Chromosomes are found in the nucleus of cells and are responsible for heredity, variation, mutation, and evolution. They vary in size from 0.1 to 33 micrometers in length and 0.2 to 2 micrometers in thickness. Chromosomes have a characteristic shape with two identical halves called sister chromatids joined at the centromere. The X chromosome is typically longer than the Y chromosome and contains more euchromatin and less heterochromatin, while the Y chromosome shows the opposite pattern.

1. By
Ajinkya M Kadu
M.Sc. - 1

2.  What are Chromosomes?
 Size
 Shape
 Structure
 Centromere
 Structure of X & Y chromosome

3. Chromosomes : Chroma – color, soma – body
Found in Nucleus of Cell
Ability of Self replication
Role in – heredity, variation, mutation & evolution
CHROMOSOMES

4. • Morphologically & genetically identical Chromosomes are
called Homologous chromosomes.

5. Euploidy – Presence of whole sets of
Cromosomes

6. Number of Chromosomes

7. Example

8. Chromosome No. in Different animals

9.  Varies from species to species
 Normally 0.1 to 33 um in length
 0.2 to 2 um in thickness
Size

10. Depends on stage of Cell Division
In Interphase = less condensed
In Metaphase = max. condensation & appear short
Shape

11.  Metaphasic chromosome has 2 identical halves called Sister
chromatids
 Each chromatid is in turn made up of sub-chromatids called
chromonemata
 Both arms are joined at Centromere
Structure

12.  Centromere is also called the
Primary constriction
 During cell division spindle
Fibres are attached at
centromere
 After primary constriction,
secondary constriction is
present
 The part of the chromosome
beyond the nucleolus is called
satellite
Centromere

13. Tip of chromosome is called Telomere
It prevents sticky ends of chromosome from attaching
The surface of a chromosome bears number of small
swellings called chromomeres.

14. Types of Chromosomes

15. • X chr is longer than Y chr
• X chr contains < Euchromatin & > Heterochromatin
• Y chr contains > Euchromatin & < Heterochromatin
• X and Y chromosomes show homologous & Non-Homologous
regions.
Structure of X & Y chr

17. REFRENCE
• Human Chromosomes by Orlando J. Miller
• Chromosome biology by R. Appels
• http://www.chromodisorder.org/CDO/
• http://www.genome.gov/26524120
• http://www.youtube.com/watch?v=zf7tbymrv9 o
• http://www.johnkyrk.com/chromosomestructu
re.html