GENETICSNAME: Rana Farrukh Hamid
ROLL NO: 15101560-036
PRESENTATION TOPIC: TYPES OF CHROMOSOMES +
SUBMIT TO: …………………………..
TYPES OF CHROMOSOMES
There are four basic types of chromosomes seen during anaphase.
–No P arm, centromere is on the end
–very small P arm, centromere is very near to the end
–P arm just a little smaller than Q arm; centromere is in the
P and q arms are exactly the same length, centromere is
in exact middle of chromosome
• CHROMOSOME PARTS:
– chromosome tips
– Important in replication, protect from
diffusion with other chromosomes
– Highly condensed, middle region
– Also repetitive sequence
– Region where spindle fibers attach
– Pulling chromatids apart during mitosis
– Monocentric and Polycentric
–during first phase (pachytene) of meiosis
– bead like structures called chromomeres.
• Satellite chromosomes:
– chromosomes that have satellite region and secondary constriction
KARYOTYPE OR IDIOGRAM
• It is the pictorial arrangement of total chromosomes of a cell
according to their size during metaphase of cell division.
• The diagrammatic representation of a chromosome complement
or karyotype is called karyogram or idiogram
• PREPERATION OF KARYOTYPE (TECHNIQUE):
When nuclei are in metaphase of mitosis it is easy to count and
A photograph of the entire set of chromosomes can be made
and pictures of individual chromosomes can be cut out
and pasted in an orderly arrangement.
Such a photograph reveals the number, shapes, and sizes of
chromosome in a cell which constitutes its karyotype.
• A karyotype may be symmetrical or asymmetrical. A perfectly symmetrical karyotype has all metacentric
chromosomes of the same size. They are known to be the primitive state from which more advanced
asymmetrical karyotype have evolved through structural changes.
• APPLICATIONS OF KARYOTYPE:
• Detection of chromosomal aberrations such as deletion, duplication, and translocation
• Loss of chromosome or addition of chromosome
• determine the risk of the individual and his future generations with such chromosomal variations