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Question
Why is pedigree analysis done in the study of human genetics? State the conclusions that can be drawn from it.
Solution
Pedigree analysis is done in the study of human genetics as
(i) It helps the genetic counsellors to guide the couples about the possibility of having children with genetic defects such as haemophilia.
(ii) It indicates that Mendel’s principles are also applicable to human genetics with some modifications found out later such as quantitative inheritance, sex-linked characters and other linkages.
Pedigree analysis is the study of the pedigree for the transmission of particular traits and finding the possibility of the absence or presence of that trait in the homozygous or heterozygous state in a particular individual.
RELATED QUESTIONS
(a) Why are thalassemia and haemophilia categorized as Mendelian disorders? Write the symptoms of these diseases. Explain their pattern of inheritance in humans.
(b) Write the genotypes of the normal parents producing a haemophilic son.
Given below is the representation of amino acid composition not the relevant translated portion of β-chain of haemoglobin, related to the shape of human red blood cells
(a) Is this representation indicating a normal human or a sufferer from certain related genetic disease? Give reason in support of your answer.
(b) What difference would be noticed in the phenotype of the normal and the sufferer related to this gene?
(c) Who are likely to suffer more from the defect related to the gene represented the males, the females or both males and females equally? And why?
Identify 'a', 'b', 'c',’d’, 'e' and 'f' in the table given below:
| No. | Syndrome | Cause | Characteristics of affected individuals | Sex Male/Female/Both |
| 1. | Down's | Trisomy of 21 | 'a' (i) (ii) |
'b' |
| 2. | 'c' | XXY | Overall masculine development. |
'd' |
| 3. | Turner's | 45 with XO | 'e' (i) (ii) |
'f' |
Name a disorder a human suffers from as a result of the monosomy of the sex chromosome. Give the karyotype and write the symptoms.
Read the following statements and select the correct option.
i. Genetic disorders are broadly categorised as, Mendelian disorders and chromosomal disorders.
ii. Mendelian disorders are caused due to absence or excess of one or more chromosomes or their abnormal arrangement.
iii. Chromosomal disorders are mainly caused due to alteration or mutation in the gene.
Match the Column I and Column II and select the correct option.
| List-I | List-II | ||
| i. | Holandric genes | a. | Pleiotropy |
| ii. | Multiple effects of a single gene | b. | Hypertrichosis |
| iii. | Skin colour in man | c. | Multiple Alleles |
| iv. | ABO Blood types | d. | Polygenic inheritance |
The correct answer is
Genes for cytoplasmic male sterility in plants are generally located in ______.
Select the incorrect statement regarding pedigree analysis.
Read the following and answer from given below:
Turner's syndrome is an example of monosomy. It is formed by the union of an allosome-free egg and a normal 'X' containing sperm or a normal egg and an allosome-free sperm. The individual has 2n = 45 chromosomes (44 + X0) instead of 46. Such individuals are sterile females who have rudimentary ovaries, underdeveloped breasts, small uterus, short stature, webbed neck, and abnormal intelligence. They may not menstruate or ovulate. This disorder can be treated by giving female sex hormones to women from the age of puberty to make them develop breasts and have menstruation. This makes them feel more normal.
Turner's syndrome is a/an ______
The technique exployed in human genetic counselling is:
