What is Penicillin? Alexander Fleming in September 1928 accidentally discovered Penicillin. He found that the fungus, Penicillium notatum prevented the growth of bacteria, Staphylococcus spp.. Later Clutterbuck and his colleagues in 1932 studied the nature of Penicillin and found it … Read more
Definition and overview of a plant cell Plant cells are multicellular eukaryotic cells that make up a plant (a group of eukaryotes belonging to the Plantae kingdom, with the ability to synthesis their own food using water, Sunlight and CO2). … Read more
Homozygous Definition Homozygous is a genetic condition where an individual inherits the same alleles of a gene from both the parents. In homozygous chromosomes, both alleles are either dominant or recessive. The dominant trait is represented by two capital letters … Read more
Phase contrast microscopy definition Unstained living cells absorb practically no light. Poor light absorption results in extremely small differences in the intensity distribution in the image. This makes the cells barely, or not at all, visible in a brightfield microscope. … Read more
Folic acids are the enzymes that are necessary for the bacterial protein synthesis and synthesis of amino acids. Trimethoprim and Sulfonamides are the antimicrobial classes that interfere with the synthesis of folic acid at different levels and are bacteriostatic. Trimethoprim … Read more
Both light microscopes and electron microscopes use radiation (light or electron beams) to form larger and more detailed images of objects which cannot be seen clearly through an unaided eye. However, each of these microscopes has distinct features and is suitable for … Read more
Plants and animals are made up of millions of cells and these cells have several similarities and differences. Considering that they are both eukaryotic cells, which means they have a true nucleus, that is enclosed and separated from other organelles … Read more
Definition of plant cell Plant cells are eukaryotic cells, that are found in green plants, photosynthetic eukaryotes of the kingdom Plantae which means they have a membrane-bound nucleus. They have a variety of membrane-bound cell organelles that perform various specific … Read more
What is Apoptosis? Apoptosis is a normal genetically programmed cell death where an aging cell at the end of its life cycle shrinks and its remaining fragments are phagocytosed without any inflammatory reaction. The term apoptosis was first introduced in … Read more
Heterochromatin Definition Heterochromatin is a tightly packed or condensed DNA that is characterized by intense stains when stained with nuclear stains, containing transcriptionally inactive sequences. It exists in multiple variations, up to four to five state, each of which is … Read more
Fluorescence microscope definition A fluorescence microscope is an optical microscope that uses fluorescence and phosphorescence instead of, or in addition to, reflection and absorption to study properties of organic or inorganic substances. Fluorescence is the emission of light by a … Read more
Epithelial Tissue Definition Epithelial tissue is a type of animal tissue, consisting of closely aggregated polyhedral cells connected firmly to one another in the form of cellular sheets that line the interior of hollow organs and cover the body surface. … Read more
Mycolic acid is the cell wall that contains α-alkylated β-hydroxylated fatty acids present in Mycobacteria, Nocardia, and Corynebacteria. Mycolic acids are the main component of the cell wall of Mycobacterium spp and plays important role in the virulence and permeability … Read more
Mollusca (Mollusks) Definition Molluscs (also know as mollusks) are soft-bodied, bilaterally symmetrical, segmented, coelomate animals; usually shelled having a mantle, ventral foot, anterior head, and a dorsal visceral mass. Phylum Mollusca (Mollusks) Characteristics They are essentially aquatic mostly marine, few … Read more
A good microscope should have three properties: Good resolution: Resolution power refers to the ability to produce separate images of closely placed objects so that they can be distinguished as two separate entities. The resolution power of: The unaided human … Read more
RNA stands for Ribonucleic acid is a polymer of ribonucleotides. Transcription is the process in which DNA is transcribed into RNA with the help of the enzyme RNA polymerase. Transcription involves three steps; elongation, initiation, and termination. Rifamycins group of … Read more
Iodine Test Definition Iodine test is a chemical test used to distinguish mono- or disaccharides from certain polysaccharides like amylase, dextrin, and glycogen. This test has a variation termed starch-iodine test that is performed to indicate the presence of glucose … Read more
Compound Microscope Definition The term microscope can be split into two separate words, ‘micro’ and ‘scope’, where the term ‘micro’ means small or tiny, and ‘scope’ means to view or to observe. Therefore, a microscope can be understood as an instrument to observe tiny elements. The optical … Read more
Protozoa Definition Protozoa may be defined as “microscopic acellular animalcules existing singly or in colonies, without tissue and organs, having one or more nuclei”. Some of the characteristics are: There are about 50,000 known species of Phylum Protozoa. Protozoans exhibit … Read more
Chromosome Definition A chromosome is a thread-like structure present in the nucleus or nuclear region of the cytoplasm that is made up of a single molecule of DNA (Deoxyribonucleic acid) and proteins, carrying some or all genetic materials of an … Read more
Nematoda Definition Nematodes (Gr., nema thread+ eidos, form) are commonly referred to as non-segmented roundworm, threadworm or pinworm, as distinct from flatworm and higher segmented annelids. Image Source: Wikipedia Phylum Nematoda Characteristics They are widely distributed, aquatic or terrestrial, parasitic … Read more