Question

Which of the following processes was discovered by Lederberg and Tatum (1946)?
A) Transduction
B) Transformation
C) Asexual reproduction
D) Conjugation

Answer 1

Hint: Lederberg and Tautum discovered conjugation. They worked on E. Coli. They showed that the bacteria E.Coli entered a sexual phase during which it could share genetic information.

Complete Answer:
A) Transduction – It refers to the process by which foreign DNA is introduced into another cell via a viral vector. It does not require physical contact between the cell donating the DNA and cell receiving the DNA.
- It is used by molecular biologists to stably introduce a foreign gene into a host cell’s genome. It was discovered by Joshua Lederberg and Norton Zinder.
B) Transformation – It refers to the process of transfer of free DNA released from a donor bacterium into the extracellular environment that results in assimilation and usually an expression of the newly acquired trait in a recipient bacterium.
- It is adopted as the most common method of gene transfer as it is the best way for the transfer of artificially altered DNA into the recipient cell.
- It was discovered by Frederick Griffith.
C) Asexual Reproduction – This reproduction method does not involve two parents. Only one parent is required to form progeny (i.e. next generation). No variations occur in new progeny if there is a sexual reproduction.
D) Conjugation – It is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by some connection. It was discovered by Lederberg Tautum.

The correct option is D.

Note: Joshua Lederberg and Edward Tautum, studied two strains of E.Coli with different nutritional requirements.
- During conjugation one bacteria serves as the donor of genetic material and the other serves as recipient.
- The donor bacterium carries a DNA sequence called fertility factor, or F-factor.