Health Science

Scanning electron microscopy utilises electron beam for producing high-resolution images of sample surfaces. It forms 3-D view of the sample. It also gives the surface topography of the sample with sufficient clarity and depth of field. The most common SEM mode is detection of the secondary electrons emitted by the atoms excited by the electron

The term growth in microbiology indicates the magnitude of total population. Microbial growth measurement is essential for: Determining the growth and reproduction rate, Determining the suitability of water, milk, and food for human consumption, Counting microflora of soil, Monitoring the fermentation process, Checking the suitability of raw material for preparing pharmaceutical products, and Checking the

In this method, an individual desired cell is picked up from the mixed culture and allowed to grow. For this purpose following two methods are used: Capillary Pipette Method : In this method (figure), a few small drops of a dilute culture medium are placed on a sterile glass-cover slip using a sterile pipette drawn

Culture is a procedure during which microorganisms are cultivated in a medium; if a culture has the population of a single type of microorganism; it is known as a pure culture. Usually, isolation and growth of pure cultures of single-celled microbes carried under aseptic conditions needs sterilised instruments in addition to filtered and still air.

To cultivate a specific microbe, following methods are used : Methods of Culturing Aerobic Bacteria : An atmosphere having oxygen in ample amount facilitates the growth of aerobic or facultative bacteria. For this, a large surface area of medium is used to increase the exposure. Numerous devices, e.g., Fernbach flask, Kolle flask, and Roux bottle

On the basis of morphology, bacteria are classified into the following three forms: Spherical : These are coccus bacteria which are spherical in shape. The word coccus originated from the Greek word kokkos meaning berry. They are the smallest form of bacteria and are almost spherical in shape and appear in many different patterns depending

Structure enclosed by the cell membrane is known as cytoplasm, which is aqueous, semitransparent, elastic, and thick. Cytoplasm consists of 80% water and remaining 20% include proteins (enzymes), carbohydrates, lipids, inorganic ions, and many low-molecular weight compounds. In the cytoplasm, most of the vital chemical reactions (metabolism) of the cells take place. In prokaryotic cytoplasm, the major structures

Immediately below the cell wall, plasma membrane is present which is also known as cytoplasmic membrane, inner membrane, or cell membrane. In prokaryotes, plasma membrane thickness is about 7.5nm (0.0075μm). Phospholipids : These constitute 40% of the plasma membrane and are arranged in two parallel layers, thus known as phospholipid bilayer. Its each molecule has two

Gram-Positive Bacterial Cell Wall Cell wall of gram-positive bacteria (figure), is approximately 80nm thick having several layers of peptidoglycan. Peptidoglycan : It contributes to 50−90% of the dry weight of the cell wall. It is thicker, stronger, and extensively cross-linked than gram-negative bacteria, in which peptidoglycan comprises of 5−10% of the wall material. Peptidoglycan layer is thin in

Despite of being the most primitive and simplest microorganism, bacteria have well developed cell structures which possess many unique biological properties. Bacteria differ from archae bacteria and other eukaryotic microorganisms in many ways. Due to their simplicity, bacteria had been studied thoroughly on the genetic level, revealing many biochemical and genetic principles that have been