PPt on chromosome structure for uni students

1. CHROMOSOME STRUCTURE
Presented by:
Rakhi Bandopadhyay
1st Semester Physiology Hons

2. Chromosomes(Introduction)
• Definition: Chromosomes are the rod-shaped, dark stained bodies
seen during metaphase of mitosis.
• Strausberger discovered chromosome in 1875.
• The term was however coined by Waldeyer in 1888.
• The word “Chromosome” comes from, Chroma- colour and Soma-
body.

3. The whole
length of
DNA is coiled
around
histones and
compacted
into a
chromosome
.

4. CHROMOSOME MORPHOLOGY
• Mitotic metaphase is the most suitable stage for studies on
chromosome morphology.
• Chromosome morphology changes during cell division.
• Chromosomes are thin,coiled,elastic,thread-like structures during
interphase.
• As cells enter mitosis, their chromosomes become highly condensed
so that they can be distributed to daughter cells.
• The structures observed in the mitotic metaphase chromosomes, are
seen in the nest slide:-

6. CHROMOSOME STRUCTURE
• Centromere
• Chromatid
• Secondary constriction and satellite
• Telomere
• Chromomere
• Chromonema
• Matrix

7. • Centromere: It is a localised area of the chromosome with which
spindle fibres are attached.
• Chromatid: One of the two distinct longitudinal subunits of a
chromosome. They are of two types, sister chromatids and non-sister
chromatids.
• Secondary constriction: Some chromosomes exhibit secondary
constriction between telomere is called as satellite or trapant.
Chromosomes having satellites are called satellite chromosomes.
• Telomere: The two ends of the chromosome are known as telomeres.
Telomeres are highly stable and they don’t fuse or unite with
telomere of other chromosomes.
• Chromomeres: The chromosomes of some species show small bead
like structures called chromomeres. The structure of chromomeres in
chromosomes are constant.

8. • Chromonema: Thread like coiled structures found in the
chromosomes and chromatids are known as chromonema( plural
chromonemata).
• Matrix: It is a fluid part in which chromonemata are embedded is
called matrix.

9. Chromosomal structure abnormalities

10. Structural abnormality disorders.
• Cri du chat syndrome: Known as 5p syndrome and cat cry syndrome
is a rare genetic condition that is caused by the deletion of genetic
material on the small(p arm) of chromosome 5.

11. • Wolf- Hirschhorn Syndrome: This a genetic disorder that occurs due
to deletion of the short arm of chromosome 4. Also called deletion 4p
syndrome.

12. • Jacobsen syndrome: This is a rare genetic disorder caused by the
deletion of the long arm of chromosome 11. Also called 11q deletion
disorder.

13. • Angelman syndrome: Deletion or mutation of maternal chromosome
15. Generally deletion in chromosomal region 15q 11-13.

14. • Prader-willi syndrome: This is a genetic disorder caused by deletion
of a part of paternal chromosome 15.