Gene therapy can cure ______________.

When a section of DNA is transferred to any cell of the body that doesn’t produce sperm or eggs, it is called _______________.

• Gene therapy has two types.
• When the segment of DNA ( gene) is introduced in cells of the patient's body other than germ cells, it is called somatic gene therapy.
• When the segment of DNA ( gene) is introduced into the germ cells of a patient's body, it is called germline gene therapy.
• Germ cells are found in reproductive organs and give rise to the gametes like sperm or ovum.
• Somatic gene therapy is used to treat disorders like muscular dystrophy and adenosine deaminase deficiency disease.

Gene therapy attempts to _______________.

• Gene therapy involves such methods that are used to treat genetic diseases.
• Genetic diseases are inherited from parents and can be passed on to the children of next generation.
• So, the patient may suffer from serious disorders like haemophilia, muscular dystrophy or cystic fibrosis.
• Such diseases are caused by change in the genetic material.
• From the genome of the patient, a single gene or multiple genes can be mutant, missing or nonfunctional.
• So the gene therapy is the only way to cure this.
• The abnormal gene is replaced by a normal gene from the patient's genetic material.

The following image represents ___________________.

• The given image is showing ex vivo delivery process.
• In this method, some cells ( stem cells) are isolated from the patient's body.
• Now in these cells, the normal genes are introduced with the help of vectors like viruses.
• Now the cells are grown in the culture medium and the transformed cells are again introduced in the body.

The following image represents _____________.

• There are three methods of gene therapy: in vivo delivery, ex vivo delivery and germline gene therapy.
• During in vivo delivery, normal gene is directly introduced into the cells of the patient's body.
• Unlike ex vivo delivery cells are not isolated from the body in the in vivo delivery process.

A/an "_____" gene is introduced into the patient to replace a/an "_____" mutant gene.

Which of the following is a chromosomal disorder?

• Chromosomes are made up of DNA (nucleic acid). They are carrying genes that controls traits in an individual.
• As we know that in diploid organisms chromosomes are found in pairs.
• Due to changes in the number of chromosomes, chromosomal disorders can occur. This is called aneuploidy.
• Down syndrome is an example of aneuploidy.
• In this disorder there is an extra copy 21 chromosomes. ( normal people have two copies of each of the 22 chromosomes, called homologous chromosomes)

Which of the following disorders is caused when there is an altered gene on the X chromosome?

• Human have total of 46 chromosomes.
• 22 pairs of chromosomes are found. These are called autosomes.
• Rest of the two are sex chromosomes (X and Y chromosomes).
• Genes are located on chromosomes at fix loci.
• There is total 900 genes found on X chromosomes.
• Any kind of alteration like deletion or duplication in any of these genes causes X-linked disorder.
• When there is any kind of alteration in the gene of autosomes, it is called autosomal linked disorder.
• For example, colors blindness is an X-linked recessive gene disorder. 

The probability of an individual having a recessive disorder increases when _______________.

• There are two alleles for a particular gene at same loci. Copies of each of these two alleles are inherited from parents. 
• Recessive allele can be mutant or defected. So, it can cause some disorder being nonfunctional,
• So, if both parents are carrying at least single copy of this gene, mean that both are heterozygous for this gene then the child can be homozygous for this gene.
• In this condition the child will have some symptoms of genetic disorder.
• Most of the genetic diseases are related to the recessive genes. But these diseases are hidden because if the person is heterozygous for this gene, then he would be a carrier but cannot suffer with this disease.
• As, we know these genes can be passed on to generations. 
• So, the people of a same family or close relatives will have one copy of this defected recessive gene and if they marry then their child will be homozygous for the defected recessive gene.
• So, there are possibilities of the child having recessive gene disorder.

Match the following:

Gene therapy is used to treat genetic diseases such as cancer, sickle cell anemia and muscular dystrophy. Genetic diseases are inherited from parents through genes. These can be caused by any defect of a particular gene or mutation in a gene. By using various techniques of gene therapy these genes are removed and replaced:

• Germline gene therapy: In this process the DNA is introduced in germ cells. Germ cells are the cells which give rise to the gametes (egg or sperm). So, the defected genes will not be transferred to the next generation through gametes. 
• In vivo delivery: In this technique gene is directly transferred into the cells of a body of a patient. These cells are the target cells in which defected or mutant gene exists. 
• Ex- vivo delivery: In this process the DNA is not directly injected into target cells. The cells of patient are separated from the body and cultured in the lab. The healthy gene is introduced in these cells with the help of vectors. Now these cells are transferred into patient's body. The selected cells are stem cells like haemopoietic cells in this process

Gene therapy can treat all forms of cancer.

• Cancer can be caused by many reasons. Like it can be genetic or can be caused by viruses
• Cancer Cells start dividing irregularly.
• These cancer cells can affect a particular organ or multiple organs.
• Brain cancer, lung cancer, liver cancer, breast cancer and ovarian cancer can be treated using gene therapy.
• Oncogenes are substituted by healthy genes.
• Oncogenes are mutant genes that causes a normal cell converted into cancer cell.

An individual having a hereditary disease can be cured with the help of _________.

Which of the following is an example of a disease caused by a mutation in a single gene?

Germline gene therapy is ____________.

Which vehicles are most commonly used for gene therapy to transfer a healthy gene?

Genetic engineering refers to ______________.