The question asks for the definition of a palindromic sequence in DNA. We need to understand the structure of DNA, specifically its double-stranded nature and the directionality of the strands, to correctly identify what constitutes a palindrome in this context.
C) Both strands read the same sequence in 5'→3' direction. This accurately describes a DNA palindrome. For example, if one strand is 5'-GAATTC-3', the complementary strand is 3'-CTTAAG-5'. When the complementary strand is read in the 5' to 3' direction (i.e., from the right end), it also reads 5'-GAATTC-3'. Thus, both strands read the same sequence when read in the 5' to 3' direction.
Gel electrophoresis is a laboratory technique used to separate macromolecules like DNA, RNA, and proteins. The separation is primarily based on two physical properties of the molecules when subjected to an electric field through a gel matrix.
Correct Option: D) Size and charge. DNA fragments are negatively charged and move towards the positive electrode. Their rate of movement through the gel matrix is inversely proportional to their size, meaning smaller fragments travel faster and further.
The question asks to identify the organism most commonly used as a host for recombinant protein production. This requires knowledge of common hosts in biotechnology and genetic engineering.
Correct Option: C) Escherichia coli
The question asks to identify the scientists credited with creating the first recombinant DNA molecule. This is a direct knowledge-based question from the field of molecular biology and genetic engineering.
Correct Option: C) Stanley Cohen and Herbert Boyer are widely recognized for creating the first recombinant DNA molecule in 1972. They developed methods to cut DNA with restriction enzymes and ligate it into a plasmid vector, which could then be introduced into bacteria.
The question asks about the company that first produced Humulin, the genetically engineered human insulin, and the organism used for its production. This is a factual question related to biotechnology and its historical milestones.
D) Eli Lilly (using E. coli) — Eli Lilly and Company was the first to market genetically engineered human insulin (Humulin) in 1982. The production process involved using Escherichia coli (E. coli) bacteria as the host organism to synthesize the insulin chains.
The question asks about the production method of recombinant human insulin, specifically focusing on how its two polypeptide chains (A and B) are handled. Understanding the historical development of recombinant insulin and its molecular structure is key to answering this question.
D) Produced separately in E. coli and combined by disulfide bonds
This option accurately describes the method developed by Eli Lilly and Company, which was the first successful large-scale production of recombinant human insulin. The A and B chains were synthesized as separate polypeptides in E. coli and then linked together chemically via disulfide bonds to form the active insulin molecule.