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# A mechanical method of seperating immiscible
liquids or solids from liquids,by the application of
centrifugal force.
# It is a piece of equipment,generally
driven by an electric motor,that puts
an object in rotation around a fixed axis,
applying a force perpendicular to the axis.
# Isolating suspensions,
# Isotope seperation,
# Aeronautics & astronautics,
# Earthquake & blast stimulation &
# Commercial applications.
# This technique concerned with the seperation,isolation &
purification of subcellular organelles,whole plasma
membrane,polysomes,ribosomes,chromatin,nucleic acids,
lipoproteins & viruses.
# This technique concerned with the study of pure, or
virtually pure macromolecules or particles.
ROTORS:
# Swinging – bucket rotors,
# Fixed – angle rotors,&
# Vertical rotors.
SWINGING – BUCKET ROTORS:
FIXED – ANGLE ROTORS:
VERTICAL ROTORS:
VERTICAL ROTORS:
# Density gradient centrifugation,
# Rate-zonal seperation,
# Isopycnic seperation.
# Differential centrifugation,
# K – factor centrifugation,
# Sucrose gradient centrifugation,
# Microcentrifugation,
# Superspeed centrifugation,&
# ultracentrifugation.
# It is useful to purify subcellular organelles & macromolecules.
# It is also useful for the determinaton of buoyant densities,&
# It is also useful for the estimation of the sedimentation coefficient.
1) Seperation of :
# Proteins,
# Enzymes,
# Hormones,
# RNA – DNA hybrids,
# Ribosomal subunits,&
# Subcellular organelles.
2)For the analysis of size distribution of samples of polysomes &
lipoprotein fractionations.
# To determine the buoyant density of a particle,
# To determine the base composition of the double – stranded DNA,
# To separate & purify viruses,
# To analyze nucleic acids.
centrifugation
Sample + Caesium chloride
Cscl molecules sedimentation
Rise or sediment
Concentration gradient
(density gradient)
Solution density = Own buoyant density
It is the most commonly used method,for the isolation of
subcellular organelles from the homogenised tissue.
# It can be used to determine the time required for pelleting a
fraction,with a known sedimentation coefficient.
# It is used to purify enveloped viruses & ribosomes.
# It will also separate cell organelles from crude cellular extracts.
# It will also purify exosomes.
# These centrifuges are run in batch to isolate small volumes of
biological macromolecules or cells.
# It will purify cells & nuclei.
# It can be used to isolate subcellular organelles such as
endoplasmic reticulum,ribosomes,cytoplasmic components,
smaller particles such as proteins & to harvest virus in pure form.
# Theodor Svedberg(1925) - Analytical centrifuge
# Edward Greydon Pickles - Vacuum centrifuge
Pickles(1946)
Spinco(1946)
Beckman instruments (1954)
Model L
# It is used for the determination of the macromolecular including
amino acid composition of protein,protein’s current conformation, &
size distribution of macromolecular samples.
They are used in biology for pelleting of fine particulate fractions.
# It is the most important widely applied research techniques in
biochemistry,cellular & molecular biology, & in medicine.