Karyotyping involves examining chromosomes from a cell sample to identify abnormalities. It produces a karyotype that arranges chromosome pairs by size, shape, and other features. Different banding techniques use dyes that bind preferentially to DNA regions, producing light and dark bands to distinguish chromosomes. Karyotyping reveals structural chromosome features and helps identify abnormalities, study evolution, and diagnose conditions like aneuploidy and translocations. Newer techniques like FISH provide higher resolution for detecting abnormalities at the gene level.

1. FUNCTIONAL GENOMICS AND PROTEOMICS (BTY-702)
Presented by:
Dr. Chhaya Rani (P-2372)
Division of Animal Genetics,
ICAR- IVRI, Izatnagar,
Bareilly
Karyotyping

2. Karyotyping
“Vehicle of inheritance”

3. Karyotyping
Karyotyping is a test to examine chromosomes in a sample of cells.
A karyotype is a preparation of the
complete diploid set of (metaphase)
chromosomes from one cell of a species
arranged in pairs on the basis of size,
shape and other distinguishing features.
 Relative size of the chromosomes.
 Shape determined by their centromeric
position.

4. Idiogram
An ideogram is a diagrammatic
representation of chromosomes
arranged in descending order of
length i.e how long each
chromosome is when it is
straightened out to show its full
length.

5. Types of Karyotype
Symmetric
karyotype
Asymmetric
karyotype
Small differences between the largest
and smallest chromosome
More no. of metacentric chromosomes.
Huge differences between the largest and
smallest chromosome
Less no. of metacentric chromosomes.

6. Cell culture procedure for preparing a Karyotype
Add
colch
icine

7. All the
chromosomes are
cut individually
with scissors
The slide is viewed by a light microscope
equipped with a camera; the sample is
seen on a computer screen.
Cell culture procedure for preparing a Karyotype
A suitable cluster
is chosen and then
photographed
Arranged and pasted on a
paper by matching pair
based on the size and shape
in diminishing order

8. Representation of a Karyotype
Each chromosomes is aligned along a horizontal axis shared by their centromeres
and numbered in descending order of their length beginning from the largest one.
The sex chromosomes are placed at the end, irrespective of their size.
Individual chromosomes are always depicted with their short p arms (“p” for
"petite," the French word for "small"—at the top) and their long q arms (q for
"queue"—at the bottom).
Based on the banding patterns, the chromosomes are divided into regions and
bands are labeled as pl, p2, q1, q2, etc., counting from the centromere to
telomeres.

9. Karyological features
Species 2n Autosomes Sex chromosome
Sm/M A X Y
Buffalo
Swamp buffalo
River buffalo
48
50
10
10
36
38
A
A
A
A
Cattle
Zebu cattle
Exotic cattle
Mithun
Yak
60
60
58
60
-
-
2
-
58
58
54
58
Sm
Sm
Sm
Sm
Sm
A
Sm
Sm
Equines
Donkey
Horse
62
64
38
26
22
36
Sm
Sm
M
M
Others
Sheep
Goat
Pig
Dog
54
60
38
78
6
-
24
-
46
58
12
76
A
A
Sm
Sm
Sm
Sm
M
Sm

10. • The basis of banding is the affinity of DNA to certain dyes.
• These dyes bind preferentially to certain zones or segment of chromosomal DNA (rather than uniformly
staining the entire chromosome) and therefore produce light and dark zones along their length.
Chromosomal banding
Around 1970, Casperson and coworkers developed some
cytological procedures, referred collectively as chromosome
banding.
Makes karyotyping more precise particularly for the species
having large no. of chromosomes with similar morphology.
Chromosome banding
Study of chromosome number and structure by staining the dividing cells with
certain dyes and then examining them under microscope for cytogenetic
analysis.

11. Chromosomal Band
Part of a chromosome which is clearly distinguishable
from its adjacent segments by appearing darker or
lighter with various banding methods.
Chromosomal banding
Ideogram illustrating banding
patterns of human chromosome
that distinguish chromosomes
numbered 4 and 5
4 5

12. Banding Techniques
R
(Reverse)
Dutrillaux
& Lejeune
Classification of Banding Techniques

13. BANDING
TECHNIQUE
PROCEDURE BANDING PATTERN
G - BANDING (G-
Giemsa)
PROTEOLYSIS WITH TRYPSIN
STAINING WITH GIEMSA DYE
DARK BANDS: AT RICH
LIGHT BANDS: GC RICH
R - BANDING (R-
Reverse)
HEAT DENATURE
STAINING WITH GIEMSA DYE
DARK BANDS: GC RICH
LIGHT BANDS: AT RICH
Q – BANDING ('Q' for
quinacrine)
STAINING WITH QUINACRINE
MUSTARD DYE
VISUALIZED UNDER UV LIGHT
DARK BANDS: AT RICH
LIGHT BANDS: GC RICH
(Similar to G banding)
C- BANDING ('C for
constitutive
heterochromatin)
DENATURE WITH BARIUM HYDROXIDE
STAINING WITH GIEMSA DYE
ONLY DARK BANDS
CONSTITUTIVE
HETEROCHROMATIN
Banding Techniques

14. • T-banding (T for telomere):
Thermal denaturation- Giemsa stain
It stains the télomeriċ (end) regions.
NOR banding (Nucleolar organizer region)/
Silver banding:
Slides are treated with silver Nitrate (AgNO3)
solution selectively staining the NORs.
Used in identification of Nucleolar organizer
region.
Other banding techniques

15. Code system for banding pattern
Three letter coding system
1st letter codes for type of banding to be done
2nd letter codes for general techniques to be used
3rd letter codes for the stain to be used
Example : QFQ banding
Q: Q banding to be done
F: Fluorescence technique to be used
Q: Quinacrin mustard stain to be used

16. Advantages of Karyotyping
• Reveals structural features of each chromosomes .
• Helps in studying chromosome banding pattern .
• Helps in the identification of chromosomal aberrations.
• To study evolutionary changes in different species.

17. Advances in Karyotyping to Detect Chromosomal Abnormalities
Chromosomal changes detectable by karyotyping is typically a
few megabases, this can be sufficient to diagnose certain
categories of abnormalities (aneuploidy, translocations).
Rapid advances are being made in newer techniques of banding
that help in identification of candidate genes within the critical
interval.
Fluorescence in situ hybridization (FISH) is one of the approach
that can potentially identify abnormalities at the level of
individual genes.