Stem cells - class-XII

There are different types of transplantations in which the donor from which the stem cells are received differs. In the case of the autologous stem cell transplantation, the stem cells are obtained from the same individual. The peripheral blood or the bone marrow stem cells can be used for the purpose of transplantation. There are no chances of rejection due to graft versus host reaction. 

Stem cell therapy is currently used to treat various blood-related disorders, including lymphoma and leukemia, by replacing damaged cells. Haematopoiesis is a process, not a disease.

Stem cells are found in all organisms and are capable of dividing to form new cells which can be differentiated into various types of specialised cells. The umbilical cord is the structure which attaches the fetus with the placenta in the maternal womb. The umbilical cord contains the embryonic stem cells which can use for the treatment of disorders during the life of an individual. The umbilical cord can be preserved during the child birth.

Animals have stem cells which are similar to the meristematic tissues in plants. They are capable to divide. These are undifferentiated cells which later on gets specialized. They divide continuously and help in the growth and repair of the body.

A- The capacity to generate a whole plant from any cell or explant is called totipotency. The first evidence of totipotency was given by F.C.Steward et al in 1950 in USA.

Totipotency is the ability of cells such as an embryonic stem cell to differentiate into any type of body cell. Plant cells are also totipotent, which helps to explain why a graft of a plant can generate a whole new individual out of just a small branch cutting.

• Stem cells are cells found in most, if not all, multicellular organisms.
• They are characterized by the ability to renewing themselves through mitotic cell division and differentiation into the diverse range of specialized cell types. Example: bone marrow cells.
  Hence, option D is correct.

The technique in which the stem cells are transplanted from donor into the patient for production of the new cells is known as the stem cell therapy. This technique was performed by James E. Till and Ernest A. Mc Culloch. These scientists were performing experiments on the bone marrow of the mice using radiations. They discovered the existence of the stem cells in the bone marrow.

Hematopoietic stem cells are obtained from the bone marrow and used for transplantation. There are different types of transplantations in which the donor from which the stem cells are received differs. In the case of the autologous stem cell transplantation, the stem cells are obtained from the same individual. In an allogeneic system, the stem cells can be obtained from any related or non-related person who is compatible with the patient. In the syngeneic stem cell transplantation, the stem cells are obtained from the identical twin.

Stem cells are the cells which can form different cells which can differentiate and perform different functions. The pluripotent stem cells are the cells which can generate all the cells in the body of an organism. The multipotent stem cells are cells which can form more than one type of cell. The totipotent cells are the cells which can differentiate to form all the type of cells in the body as well as the extraembryonic structures like the placenta. 

The inner cells present in the blastocyst are the embryonic stem cells. When the embryonic culture is performed for obtaining the stem cells, the embryo is cultured till the blastocyst stage. The cells present as the inner cell mass are removed which act as a source of pluripotent stem cells which can differentiate into cells of the complete body.

The cells, tissues, semen and embryo can be preserved for longer periods at lower temperatures using cryopreservation. When the cells are frozen, there is formation of ice crystals in the cells which will rupture the cells. The cryoprotectants like DMSO (dimethylsulphoxide) prevents the formation of these crystals when the cells are stored in liquid nitrogen. 

Stem cells are found in all organisms and are capable of dividing to form new cells which can be differentiated into various types of specialised cells. The progenitor cells have the capability to differentiate into one type of cell. Due to this property, they are also known as unipotent stem cells. The pancreatic progenitor cells can from the cells in the pancreas. 

Many mechanisms are used to obtain the stem cells. The somatic cells or the reproductive cells can be induced to form the stem cells using genetic reprogramming method. Reprogramming can be performed using the factors or proteins which induce the normal body cells to be stimulated to form stem cells. Pluripotent stem cells are generally formed with the help of the induction mechanism. 

Autologous adult stem cells can be harvested from both adipose tissue (fat) and bone marrow. Therefore, both A and C are valid sources.

The amniotic fluid is present in the amniotic cavity in which the embryo develops. The amniotic fluid contains the stem cells. These cells can be checked by karyotyping for the presence of any chromosomal disorder. These stem cells are present till the childbirth because after birth, the structures are expelled out. 

The pericytes are the stem cells which are found in the adult tissues. These cells are generally found in the outer layer of the blood vessels. These cells can be used for transplantation in the individual who suffers from muscular dystrophy. Muscular dystrophy is a genetic disorder which results in weakening and wasting of the muscle tissues. The pericytes are the stem cells which can help in the production of the new muscle tissues.

SCNT stand for somatic cell nuclear transfer. It is a laboratory technique for creating an ovum with a donor nucleus. It can be used in embryonic stem cell research, or in regenerative medicine.

The stem cell transplantation is the method which can be used for the treatment of many disorders like cancer, genetic defects, etc. The main complication of this method is graft rejection by the host. The graft may contain antigens which act as a foreign body in the host. The antibodies are produced against this organ which results in the rejection and destruction of the organ in the host. The rejection is also referred as graft failure. 

Stem cells are undifferentiated (a), can differentiate into various cell types (b), and can multiply (c). Statement d is false because they can transform into cardiac/nerve cells, and e is false because they are not limited to reproductive progeny.

Embryonic stem cells are derived from embryos. In human beings, they are derived from inner cell mass of 3 to 5 days old hollow microscopic ball of cells called blastocyst.

Totipotency refers to the ability of many cells to retain the full genetic potential characteristic of the mature organism from which any of the cells were obtained, and thus enable the cell to regenerate the organism’s tissues and organs under favorable conditions. The possibility of regenerating an entire plant from a single or few non-zygotic cells was proposed by Gottlieb Haberlandt in 1902. Haberlandt is popularly called the father of tissue culture.

Stem cells are found in all organisms and are capable of dividing to form new cells which can be differentiated into various types of specialised cells. The umbilical cord is the structure which attaches the fetus with the placenta in the maternal womb. The cord blood is the sample of blood which is collected from the umbilical cord. The umbilical cord contains the embryonic stem cells which can use for the treatment of disorders during the life of an individual and so, they are preserved. 

The technique in which the stem cells are transplanted from donor into the patient for production of the new cells is known as the stem cell therapy. Heller was the scientist who performed experiments on the hair cells in the cochlea. The damaged hair cells were transplanted with the embryonic stem cells. The damaged cells showed growth and differentiated to form the hair cells. 

There are different types of transplantations in which the donor from which the stem cells are received differs. In the case of the syngeneic stem cell transplantation, the stem cells are obtained from the identical twin. There are very fewer chances of graft versus host reaction and rejection in these type of transplantation.

The stem cell transplantation is the method which can be used for the treatment of many disorders like cancer, genetic defects, etc. The main complication of this method is graft rejection by the host. The graft may contain antigens which act as a foreign body in the host. The antibodies are produced against this organ which results in the rejection and destruction of the organ in the host. 

Totipotency was first demonstrated by Steward and Reinert in the 1950s. Professor F. C. Steward discovered and laid the foundation for plant tissue culture; genetic engineering and plant biotechnology of food crops or trees.