Answers to the Questions from Chapter 9 Genetics: Applications of Genetics

Chapter 9: Applications of Genetics

2 marks:

1.     What is genetic counseling?

Ans:

        i.            Genetic counseling is the process of hwlping people to understand and cope up with the medical, psychological and familial implications of the genetic diseases.

     ii.            It is of two types:

a.     Prospective counseling

b.     Retrospective counseling

2.     What is genetic engineering?

Ans:

        i.            Manipulation in the genetic make-up of an organism is called as genetic engineering.

     ii.            The organism is called as genetically engineered organism.

3.     Explain cloning.

Ans:

        i.            It is a process in which exact copy of the original gene or organism is prepared.

     ii.            Cloning can be limited to genetic level or even organisms i.e. plants and animals can also be cloned e.g. Dolly sheep.

4.     What is restriction enzyme?

Ans:

    i.            It is an enzyme which cuts the double stranded DNA molecule.

  ii.            It is also called as “Molecular scissor”

iii.            It cuts the DNA in middle of the strand

5.     What are vectors?

Ans:

        i.            Vectors are the molecules which carry the DNA from one organism to another

     ii.            e.g. Plasmid DNA

6.     Explain tandem repeats.

Ans:

        i.            It is the segment of DNA containing identical or repetitive DNA sequences.

     ii.            The pattern, length and number of repeats are unique for each individual.

7.     What is DNA fingerprinting?

Ans:

        i.            It is a unique identification test which utilizes genetic differences to differentiate between people

     ii.            It is commonly used in forensic science.

8.     What is gene therapy?

Ans:

        i.            It is a therapy used to treat genetic diseases.

     ii.            In this therapy, the diseased gene is replaced by a healthy gene.

9.     What is eugenics?

Ans:

       i.            It is a science which deals with all influences that improve the inborn qualities of a race.

     ii.            It is of two types:

a)     Positive eugenics

b)    Negative eugenics

10.What is plasmid?

Ans:

                    i.            It is extra chromosomal, double stranded circular DNA molecule found in bacterial cell

                 ii.            It is extensively used in genetic engineering

4 marks:

1.     What is genetic counseling? Explain its types.

Ans:

        i.            Genetic counseling is the process of helping people to understand and cope up with the medical, psychological and familial implications of the genetic diseases.

     ii.            It is of two types:

a.     Prospective counseling:

§ This type of counseling is given to the parents or couple during first pregnancy or even before pregnancy.

§  It is generally given to the couples with family history ofsome genetic defects.

b.     Retrospective counseling:

§ This type of counseling is given to parents who already have a child with some genetic disease.

§  Such counseling is given to help the parents in managing the genetically diseased child, coping with the emotional stress and to ensure that their other children born later are disease free.

2.     What is genetic engineering? Add a note on the steps involved in it.

Ans:

        i.            Manipulation in genetic make up of the organism is called as genetic engineering.

     ii.            Steps involved in genetic engineering (taking example of gene cloning:

a.     The gene of interest is selected and isolated.

b.     A bacterial host system is selected.

c.      Plasmid DNA is isolated from the selected bacteria.

d.     Plasmid DNA is opened using restriction enzyme.

e.      The gene of interest is inserted in the plasmid DNA and joined with help of DNA ligase enzyme.

f.       The plasmid DNA formed after insertion of gene of interest is called as recombinant plasmid DNA.

g.     This recombinant plasmid DNA is inserted in the selected bacterial cells.

h.     As the bacterial cells multiply, the gene of interest also multiplies and multiple copies of gene of interest is formed i.e. gene of interest is cloned.

3.     Describe the process of cloning.

Ans:

        i.   The gene of interest is selected and isolated.

     ii.  A bacterial host system is selected.

   iii.     Plasmid DNA is isolated from the selected bacteria.

   iv.    Plasmid DNA is opened using restriction enzyme.

     v. The gene of interest is inserted in the plasmid DNA and joined with help of DNA ligase enzyme.

   vi.  The plasmid DNA formed after insertion of gene of interest is called as recombinant plasmid DNA.

vii.  This recombinant plasmid DNA is inserted in the selected bacterial cells.

viii.As the bacterial cells multiply, the gene of interest also multiplies and multiple copies of gene of interest is formed i.e. gene of interest is cloned.

4.     Explain the process of DNA fingerprinting.

Ans:

        i.            Cells or tissue from which DNA could be isolated is taken

     ii.            DNA is cut into fragments using restriction enzymes

   iii.            The fragments of DNA are separated by the process of gel electrophoresis.

   iv.            The pattern of fragments formed is transferred to a nylon membrane

     v.            Radioactive DNA probe is added.

   vi.            The DNA probe attaches to its complimentary DNA fragment.

vii.            Excess probe is washed away.

viii.            The radioactive DNA pattern autoradiographed using X- rays.

   ix.            When the film is developed after X- ray exposure, a visible DNA fingerprint is formed.

5.     Explain the principle of DNA fingerprinting.

Ans:

        i.            DNA fingerprinting process was first given by Sir Alec Jeffery.

     ii.            This process is based upon the fact that, DNA of all individuals is unique (except identical twins).

   iii.            DNA in all individuals is interrupted by a series of identical DNA sequences called as repetitive DNA or tandem repeats.

   iv.            The pattern, length and number of nucleotides in this repeat sequence varies from person to person.

     v.            Thus, by detecting the tandem repeats and observing the difference amongst them, one can differentiate between any two individuals.

6.     What is gene therapy? Explain its types.

Ans:

        i.            It is a therapy used to treat genetic diseases.

     ii.            In this therapy, the diseased gene is replaced by a healthy gene.

   iii.            Following are the types of gene therapies:

a)     Targeted gene therapy:

·        Genes are introduced by traditional gene transfer methods.

·        The important part is the healthy gene gets incorporated at a specific site i.e. random insertion of healthy gene is not there.

b)    Augmented gene therapy:

·        In this method, many copies of healthy genes are introduced in the cell

·        There is no specific site for incorporation of the healthy gene.

7.     What is eugenics? Add a note on its types.

Ans:

        i.            Eugenics is a science which deals with all influences that improve the inborn qualities of a race.

     ii.            Types of eugenics:

a)     Positive eugenics:

·        In this approach, measures are taken to increase the frequency of desirable traits.

·        It can be achieved by providing better education, chance to select desirable match, improving genetic research etc.

b)    Negative eugenics:

·        In this approach, measures are taken to decrease the frequency of undesirable traits.

·        It can be achieved by restricting consanguineous marriages, control on immigration, etc.

8.     What are the applications of genetic engineering?

Ans:

         i.            Engineering of bacteria to carry out specific processes or to produce important molecules such as hormones and antibiotics.

       ii.            Altering the genotypes of plants as an aid in plant breeding

     iii.            Altering of animals so as to produce human therapeutic products.

     iv.            DNA fingerprinting

       v.            Gene therapy

8 marks:

1.     Describe genetic counseling.

Ans:

        i.            Genetic counseling is the process of helping people to understand and cope up with the medical, psychological and familial implications of the genetic diseases.

     ii.            It involves providing specific counseling to people having or expecting genetic problems in their family.

   iii.            The aim of genetic counseling is to help people in making responsible decision so as to form a disease free society.

   iv.            It is of two types:

a.     Prospective counseling

b.     Retrospective counseling

     v.            Prospective counseling

§ This type of counseling is given to the parents or couple during first pregnancy or even before pregnancy.

§  It is generally given to the couples with family history of some genetic defects.

   vi.            Retrospective counseling

§ This type of counseling is given to parents who already have a child with some genetic disease.

§ Such counseling is given to help the parents in managing the genetically diseased child, coping with the emotional stress and to ensure that their other children born later are disease free.

2.     Explain the principle and process of DNA fingerprinting.

Ans:

Principle of DNA fingerprinting:

        i.            DNA fingerprinting process was first given by Sir Alec Jeffery.

     ii.            This process is based upon the fact that, DNA of all individuals is unique (except identical twins).

   iii.            DNA in all individuals is interrupted by a series of identical DNA sequences called as repetitive DNA or tandem repeats.

   iv.            The pattern, length and number of nucleotides in this repeat sequence varies from person to person.

     v.            Thus, by detecting the tandem repeats and observing the difference amongst them, one can differentiate between any two individuals.

Process of DNA fingerprinting:

        i.            Cells or tissue from which DNA could be isolated is taken

     ii.            DNA is cut into fragments using restriction enzymes

   iii.            The fragments of DNA are separated by the process of gel electrophoresis.

   iv.            The pattern of fragments formed is transferred to a nylon membrane

     v.            Radioactive DNA probe is added.

   vi.            The DNA probe attaches to its complimentary DNA fragment.

vii.            Excess probe is washed away.

viii.            The radioactive DNA pattern autoradiographed using X- rays.

   ix.            When the film is developed after X- ray exposure, a visible DNA fingerprint is formed.

3.     What is positive eugenics? Explain.

Ans:

        i.            It is strategy of eugenics which focuses on increasing the frequency of desirable traits amongst population

     ii.            There are following aspects considered in positive eugenics:

a)     Better education: people should be educated about basics of human biology and genetics. Understanding genetic diseases and their long term effects would help further in eliminating these diseases.

b)    Social hindrance: selection of right partner is not allowed in many societies due to social compulsions. Marriages between individuals of different castes or communities is prohibited which in turn results in restriction in mixing of good germplasm.

c)     Subsidizing the fit: Galton has suggested that a few selected men and women of good eugenic value should be encouraged to increase their birth rate. Such parents must be granted with family allowances and relief of taxation etc.

d)    Immigration: immigration in a country is one of the factors that influences the frequency of a particular gene in population. Thus, there should be controlled immigration.

e)     Improvement of environmental conditions: environment plays important role in expression of certain genes. In such case, good environmental conditions such as better school facilities, training, medical aids, nutrition, good living conditions etc. should be provided to the people.

4.     What is negative eugenics? Explain.

Ans:

§  It is strategy of eugenics which focuses on decreasing the frequency of undesirable traits amongst population

§  Following are some important aspects considered in negative eugenics:

a)     Restriction on marriage: there should be restrictions on consanguineous marriages i.e. marriages within close relations. Close relatives have same parental stock genes from at least two generations before. Thus, chances of diseases in children born from such marriages are more .

b)    Control on immigration: immigrants should be controlled so as to eliminate any bad genetic pool mixing with the present gene pool of the country.

c)     Sterlization: people with defective germplasm should be sterilized so as to control of stop the flow of defective germplasm in future generations.

d)    Segregation: individuals suffering from psychological diseases should be isolated from the society and should not be allowed to marry or reproduce so that the hereditary defective genes are not passed on to the future generation.

16 marks:

1.     What is positive eugenics? Explain.

Ans:

§  It is strategy of eugenics which focuses on increasing the frequency of desirable traits amongst population

§  There are following aspects considered in positive eugenics:

a)     Better education: people should be educated about basics of human biology and genetics. Understanding genetic diseases and their long term effects would help further in eliminating these diseases.

b)    Social hindrance: selection of right partner is not allowed in many societies due to social compulsions. Marriages between individuals of different castes or communities is prohibited which in turn results in restriction in mixing of good germplasm.

c)     Subsidizing the fit: Galton has suggested that a few selected men and women of good eugenic value should be encouraged to increase their birth rate. Such parents must be granted with family allowances and relief of taxation etc.

d)    Immigration: immigration in a country is one of the factors that influences the frequency of a particular gene in population. Thus, there should be controlled immigration.

e)     Improvement of environmental conditions: environment plays important role in expression of certain genes. In such case, good environmental conditions such as better school facilities, training, medical aids, nutrition, good living conditions etc. should be provided to the people.

f)      Prevention of germinal waste: due to social hindrance or death of individuals with good germplasm, loss of good gene pool takes place.

g)     Genetic research: though there has been sufficient research on human heredity still this education has not reached to common people. Thus, further knowledge to all people is required. Also, genetic research should continue for betterment of human race.

2.     What is eugenics? Explain its types.

Ans:

       i.            It is a science which deals with all influences that improve the inborn qualities of a race.

     ii.            It is of two types:

c)     Positive eugenics

d)    Negative eugenics

  iii.            Positive Eugenics:

§  It is strategy of eugenics which focuses on increasing the frequency of desirable traits amongst population

§  There are following aspects considered in positive eugenics:

a)     Better education: people should be educated about basics of human biology and genetics. Understanding genetic diseases and their long term effects would help further in eliminating these diseases.

b)    Social hindrance: selection of right partner is not allowed in many societies due to social compulsions. Marriages between individuals of different castes or communities is prohibited which in turn results in restriction in mixing of good germplasm.

c)     Subsidizing the fit: Galton has suggested that a few selected men and women of good eugenic value should be encouraged to increase their birth rate. Such parents must be granted with family allowances and relief of taxation etc.

d)    Immigration: immigration in a country is one of the factors that influences the frequency of a particular gene in population. Thus, there should be controlled immigration.

e)     Improvement of environmental conditions: environment plays important role in expression of certain genes. In such case, good environmental conditions such as better school facilities, training, medical aids, nutrition, good living conditions etc. should be provided to the people.

f)      Prevention of germinal waste: due to social hindrance or death of individuals with good germplasm, loss of good gene pool takes place.

g)     Genetic research: though there has been sufficient research on human heredity still this education has not reached to common people. Thus, further knowledge to all people is required. Also, genetic research should continue for betterment of human race.

  iv.            Negative Eugenics:

§  It is strategy of eugenics which focuses on decreasing the frequency of undesirable traits amongst population

§  Following are some important aspects considered in negative eugenics:

a)     Restriction on marriage: there should be restrictions on consanguineous marriages i.e. marriages within close relations. Close relatives have same parental stock genes from at least two generations before. Thus, chances of diseases in children born from such marriages are more .

b)    Control on immigration: immigrants should be controlled so as to eliminate any bad genetic pool mixing with the present gene pool of the country.

c)     Sterlization: people with defective germplasm should be sterilized so as to control of stop the flow of defective germplasm in future generations.

d)    Segregation: individuals suffering from psychological diseases should be isolated from the society and should not be allowed to marry or reproduce so that the hereditary defective genes are not passed on to the future generation.