The suspended cells are disrupted via physical means (grinding, osmotic shock, ultrasonic vibrations) to achieve homogenization. Outcome: A liquid containing cell organelles, now called homogenates. Preservation: The isotonic solution preserves the cellular organelles. Centrifugation: Definition: Separation of cell homogenates into fractions by spinning at high speed. Principle: Particles separate based on shape, size, density, and viscosity. First Centrifuge: Developed by Svedberg in 1923. Basic Principles: Centrifugation relies on sedimentation: Particles settle due to gravity or centrifugal force. The particles move outward radially based on the applied centrifugal field 𝐺 G. Applications of Centrifuge: To separate two miscible substances. To analyze hydrodynamic properties of macromolecules. To purify mammalian cells. To produce skimmed milk. Separation of proteins using purification techniques. Types of Centrifugation: Differential Centrifugation: Separates based on size, commonly used for crude particle separation. Density Gradient Centrifugation: Separates based on density using media like sucrose or cesium chloride. Analytical Centrifugation: Used for quantitative analysis. Ultra Centrifugation: High-speed centrifugation, used for ribosomes, viruses, etc. Sucrose Density Gradient: Definition: Commonly used for preparing density gradients for separating subcellular particles and viruses. Cesium Chloride (CsCl) Density Gradient: Usage: Proves the semi-conservative replication mechanism of DNA using nitrogen isotopes. Analytical Centrifugation (AUC): Purpose: Separates particles based on their density using centrifugal force, commonly for macromolecular analysis. Ultra Centrifugation: Operates at very high speeds for advanced separation tasks, such as determining the shape, size, and density of macromolecules. Radioisotopes: Definition: Atoms with the same atomic number but different atomic masses (e.g., isotopes of carbon or nitrogen). Use: Radioisotopes are used in biological research, including tracing metabolic pathways, carbon dating, and biochemical analysis. Autoradiography: Definition: A bioanalytical technique to visualize the distribution of radioactive-labeled substances. Pulse-Chase Experiment: A two-phase experiment used to study the nature of DNA replication and the transport of proteins.