Characteristic Features 7. Additional protein structures called histones support the DNA molecule within the chromosome. The pair of sex chromosomes determines whether a fetus becomes male or female. 7 Chromosome Structure The of chromosomes varies widely. iPad
special types polytene chromosomes It has closed circular DNA. Linear chromosomes are found in eukaryotes. Before applying stain to the chromosomes, they must first be treated with trypsin, which is a digestive fluid found in many animals. Thus the chromosomes are appeared as mass of stained material. This name was given because it is similar in appearance to the brushes used to clean lamp chimneys in centuries past.
Polytene chromosomes are found in dipteran flies: the best understood are those of Drosophila, Chironomus and Rhynchosciara. In certain plants, they are found in the suspensors of the embryo. (Fig. Females have two X chromosomes, one from the mother and one from the father. Aneuploidy can be the cause of disorders such as Down Syndrome. Most web browsers block content or generate a “mixed content” warning when users access web pages via HTTPS that contain embedded content loaded via HTTP. A male’s X comes from his mother and the Y comes from his father. Centromere Definition. Each bivalent has four chromatids two in each homologue. Nowell and Hungerford examined cancer cells from two patients with CML and noticed something peculiar—one of the 46 chromosomes was abnormally short. Usually we have 46 chromosomes in most cells.
Slide 6: The axis of each homologue consists of row of granules or Chromomeres each of which have two loop like lateral extensions,one for each chromatid. Usually we have 46 chromosomes in most cells. Slide 14: large chromosomes from salivary glands of Diptera that have hundreds of strands of DNA together, along with homologous chromosomes stuck together; Accessory chromosomes: Accessory chromosomes In many species some chromosomes are found in addition to normal somatic chromosomes. Enter one or more tags separated