DR . R. MAHENDIRAN RAMASAMY

 GENERAL PROPERTIES OF VIRUS: 1. Acellular structure:          They are acellular particles consisting of genetic materials [DNA &RNA] enclosed in a protein coat called capsids. Some viruses also consist of lipid envelopes obtained from the host. 2. Obligate intracellular parasites:          They cannot reproduce or perform metabolic pathways independently. So, they require a host cell for replication and metabolic processes. 3. Genetic material:         Viruses contain either DNA or RNA but not both.          The genetic material can either be single-stranded or double-stranded. 4. Capsid:         It helps in protecting the viral genome and helps in attachment to host cells.         Capsids are made of protein subunits called capsomers. 5. Size:        It is usually in 20 to 300 nanometers. e.g., smallest virus bacteriophage...

 It is an instrument used to measure the amount of absorbance of light by a sample.  It is used to measure the absorbance of light by placing samples in a cuvette in the instrument  It was invented by Arnold J. Beckman and his colleagues at National Technologies Laboratory (NTL) in 1940. Principle: It is used to measure the light intensity as a function of wavelength. The diffraction of light by a prism into different wavelengths was detected by the charged couplers or detectors. Instrumentation: Energy source Monochromator- used to break polychromatic radiation into its component wavelengths. Prism- types used are 600 Cornu quartz prism and 300 Littrow prism. Grating- used in monochromators of instruments operating in the ultraviolet, visible, and infrared regions. Cuvettes- It is made up of quartz material where the samples are loaded and placed in the instrument for operation. Detector- It is based on photoelectric current and is amplified and recorded. Applications: d...

  Centrifugation  is a term used to describe a method of separating mixtures using spinning and centrifugal force. Several characteristics can separate particles during centrifugation, including size, shape, density, and viscosity. British military engineer Benjamin Robins, who built a device that resembled an arm rotating around an axis to gauge drag on items. The Prandtl brothers later made the first practical centrifuge to separate milk from the cream by improving this design. By rapidly rotating a container containing material, separation is accomplished, the centrifugal force forces heavier elements to the outside of the container. Principles of Centrifuge: The centrifuge utilizes the sedimentation principle due to gravitational force. The centrifugation technique uses a centrifugal field to separate particles suspended in a liquid medium. These are put in the centrifuge’s rotor either in bottles or tubes. Sedimentation is a process in which gravity causes suspended parti...

An autoclave is a machine that provides a physical method of sterilization by killing bacteria, viruses, and even spores present in the material put inside the vessel using steam under pressure. Autoclave Principle/ Working The autoclave works on the principle of moist heat sterilization, where steam under pressure is used to sterilize the material present inside the chamber. The high pressure increases the boiling point of water and thus helps achieve a higher temperature for sterilization. Water usually boils at 100°C under normal atmospheric pressure (760 mm of Hg); however, the boiling point of water increases if the pressure is increased. Similarly, the high pressure also facilitates the rapid penetration of heat into deeper parts of the material, and the moisture present in the steam causes the coagulation of proteins, causing an irreversible loss of function and activity of microbes. This principle is employed in an autoclave where the water boils at 121°C at the pressure of 15 ...

  REAL TIME PCR   AIM:  Demonstration of Real-Time PCR through experimental samples  INTRODUCTION:  Real-time quantitative PCR allows the sensitive, specific and reproducible quantitation ofnucleic acids. It monitors the amplification of a targeted DNA molecule during the PCR (i.e.in real time), not at its end, as in conventional PCR. Real-time PCR is the technique ofcollecting data throughout the PCR process as it occurs, thus combining amplification and detection into a single step. Using PCR, specific sequences within a DNA or cDNA template can be copied, or “amplified”, many thousand- to a million-fold using sequence specific oligonucleotides, heat stable DNA polymerase, and thermal cycling. The PCR is the cyclic reaction based on the rapid change in temperature during each step. During PCR, our gene of interest is amplified as well as quantified. Real-time quantitative PCR is the reliable detection and measurement of products generated during each cycle of...

  I SOL A T I ON A N D SE P ARA T I ON OF C H R O M OSO MA L D N A FR OM B A C TE R I A   AI M : To iso l a te a nd s e p a r a te t h e c h r omosomal D N A f r o m ba c te r ia   P RI N C I P LE:   G e nom i c ( c h romosomal) D N A f rom e i t h e r b ac t e r ia, plant or a ni m a l ce ll c a n be iso l a ted b y l y sis m e thod. F or pl a nt ce ll or b ac t e ri a l c e l l , f i rst ce ll w a ll is me c h a nic a l l y disrupted. The ce ll w a ll is b r o k e n e n z y ma t ic a l l y using e n z y m e s l i ke l y so z y me. W h e n b a c te r ia a r e l y s e d und e r a lkaline c ondi t ions both D N A a nd p r oteins a re p rec ip i tat e d. A f ter the a ddi t i on of ace tate- c ontaining n e utr a l iz a t i on buf f e r the la r ge a nd le s s supe rc oi l e d c h r omos o mal D N A a nd p rot e ins p rec ip i tat e , but the small b ac te r ial D N A plasmids ca n r ...