To study various syndromes and their karyotypes in human beings

Practical Notebook Biology Standard XII

Biology 

Answeres

Practical Notebook
Standard XII 

Class-12th

science

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15. To study various syndromes and their karyotypes in human beings.  

Alm - 

To study the various syndromes and their karyotypes.  A karyotype is a name given to the whole group of characteristics that allow the identification of a particular chromosome set.  It includes the number and size of chromosomes that are constant for a species.  Chromosomes are arranged in a series of decreasing lengths representing what is called an idiogram.  

The characteristics of chromosomes in making an idiogram are a number, length, position of the centromere, secondary constrictions, length of chromosome arms, arm ratio, banding pattern, etc.  The position of the centromere is different in different chromosomes but it is always constant for a particular chromosome.  You have already studied four different shapes of chromosomes based on the position of the centromere.  Figure Date: The idiogram is an arrangement of chromosomes according to their decreasing size, keeping the position of centromeres aligned.  The sex chromosomes are always shown at the end.  }}} 4 S 111 1 9 A XXXX 10 ||  12 11 14 15 16 17 18 19 20 21 22 1) 11 A normal human being shows 46 chromosomes (23 pairs) out of which first 44 chromosomes i.e.  22 pairs are of autosomes and the last 2 chromosomes i.e.  23 pairs represents sex chromosomes.  

The first 22 pairs are arranged according to their size in descending order.  In humans, chromosomes or classified into 7 groups viz.  A, B, C, D, E, F, and G. Sex chromosomes diagrams are placed at the end on the right side of group 'G', Human karyotype is represented in the above The karyotype is advantageous to study and dignified different types of  Syndromes Syndromes are structural or numerical abnormalities of human chromosomes Observe the given idiograms and comment on the syndrome.  1,64