नमस्कार विद्यार्थी मित्रांनो To study various syndromes and their karyotypes in human beings हे प्रॅक्टिकल Experiments to be performed - PART A मधील आहे. याचाच अर्थ तुम्हाला हे प्रॅक्टिकल Exam मध्ये Examiner ला Performe करून दाखवायचे आहे. म्हणूनच प्रॅक्टिकल Exam च्या दृष्टीने हे Experiment अतिशय महत्त्वाचे आहे. या ब्लॉग मध्ये आपण Practical Book मधील या Experiment Number - 13 ची उत्तरे पाहणारं आहोत. ही उत्तरे काळजीपूर्वक वाचून आपल्या Practical Book मध्ये लिहा किंवा तुमच्या कॉलेजमधील संबंधित विषय शिक्षकांची मदत घ्या.
15. To study various syndromes and their karyotypes in human beings.
Aim :- To study the various syndromes and their karyotypes.
Principle :- Karyotype is the 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 their decreasing lengths representing what is called idiogram. The characteristics of the chromosome in making idiogram are the number, length, position of centromere, secondary constrictions, length of chromosome arms, arm ratio, banding pattern, etc.
The position of 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 centromere.
The idiogram is the arrangement of chromosomes according to their decreasing size, keeping the position of centromeres aligned. The sex chromosomes are always shown at the end.
Figure :-
Procedure :-
A normal human being shows 46 chromosomes (23 pairs) out of which the first 44 chromosomes i.e. 22 pairs are of autosomes and the last 2 chromosomes i.e. 23d pair represent sex chromosomes. The first 22 pairs are arranged according to their size in desending order. In humans, chromosomes are classified into 7 groups viz. A, B, C, D, E, F and G. Sex chromosomes are placed at the end on the right side of group 'G'. The human karyotype is represented in the above diagram.
The karyotype is advantageous to study and dignose different types of syndromes. Syndromes are structural or numerical abnormalities of human chromosomes
Observe the given idiograms and comment on syndrome.
1. Sample Karyotype I :-
Chromosomal condition or syndrome (if any) :- Turner's Syndrome (44 + X)
Symptoms :
1) Genetic Disorder: It is a genetic condition where females have only one X chromosome, a condition known as monosomy X.
2) Short Stature: Individuals with Turner's syndrome often exhibit shorter height compared to their peers.
3) Physical Features: They may have a webbed neck, and their hands and feet may appear unusually small.
4) Absence of Menstruation: There is typically no onset of menstrual periods, and affected individuals may have underdeveloped secondary sexual characteristics.
2. Sample Karyotype II :-
Chromosomal condition or syndrome (if any) :- Klinefelter's Syndrome ( 44 + XXY)
Symptoms :
1. Genetic Disorder: It is a genetic condition in which males have an additional copy of the X chromosome.
2. Primary Features: The main features include infertility and small, poorly functioning testicles.
3. Physical Symptoms: Individuals may have weaker muscles, increased height, less body hair, and breast development.
4. Cognitive Impact: While intelligence is typically normal, there may be difficulties with reading and more common issues with speech.
3. Sample Karyotype III :-
Chromosomal condition or syndrome (if any) :- Down's Syndrome or trisomy 21
Symptoms :
1. Genetic Disorder: It is a genetic condition caused by the presence of an extra copy of chromosome 21.
2. Physical Growth: Individuals with Down syndrome often exhibit delayed physical growth.
3. Intellectual Disabilities: They may have mild to moderate intellectual disabilities, with an average IQ typically lower than the general population.
4. Physical Features: Common physical traits include abnormal teeth, shorter hands, and slanted eyes.
Questions
1. What is trisomy?
Ans :- Trisomy is a condition where there is an extra copy of a chromosome in the nucleus of a cell, leading to developmental abnormalities. An example is Trisomy 21, which causes Down syndrome.
2. What is autosome?
Ans :- Autosomes are chromosomes that are not involved in sex determination but play a role in controlling other general body traits.
3. Define monosomy and mention how does it differ from trisomy.
Ans :- Monosomy is the condition where there is an absence of one chromosome from a pair, resulting in a total of only one chromosome instead of the usual two.
Trisomy on the other hand, is when an extra chromosome is present, resulting in three chromosomes instead of the usual two in a pair.
In summary, monosomy involves a missing chromosome, while trisomy involves an extra chromosome.
4. What is non-disjunction of chromosomes?
Ans :- Non-disjunction of chromosomes refers to the failure of chromosomes to separate or segregate properly during meiosis.
5. Explain - the karyotype.
Ans :- A karyotype is the study of the number and visual appearance of chromosomes within the cell nuclei of an organism.
Multiple Choice Questions
1. Down's syndrome is due to...
a. crossing over
b. linkage
c. sex linked inheritance
d. non-disjunction of chromosomes
Ans :- d. non-disjunction of chromosomes
2. Ovum producing Klinfelter's syndrome shall have a chromosome number...
a. 21
b. 22
c. 23
d. 24
Ans :- d. 24
3. The chromosome number of Down's syndrome or Mongolism is...
a. 46
b. 44
c. 48
d. 47
Ans :- d. 47
4. Chromosomes were first seen by...
a. Strassburger
b. Hofmeister
c. Flemming
d. Waldeyer
Ans :- c. Flemming
5. In human beings, single X / XO abnormality causes...
a. Down's syndrome
b. Klinfelter's syndrome
c. Turner's syndrome
d. Patau's syndrome
Ans :- c. Turner's syndrome
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