Category: B.SC 1 YEAR

This video is about the Nucleosome Model proposed by P. Outdet. In chromosomal organization the DNA is associated with Histone proteins .The nucleosome is the repeating unit that consists of Core particles of octamer of Histones- H2a, H2b, H3 and H4, and 140bp DNA coiled around it. The 60bp DNA is linked from outside to H1 Histone protein through loose bond. This is universally accepted model that shows the lowest level coiling of DNA and it appears as “String On Beads”.

This video is about the structure of Nephridia of Neres. It is an excretory organ of Neres, which is a Polychete Annelidan. Neres has Metanephridia which are exonephric type. There are one pair nephridia per segment except the head segments and pygidium. In structure nephridia have a syncytial connective tissue body consisting of nephridial tubule and the neck. The tubule opens at one end by Nephrostome and by nephridiopore at other end. The neck lies dipped into coelom of the adjacent segment and the nephridiopore opens outside in which body lies transversally in ventro lateral position. The waste products are absorbed by gland cells of nephridial tubule and by ciliates nephrostome and discharged outside through nephridiopore.

This video is about the morphology of the chromosome. Chromosomal body has elongated highly coiled DNA fibrils known as chromonema which are embedded in the matrix and matrix is covered with the pellicle. The size, shape and number of chromosome are fixed according to species. Organism having one set of chromosome are Haploid(n), with double set they are diploid, more than two set are known as polyploids.