Answer:
Before Frederick Griffith's research on pneumococci bacteria, scientists had some knowledge about inherited traits, but their understanding was incomplete. Here are a few key points regarding the knowledge scientists had at that time:
1. Gregor Mendel's Laws of Inheritance: In the mid-19th century, Gregor Mendel conducted experiments on pea plants and established the fundamental principles of inheritance. His laws, known as Mendelian inheritance, described how certain traits are passed from parents to offspring through discrete units called genes.
2. Dominant and Recessive Traits: Mendel's experiments also revealed the concept of dominant and recessive traits. Dominant traits are those that are expressed when an individual has one or two copies of the corresponding gene, while recessive traits are only expressed when an individual has two copies of the recessive gene.
3. Inheritance of Chromosomes: Scientists had discovered that chromosomes, thread-like structures found in the nucleus of cells, played a role in inheritance. However, the nature of chromosomes and their relationship to genes and traits were not yet fully understood.
4. Blending Inheritance Theory: Before Mendel's work, scientists often adhered to the theory of blending inheritance, which proposed that offspring inherit a blend of traits from their parents. This theory could not explain the observation that certain traits seemed to disappear in one generation but reappear in subsequent generations.
5. Lack of Knowledge on Molecular Basis: Scientists had yet to discover the molecular basis of inheritance. The understanding of DNA as the carrier of genetic information and its structure was still unknown at the time.
Overall, scientists had some understanding of inheritance and the transmission of traits, but Mendel's work provided a more comprehensive framework and laid the foundation for modern genetics. It was through subsequent research, including Griffith's work, that scientists began to unravel the complexities of inheritance and the role of DNA in transmitting genetic information.