MIT生物学导论

1、(00'00''-03'10'')As I'm going to argue repeatedly today, Biology has become a science over the last 50 years. And as a consequence, we can talk about some basic principles, we can talk about some laws, and then begin to apply them to very interesting biological problems.

2、And so, our general strategy this semester, as it has been in the past, is to spent roughly the first half of the semester talking about the basic laws, and rules that govern all forms of biological life on this planet, and then the second half of the semester to begin to apply what we learned in th

3、e first half to specific kinds of problems. And you can see some of the specific kinds of problems including the problem of cancer, how cancer cells begin to grow abnormally, how viruses proliferate, how the immune system functions, how the nerve system functions, stem cells , and how they work and

4、their impact on modern biology, molecular medicine, and finally, perhaps the future of biology, and even certain aspects of evolution. The fact of the matter is that we now understand lots of these things in ways that were inconceivable 50 years ago. And now we can begin to talk about things that 50

5、 years ago, people could not dreamed of. When I took this course, and I did take it in 1961, we didn't know about 80% of what we now know. You cant say that about mechanics, about physics, you cant say that about circuit theory and / electronics, you cant say that obviously about chemistry. And

6、I'm mentioning that to you, um, simply because this fill, this changing enormously over the ensuing 4 decades. I won't tell you what grade I got in 701, because if I would, you may pry it out me later in this semester. You probably would never show up again in lecture, but in any case, pleas

7、e know that this has been an area of enormous ferment. And the reason it's been in such an enormous ferment is of the discovery in 1953 by Watson and Crick of the structure of DNA double helix. Last year I said that we are so close to the discovery that both Watson and Crick are alive and with u

8、s metabolically active. And more than 50 years, well exactly 50 years after the discovery. Sadly, several months ago, one of the two characters, Francis Crick died while / into his eighties. And so he is no longer with us. But I want to impress on you the notion that 200 years from now, we will talk

9、 about Watson and Crick the same way that people talk about Isaac Newton in terms of physics. And that would be so because we are only beginning to perceive the ramifications of this enormous evolution that was triggered by their discovery that is the field of molecular biology and genetics and bioc

10、hemistry which has totally changed our perceptions of how life on earth is actually organized.Vocabulary:immune system(免疫系统)stem cells (干细胞)molecular (分子)DNA double helix (DNA双螺旋结构)metabolic (新陈代谢的)2. (3'10''-7'30'')Much of the biology to which you may have been exposed until

11、 now has been a highly descriptive science, that is, you may have courses in high school where you have to memorize the names of different organisms, where you have to understand how evolutionary phylogenies were organized, (where) you have to name, learn the names of different organelles. And biolo

12、gy for you is filled of memorization. And one point we would like hopefully, successfully to drive home this semester is the notion that biology has now achieved a logical and rational coherence that allows us to articulate a whole set of rules that explain how all life forms on this planet are orga

13、nized. Its no longer just a collection of jumbled facts. Indeed, if one masters these molecular and genetic principles, one can understand the principle a large number of processes that exist in the biosphere and begin to apply ones molecular biology solving new problems in this arena. One of the im

14、portant ideas we referred to repeatedly this semester is the fact many of the biological attributes that we possess now were already developed a very long time ago early in the inception of life on this planet. So if you look at the history of earth, here the history of earth is given as 5 billion y

15、ears. It is in thousands, obviously. The earth probably is not that old. Its probably 4.5 or 4.3 billion years. But anyhow, thats one of planet first aggregator as far as we know, one believes that no life existed for perhaps the first half billion years, but after half a billion of years, which is

16、a lot of time, to be sure, there already begins to be traces of life forms on the surface of this planet. And that itself is extraordinary testimonial. We dont know testimonial to how evolutionary processes occur. We dont know how many planets there are in the universe with similar things happened.

17、And we dont know whether the solutions that were arrived at by other lives systems and other places in universe which we may or may not ever discover. Where the similar solutions to the ones that has been arrived at here. Its clear, for example, that to the Darwinian evolution governs the developmen

18、t of life forms on this planet. That is not an artifact of the earth. Darwinian evolution is a logic which is applicable to all life forms and all biosystems that may exist in universe, even the ones weve not discovered. However there are specific solutions that were arrived at during the developmen

19、t of life on earth, which may be peculiar to earth, the structure of the DNA double helix, the use of rivals, the choice of amino acids to make proteins, and those specific solutions may not be universal. Whether theyre universal (is) in the sense of existing in all life forms across the planet. The

20、 fact is that many of the biochemical on molecular solutions that are represented in our own cells today. These solutions, these problems were solved already 2 or 3 billion years ago. And once they were solved, they were kept and conserved almost unchanged for the intervening 2 or 3 billion years. A

21、nd that strong degree of conservation means that we can begin to figure out what the principles were early on in evolution of life on this planet and begin to apply them to all modern life forms. From the point of view of evolution, almost all animals are identically in terms of their biochemistry a

22、nd in terms of their physiology. The molecular biology of all you carried out itself, that is, all cells that have nucleotide in them is almost the same. And therefore, were not going to focus much in this course this semester on specific species, but rather focus on general principles that all allo

23、wed us to understand the cells and tissues and the physiological processes. They are applicable to all species on the surface of the planet. Lets just look here and get out some perspectives of this because the fact that matter(s) is that multi-cellular life forms like ourselves. Vocabulary descript

24、ive science（记述科学）evolutionary phylogenies (进化发展史)organelles (细胞器官)(biosphere 生物圈)DNA double helix(DNA双螺旋)Intervene (插入, 介入, (指时间)介于其间)Physiology (生理学)nucleotide (核苷)amino acid (氨基酸, 胺)3. (7'30''-9'49'')perspective of this, because the fact that matter(s) is that multicellular

25、 life forms like ourselves. We have, the average human being has roughly 3 or 4, 5 times tend of 13 cells in the body, the interesting figure. The average human being goes through roughly 10 to the 16 cell divisions in the life time, i.e. 10 to 16 times in your body there will be cells that divide,

26、grow and divide. Every day in your body there are roughly ten to eleventh cells that're grown and divided. Think of that, ten to eleventh, and you can divide that by the number of minutes in a day and come up with a standing degree of cellular replacation going on. All of these processes can be

27、traceable back to solutions that were arrived at very early in the evolution of life on this planet. Perhaps 5500-6000 million years ago when the first multicellular life forms began to evolve. Before that time, that is to say, before five to six hundred million years ago, there were single cell org

28、anisms. Many of them survived till this day. There were yeast-like organisms and there were bacteria. And we make one large and major distinction between the two major cell life forms on the planet in terms of cells. One are the prokayotic cells. And these are the cells or bacteria I'll show you

29、 image of them shortly which lack nuclei. And the eukaryotic cells which possess nuclei and indeed have highly complex cytoplasm and overall cellular architecture. We think that the prokaryotic life forms on this planet evolve first probably on the order of 3 billion years ago maybe 3 and a half bil

30、lion years ago. And that about one and half billion years ago, cells evolved that had contained nuclei, again Ill show them to you shortly. And these nucleonic cells, the eukaryotes then existed in single cell-form for perhaps the next 7 or 8 hundred million years until multicellular aggregates of e

31、ukaryotic cells first assembled to become the ancestors of the multicellular plants and the multicellular animals that exist on the surface of the earth today.Vocabulary:prokayotic 生原核生物的 nucleus (复数为 nuclei) 核,中心;(生)细胞核eukaryotic .生真核细胞的;真核生物的 cytoplasm 【生】细胞质4. (9'49''-12'06'&#

32、39;)To put that in perspective our species is only being on the planet for about 150,000 years. So weve all been here for that period of time. And 150,000 sounds like a long time in one sense. But its just a blink in the eye of The Lord as one says in terms with the history of life on this planet, a

33、nd I will see the history of the universe which is somewhere between 13 and 15 billion years old. You can begin to see that the appearance of humans represents a very small segment of the entire history of life on this planet. And here you can roughly see the way that life has developed during this

34、period of time. From the fossil record, you see that many plants are actually go back a reasonable length of time, but not more than maybe three or four hundred million years. Here the metazoan and this represents(Well, can you hear me? Yeah. Wow.)6:15 came into handy. Ok, so, if we talk about anoth

35、er major division. We talk about protozoan and metazoan, the suffix -zoan refers to animals as in the zoo. And protozoan represents single cell organisms that metazoan represent multi-cellular organisms. And were going to be focusing largely on the biology of metazoan cells this semester. And were g

36、oing to spending almost no time on plant. Its not that plants are unimportant. Its just we dont have time to cover everything and indeed the molecular biology thats to learn this semester will ultimately enable you to understand much about the physiology of multi-cellular plants which happens to be

37、called metaphyta, a term you may never hear again in your entire life after today. Vocabulary:Species 【生】(物)种, 人种Fossil n.化石, 僵化的事物adj.化石的, 陈腐的,守旧的metazoan 动后生动物, 多细胞动物protozoan 动原生动物metaphyta 有胚植物 5. (12'08''-15'00'')That reminds me by the way that both Doctor Lander and I s

38、ometimes use big words. And people come up to me afterwards each semester, each year and say, “Professor Weinberg, why dont you talk simple, why dont you talk the way we heard things in high school. And please understand that if I use big words sometimes, its to broaden your vocabulary, so you can l

39、earn big words. If you want of one of those things you should be one of the big / lessons of this course should be that your vocabulary is expanded not just your scientific vocabulary but your general working English vocabulary. Perhaps the biggest goal of this course, by the way, is not that you le

40、arn the name of all the organelles and cells but that you learn how to think in a scientific and rational way. Not just because of this course, but that this course helps you to do so. And that such we dont place that much emphasis on memorization but well be able to think logically about scientific

41、 problems. Here we can begin to see the different kinds of metazoan, the animals, here the metaphyta and here the protozoan, different words for all of these. And here we see our own fellow that(s) chordates. And again keep in mind that this line right down here is about 550-600 million years ago, j

42、ust to give you a time scale for whats been going on on this planet. One point well return to repeatedly throughout this semester is that all life forms on this planet are related to one another. Its not as if life was invented multiple times on this planet. And that therere multiple independent inv

43、entions to the extensive life for roles more than once on this planet and it may / the other alternative or competing life forms resume liked out by our ancestors, single cellular ancestors 3 billion years ago. And therefore everything that exists today on this planet represents the sentence of that

44、 successful group of cells that existed a very long time ago. Here we have all this family tree of the different metazoan forms that have been created by the florid hand of evolution. And were going to study those phylogenies simply because we wanna(=want to 不规范) understand principles that explain a

45、ll of them, not just how this or that particular organism is able to digest its food or is able to reproduce. Heres another thing were not going to talk about. Were not going to talk about complicated life forms. Were not going to talk very much, in fact, hardly at all, about ecology. This is just o

46、ne such the way that a parasite is able to take forms able to infect people. This is, again Im showing this not to say this is what were going to talk about. Were not going to talk about that. Theres a wealth of detail thats known about the way life exists in Vocabulary:Chordate adj.有脊索的, 脊索动物的n.脊索动

47、物 Phylogeny n. 发展史 Ecology n.生态学, 社会环境适应学, 均衡系统parasite 寄生虫6 (15'01''-18'05'')in ah, the biosphere. Then we're simply gonna turn our backs on by focusing on some basic principles. We are also now gonna talk about anatomy. Here in quick order are some of the anatomies you

48、may have learned about in high school. And I am giving them to you each with a 3-second minute on 3-second showing. To say we are not going to do all this, and rather just to reinforce our focus. We're gonna limit ourselves to a very finite part of the biosphere. Here's one way of depicting

49、the biosphere. It's obviously an arbitrary way of doing so but it's quite illustrative. Here we start from molecules and in fact we will occasionally go down to sub-molecule atoms. And here is next dimension of complexity- organelles- that is, these specialized little organs within cells. We

50、're gonna focus on them as well. We're gonna focus on cells. And when we start getting to tissues, we're gonna start not talking so much about them. And we're gonna talk about organisms and organs or entire organisms or higher complex ecological communities. And the reason we're

51、doing that is that for 40 years in this department and increasingly the rest of the world, there's the exception of the notion that we understand what goes on down here in these first three steps. We can understand almost everything else in principle. Of course in practice, we may not be able to

52、 apply those principles to how an organism works, or to how the human brain works yet. Maybe we never will. But in general if one begins to understand these principles down here, one can understand much about how organisms and embryologic development occurs. One can understand a lot about whole vari

53、ety of disease processes. One can understand how one inherits disease susceptibilities. And one can understand why many organisms look the way they do, i.e. the process of development of biology. And so keep in mind that if you came to hear about all these things we're gonna let you down. That&#

54、39;s not what this is going to be about. That also dictates the dimensions of the universe we're gonna talk about because we're going to limit ourselves the very, very small and not to the microscopic. On some occasions we'll limit ourselves to items that are so small that you can't

55、see them in the light-microscope. On other occasions we may widen our gates to look at things that are as large as a millimeter. But basically we are staying very, very small. Again because we view, correctly or not, the fact that the big processes can be understand by delving into the molecular det

56、ails of what happens invisibly, and can not be seen by most of ways of visualizing things including the lighten, and often even the electronic-microscope.Vocabulary:Part I terms: Anatomy n. 剖析, 解剖学Sub-molecule n. 亚分子ecological communities 生态群落embryologic (=bryological)胚胎学的 Part II others:Depict 描述,

57、描写Dimension 尺寸, 尺度, 维(数), 度(数), 元Susceptibility 易感性, 感受性, 感情Delve into 钻研, 深入研究7 (18'05''-21'11'')Keep in mind that 50 years ago, we didn't know any of this for all practical purposes, or very little of this. And keep in mind that we are so close to this revolution that w

58、e don't really understand its ramifications. I imagine it would be another 50 years before we really begin to appreciate the fallout, the long-term consequences of this revolution of biology which began 51 years ago. And so you are part of that, and you are going to experience it much more than

59、my generation did. And indeed, one of the reasons why MIT decided, about 10 or 12 years ago, that every MIT undergraduate need to have at least one semester of biology, is that the biology in the same way as physics, chemistry and math has become an integral part of every educated persons' knowledge base, in terms of their ability to deal with the world in a rational way, in terms of public policy, in terms of all kinds of ethical issues: they need to understand what's really going on. Many of the issues that one tal