18 Questions
What is the main objective of differential centrifugation?
Separating particles based on their density
Which technique involves macromolecules moving through a density gradient until they reach a density equal to their own?
Density gradient centrifugation
What is the purpose of molecular and biochemical analysis in biological systems?
Studying genetic information
Which technique involves breaking cell membranes to release organelles and cytosol before subjecting the lysate to repeated centrifugations?
Manual homogenization
Which method allows scientists to determine gene expression patterns and investigate genetic variation?
DNA sequencing
What is the primary purpose of ultrasonic homogenization (sonication) in laboratory procedures?
Disrupting cell structures with ultrasonic waves
What is the primary objective of cell fractionation?
To study the molecular composition of isolated components
Which step of cell fractionation involves placing sample tissue under mild conditions?
Extraction
Why is ice-cold solution used in the extraction step of cell fractionation?
To prevent water from moving into organelles via osmosis
What is the purpose of using isotonic solution in cell fractionation?
To prevent water from entering organelles
Which technique is used to separate cellular components based on their density in cell fractionation?
Centrifugation
Why is buffered solution used in cell fractionation?
To prevent denaturation of organelle proteins
What does the process of centrifugation aim to achieve?
Separate components of a mixture based on density and/or particle size
Which technique is used to separate organelles based on their sedimentation rate?
Density gradient centrifugation
What happens to the organelles during sonication or ultrasonic homogenization?
They become fragmented
In differential centrifugation, what is the primary purpose of the procedure?
Separate organelles and other sub-cellular components based on density
How are components separated in density gradient centrifugation?
Based on their density in a dense medium
What is the main purpose of filtration in laboratory processes?
To separate solid particles from a liquid by passing it through a porous material
Study Notes
Cell Fractionation
- Cell fractionation is a technique used to separate cellular components while keeping their distinct functions, also known as subcellular fractionation.
- The primary objective of cell fractionation is to separate components and organelles, so that the structures, functions, and molecular compositions of isolated components may be studied.
Steps of Cell Fractionation
- Extraction: sample tissue is placed under mild conditions (cell-free systems) before being used to protect its integrity, using a cold, isotonic, buffer solution.
- Homogenization: organelles leak out due to lysis, and membranous organelles become fragmented and form spherical membranous vesicles, resulting in a homogenate.
- Filtration: the homogenate is filtered through a gauze to produce a solution (filtrate) that contains a mixture of organelles.
- Centrifugation: a mechanical process that utilizes an applied centrifugal force field to separate the components of a mixture according to density and/or particle size.
Centrifugation Techniques
- Density gradient centrifugation: separates components based on their density, using a dense medium or density gradient in a centrifuge, and reagent in separation of cells.
- Differential centrifugation: separates organelles based on their sedimentation rate, using a procedure to separate organelles and other sub-cellular components.
Importance of Cell Fractionation
- Electron microscopy provides information on the structure and function of cellular organelles, but fails to provide insight into the molecular composition of these structures.
- Cell fractionation allows scientists to study the structures, functions, and molecular compositions of isolated components.
Molecular and Biochemical Analysis
- Molecular analysis involves the study of nucleic acids (DNA and RNA) and their functions within cells.
- Techniques used in molecular analysis include DNA sequencing, polymerase chain reaction (PCR), gene expression analysis, and DNA fingerprinting.
- Molecular and biochemical analysis provides insights into the structure, function, and interactions of molecules such as DNA, RNA, proteins, and metabolites.
Test your knowledge on cell fractionation techniques used to separate cell components based on density and size. Learn about processes like lysis, homogenization, filtration, and centrifugation.
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