Saran's Learn Microbiology

ROTORS Rotor is the rotating unit of Centrifuge. Rotor is the movable part of machine which separated the particles present in the sample. For low speed centrifugation, rotor is made up of Brass or Steal (low stress) and for high speed centrifugation, rotor is made up of   Aluminium or Titanium (high stress). DIFFERENT TYPES OF ROTORS (i) Vertical tube rotors Vertical tube rotors are first introduced during 1970’s for high speed and ultracentrifuges. The Vertical tube rotor is a fixed zero angle rotor. In this, the tubes are aligned vertically in the body of the rotor at all times. In Vertical tube rotor, the pellet is deposited along the entire length of the outer wall of the centrifuge tube. It is the major disadvantage because the pellet tends to fall back into the solutions at the end of centrifugation. (ii) Fixed angle rotors Fixed-angle rotors are the most ubiquitous rotors used in centrifugation. In Fixed angle rotors, the tubes are placed at a fixed angle between 14° ...

  CENTRIFUGATION Centrifugation is a separation process which uses the action of centrifugal force (a force which acts on a body moving in a circular path and is directed towards the centre around which the body is moving) to promote accelerated settling of particles in a solid-liquid mixture. Centrifugation is the process where a mixture is separated through spinning. During Centrifugation, the solid particles were separated from the liquid particles. In 1864, Antonin Prandl invented the first dairy centrifuge in order to separate cream from milk. In 1879, Gustaf de Laval demonstrated the first continuous centrifugal separator, making its commercial application feasible. CENTRIFUGE The Centrifugation process was carried out in conical tubes (centrifuge tubes) with the help of an instrument named “Centrifuge”. The centrifuge separates the particles from a solution according to their size, shape, density, viscosity of the medium and rotor speed. A centrifuge is used to separa...

pH METER pH pH is an abbreviation of the French word “pouvoir hydrogene” that represents “hydrogen power” and was proposed by the Danish scientist Soren Peter Lauritz Sorensen in 1909 in order to express the very small concentrations of hydrogen ions. The pH is defined as the negative log of hydrogen ion activity. It does not indicates the hydrogen ion concentration. pH = - log (H + ) pH is an important parameter because many of nature's processes are highly dependent on pH. However, as most chemical and biological reactions are governed by the hydrogen ion activity. Every aqueous solution can be measured to determine its pH value. This value ranges from 0 to 14 pH. Values below 7 pH exhibit acidic properties. Values above 7 pH exhibit basic (also known as caustic or alkaline) properties. Since, 7 pH is the center of the measurement scale, it is neither acidic nor basic, it is called "neutral." pH MEASUREMENT pH in an aqueous solution can be measured in a variety of w...

Practice Quiz 1 - History of Microbiology (Part 1) 1. One millimetre (mm) is equal to a) 100000 µm b) 10000 µm c) 1000 µm d) 100 µm 2. One micrometre (µm) is equal to a) 100000 nm b) 10000 nm c) 1000 nm d) 100 nm 3. Who is Father of Biology? a) Anton van Leeuwenhoek b) Aristotle c) Louis Pasteur d) Robert Hooke 4. Spontaneous Generation Theory was proposed by a) Aristotle b) Robert Hooke c) Louis Pasteur d) Robert Koch 5. Spontaneous Generation Theory or Abiogenesis means “Living things can arise...