Jjagagag

1. ● Shivam Sharma
● Group:-19
●

2. Chromosome
Sister Chromatides

3. Definition
⦿Centromere Particular chromosome
complement of an individual or a related
group of individuals, as defined by the
chromosome size, morphology, and
number –Karyotype.

4. General morphology
⦿Size of chromosome
⦿Position of centromere
⦿Presence of secondary constriction
⦿Size of satellite
of somatic chromosome
complement of an individual constitutes its
Karyotype.

5. Karyotype
⦿The complete chromosomal set of nucleus in
the cell.
⦿ The preparation and study of
KARYOTYPES is a part of
CYTOGENETICS.
⦿ Cytogenetics = The study of
chromosome number, structure, function,
and behavior in relation to gene inheritance,
organization and expression

6. History of karyotyping
•Grygorii Levitsky (1931) seems to have
been the first person to define the karyotype as
the “phenotypic appearance of
the somatic chromosomes, in contrast to
their genic contents”.

7. Chromosome structure
⦿Chromosomes are composed of chromatin ,a
combination of nuclear DNAand protein.
⦿For KARYOTYPING cells are captured in
metaphase.Ametaphase stage in mitosis at
⦿which the chromosomes are aligned along
the cell equator.

8. CENTROMERE
POSITIONS
Telocentric Acrocentric
Sub metacentric Metacentric

9. CLASSIFICATION OF
CHROMOSOMES FOR
KARYOTYPING
GroupA: chromosomes 1,2,3
largest metacentric
and sub metacentric
Group B: chromosomes 4,5
large sub metacentric
Group C: chromosomes
6,7,8,9,10,11,12
medium sub metacentric

10. Continue…
Group D: chromosomes 13, 14, 15
medium acrocentric
Group E: chromosomes 16, 17, 18
short metacentric or sub metacentric
Group F: chromosomes 19, 20
short metacentric
Group G: chromosomes 21, 22
very short acrocentric

11. X-chromosome – SUBMETACENTRIC
Y-chromosome - AGROCENTRIC

12. The human karyotype
⦿ The normal human karyotypes contain 22pairs
of autosomal chromosomes and one pair of sex
chromosomes.
⦿ Normal karyotypes for females contain two X
chromosomes and are denoted 46,XX; males
have both an X and a Y chromosome denoted
46,XY.
⦿Any variation from the standard karyotype may
lead to developmental abnormalities.

13. Karyotype
MALE KARYOTYPE FEMALE KARYOTYPE

14. SPECIMENS USED
Peripheral Blood
Bone Marrow
Cultured Skin Fibroblast
Amniotic Fluid

15. Trisomy 21
⦿Abnormality
shown in
karyotype
⦿Note that there
are three copies
of #21
chromosome.
⦿This person has
Down Syndrome.

16. Turner syndrome
⦿Abnormality shown
in karyotype
⦿Note this person
only has 1 copy of
the X chromosome.
⦿This female has
Turner’s syndrome.

17. Klinefelter syndrome

18. Advantages of
Karyotyping
•Reveals structural features of each
chromosomes.
•Helps in studying chromosome banding
pattern.
•Helps in the identification of chromosomal
aberrations.
• Diagnosis of prenatal genetic defects.