The history of genetics

Hello, my name is Travis Monk. This is one of a series of videos involving genetics. In this video, some of the most important research involving genetics will be discussed. Emphasis in this video is not so much on the history of genetics in itself, but how some of the most famous scientists on earth discovered what they did. The image on this slide shows some insight for scientific research. Most scientific research involves seeing what countless others have seen while coming up with original insight. Gregor Mendel is one of the most famous biologists of all time, renowned for his contributions to the understanding of modern genetics. He is often referred to as the father of modern genetics. Gregor Mendel was an Augustinian monk that lived from 1822 to 1884. Mendel lived in a time before anyone knew what DNA was, much less what it did. His most famous research involved pea plants that he tended in his monastery. Gregor Mendel's research, as I just mentioned, involved pea plants. Mendel studied these pea plants over a period of eight years, looking at a host of different physical characteristics. Gregor evaluated seven different characteristics that had two different appearances, plants that were short or tall, pink-flowered or white-flowered, that contained yellow or green peas. Based solely upon his excellent observations and his good scientific design, no fancy equipment, he discovered the basis of inheritance. Gregor Mendel's research, in retrospect, was really quite simple. What he did was find plants that were pure breeding for certain characteristics. What this means is that when these plants are self-pollinated, or when you spread the pollen from a flower onto its own anther, they always produce the same physical characteristic. He then crossed pure breeding plants with different traits, pink and white flowers, in this picture, for example, and observed what occurred. What he found for each of the seven traits that he evaluated is that one characteristic always covered up another. Mendel called traits that covered up others dominant, while the ones that were covered up recessive. While these observations that Mendel made were significant, as nothing of the kind had really been observed or written down before, Mendel had the insight to continue his research. What he did next was to take the offspring from his first generation and then to self-pollinate them. What he observed is that while the white trait had disappeared when he crossed it originally with the pink flower, that it could reappear in the next generation. Mendel's careful observations and record-keeping showed him something quite interesting. While there were pink flowers and white flowers in this third generation, the results in all traits were quite similar. About three-quarters of the offspring showed the dominant characteristic, or pink in this case, while about one-fourth of the offspring showed the recessive trait, white in this circumstance. As I mentioned before, Gregor Mendel studied seven different pea plant traits. This slide exhibits all the characteristics that Gregor Mendel studied. It shows the thousands of trials that he conducted, as well as his consistent three-to-one ratio of dominant to recessive traits shown on the right-hand side. Gregor Mendel was successful and contributed a tremendous amount of information to science for a number of different reasons. Number one, he concentrated on one trait at a time. He had one independent variable in his experiment and was able to evaluate that the effect that that one variable had very clearly. Number two, Gregor Mendel used a large number of organisms to reduce the influence of chance. The more trials that you conduct when experimenting, the better your results should be. Three, Gregor Mendel used the rules of probability to analyze his results. A considerable amount of this unit will be devoted to probability and genetics using a tool exhibited to the right. It's called a Punnett square. Number four, Gregor kept meticulous notes and took incredible care in his studies with his observations. And five, there has been considerable speculation that Mendel made up some of his results to support his idea. The most reliable research conducted today involves double-blind studies to reduce bias. Another set of the most famous scientists on earth were James Watson and Francis Crick, who are credited with the discovery of the structure of DNA in 1953. The image on this slide shows all the science recipients for the Nobel Prize in 1963, when Watson and Crick were recognized for their important discovery. Watson and Crick, again, are renowned for their discovery of the structure of DNA. The picture on this slide exhibits the two showing off their model of DNA shortly after announcing and publishing their findings. This three-dimensional model was very important for their determination of the structure of DNA. While Watson and Crick's discovery was in itself useful, it also provided scientists with the ability to determine so much more about how genetic information is stored, coded for, and how traits are passed on over time. Specifically, Watson and Crick's research helped determine how DNA copies itself in a process called replication, and then codes for RNA and proteins in the processes of transcription and translation. All these processes will be described in later videos. Watson and Crick were successful for a number of reasons, but not their own insightful research. First, Watson and Crick used models in their research. At the time, there was considerable research into DNA and the elements that it contained, but there was no way to actually observe this biomolecule. By creating larger models to fit the research data, they were able to learn a lot. Models can be frequently used in science to gain a better understanding of otherwise unviewable things. Second, James Watson and Francis Crick used every bit of information that was available from the research of others to build their models. In fact, Watson and Crick used x-ray crystallography data on the structure of DNA from a woman named Rosalind Franklin to put all the pieces of this puzzle together. Rosalind Franklin's research was used, without her knowledge at the time, to aid in Watson and Crick's discoveries, and she was not recognized for her role in this until after her death. This video outlining the history of genetics was not used to merely introduce you to famous scientists or what they contributed, but to highlight why these individuals were successful. The use of models to gain a better understanding of things, scientific collaboration, the scientific method, and excellent observations allowed Gregor Mendel, James Watson, and Francis Crick come to their remarkable discoveries. That is the end of this video outlining the history of genetics. If you are interested in learning about any other topics involving genetics, or any other theme to biology, please subscribe to my channel. Thank you.