Discovery: The ER was discovered by K. R. Porter, Claude and Thompson in 1945, but the name ER was given by Porter (1953). Location: The ER occurs in all eukaryotic cells except ova, embryonic cells and mature RBCs. It is also absent in prokaryotic cells. ER is quite extensive in metabolically active cells, simple in storage cells and reduced in [...]
Chromosomes are threadlike deeply stained compact DNA protein complex that carry genetic information in a linear sequence of genes. They are the physical basis of heredity or hereditary vehicles as they store, replicate, transcribe and transmit the genetic information. Though the scope of the term include the bacterial nucleoid (prochromosome), organelle genomes, viral genomes and eukaryotic nuclear chromosome, but only [...]
Plastids are double membre bounded cytoplasmic organneles found in all plant cells and in euglenoides. They are easily observed under light microscope. E. Haeckel (1866) introduced the term plasmid. On the basis of types of pigments they contain, Schimper (1883) classified them in three types: (i) Leucoplasts- Colourless plastids (ii) Chromoplasts - Coloured plastids (other than green) (iii) Chloroplasts- Green [...]