Cloning - class-XI

• Sir Ian Wilmut, (born July 7, 1944, Hampton Lucy, Warwickshire, Eng.), British developmental biologist who was the first to use the nuclear transfer of differentiated adult cells to generate a mammalian clone, a Finn Dorset sheep named Dolly.
  
• It was a female domestic sheep, and the first mammal cloned from an adult somatic cell, using the process of nuclear transfer.
• Hence Clone Dolly was produced by the attempts of Ian Wilmut.
• So, the correct answer is 'Ian Wilmut'.

Cloning is the process of producing genetically identical copies of a biological entity. Therefore, its primary purpose is to preserve the genotype of the original organism.

Cybrids are artificial hybrid cell produced by inserting nuclear material from one organism into an enucleated cell. Clones are the population of genetically identical individuals which are produced by asexual or vegetative reproduction. Hybrids are the recombinant individuals, that have genes from both parents and thus, show new combination of traits. Sexual reproduction does not produce clones owing to the three processes that causes recombination of genetic material and produce variations in progeny. These three processes are cross over during meiosis, independent assortment of chromosomes during meiosis and random fusion of gametes. The resultant progeny will be a hybrid. Asexual reproduction does not include meiosis and fusion of gametes; omits the variation creating processes and produce clones. 

Clone formation is due to asexual reproduction. As meiosis does not occur here, so no gamete formation, hence no fusion of gametes occurs in clone formation.

• Salmonella (S.) typhi is an important intracellular pathogen, exclusively for humans  that causes typhoid or enteric fever that make most suitable as a vaccine vector carrying antigens of other pathogens. The hybrids are studied for  induced immune response against response to both the Salmonella bacteria and the antigen of the pathogen in under study.
• Retroviral vectors are created by replacing retroviral gag, pol, and env genes with therapeutic gene and used in gene therapy which is the process of introduction of DNA into living human beings in order to treat disease. It is used to replace a missing gene product or to correct mutant alleles.
• Baculoviruses have rod-shaped capsids and large, double-stranded DNA genomes that infect insects. Their polyhedrin gene is replaced with foreign DNA which is expressed at high levels under the control of the endogenous polyhedrin promoter and is mainly used for high-level transient protein expression in insects and insect cells.
•  Rhizopus nigricans is used as host vector system for mass synthesis of protein encoded by gene cloned in plasmid vectors.
  
• So, the correct answer is 'Retrovirus'.
  

Human cloning has been used to create stem cells which can cure many genetic and acquired diseases. If a person is suffering from kidney disease and requires a new kidney, he can be provided by kidney developed from his own stem cells using cloning technique. This technique is used to create healthy stem cells from a diabetic patient which will produce insulin after successful transplantation into the body. However, cloning technique would be help in curing acquired diseases. 

PCR (Polymerase Chain Reaction) is a technique used to amplify specific DNA sequences, making it possible to detect and analyze DNA in a clone or sample.

During sexual reproduction, fertilization creates a single-celled zygote which includes genetic material from both gametes. In a process called genetic recombination, genetic material (DNA) joins up so that homologous chromosome sequences are aligned with each other, and this is followed by an exchange of genetic information. Whereas, cloning is the process of producing genetically identical individuals of an organism either naturally or artificially. In nature, many organisms produce clones through asexual reproduction.

Vector DNA, with foreign gene is called recombinant DNA. rDNA undergo multiplication by binary fission of host cells or gene cloning process.

So,
the correct option is ‘it’s host bacterium divides by binary fisison’.

Dolly was a female domestic sheep, and the first animal to be cloned from an adult somatic cell, using the process of nuclear transfer. She was cloned by Ian Wilmut, Keith Campbell and colleagues at the Roslin institute, based near Edinburgh. She was born on 5 July, 1996 and died from a progressive lung disease 5 months before her seventh birthday. The cell used as the donor for the cloning of Dolly was taken from a mammary gland, and the production of a healthy clone therefore, proved that a cell taken from a specific part of the body could recreate a whole individual. Hence, option A is correct. 

Molecular cloning involves using enzymes like DNA ligase to join a donor DNA fragment into a vector (like a plasmid), creating recombinant DNA.

• Embryo transfer is the technique in which the developing embryo from a pregnant superior breed is removed and transferred to another female with inferior characters for establishing the pregnancy and in whose body further development takes place till birth. It is used in humans as well as animals.

Cloning is the production of identical genetic copies. All forms of asexual reproduction are variations of the cell division process of mitosis. Asexual reproduction is sometimes called as cloning and the individual copy produced by cloning method is called as a clone.

It is given that the recipient cell has  been enucleated. It means its nucleus or genetic material has been removed. Hence, the organism that will develop from it would have the nuclear genes of donor embryonal/ somatic cell. Hence, the organism will have extra nuclear genes of recipient cell. 

Clones are organisms that are genetically identical to their parent, meaning they share the exact same genetic makeup (DNA sequence).

Cloning in biotechnology refers to the process of creating clones i.e. exact copies of an organism. Biotechnology is technology that utilizes biological systems, living organisms or parts of this to develop or create different products. Due to the advancement of biotechnological processes like DNA cloning, amplification, isolation, recombination etc. It has been possible to create clones of animals. 

Offspring produced through asexual reproduction from a single parent are genetically identical to the parent and to each other; these are defined as clones.

Retroviruses, though have single-stranded RNA genomes but provide perhaps the most promising vector system of all. During the process of reverse transcription, sequences from the termini of viral RNA are duplicated to generate long terminal repeats(LTRs). These long terminal repeats contain both the promoter and the polyadenylation signal for the transcription of viral mRNAs. The specificity of proviral DNA integration is also determined by the long terminal repeats. Although retroviruses can integrate at many sites within the cellular genome, integrative recombination always occurs at particular sites at the ends of the LTRs. The sequences appropriately inserted between the two LTRs will be integrated intact which contrasts sharply with the integration of papovavirus or adenovirus DNA, during which extensive rearrangements of the integrated viral sequences are commonplace. A further great advantage of retroviruses is that they are natural transducing viruses.

Cloning is the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. The term clone is used in horticulture to refer to descendants of a single plant which were produced by vegetative reproduction. Many horticultural plant cultivars are clones, derived from a single individual, multiplied by some process other than sexual reproduction.

Dolly was a female domestic sheep, and the first mammal cloned from an adult somatic cell, using the process of nuclear transfer ie, cloning me.method called Somatic Cell Nuclear Transfer or SCNT. A clone has the same DNA sequence as its parent and so they are genetically identical. In SCNT, the nucleus of an egg cell is removed and replaced with the nucleus of a donor adult cell. Since 99.9% of the cell’s DNA is contained in the nucleus, the resulting animal will share almost exactly the same DNA as the original donor cell. So, the correct answer is option B.