Chromosomes - The Veterinary Site

Chromosomes


Chromosomes
(by MAAZ AHMED SIDDIQUI )
       The chromosome comes from Greek
       – Chroma = color
       – Soma= body (the colored body)
       Chromosome is the highly condensed form of DNA
       Wrapped into nucleosomes
                -Each nucleosome is composed of a little less     than two turns of DNA wrapped around a set of eight proteins called histones
                -Also known as histone octamer.
       histones are highly alkaline proteins found in eukaryotic cell nuclei that package the DNA
       Nucleosomes wrapped into chromatin fiber
                - The DNA + histone = chromatin
       Condensed during metaphase into the familiar shape
Chromosome Parts
       Heterochromatin:
      More condensed
      Silenced genes (methylated)
      high AT content
      Stains darker
       Euchromatin:
      Less condensed
      Gene expressing
      higher GC content
      Stains lighter
       Telomeres – chromosome tips
      Repeats
      Act as sort of biological clock
      Being whittled down at each Mitosis
       Centromeres – middle
      Highly condensed
      Also repetitive sequence
      Region where spindle fibers attach
      Pulling chromatids apart during Mitosis
       p arm – the smaller of the two arms
      p stands for petite
       q arm – the longer of the two arms
       - q stands for grand
Chromosome Types
There are four types of chromosomes:
  1. Telocentric
  2. Acrocentric
  3. Submetacentric
  4. Metacentric
       Divided based on the position of the centromere
       Telocentric – no p arm; centromere is on end
       Acrocentric – very small p arm; centromere is very near end
       Submetacentric – p arm just a little smaller than q arm; centromere in middle
       Metacentric – p and q arms are exactly the same length; centromere in exact middle of chromosome
Cytogenetics
       Study of chromosomes and chromosomal abnormalities
       Study Karyotypes –picture of an individual’s chromosomes in Metaphase, spread out on a slide


Chromosomes Chromosomes Reviewed by Maaz ahmed siddiqui on 15 May Rating: 5

No comments:

Powered by Blogger.