Centrifugation Flashcards
The most popular technique used in biological sciences for separation of particles/microorganisms by centrifuge
Centrifugation
a device for separation of microorganisms from the suspended fluid using centrifugal force (g-force)
Centrifuge
In a solution, _____ particles sediment in influence of gravitational field
higher density
When centrifugal force applied by the centrifuge, the particles _____
move faster
Expressed as a multiple of acceleration (G) due to gravity (g)
Relative Centrifugal Force
When a biological sample moves in centrifuge, it experiences an _____
Outward centrifugal force
Rate of sedimentation of biological sample is dependent on the _____
Applied centrifugal force
The applied centrifugal force is determined by the _____ of the particle from the axis of rotation
Radial distance
Can be defined as numbers of revolutions (cycles) per second
Frequency
the ratio of the centrifugal acceleration (G) and gravitational acceleration (g)
Relative centrifugal force (RCF)
Sedimenting particles have only short distance to travel before pelleting, has a shorter run time, and is the most widely used rotor type
Fixed angle rotor
Longer distance of travel may allow better separation, such as in density gradient centrifugation
Swinging bucket rotor
Easier to withdraw supernatant without disturbing pellet
Swinging bucket rotor
Super speed centrifuge
High-speed centrifuges
Which centrifuge type can handle larger sample volumes, from a few tens of mL to several L?
High-speed centrifuge
The rotors may come with different adapters to hold various sizes of test tubes, bottles, or microliter plates
High-speed centrifuge
RPM of High-speed centrifuge
3000 rpm (1500-20000 rpm)
Maximum angular velocity of ultracentrifuge
70000 rpm (65000 rpm)
Can be used in the study of membrane fractionation
Ultracentrifuge
Can separate molecules in batch or continuous flow systems
Ultracentrifuge
During the run of this centrifuge, the particles or molecules will migrate through the test tube at different speeds depending on their physical properties and the properties of the solution
Ultracentrifuge
A centrifuge that is normally refrigerated and is often used for research applications
High-speed centrifuge
Expensive and requires a special rotor and the care in use balance is critical
Ultracentrifuge
Used to process small volumes of biological molecules, cells, or nuclei
Microcentrifuge
Volume of tubes that holds the liquid of microcentrifuge
0.5-2mL
Maximum angular speed of microcentrifuge
12000-13000 rpm
Small enough to fit on a table-top and have rotors that can quickly change speeds
Microcentrifuge
Simple centrifuges that are used to separate erythrocytes, blood samples, coarse precipitates, and cells
Small bench/laboratory centrifuge
Speed range and centrifugal force of small bench centrifuge
4000-6000 rpm and 3000-7000 g
Volume of liquid processed by small bench centrifuge and how much time does it take
250 mm3 - 1.5 cm3 , for 1-2 min
Common use of microcentrifuge
biochemistry/ molecular biology/ biological labs
Common use of small bench top centrifuge
clinical labs (blood/ plasma/ serum/ separation)
How much tubes is the approximate capacity of small bench top centrifuge?
100 tubes
How much is the maximum generated force of microcentrifuge?
15000 x g
Helps in preserving the morphology and activity of subcellular fractions
Sucrose and Ficoll
Useful in isopycnic density gradient centrifugation technique
Cesium chloride and Potassium bromide
Because of its low osmolarity, low viscosity and large particle size, is suitable for separating cells, bacteria, viruses, and subcellular organelles
Percoll
For the isolation of membrane fractions by floatation
Metrizamide and Nycodenz
For cell fractionation
Renografin
Centrifugal force required for nuclei
800 - 1000 g
Centrifugal force required for mitochondria
20000 - 30000 g
Centrifugal force required for chloroplasts
20000 - 30000 g
Centrifugal force required for lysosomes
20000 - 30000 g
Centrifugal force required for microbodies
20000 - 30000 g
Centrifugal force required for RER (microsomes)
50000 - 80000 g
Centrifugal force required for plasma membranes, SER membranes
80000 - 100000 g
Centrifugal force required for free ribosome particles
150000 - 300000 g
Typical separation method for DNA and RNA and its most appropriate rotor
CaCl gradient, 4000000xg; Ethidium Bromide staining ; vertical and fixed angle
Typical separation method for viruses and its most appropriate rotor
Sucrose gradients, 100000xg ; swinging bucket
Typical separation method for proteins and its most appropriate rotor
Rate-zonal separation, 600000xg ; fixed angle
Typical separation method for cells and organelles and its most appropriate rotor
Differential pelleting-low speeds for cells; high speeds-smaller organelles ; fixed angle
Used to measure the sedimentation velocity in an ultracentrifuge and to determine molecular weight by substitution in an equation
Svedberg unit
Relationship between RPM and RCF
Direct
Relationship between G and size particles
Inverse
For swinging bucket type, what is the relationship between distance and separation level?
Direct (more distance means better separation)
A process of combination of sediments after centrifugation
Pelleting
A quality control instrument that checks the speed of centrifuge (in RPM)
Tachometer