Genetic Engineering and Biotechnology

Golden rice is a rice variety obtained by recombinant DNA technology. The name ‘golden rice’ is given to it because the seeds are golden yellow in colour, as β – carotene is present.

GM food stands for genetically modified food, which refers to food products derived from organisms whose genetic material has been altered using genetic engineering techniques. This is different from geographical modifications or genetic measures.

Bacillus subtilis is a prokaryotic bacterium commonly used as a host in genetic engineering. It's a Gram-positive, non-pathogenic bacterium that can be easily transformed and has well-characterized genetics. B. subtilis is particularly useful for expressing proteins, studying gene regulation, and as a model organism for prokaryotic research.

Bacteriophage plasmids serve as vectors in genetic engineering, carrying foreign DNA into host cells. They are not genomes (complete genetic material), biological scissors (restriction enzymes), or splicers (DNA ligases).

A protoplast fusion technique between Protaminobacter rubber and Rhodopseudomonas spheroides resulted in a hybrid strain called Rhodopseudomonas protamicus. This is the highest yielding strain of vitamin B₁₂. This new strain can produce as high as 135 mg/l of vitamin B₁₂ utilising a carbon source.

Genetically engineered strains of S. rimosus have been developed for increasing synthesis of oxytetracycline.

Plants are more readily manipulated by genetic engineering than animals because plant cells are totipotent.

The organisms which lack the formation of regulatory end product are called auxotrophic mutants. The intermediates of the metabolic pathways accumulate and get excreted.

Bt cotton plants are genetically modified with Cry1Ac gene from Bacillus thuringiensis, which produces a protein toxic to bollworm pests. This was a key component of India's GM cotton revolution.

Bioethics is a set of standards used to regulate own or community activity in relation to the biological world.

Antisense therapy uses synthetic DNA/RNA sequences to bind target mRNA and block protein expression. It's been applied to treat acute leukemia (blocking oncogene expression), HIV infection (inhibiting viral replication), and papillomavirus infections. The other options describe different applications: B is DNA fingerprinting, C is genetic testing, D is PCR-based diagnostics, and E is virology techniques.

DNA probes are labeled single-stranded DNA sequences complementary to the target gene of interest. When added to a genomic library, they hybridize specifically to their complementary sequences through base pairing, allowing researchers to identify and select clones containing the desired gene. This is called colony or plaque hybridization.

In vivo gene therapy delivers genetic material directly into the patient's body. This nasal spray delivers the CFTR gene directly to lung epithelial cells via adenovirus vectors, compensating for the defective gene in cystic fibrosis patients. This contrasts with ex vivo therapy, where cells are modified outside the body before reinfusion.

GFP作为生物标记物，可以在多种生物过程中追踪细胞和蛋白质，包括大脑发育、肿瘤生长和癌细胞扩散。选项D是正确的，因为它涵盖了所有有效应用。