1 MCB 502A-2015. Lecture #1 Introduction to Molecular Biology. DNA as the main information carrier of life “It is better to know some of the questions than all of the answers.” James Thurber Course introduction — the questions — the nature of the “scientific fact” The objective of this course is to teach you how to think as a Molecular Biologist. I will neither bombard you with tons of information, nor confuse you with the most recent, often still questionable, developments in the field. Rather, we will follow the logic of select experiments, so that you will see not only what is known today, but what were the original questions, what were the approaches to address them, the ideas to explain the experimental observations, and where the major contradictions persist till this day. In fact, you will eventually realize that the only way to maintain useful knowledge is to keep alive the original questions, rather than to memorize the facts of the field. The idea is that thinking and enthusiastic experimentalists, starting with important questions, will eventually produce useful answers themselves and may even learn something new in the process. On the other hand, without thinking, even having all the "right" answers, we may not be able to apply them anyway, — because of the ever-changing circumstances of our life... or just because we are not thinking! I would like to start with a brief discussion of the nature of the “scientific fact”. You should get comfortable with the idea that experimental science does not produce “facts”, — it produces only understanding, and understanding is a process, rather than a product. That is, understanding exists only in thinking brains, and as soon as brains stop thinking, understanding vanishes, like shadows without sun. You either practice it or you will lose it. The instrument of understanding is idea, which can be developed into a hypothesis and then into a concept and eventually into a theory, but even the most respectable theory is still only an instrument. It sounds paradoxical for non-scientists, who take scientific theories for “facts”, but a theory does not need to be correct to be “right” (useful at the moment). A theory may eventually turn out to be incorrect (either generally or in important details), but it still can be the right theory for the moment, as long as it brings order to most of the extant data and is testable (“falsifiable”). In this respect, you will later appreciate the apt comparison of “scientific fact” with a red flag that simply marks the point at which it was decided to stop further experimentation. You can learn only what you understand, and you can understand only what you can draw or sketch. Although I will be emailing you a complete text of every lecture after it has been delivered, expect no schemes or illustrations there. Thus, I strongly encourage you to sit closer and draw everything I draw. You will be expected to draw similar schemes on exams. The format of the course was evolving over the years before arriving at its current unique form, which plunges students into the information race of the modern scientific conference, which is brutally fast. Basically, the course will teach you how to be an efficient note-taker and will prepare you to take full advantage of the future conferences you will almost certainly have to go to. The big difference is that at conferences one has to pick up information from slides, whereas in this course the pace is much more comfortable, being limited by speed of my handwriting on the board. But similar to conferences, most of my time I will be speaking to the board, rather than to you, and you will be trained to understand me anyway. At the end of the course you will have a chance to give me your feedback, filling out the ICES forms and leaving comments. I actually study all of them, so if you liked the course, I would appreciate you say so. If you offer a2 helpful suggestion, I will try my best to incorporate it next year. Please do not suggest to slow down further, or to stop and offer certain points for general discussion, or to make all the diagrams available to you — nothing like this happens at the real conferences, so why to train you for something that is not there? If you do have burning questions, come to me after the lecture, or during the office hour, and we will have fun thinking about them together. The material of this course is evolving, and new topics are added every year, which, unfortunately, also means that I have to skip other topics in my presentations. Since some of these skipped topics are still important for the completeness of the story or concept, they will be retained in the lecture texts and identified there by boxes (borders). Although not mentioned during lectures, the bordered material is the regular course material and is equally covered by homework and exam problems. "The eternal mystery of the world is its comprehensibility" Albert Einstein Introduction into Molecular Biology What is Molecular Biology? A trivial definition of Molecular Biology is “experimental study of the molecular basis of Life”. The three important points in this definition are 1) experimental; 2) molecular; 3) Life. “Molecular” should be clear (it refers to the “chemical” level of organization of the matter), but what is “experimental” and what is “Life”? There are several characteristics that distinguish a live matter from the dead one (like active transport or the ability to sense), but most of them will be shared only by a subset of life forms. In fact, there are only two functional principles defining life that all life forms must perform: 1) the ability to extract from the environment and process energy (e) and matter (m), — we call it “metabolism”, or (e+m) acquisition/processing. 2) the ability to produce independently-functioning and almost exact copies of itself, — we call it self-replication. Functionally, Life can be described as self-replication of metabolism. Or metabolism-driven self-replication, if you prefer the other emphasis. Parenthetically, not only all forms of Life possess metabolism and self-replication, but they also constantly strive to excel in both through the process of Evolution (propagation of the fittest). Both metabolism and reproduction would be impossible if the organism cannot secure resources to maintain and perform the two functions. The ability to
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