Plant Tissue Culture Techniques
CALLUS CULTURE Callus is amorphous mass of loosely arranged thin walled parenchyma cells developing from proliferating cells the parent tissue. Plants are regenerated by forming a normal shoot, root and embryoids ultimately forming a plant. Importance: Plant breeding: Callus culture provides genetic variability which is important for successful plant breeding. Somaclonal variations: Many agriculturally useful […]
Plant Tissue Culture
Plant tissue culture broadly refers to the in vitro cultivation of plants, seeds and various parts of the plants (organs, embryos, tissues, single cells, protoplasts). The cultivation process is invariably carried out in a nutrient culture medium under aseptic conditions. History of Plant Tissue Culture Callus Culture Method German botanist Gottlieb Haberlandt (1902), regarded as […]
Mineral Nutrients Required by Plants
Element Physiological Roles Deficiency symptoms NITROGEN Proteins, chlorophyll, nucleic acids. Cell membranes Enzymes, coenzymes etc. Chlorosis, Leaf fall Stunted growth Poor flowering SULPHUR Amino acids; Methionine, cysteine, Vitamins, biotin, thiamine, Coenzymes etc. Leaf fall, Leaf rolling Chlorosis Inhibition of apical bud Young leaves affects first PHOSPHORUS Proteins, nucleic acids. Cell membranes ATP, ADP, NADP Oxidation […]
Difference between mitosis and meiosis
Meiosis
A special type of cell division, which reduces the number of chromosomes to half in daughter cells as compared to parent cell. It always occur in diploid cells (2n) or tetraploid cells (4n). In animals it takes place at the time of gamete formation (gametogenesis), while in plants at the time of spore formation (sporogenesis). […]
Sex Linkage
The X and Y chromosomes are divided into two regions homologous and differential regions. In humans the homologous regions contain DNA sequences that are substantially similar on both sex chromosomes. The differential regions contain genes that have no counterparts on the other sex chromosome. Hence in males these genes in the differential regions are […]
Antibody structure and function
The world is full of infectious microorganisms, all looking for a suitable host to infect. Bacteria, viruses, and protozoans are constantly attempting to gain entry into our tissues. If nothing was done about these attempts at invasion, no human could survive. Fortunately, cells of the immune system patrol the internal tissues, the bloodstream, and the […]
Meselson–Stahl experiment
The first problem in understanding DNA replication was to figure out whether the mechanism of replication was semiconservative, conservative, or dispersive. In 1958, two young scientists, Matthew Meselson and Franklin Stahl, set out to discover which of these possibilities correctly described DNA replication. Their idea was to allow parental DNA molecules containing nucleotides of one […]
DNA Replication
The copying mechanism to which Watson and Crick referred is called semiconservative. The sugar-phosphate backbones are represented by thick ribbons, and the sequence of base pairs is random. Let’s imagine that the double helix is like a zipper that unzips, starting at one end (at the bottom in Figure 1) We can see that, if […]
DNA: the genetic material
Before we see how Watson and Crick solved the structure of DNA, let’s review what was known about genes and DNA at the time that they began their historic collaboration: 1. Genes— the hereditary “factors” described by Mendel—were known to be associated with specific character traits, but their physical nature was not understood. Similarly, mutations […]