Tag: zoology

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. 

B) A population of genetically identical individuals, obtained from asexual reproduction is a clone because fusion of gametes does not take place in vegetative propagation so there is no chance of recombination and variation. The parent cell divides to form daughter cell by mitosis due to which the offspring are genetically identical to the parent. The offspring produced are clones of their parent and have the same number of chromosomes.

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. 

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.