Razzaq Archive
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 …
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. …
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 …
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 …
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 …
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 …
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 …
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, …
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 …