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Introduction ( from MIT Testo inglese
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As I'm going to argue repeatedly today, biology has become

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As I'm going to argue repeatedly today,

biology has become a science over the last 50 years,


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,

And so our general strategy this semester,

as it has been in the past,

is to spend 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 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 nervous system functions,

stem cells and how they work and 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 could begin to talk about things that 50 years ago people could not have dreamt 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 cannot say that about mechanics in physics,

you cannot say that about circuit theory in electronics,

and you cannot say that,


about chemistry,

And I’m mentioning that to you simply because this field has changed enormously over the ensuing four decades,

I won’t tell you what grade I got in 7.01 because if I would,

and you might pry it out of me later in the semester,

you probably would never show up again in lecture,

But in any case,

please know that this has been an area of enormous ferment,

And the reason it’s been in such enormous ferment is of the discovery in 1953 by Watson and Crick of the structure of the DNA double helix,

Last year I said that we were so close to this discovery that both Watson and Crick are alive and with us and metabolically active,

and more than 50 years,


exactly 50 years after the discovery,


several months ago one of the two characters,

Francis Crick died well 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 about Watson and Crick the same way that people talk about Isaac Newton in terms of physics,

And that will be so because we are only beginning to perceive the ramifications of this enormous revolution that was triggered by their discovery,

That is the field of molecular biology and genetics and biochemistry which has totally changed our perceptions of how life on Earth is actually organized,

Much of the biology to which you may have been exposed until now has been a highly descriptive science,

That is you may have had courses in high school where you had to memorize the names of different organisms,

where you had to understand how evolutionary phylogenies were organized,

where you had to learn the names of different organelles,

and that biology was,

for you,

a field 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 organized,

It’s no longer just a collection of jumbled facts,


if one masters these molecular and genetic principles,

one can understand in principle a large number of processes that exist in the biosphere and begin to apply one’s molecular biology to solving new problems in this arena,

One of the important ideas that we’ll refer to repeatedly this semester is the fact that many of the biological attributes that we posses now were already developed a very long time ago early in the inception of life on this planet,

So if we look at the history of Earth,

here the history of Earth is given as 5 billion years,

this is in thousands obviously,

The Earth is probably not that old,

It’s probably 4.5 or 4 or 3 billion years but,


that’s when the planet first aggregated,

as far as we know,

One believes that no life existed for perhaps the first half billion years,

but after half a billion years,

which is a lot of time to be sure,

there already begins to be traces of life forms on the surface of this planet,

And that,


is an extraordinary testimonial,

a testimonial to how evolutionary processes occur,

We don’t know how many planets there are in the universe where similar things happened,

And we don’t know whether the solution that were arrived at by other life systems in other places in the universe,

which we may or may not ever discover,

were the similar solutions to the ones that have been arrived at here,

It’s clear,

for example,

that to the extent that Darwinian Evolution governs the development 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 the universe,

even the ones we have not discovered,


there are specific solutions that were arrived at during the development of life on Earth
which may be peculiar to Earth,

The structure of the DNA double helix,

The use of ribose in deoxyribose,

The choice of amino acids to make proteins,

And those specific solutions may not be universal,

Whether they’re universal in the sense of existing in all life forms across the planet,

the fact is that many of the biochemical and molecular solutions that are represented in our own cells today,

these solutions,

these problems were solved already 2 and 3 billion years ago,

And once they were solved they were kept and conserved almost unchanged for the intervening 2 or 3 billion years,

And that strong degree of conservation means that we can begin to figure out what these 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 identical in terms of their biochemistry and in terms of their physiology,

The molecular biology of all eukaryotic cells,

that is all cells that have nuclei in them,

is almost the same,



we’re not going to focus much in this course this semester on specific species but rather focus on general principles that would allow us to understand the cells and the tissues and the physiological processes that are applicable to all species on the surface of the planet,

Let’s just look here and get us some perspective on this because,

the fact of the matter is,

is that multicellular life forms,

like ourselves,

we have,

the average human being has roughly three or four or five times ten to the thirteenth cells in the body,

That’s an interesting figure,

The average human being goes through roughly ten to the sixteenth cell divisions in a lifetime,


ten to the sixteenth times in your body there will be cells that divide,

grow and divide,

Every day in your body there are roughly ten to the eleventh cells that grow and divide,

Think of that,

ten to the eleventh,

And you can divide that by the number of minutes in a day and come up with an astounding degree of cellular replication going on,

All of these processes can be traceable back to solutions that were arrived at very early in the evolution of life on this planet,

perhaps 550,

600 million years ago when the first multicellular life forms began to evolve,

Before that time,

that is to say before 500 to 600 million years ago,

there were single-cell organisms,

For example,

many of them survive to this day,

There were yeast-like organisms,

And there were bacteria,

And we make one large and major distinction between the two major life forms on the planet in terms of cells,

One are the prokaryotic cells,

And these are the cells of bacteria,

I’ll show you an image of them shortly,

which lack nuclei,

And the eukaryotic cells which poses nuclei and indeed have a highly complex cytoplasm and overall cellular architecture,

We think that the prokaryotic life forms on this planet evolved first probably on the order of 3 billion years ago,

maybe 3.5 billion years ago,

and that about 1.5 billion years ago cells evolved that contained nuclei,


I’ll show them to you shortly,

And these nucleated cells,

the eukaryotes then existed in single-cell form for perhaps the next 700 or 800 million years until multi-cellular aggregates of eukaryotic cells first assembled to become the ancestors of the multi-cellular plants and the multi-cellular animals that exist on the surface of the Earth today,

To put that in perspective,

our species has only been on the planet for about 150,

000 years,

So we’ve all been here for that period of time,

And a 150,

000 sounds like a long time,

in one sense,

but it’s just ìa blink in the eye of the Lordî as one says in terms of the history of life on this planet,

and obviously 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 period of time from the fossil record,

You see that many plants actually go back a reasonable length of time,

but not more than maybe 300 or 400 million years,

Here are the Metazoa,

And this represents - Well,

can you hear me? Wow,

614 came in handy,


So if we talk about another major division,

we talk about protozoa and metazoa,

The suffix zoa refers to animals,

as in a zoo,

And the protozoa represents single-cell organisms,

The metazoa represent multi-cellular organisms,

And we’re going to be focusing largely on the biology of metazoan cells this semester,

and we’re going to be spending almost no time on plants,

It’s not that plants aren’t important,

It’s just that we don’t have time to cover everything,



the molecular biology that you learn this semester will ultimately enable you to understand much about the physiology of multi-cellular plants which happen to be called metaphyta,

a term you may never hear again in your entire life after today,

That reminds me,

by the way,

that both Dr,

Lander and I sometimes use big words,

And people come up to me afterwards each semester each year and say Professor Weinberg,

why don’t you talk simple,

why don’t you talk the way we heard things in high school? And please understand that if I use big words sometimes it’s to broaden your vocabulary so you can learn big words,

One of the things you should be able,

one of the big take-home 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 learn the names 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 as such,

we don’t place that much emphasis on memorization but to be able to think logically about scientific problems,

Here we can begin to see the different kinds of metazoa,

the animals,

Here are the metaphyta and here are the protozoa,

different words for all of these,

And here we see our own phylum,

the chordates,



keep in mind that this line right down here is about 550 to 600 million years ago,

just to give you a time scale for what’s been going on,

on this planet,

One point we’ll return to repeatedly throughout the semester is that all life forms on this planet are related to one another,

It’s not as if life was invented multiple times on this planet and that there are multiple independent inventions to the extent that life arose more than once on this planet,

and it may have,

The other alternative or competing life forms were soon wiped out by our ancestors,

our single-cellular ancestors 3 billion years ago,



everything that exists today on this planet represents the descendents of that 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 we’re not going to study those phylogenies simply because we want to understand principles that explain all of them,

Not just how this or that particular organism is able to digest its food or is able to reproduce,

Here’s another thing we’re not going to talk about,

We’re not going to talk about complicated life forms,

We’re not going to talk very much,

in fact hardly at all,

about ecology,

This is just one such thing,

the way that a parasite is able to,

a tapeworm is able to infect people,

This is,


I’m showing you this not to say this is what we’re going to talk about,

we’re not going to talk about that,

We’re not going to talk about that,

There’s a wealth of detail that’s known about the way life exists in the biosphere that we’re simply going to turn our backs on by focusing on some basic principles,

We’re also not going to talk about anatomy,

Here in quick order are some of the anatomies you may have learned about in high school,

and I’m giving them to you each with a three- second minute,

a three-second showing to say we’re not going to do all this,

And rather just to reinforce our focus,

we’re going to limit ourselves to a very finite part of the biosphere,

And here is one way of depicting the biosphere,

It’s obviously an arbitrary way of doing so but it’s quite illustrative,

Here we start from molecules,


in fact,

we will occasionally go down to submolecular atoms,

And here’s the next dimension of complexity,


That is these specialized little organs within cells,

We’re going to focus on them as well,

We’re going to focus on cells,

And when we start getting to tissues,

we’re going to start not talking so much about them,

And we’re not going to talk about organisms and organs or entire organisms or higher complex ecological communities,

And the reason we’re doing that is that for 40 years in this department,

and increasingly in the rest of the world there is the acceptance of the notion that if 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 apply those principles to how an organism works or to how the human brain works yet,

Maybe we never will,


in general,

if one begins to understand these principles down here,

one can understand much about how organismic embryologic develop occurs,

one can understand a lot about a whole variety of disease processes,

one can understand how one inherits disease susceptibilities,

and one can understand why many organisms look the way they do,


the process of developmental biology,

And so,

keep in mind that if you came to hear about all of these things,

we’re going to let you down,

That’s not what this is going to be about,

This also dictates the dimensions of the universe that we’re going to talk about because we’re going to limit ourselves to the very,

very small and not to the microscopic,

On some occasions we’ll limit ourselves to items that are so small you cannot see them in the light microscope,

On other occasions we may widen our gaze to look at things that are as large as a millimeter,

but basically we’re staying very,

very small,


because we view,

correctly or not,

the fact that the big processes can be understood by delving into the molecular details of what happens invisibly and cannot be seen by most ways of visualizing things,

including the light and often even the electron microscope,

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’re so close to this revolution that we don’t really understand its ramifications,

I imagine it will be another 50 years before we really begin to appreciate the fallout,

the long-term consequences of this revolution in biology which began 51 years ago,

And so you’re part of that and you’re going to experience it much more than my generation did,

And indeed one of the reasons why MIT decided about 10 or 12 years ago that every MIT undergraduate needed to have at least one semester of biology is that biology,

in the same way as physics and chemistry and math,

has become an integral part of every educated person’s 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 talks about today about bioethics are articulated by people who haven’t the vaguest idea about what we’re talking about this semester,

You will know much more than they will,

and hopefully some time down the road,

when you become more and more influential voices in society,

you’ll be able to contribute what you understood here,

what you learned here to that discussion,

Right now much of bioethical discussion is fueled by people who haven’t the vaguest idea what a ribosome or mitochondrion or even a gene is,

and therefore is often a discussion of mutually shared ignorance which you can diffuse by learning some basics,

by learning some of the essentials,

Here is the complexity of the cell we’re going to focus on largely this semester,

which is to say the eukaryotic rather than the prokaryotic cell,

And this is just to give you a feeling for the overall dimensions of the cell and refer to many of the landmarks that will repeatedly be brought up during the course of this semester,

Here is the nucleus,

The term karion comes from the Greek meaning a seed or a kernel,

And the nucleus is what gives the eukaryotic cell its name,

Within the nucleus,

although not shown here,

are the chromosomes which carry DNA,

You may have learned that a long time ago,

Outside of the nucleus is this entire vast array of organelles that goes from the nuclear membrane,

and I’m point to it right here,

all the way out to the outside of the cell,

The outside limiting membrane,

the outer membrane of the cell is called the plasma membrane,

And between the nucleus and the plasma membrane there is an enormous amount of biological and biochemical activity taking place,

Here are,

for example,

the mitochondria,

And the mitochondria,

as one has learned,

are the sources of energy production in the cell,



we’ll touch on them very briefly,

This is an artist’s conception of what a mitochondrion looks like,

Almost always artists’ conceptions of these things have only vague resemblance to the reality,


in any case,

you can begin to get a feeling for what one thinks about their appearance,

Here are mitochondria sliced open by the hand of the artist,



mitochondria have their own DNA in them,

One now accepts the fact that mitochondria are the descendents of bacteria which insinuated themselves into the cytoplasms of larger cells,

roughly 1.5 billion years ago,

and began to do a specialized job which increasingly became the job of energy production within cells,

To this day,

mitochondria retain some vestigial attributes of the bacterial ancestors which initially colonized or parasitized the cytoplasm of the cell,

When I say parasitized,

you might imagine that the mitochondria are taking advantage of the cell,


in fact,

the mitochondria represent the essential sources of energy production in the cell,

Without our mitochondria,

as you might learn by taking cyanide,

for example,

you don’t live for very many minutes,

And the vestiges of bacterial origins of mitochondria are still apparent in the fact that mitochondria still have their own DNA molecule,

their own chromosome,

They still have their own ribosomes and protein synthetic apparatus,

even though the vast majority of the proteins inside mitochondria are imported from the cytoplasm,


these vestigial bacteria now rely on proteins made by the cell at large that are imported into the mitochondrion to supplement the small number of vestigial bacterial proteins which are still made here inside the mitochondrion and used for essential function in energy production,

Here is the Golgi apparatus,

And the Golgi apparatus up here is used for the production of membranes,

As one will learn throughout the semester,

the membranes of a cell are in constant flux and are being pulled in and remodeled and regenerated,

The Golgi apparatus is very important for that,

Here’s the rough endoplasmic reticulum,

That’s important for the synthesis of proteins which are going to be displayed on the surface of cells,

you don’t see them depicted here,

or are going to be secreted into the extracellular space,

Here are the ribosomes,

which I might have mentioned briefly before,

And these ribosomes are the factories where proteins are made,


we’re going to talk a lot about them,



several other aspects,

the cytoskeleton,

The physical integrity,

the architecture of the cell is maintained by a complex network of proteins which together are considered to be the cytoskeleton,

And they enable the cell to have some rigidity,

to resist tensile forces,

and actually to move,

Cells can actually move from one place to the other,

They have motile properties,

They’re able to move from one location to another,

The process of cell motility,

if that’s a word you’d like to learn,

Here is what a prokaryotic cell looks like by contrast,

And I just want to give you a feeling,

First of all,

it looks roughly like a mitochondrion that I discussed before,

But you see that there is the absence of a nuclear membrane,

There’s the absence of the highly complex cytoarchitecture,

Cyto always refers to cells,

There’s the absence of the complex cytoarchitecture that one associates with eukaryotic cells,

In fact,

all that a bacterium has is this area in the middle,

It’s called the nucleoid,

a term which you also will probably never hear in your lifetime,

And it represents simply an aggregate of the DNA of the chromosomes of the bacterium,


in most bacteria,

the DNA consists of only a single molecule of DNA which is responsible for carrying the genetic information of the bacteria,

There’s no membrane around this nucleoid,

And outside of this area where the DNA is kept are largely ribosomes which are important for protein synthesis,

There’s a membrane on the outside of this called the plasma membrane,

very similar to the plasma membrane of eukaryotic cells,

And outside of that is a meshwork that’s called the outer membrane,

it’s sometimes called the cell wall of the bacterium,

which is simply there to impart structural rigidity to the bacterium making sure that it doesn’t explode and holding it together,

And then there are other versions of eukaryotic cells,

Here’s what a plant cell looks like,

And it’s almost identical to the cells in our body,

except for two major features,

For one thing,

it has chloroplasts in it which are also,

one believes now,

the vestiges of parasitic bacteria that invade into the cytoplasm of eukaryotic cells,


in addition to mitochondria which are responsible for energy production in all eukaryotic cells,

we have here the chloroplasts which are responsible for harvesting light and converting it into energy in plant cells,

The rest of the cytoplasm of a plant cell looks pretty much the same,

One feature that I didn’t really mention when I talked about an animal cell is in the middle of the nucleus,

here you can see,

is a structure called a nucleolus,

And a nucleolus,

or the nucleolus in the eukaryotic cell is responsible for making the large number of ribosomes which are exported from the nucleus into the cytoplasm,


as I mentioned just before,

the ribosomes are responsible for protein synthesis,

It turns out this is a major synthetic effort on the part of most cells,


like our own,

have between 5 and 10 million ribosomes in the cytoplasm,

So it’s an enormous amount of biomass in the cytoplasm whose sole function is to synthesize proteins,

As we will learn also,

proteins that are synthesized by the ribosomes don’t sit around forever,

Some proteins have long lives,

Some proteins have lifetimes of 15 minutes before they’re degraded,

before they’re turned over,

One other distinction between our cells,

that is the cells of metazoa and metaphyta,

are the cell walls,

analogous to the cell walls of bacteria,

this green thing on the outside,

As I said before,

we do not have cell walls around our cells,

And we will,

as the semester goes on,

go into more and more details about different aspects of this cytoarchitecture during the first half of the semester,


for example,

is an artist’s depiction of the endoplasmic reticulum,

Why it has such a complex name,

I cannot tell you,

but it does,

It’s called the ER in the patois of the street,

The ER,

And the endoplasmic reticulum is a series of membranes,

Keep in mind,

not the only membrane in the cell is the plasma membrane,

Within the cytoplasm there are literally hundreds of membranes which are folded up in different ways,

Here you see them depicted,

And one set of these membranes,

often they’re organized much like tubes,

represents the membranes of the endoplasmic reticulum which either lacks ribosomes attached to it or has these ribosomes attached to it which cause this to be called the rough endoplasmic reticulum to refer to its rough structure which is created by the studding of ribosomes on the surface,

As we will learn,

just trying to give you a feeling for the geography of what we’re going to talk about this semester,

these ribosomes on the surface of the endoplasmic reticulum are dedicated to the task of making highly specialized proteins which are either going to be dispatched to the surface of the cell where they will be displayed on the cell’s surface or actually secreted into the extracellular space,

Many of the proteins that are destined for our body are not kept within cells but are released into the extracellular space where they serve important functions,

and so we’re going to focus very much on them,

Here’s actually what some of these things look like in the electron microscope to see whether we can either believe or fully discredit the imaginations of the artists,

Here’s the rough endoplasmic reticulum I showed you in schematic form before,

And you can see why it’s called rough,

All these black dots are ribosomes attached on the outside,

Here’s the Golgi apparatus,

You see these vesicles indicated here,

And a vesicle,

just to use a new word,

is simply a membranous bag,

And keep in mind,

by the way,

that we’re not going to spend the semester with these highly descriptive discussions,

Our intent today is to get a lot of these descriptive discussions out of the way so that we can begin to talk in a common parlance about many of the parts,

the molecular parts of cells and organisms,

Here is the mitochondrion which we saw depicted before,

It looks similar to,

but not identical to the artist’s description of that,

And keep in mind that the mitochondrion in our cells,

as I said before,

are the descendents of parasitic bacteria,

Here’s the endoplasmic reticulum,

and the way it would look,

as it does in certain parts of the cell when it doesn’t have all of these ribosomes studded on the surface,

The endoplasmic reticulum here is involved in making membranes,

The endoplasmic reticulum here is involved in the synthesis and export of proteins to the cell’s surface and for secretion,

as I mentioned before,

Much of what we’re going to talk about over the next days is going to be focused on the nucleus of the cell,

that is on the chromosomes on the cell and on the material which is called chromatin which carries the genetic material,

So the term chromatin is used in biology to refer simply to the mixture of DNA and proteins,

which together constitutes the chromosomes,

So chromatin has within it DNA,

it has protein,

and it has a little bit of RNA in it,

And we’re going to focus mostly on the DNA in the chromatin,

because if we can begin to understand the way the DNA works and functions many other aspects will flow from that,

I mentioned the cell’s surface,

and I just want to impress on you the fact that the plasma membrane of a cell is much more complicated than was depicted in these drawings that I showed you just before,

If we had a way of visualizing the plasma membrane of a cell,

we would discover that it’s formed from lipids,

We see such lipids there,


many of them,

We’ll talk about them shortly,

That the outside of the cell,

there are many proteins,

you see them here,

which thread their way through the plasma membrane,

have an extracellular and intracellular part,

And these transmembrane proteins,

which reach from outside to inside,

represent a very important way by which the cell senses its environment,

This plasma membrane,

as we’ll return to,

represents a very effective barrier to segregate what’s inside the cell from what’s outside of the cell to increase concentrations of certain biochemical entities,

But at the same time it creates a barrier to communication,

And one of the things that cells have had to solve over the last 700 to 800 million years is ways by which the exterior of the cell is able to send certain signals and transmit that information to the interior of the cell,

At the same time,

cells have had to use a number of different,

invent a number of different proteins,

some of them indicated here,

which are able to transport materials from the outside of the cell into the cell,

or visa versa,

So the existence of the plasma membrane represents a boon to the cell in the sense that it’s able to segregate what’s on the inside from what’s on the outside,

But it represents an impediment to communication which had to be solved,

as well as an impediment to transport,

And many of these transmembrane proteins are dedicated to solving those particular problems,

Here you see,

once again an artist’s depiction form,

aspects of the cytoskeleton of the cell,

And when we talk about the cytoskeleton we talk about this network of proteins which,

as I said before,

gives the cell rigidity,

Keep in mind that the prefix cyto or the suffix cyt refers always to cells,

Allows the cell to have shape,

And here you can see this network as depicted in one way,

but here it’s depicted actually much more dramatically,

And here you begin to see the complexity of what exists inside the cell,

Here are these proteins,

These are polymers of proteins called vimentin which are present in very many mesenchymal cells,

Here are microtubules made from another kind of protein,

Here are microfilaments,

in this case made of the molecule actin,

And if we looked at individual molecules of actin they would be invisible,

This is end-to-end polymerization of many actin molecules,

And we’re looking here under the microscope from one end of the cell to the other end of the cell,

And you can see how these molecules,

they create stiffness,

and they also enable the cell to contract and to move,

Some people might think that the interior of the cell is just water with some molecules floating around them,

But if you actually look at what’s present in the cell,

more than 50% of the volume is taken up by proteins,

It’s not simply an aqueous solvent where everything moves around freely,

It’s a very viscous slush,

a mush,

And it’s quite difficult there for many cells to move around from one part of the cell to the other,

Here you begin to get a feeling now for how the connection,

which we’ll reinforce shortly in great detail,

between individual molecules and the cytoskeleton,

And here you see these actin fibers,

I showed them to you just moments ago stretching from one end of the cell to the other,

And each of these little globules is a single actin monomer which polymerize end-to-end and then form multi-strand aggregates to create the actin cytoskeleton,

Here’s an intermediate filament and here’s the microtubules that are formed,

once again giving us this impression that the cell is actually highly organized and that that high degree of organization is able to give it some physical structure and shape and form,

I think we’re going to end today two minutes early,

You probably won’t object,

ǽz ájm góɪŋ tú ɑ́rgju rəpítədli tədé,

bajɑ́lədʒi hǽz bɪkə́m ə sájəns óvər ðə lǽst 50 jɪ́rz,


ǽz ə kɑ́nsəkwəns,

wí kǽn tɒ́k əbáwt sə́m bésɪk prɪ́nsəpəlz,

wí kǽn tɒ́k əbáwt sə́m lɒ́z ǽnd ðɛ́n bɪgɪ́n tú əpláj ðɛ́m tú vɛ́ri ɪ́ntrəstɪŋ bɑ̀jəlɑ́dʒɪkəl prɑ́bləmz,

ǽnd só áwər dʒɛ́nərəl strǽtədʒi ðɪ́s səmɛ́stər,

ǽz ɪ́t hǽz bɪ́n ɪn ðə pǽst,

ɪ́z tú spɛ́nd rə́fli ðə fə́rst hǽf ə́v ðə səmɛ́stər tɒ́kɪŋ əbáwt ðə bésɪk lɒ́z ǽnd rúlz ðǽt gə́vərn ɒ́l fɔ́rmz ə́v bɑ̀jəlɑ́dʒɪkəl lájf ɑ́n ðɪ́s plǽnət,

ǽnd jú kǽn sí sə́m ə́v ðə spəsɪ́fɪk kájndz ə́v prɑ́bləmz,

ɪ̀nklúdɪŋ ðə prɑ́bləm ə́v kǽnsər,

háw kǽnsər sɛ́lz bɪgɪ́n tú gró æbnɔ́rməli,

háw vájrəsəz prolɪ́fərèt,

háw ðə ɪ̀mjún sɪ́stəm fə́ŋkʃənz,

háw ðə nə́rvəs sɪ́stəm fə́ŋkʃənz,

stɛ́m sɛ́lz ǽnd háw ðé wə́rk ǽnd ðɛ́r ɪ̀mpǽkt ɑ́n mɑ́dərn bajɑ́lədʒi,

məlɛ́kjələr mɛ́dəsən,

ǽnd fájnəli pərhǽps ðə fjútʃər ə́v bajɑ́lədʒi ǽnd ívən sə́rtən ǽspɛ̀kts ə́v ɛ̀vəlúʃən,

ðə fǽkt ə́v ðə mǽtər ɪ́z ðǽt wí náw ə̀ndərstǽnd lɑ́ts ə́v ðíz θɪ́ŋz ɪn wéz ðǽt wər ɪ̀nkənsívəbəl 50 jɪ́rz əgó,

ǽnd náw wí kʊ́d bɪgɪ́n tú tɒ́k əbáwt θɪ́ŋz ðǽt 50 jɪ́rz əgó pípəl kʊ́d nɑ́t hǽv drɛ́mt ə́v,

wɛ́n áj tʊ́k ðɪ́s kɔ́rs,

ǽnd áj dɪ́d ték ɪ́t ɪn 1961,

wí didn tknow əbáwt 80% ə́v wə́t wí náw nó.

jú kǽnat sé ðǽt əbáwt məkǽnɪks ɪn fɪ́zɪks,

jú kǽnat sé ðǽt əbáwt sə́rkət θɪ́ri ɪn əlɛ̀ktrɑ́nɪks,

ǽnd jú kǽnat sé ðǽt,


əbáwt kɛ́məstri,

ǽnd áj mmentioning ðǽt tú jú sɪ́mpli bɪkɒ́z ðɪ́s fíld hǽz tʃéndʒd ənɔ́rməsli óvər ðə ɛ́nsuɪŋ fɔ́r dɛkédz,

áj wə́n ttell jú wə́t gréd áj gɑ́t ɪn 7,

01 bɪkɒ́z ɪ́f áj wʊ́d,

ǽnd jú májt práj ɪ́t áwt ə́v mí létər ɪn ðə səmɛ́stər,

jú prɑ́bəbli wʊ́d nɛ́vər ʃó ə́p əgɛ́n ɪn lɛ́ktʃər.

bə́t ɪn ɛ́ni kés,

plíz nó ðǽt ðɪ́s hǽz bɪ́n ǽn ɛ́riə ə́v ənɔ́rməs fərmɛ́nt,

ǽnd ðə rízən ɪ́t sbeen ɪn sə́tʃ ənɔ́rməs fərmɛ́nt ɪ́z ə́v ðə dɪ̀skə́vəri ɪn 1953 báj wɑ́tsən ǽnd krɪ́k ə́v ðə strə́ktʃər ə́v ðə dna də́bəl hílɪks,

lǽst jɪ́r áj sɛ́d ðǽt wí wər só klós tú ðɪ́s dɪ̀skə́vəri ðǽt bóθ wɑ́tsən ǽnd krɪ́k ɑ́r əlájv ǽnd wɪθ ə́s ǽnd metabolically ǽktɪv,

ǽnd mɔ́r ðǽn 50 jɪ́rz,


ɪgzǽktli 50 jɪ́rz ǽftər ðə dɪ̀skə́vəri.


sɛ́vrəl mə́nθs əgó wə́n ə́v ðə tú kǽrɪktərz,

frǽnsəs krɪ́k dájd wɛ́l ɪ̀ntú hɪ́z étiz,

ǽnd só hí ɪ́z nó lɒ́ŋgər wɪθ ə́s,

bə́t áj wɑ́nt tú ɪ̀mprɛ́s ɑ́n jú ðə nóʃən ðǽt 200 jɪ́rz frə́m náw,

wí wɪ́l tɒ́k əbáwt wɑ́tsən ǽnd krɪ́k ðə sém wé ðǽt pípəl tɒ́k əbáwt ájzək nútən ɪn tə́rmz ə́v fɪ́zɪks,

ǽnd ðǽt wɪ́l bí só bɪkɒ́z wí ɑ́r ónli bɪgɪ́nɪŋ tú pərsív ðə ræ̀məfəkéʃənz ə́v ðɪ́s ənɔ́rməs rɛ̀vəlúʃən ðǽt wəz trɪ́gərd báj ðɛ́r dɪ̀skə́vəri,

ðǽt ɪ́z ðə fíld ə́v məlɛ́kjələr bajɑ́lədʒi ǽnd dʒənɛ́tɪks ǽnd bɑ̀jokɛ́məstri wɪ́tʃ hǽz tótəli tʃéndʒd áwər pərsɛ́pʃənz ə́v háw lájf ɑ́n ə́rθ ɪ́z ǽktʃəwəli ɔ́rgənɑ̀jzd,

mə́tʃ ə́v ðə bajɑ́lədʒi tú wɪ́tʃ jú mé hǽv bɪ́n ɪkspózd əntɪ́l náw hǽz bɪ́n ə hájli dəskrɪ́ptɪv sájəns,

ðǽt ɪ́z jú mé hǽv hǽd kɔ́rsəz ɪn háj skúl wɛ́r jú hǽd tú mɛ́mərɑ̀jz ðə némz ə́v dɪ́fərənt ɔ́rgənɪ̀zəmz,

wɛ́r jú hǽd tú ə̀ndərstǽnd háw ɛ̀vəlúʃənɛ̀ri phylogenies wər ɔ́rgənɑ̀jzd,

wɛ́r jú hǽd tú lə́rn ðə némz ə́v dɪ́fərənt ɔ̀rgənɛ́lz,

ǽnd ðǽt bajɑ́lədʒi wəz,

fɔ́r jú,

ə fíld ə́v memorization,

ǽnd wə́n pɔ́jnt wí wʊ́d lájk,

hópfəli səksɛ́sfəli,

tú drájv hóm ðɪ́s səmɛ́stər ɪ́z ðə nóʃən ðǽt bajɑ́lədʒi hǽz náw ətʃívd ə lɑ́dʒɪkəl ǽnd rǽʃənəl kohɪ́rəns ðǽt əláwz ə́s tú artɪ́kjəlèt ə hól sɛ́t ə́v rúlz ðǽt ɪksplén háw ɒ́l lájf fɔ́rmz ɑ́n ðɪ́s plǽnət ɑ́r ɔ́rgənɑ̀jzd,

ɪ́t sno lɒ́ŋgər dʒə́st ə kəlɛ́kʃən ə́v dʒə́mbəld fǽkts,


ɪ́f wə́n mǽstərz ðíz məlɛ́kjələr ǽnd dʒənɛ́tɪk prɪ́nsəpəlz,

wə́n kǽn ə̀ndərstǽnd ɪn prɪ́nsəpəl ə lɑ́rdʒ nə́mbər ə́v prɑ́sɛsəz ðǽt ɪgzɪ́st ɪn ðə bájosfɪ̀r ǽnd bɪgɪ́n tú əpláj wə́n smolecular bajɑ́lədʒi tú sɑ́lvɪŋ nú prɑ́bləmz ɪn ðɪ́s ərínə,

wə́n ə́v ðə ɪ̀mpɔ́rtənt ajdíəz ðǽt wí llrefer tú rəpítədli ðɪ́s səmɛ́stər ɪ́z ðə fǽkt ðǽt mɛ́ni ə́v ðə bɑ̀jəlɑ́dʒɪkəl ǽtrəbjùts ðǽt wí pɑ́siz náw wər ɒlrɛ́di dɪvɛ́ləpt ə vɛ́ri lɒ́ŋ tájm əgó ə́rli ɪn ðə ɪ̀nsɛ́pʃən ə́v lájf ɑ́n ðɪ́s plǽnət.

só ɪ́f wí lʊ́k ǽt ðə hɪ́stəri ə́v ə́rθ,

hɪ́r ðə hɪ́stəri ə́v ə́rθ ɪ́z gɪ́vən ǽz 5 bɪ́ljən jɪ́rz,

ðɪ́s ɪ́z ɪn θáwzəndz ɑ́bviəsli,

ðə ə́rθ ɪ́z prɑ́bəbli nɑ́t ðǽt óld,

ɪ́t sprobably 4.5 ɔ́r 4 ɔ́r 3 bɪ́ljən jɪ́rz bə́t,


ðǽt swhen ðə plǽnət fə́rst ǽgrəgètəd,

ǽz fɑ́r ǽz wí nó,

wə́n bəlívz ðǽt nó lájf ɪgzɪ́stəd fɔ́r pərhǽps ðə fə́rst hǽf bɪ́ljən jɪ́rz,

bə́t ǽftər hǽf ə bɪ́ljən jɪ́rz,

wɪ́tʃ ɪ́z ə lɑ́t ə́v tájm tú bí ʃʊ́r,

ðɛ́r ɒlrɛ́di bɪgɪ́nz tú bí trésəz ə́v lájf fɔ́rmz ɑ́n ðə sə́rfəs ə́v ðɪ́s plǽnət,

ǽnd ðǽt,


ɪ́z ǽn ɪkstrɔ́rdənɛ̀ri tɛ̀stəmóniəl,

ə tɛ̀stəmóniəl tú háw ɛ̀vəlúʃənɛ̀ri prɑ́sɛsəz əkə́r,

wí dɑ́n tknow háw mɛ́ni plǽnəts ðɛ́r ɑ́r ɪn ðə júnɪvə̀rs wɛ́r sɪ́mələr θɪ́ŋz hǽpənd,

ǽnd wí dɑ́n tknow wɛ́ðər ðə səlúʃən ðǽt wər ərájvd ǽt báj ə́ðər lájf sɪ́stəmz ɪn ə́ðər plésəz ɪn ðə júnɪvə̀rs,

wɪ́tʃ wí mé ɔ́r mé nɑ́t ɛ́vər dɪ̀skə́vər,

wər ðə sɪ́mələr səlúʃənz tú ðə wə́nz ðǽt hǽv bɪ́n ərájvd ǽt hɪ́r,

ɪ́t sclear,

fɔ́r ɪgzǽmpəl,

ðǽt tú ðə ɪkstɛ́nt ðǽt dɑ̀rwɪ́niən ɛ̀vəlúʃən gə́vərnz ðə dɪvɛ́ləpmənt ə́v lájf fɔ́rmz ɑ́n ðɪ́s plǽnət ðǽt ɪ́z nɑ́t ǽn ɑ́rtəfæ̀kt ə́v ðə ə́rθ,

dɑ̀rwɪ́niən ɛ̀vəlúʃən ɪ́z ə lɑ́dʒɪk wɪ́tʃ ɪ́z ǽpləkəbəl tú ɒ́l lájf fɔ́rmz ǽnd ɒ́l bájosɪ̀stəmz ðǽt mé ɪgzɪ́st ɪn ðə júnɪvə̀rs,

ívən ðə wə́nz wí hǽv nɑ́t dɪ̀skə́vərd,


ðɛ́r ɑ́r spəsɪ́fɪk səlúʃənz ðǽt wər ərájvd ǽt dʊ́rɪŋ ðə dɪvɛ́ləpmənt ə́v lájf ɑ́n ə́rθ wɪ́tʃ mé bí pəkjúljər tú ə́rθ,

ðə strə́ktʃər ə́v ðə dna də́bəl hílɪks,

ðə jús ə́v ribose ɪn deoxyribose,

ðə tʃɔ̀js ə́v əmíno ǽsədz tú mék prótìnz,

ǽnd ðóz spəsɪ́fɪk səlúʃənz mé nɑ́t bí jùnɪvə́rsəl,

wɛ́ðər ðé reuniversal ɪn ðə sɛ́ns ə́v ɪgzɪ́stɪŋ ɪn ɒ́l lájf fɔ́rmz əkrɒ́s ðə plǽnət,

ðə fǽkt ɪ́z ðǽt mɛ́ni ə́v ðə bɑ̀jokɛ́məkəl ǽnd məlɛ́kjələr səlúʃənz ðǽt ɑ́r rɛ̀prəzɛ́ntəd ɪn áwər ón sɛ́lz tədé,

ðíz səlúʃənz,

ðíz prɑ́bləmz wər sɑ́lvd ɒlrɛ́di 2 ǽnd 3 bɪ́ljən jɪ́rz əgó.

ǽnd wə́ns ðé wər sɑ́lvd ðé wər kɛ́pt ǽnd kənsə́rvd ɒ́lmòst əntʃéndʒd fɔ́r ðə ɪ̀ntərvínɪŋ 2 ɔ́r 3 bɪ́ljən jɪ́rz,

ǽnd ðǽt strɒ́ŋ dɪgrí ə́v kɑ̀nsərvéʃən mínz ðǽt wí kǽn bɪgɪ́n tú fɪ́gjər áwt wə́t ðíz prɪ́nsəpəlz wər ə́rli ɑ́n ɪn ɛ̀vəlúʃən ə́v lájf ɑ́n ðɪ́s plǽnət ǽnd bɪgɪ́n tú əpláj ðɛ́m tú ɒ́l mɑ́dərn lájf fɔ́rmz,

frə́m ðə pɔ́jnt ə́v vjú ə́v ɛ̀vəlúʃən,

ɒ́lmòst ɒ́l ǽnəməlz ɑ́r ajdɛ́ntɪkəl ɪn tə́rmz ə́v ðɛ́r bɑ̀jokɛ́məstri ǽnd ɪn tə́rmz ə́v ðɛ́r fɪ̀ziɑ́lədʒi,

ðə məlɛ́kjələr bajɑ́lədʒi ə́v ɒ́l eukaryotic sɛ́lz,

ðǽt ɪ́z ɒ́l sɛ́lz ðǽt hǽv núkliɑ̀j ɪn ðɛ́m,

ɪ́z ɒ́lmòst ðə sém,



wí renot góɪŋ tú fókəs mə́tʃ ɪn ðɪ́s kɔ́rs ðɪ́s səmɛ́stər ɑ́n spəsɪ́fɪk spíʃiz bə́t rǽðər fókəs ɑ́n dʒɛ́nərəl prɪ́nsəpəlz ðǽt wʊ́d əláw ə́s tú ə̀ndərstǽnd ðə sɛ́lz ǽnd ðə tɪ́sjùz ǽnd ðə fɪ̀ziəlɑ́dʒɪkəl prɑ́sɛsəz ðǽt ɑ́r ǽpləkəbəl tú ɒ́l spíʃiz ɑ́n ðə sə́rfəs ə́v ðə plǽnət,

lɛ́t sjust lʊ́k hɪ́r ǽnd gɛ́t ə́s sə́m pərspɛ́ktɪv ɑ́n ðɪ́s bɪkɒ́z,

ðə fǽkt ə́v ðə mǽtər ɪ́z,

ɪ́z ðǽt multicellular lájf fɔ́rmz,

lájk awərsɛ́lvz,

wí hǽv,

ðə ǽvərɪdʒ hjúmən bíɪŋ hǽz rə́fli θrí ɔ́r fɔ́r ɔ́r fájv tájmz tɛ́n tú ðə θə́rtínθ sɛ́lz ɪn ðə bɑ́di,

ðǽt sǽn ɪ́ntrəstɪŋ fɪ́gjər,

ðə ǽvərɪdʒ hjúmən bíɪŋ góz θrú rə́fli tɛ́n tú ðə sɪkstínθ sɛ́l dɪvɪ́ʒənz ɪn ə lájftɑ̀jm,



tɛ́n tú ðə sɪkstínθ tájmz ɪn jɔ́r bɑ́di ðɛ́r wɪ́l bí sɛ́lz ðǽt dɪvájd,

gró ǽnd dɪvájd,

ɛ́vəri dé ɪn jɔ́r bɑ́di ðɛ́r ɑ́r rə́fli tɛ́n tú ðə əlɛ́vənθ sɛ́lz ðǽt gró ǽnd dɪvájd,

θɪ́ŋk ə́v ðǽt,

tɛ́n tú ðə əlɛ́vənθ,

ǽnd jú kǽn dɪvájd ðǽt báj ðə nə́mbər ə́v mɪ́nəts ɪn ə dé ǽnd kə́m ə́p wɪθ ǽn əstáwndɪŋ dɪgrí ə́v sɛ́ljələr rɛ̀pləkéʃən góɪŋ ɑ́n.

ɒ́l ə́v ðíz prɑ́sɛsəz kǽn bí trésəbəl bǽk tú səlúʃənz ðǽt wər ərájvd ǽt vɛ́ri ə́rli ɪn ðə ɛ̀vəlúʃən ə́v lájf ɑ́n ðɪ́s plǽnət,

pərhǽps 550,

600 mɪ́ljən jɪ́rz əgó wɛ́n ðə fə́rst multicellular lájf fɔ́rmz bɪgǽn tú ɪvɑ́lv,

bəfɔ́r ðǽt tájm,

ðǽt ɪ́z tú sé bəfɔ́r 500 tú 600 mɪ́ljən jɪ́rz əgó,

ðɛ́r wər sɪ́ŋgəl- sɛ́l ɔ́rgənɪ̀zəmz,

fɔ́r ɪgzǽmpəl,

mɛ́ni ə́v ðɛ́m sərvájv tú ðɪ́s dé,

ðɛ́r wər jíst- lájk ɔ́rgənɪ̀zəmz,

ǽnd ðɛ́r wər bæktɪ́riə,

ǽnd wí mék wə́n lɑ́rdʒ ǽnd médʒər dɪ̀stɪ́ŋkʃən bətwín ðə tú médʒər lájf fɔ́rmz ɑ́n ðə plǽnət ɪn tə́rmz ə́v sɛ́lz,

wə́n ɑ́r ðə prokaryotic sɛ́lz,

ǽnd ðíz ɑ́r ðə sɛ́lz ə́v bæktɪ́riə,

áj llshow jú ǽn ɪ́mədʒ ə́v ðɛ́m ʃɔ́rtli,

wɪ́tʃ lǽk núkliɑ̀j,

ǽnd ðə eukaryotic sɛ́lz wɪ́tʃ pózəz núkliɑ̀j ǽnd ɪ̀ndíd hǽv ə hájli kɑ́mplɛks sájtəplæ̀zəm ǽnd óvərɒ̀l sɛ́ljələr ɑ́rkətɛ̀ktʃər,

wí θɪ́ŋk ðǽt ðə prokaryotic lájf fɔ́rmz ɑ́n ðɪ́s plǽnət ɪvɑ́lvd fə́rst prɑ́bəbli ɑ́n ðə ɔ́rdər ə́v 3 bɪ́ljən jɪ́rz əgó,

mébi 3,

5 bɪ́ljən jɪ́rz əgó,

ǽnd ðǽt əbáwt 1,

5 bɪ́ljən jɪ́rz əgó sɛ́lz ɪvɑ́lvd ðǽt kənténd núkliɑ̀j,


áj llshow ðɛ́m tú jú ʃɔ́rtli,

ǽnd ðíz nucleated sɛ́lz,

ðə eukaryotes ðɛ́n ɪgzɪ́stəd ɪn sɪ́ŋgəl- sɛ́l fɔ́rm fɔ́r pərhǽps ðə nɛ́kst 700 ɔ́r 800 mɪ́ljən jɪ́rz əntɪ́l mə́lti- sɛ́ljələr ǽgrəgəts ə́v eukaryotic sɛ́lz fə́rst əsɛ́mbəld tú bɪkə́m ðə ǽnsɛ̀stərz ə́v ðə mə́lti- sɛ́ljələr plǽnts ǽnd ðə mə́lti- sɛ́ljələr ǽnəməlz ðǽt ɪgzɪ́st ɑ́n ðə sə́rfəs ə́v ðə ə́rθ tədé,

tú pʊ́t ðǽt ɪn pərspɛ́ktɪv,

áwər spíʃiz hǽz ónli bɪ́n ɑ́n ðə plǽnət fɔ́r əbáwt 150,

000 jɪ́rz,

só wí veall bɪ́n hɪ́r fɔ́r ðǽt pɪ́riəd ə́v tájm,

ǽnd ə 150,

000 sáwndz lájk ə lɒ́ŋ tájm,

ɪn wə́n sɛ́ns,

bə́t ɪ́t sjust áj ablink ɪn ðə áj ə́v ðə lɔ́rdi ǽz wə́n sɛ́z ɪn tə́rmz ə́v ðə hɪ́stəri ə́v lájf ɑ́n ðɪ́s plǽnət,

ǽnd ɑ́bviəsli ðə hɪ́stəri ə́v ðə júnɪvə̀rs wɪ́tʃ ɪ́z sə́mwɛ̀r bətwín 13 ǽnd 15 bɪ́ljən jɪ́rz óld,

jú kǽn bɪgɪ́n tú sí ðǽt ðə əpɪ́rəns ə́v hjúmənz rɛ̀prəzɛ́nts ə vɛ́ri smɒ́l sɛ́gmənt ə́v ðə ɛntájər hɪ́stəri ə́v lájf ɑ́n ðɪ́s plǽnət,

ǽnd hɪ́r jú kǽn rə́fli sí ðə wé ðǽt lájf hǽz dɪvɛ́ləpt dʊ́rɪŋ ðɪ́s pɪ́riəd ə́v tájm frə́m ðə fɑ́səl rəkɔ́rd,

jú sí ðǽt mɛ́ni plǽnts ǽktʃəwəli gó bǽk ə rízənəbəl lɛ́ŋkθ ə́v tájm,

bə́t nɑ́t mɔ́r ðǽn mébi 300 ɔ́r 400 mɪ́ljən jɪ́rz,

hɪ́r ɑ́r ðə metazoa,

ǽnd ðɪ́s rɛ̀prəzɛ́nts - wɛ́l,

kǽn jú hɪ́r mí? wáw,

614 kém ɪn hǽndi,


só ɪ́f wí tɒ́k əbáwt ənə́ðər médʒər dɪvɪ́ʒən,

wí tɒ́k əbáwt pròtəzóə ǽnd metazoa.

ðə sə́fɪks zoa rəfə́rz tú ǽnəməlz,

ǽz ɪn ə zú,

ǽnd ðə pròtəzóə rɛ̀prəzɛ́nts sɪ́ŋgəl- sɛ́l ɔ́rgənɪ̀zəmz,

ðə metazoa rɛ̀prəzɛ́nt mə́lti- sɛ́ljələr ɔ́rgənɪ̀zəmz,

ǽnd wí regoing tú bí fókəsɪŋ lɑ́rdʒli ɑ́n ðə bajɑ́lədʒi ə́v metazoan sɛ́lz ðɪ́s səmɛ́stər,

ǽnd wí regoing tú bí spɛ́ndɪŋ ɒ́lmòst nó tájm ɑ́n plǽnts,

ɪ́t snɒ́t ðǽt plǽnts ɑ́rən timportant,

ɪ́t sjust ðǽt wí dɑ́n thave tájm tú kə́vər ɛ́vriθɪ̀ŋ,



ðə məlɛ́kjələr bajɑ́lədʒi ðǽt jú lə́rn ðɪ́s səmɛ́stər wɪ́l ə́ltəmətli ɛnébəl jú tú ə̀ndərstǽnd mə́tʃ əbáwt ðə fɪ̀ziɑ́lədʒi ə́v mə́lti- sɛ́ljələr plǽnts wɪ́tʃ hǽpən tú bí kɒ́ld metaphyta,

ə tə́rm jú mé nɛ́vər hɪ́r əgɛ́n ɪn jɔ́r ɛntájər lájf ǽftər tədé,

ðǽt rimájndz mí,

báj ðə wé,

ðǽt bóθ drájv,

lǽndər ǽnd áj səmtájmz jús bɪ́g wə́rdz,

ǽnd pípəl kə́m ə́p tú mí ǽftərwərdz ítʃ səmɛ́stər ítʃ jɪ́r ǽnd sé prəfɛ́sər wájnbərg,

wáj dɑ́n tyou tɒ́k sɪ́mpəl,

wáj dɑ́n tyou tɒ́k ðə wé wí hə́rd θɪ́ŋz ɪn háj skúl? ǽnd plíz ə̀ndərstǽnd ðǽt ɪ́f áj jús bɪ́g wə́rdz səmtájmz ɪ́t sto brɒ́dən jɔ́r vokǽbjəlɛ̀ri só jú kǽn lə́rn bɪ́g wə́rdz,

wə́n ə́v ðə θɪ́ŋz jú ʃʊ́d bí ébəl,

wə́n ə́v ðə bɪ́g ték- hóm lɛ́sənz ə́v ðɪ́s kɔ́rs ʃʊ́d bí ðǽt jɔ́r vokǽbjəlɛ̀ri ɪ́z ɪkspǽndəd.

nɑ́t dʒə́st jɔ́r sɑ̀jəntɪ́fɪk vokǽbjəlɛ̀ri bə́t jɔ́r dʒɛ́nərəl wə́rkɪŋ ɪ́ŋglɪ̀ʃ vokǽbjəlɛ̀ri,

pərhǽps ðə bɪ́gəst gól ə́v ðɪ́s kɔ́rs,

báj ðə wé,

ɪ́z nɑ́t ðǽt jú lə́rn ðə némz ə́v ɒ́l ðə ɔ̀rgənɛ́lz ǽnd sɛ́lz bə́t ðǽt jú lə́rn háw tú θɪ́ŋk ɪn ə sɑ̀jəntɪ́fɪk ǽnd rǽʃənəl wé,

nɑ́t dʒə́st bɪkɒ́z ə́v ðɪ́s kɔ́rs bə́t ðǽt ðɪ́s kɔ́rs hɛ́lps jú tú dú só.

ǽnd ǽz sə́tʃ,

wí dɑ́n tplace ðǽt mə́tʃ ɛ́mfəsɪ̀s ɑ́n memorization bə́t tú bí ébəl tú θɪ́ŋk lɑ́dʒɪkli əbáwt sɑ̀jəntɪ́fɪk prɑ́bləmz,

hɪ́r wí kǽn bɪgɪ́n tú sí ðə dɪ́fərənt kájndz ə́v metazoa,

ðə ǽnəməlz,

hɪ́r ɑ́r ðə metaphyta ǽnd hɪ́r ɑ́r ðə pròtəzóə,

dɪ́fərənt wə́rdz fɔ́r ɒ́l ə́v ðíz.

ǽnd hɪ́r wí sí áwər ón fájləm,

ðə kɔ́rdèts,



kíp ɪn májnd ðǽt ðɪ́s lájn rájt dáwn hɪ́r ɪ́z əbáwt 550 tú 600 mɪ́ljən jɪ́rz əgó,

dʒə́st tú gɪ́v jú ə tájm skél fɔ́r wə́t sbeen góɪŋ ɑ́n,

ɑ́n ðɪ́s plǽnət,

wə́n pɔ́jnt wí llreturn tú rəpítədli θruáwt ðə səmɛ́stər ɪ́z ðǽt ɒ́l lájf fɔ́rmz ɑ́n ðɪ́s plǽnət ɑ́r rəlétəd tú wə́n ənə́ðər,

ɪ́t snɒ́t ǽz ɪ́f lájf wəz ɪ̀nvɛ́ntəd mə́ltəpəl tájmz ɑ́n ðɪ́s plǽnət ǽnd ðǽt ðɛ́r ɑ́r mə́ltəpəl ɪ̀ndəpɛ́ndənt ɪ̀nvɛ́nʃənz tú ðə ɪkstɛ́nt ðǽt lájf əróz mɔ́r ðǽn wə́ns ɑ́n ðɪ́s plǽnət,

ǽnd ɪ́t mé hǽv,

ðə ə́ðər ɒltə́rnətɪv ɔ́r kəmpítɪŋ lájf forms were soon wiped out by our ancestors,

our single-cellular ancestors 3 billion years ago,



everything that exists today on this planet represents the descendents of that 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 we’re not going to study those phylogenies simply because we want to understand principles that explain all of them,

nɑ́t dʒə́st háw ðɪ́s ɔ́r ðǽt pərtɪ́kjələr ɔ́rgənɪ̀zəm ɪ́z ébəl tú dajdʒɛ́st ɪ́ts fúd ɔ́r ɪ́z ébəl tú rìprədús,

hɪ́r sanother θɪ́ŋ wí renot góɪŋ tú tɒ́k əbáwt,

wí renot góɪŋ tú tɒ́k əbáwt kɑ́mpləkètəd lájf fɔ́rmz,

wí renot góɪŋ tú tɒ́k vɛ́ri mə́tʃ,

ɪn fǽkt hɑ́rdli ǽt ɒ́l,

əbáwt ɪkɑ́lədʒi,

ðɪ́s ɪ́z dʒə́st wə́n sə́tʃ θɪ́ŋ,

ðə wé ðǽt ə pɛ́rəsɑ̀jt ɪ́z ébəl tú,

ə tapeworm ɪ́z ébəl tú ɪ̀nfɛ́kt pípəl,

ðɪ́s ɪ́z,


áj mshowing jú ðɪ́s nɑ́t tú sé ðɪ́s ɪ́z wə́t wí regoing tú tɒ́k əbáwt,

wí renot góɪŋ tú tɒ́k əbáwt ðǽt,

wí renot góɪŋ tú tɒ́k əbáwt ðǽt,

ðɛ́r sɑ́ wɛ́lθ ə́v dətél ðǽt sknown əbáwt ðə wé lájf ɪgzɪ́sts ɪn ðə bájosfɪ̀r ðǽt wí resimply góɪŋ tú tə́rn áwər bǽks ɑ́n báj fókəsɪŋ ɑ́n sə́m bésɪk prɪ́nsəpəlz,

wí realso nɑ́t góɪŋ tú tɒ́k əbáwt ənǽtəmi.

hɪ́r ɪn kwɪ́k ɔ́rdər ɑ́r sə́m ə́v ðə anatomies jú mé hǽv lə́rnd əbáwt ɪn háj skúl,

ǽnd áj mgiving ðɛ́m tú jú ítʃ wɪθ ə θrí- sɛ́kənd mɪ́nət,

ə θrí- sɛ́kənd ʃóɪŋ tú sé wí renot góɪŋ tú dú ɒ́l ðɪ́s,

ǽnd rǽðər dʒə́st tú rìɪ̀nfɔ́rs áwər fókəs,

wí regoing tú lɪ́mət awərsɛ́lvz tú ə vɛ́ri fájnɑ̀jt pɑ́rt ə́v ðə bájosfɪ̀r.

ǽnd hɪ́r ɪ́z wə́n wé ə́v dəpɪ́ktɪŋ ðə bájosfɪ̀r,

ɪ́t sobviously ǽn ɑ́rbətrɛ̀ri wé ə́v dúɪŋ só bə́t ɪ́t squite ɪ̀lə́strətɪv,

hɪ́r wí stɑ́rt frə́m mɑ́ləkjùlz,


ɪn fǽkt,

wí wɪ́l əkéʒənəli gó dáwn tú submolecular ǽtəmz,

ǽnd hɪ́r sthe nɛ́kst dɪ̀mɛ́nʃən ə́v kəmplɛ́ksəti,


ðǽt ɪ́z ðíz spɛ́ʃəlɑ̀jzd lɪ́təl ɔ́rgənz wəðɪ́n sɛ́lz,

wí regoing tú fókəs ɑ́n ðɛ́m ǽz wɛ́l,

wí regoing tú fókəs ɑ́n sɛ́lz,

ǽnd wɛ́n wí stɑ́rt gɛ́tɪŋ tú tɪ́sjùz,

wí regoing tú stɑ́rt nɑ́t tɒ́kɪŋ só mə́tʃ əbáwt ðɛ́m,

ǽnd wí renot góɪŋ tú tɒ́k əbáwt ɔ́rgənɪ̀zəmz ǽnd ɔ́rgənz ɔ́r ɛntájər ɔ́rgənɪ̀zəmz ɔ́r hájər kɑ́mplɛks ikəlɑ́dʒɪkəl kəmjúnətiz,

ǽnd ðə rízən wí ridúɪŋ ðǽt ɪ́z ðǽt fɔ́r 40 jɪ́rz ɪn ðɪ́s dəpɑ́rtmənt,

ǽnd ɪ̀nkrísɪŋli ɪn ðə rɛ́st ə́v ðə wə́rld ðɛ́r ɪ́z ðə æksɛ́ptəns ə́v ðə nóʃən ðǽt ɪ́f wí ə̀ndərstǽnd wə́t góz ɑ́n dáwn hɪ́r ɪn ðíz fə́rst θrí stɛ́ps,

wí kǽn ə̀ndərstǽnd ɒ́lmòst ɛ́vriθɪ̀ŋ ɛ́ls ɪn prɪ́nsəpəl.

ə́v kɔ́rs,

ɪn prǽktɪ̀s wí mé nɑ́t bí ébəl tú əpláj ðóz prɪ́nsəpəlz tú háw ǽn ɔ́rgənɪ̀zəm wə́rks ɔ́r tú háw ðə hjúmən brén wə́rks jɛ́t,

mébi wí nɛ́vər wɪ́l,


ɪn dʒɛ́nərəl,

ɪ́f wə́n bɪgɪ́nz tú ə̀ndərstǽnd ðíz prɪ́nsəpəlz dáwn hɪ́r,

wə́n kǽn ə̀ndərstǽnd mə́tʃ əbáwt háw ɔ̀rgənɪ́zmɪk embryologic dɪvɛ́ləp əkə́rz,

wə́n kǽn ə̀ndərstǽnd ə lɑ́t əbáwt ə hól vərájəti ə́v dɪ̀zíz prɑ́sɛsəz,

wə́n kǽn ə̀ndərstǽnd háw wə́n ɪ̀nhɛ́rəts dɪ̀zíz susceptibilities,

ǽnd wə́n kǽn ə̀ndərstǽnd wáj mɛ́ni ɔ́rgənɪ̀zəmz lʊ́k ðə wé ðé dú,



ðə prɑ́sɛ̀s ə́v dɪvɛ̀ləpmɛ́ntəl bajɑ́lədʒi,

ǽnd só,

kíp ɪn májnd ðǽt ɪ́f jú kém tú hɪ́r əbáwt ɒ́l ə́v ðíz θɪ́ŋz,

wí regoing tú lɛ́t jú dáwn,

ðǽt snɒ́t wə́t ðɪ́s ɪ́z góɪŋ tú bí əbáwt,

ðɪ́s ɒ́lso dɪktéts ðə dɪ̀mɛ́nʃənz ə́v ðə júnɪvə̀rs ðǽt wí regoing tú tɒ́k əbáwt bɪkɒ́z wí regoing tú lɪ́mət awərsɛ́lvz tú ðə vɛ́ri,

vɛ́ri smɒ́l ǽnd nɑ́t tú ðə mɑ̀jkrəskɑ́pɪk,

ɑ́n sə́m əkéʒənz wí lllimit awərsɛ́lvz tú ájtəmz ðǽt ɑ́r só smɒ́l jú kǽnat sí ðɛ́m ɪn ðə lájt májkrəskòp,

ɑ́n ə́ðər əkéʒənz wí mé wájdən áwər géz tú lʊ́k ǽt θɪ́ŋz ðǽt ɑ́r ǽz lɑ́rdʒ ǽz ə mɪ́ləmìtər,

bə́t bésɪkli wí restaying vɛ́ri,

vɛ́ri smɒ́l.


bɪkɒ́z wí vjú,

kərɛ́ktli ɔ́r nɑ́t,

ðə fǽkt ðǽt ðə bɪ́g prɑ́sɛsəz kǽn bí ə̀ndərstʊ́d báj dɛ́lvɪŋ ɪ̀ntú ðə məlɛ́kjələr dətélz ə́v wə́t hǽpənz invisibly ǽnd kǽnat bí sín báj móst wéz ə́v vɪ́ʒwəlɑ̀jzɪŋ θɪ́ŋz,

ɪ̀nklúdɪŋ ðə lájt ǽnd ɒ́fən ívən ðə əlɛ́ktran májkrəskòp,

kíp ɪn májnd ðǽt 50 jɪ́rz əgó wí didn tknow ɛ́ni ə́v ðɪ́s,

fɔ́r ɒ́l prǽktəkəl pə́rpəsəz,

ɔ́r vɛ́ri lɪ́təl ə́v ðɪ́s,

ǽnd kíp ɪn májnd ðǽt wí rɪ́zo klós tú ðɪ́s rɛ̀vəlúʃən ðǽt wí dɑ́n treally ə̀ndərstǽnd ɪ́ts ræ̀məfəkéʃənz,

áj ɪ̀mǽdʒən ɪ́t wɪ́l bí ənə́ðər 50 jɪ́rz bəfɔ́r wí rɪ́li bɪgɪ́n tú əpríʃièt ðə fɒ́lɑ̀wt,

ðə lɒ́ŋ- tə́rm kɑ́nsəkwɛ̀nsəz ə́v ðɪ́s rɛ̀vəlúʃən ɪn bajɑ́lədʒi wɪ́tʃ bɪgǽn 51 jɪ́rz əgó,

ǽnd só jú repart ə́v ðǽt ǽnd jú regoing tú ɪkspɪ́riəns ɪ́t mə́tʃ mɔ́r ðǽn máj dʒɛ̀nəréʃən dɪ́d,

ǽnd ɪ̀ndíd wə́n ə́v ðə rízənz wáj ɛ́májtí dəsájdəd əbáwt 10 ɔ́r 12 jɪ́rz əgó ðǽt ɛ́vəri ɛ́májtí ə̀ndərgrǽdʒəwət nídəd tú hǽv ǽt líst wə́n səmɛ́stər ə́v bajɑ́lədʒi ɪ́z ðǽt bajɑ́lədʒi,

ɪn ðə sém wé ǽz fɪ́zɪks ǽnd kɛ́məstri ǽnd mǽθ,

hǽz bɪkə́m ǽn ɪ́ntəgrəl pɑ́rt ə́v ɛ́vəri ɛ́dʒəkètəd pə́rsən sknowledge- bés ɪn tə́rmz ə́v ðɛ́r əbɪ́ləti tú díl wɪθ ðə wə́rld ɪn ə rǽʃənəl wé.

ɪn tə́rmz ə́v pə́blɪk pɑ́ləsi,

ɪn tə́rmz ə́v ɒ́l kájndz ə́v ɛ́θɪkəl ɪ́ʃuz,

ðé níd tú ə̀ndərstǽnd wə́t sreally góɪŋ ɑ́n,

mɛ́ni ə́v ðə ɪ́ʃuz ðǽt wə́n tɒ́ks əbáwt tədé əbáwt bɑ̀joɛ́θɪks ɑ́r artɪ́kjəlètəd báj pípəl hú hévən tthe végɪ̀st ajdíə əbáwt wə́t wí retalking əbáwt ðɪ́s səmɛ́stər.

jú wɪ́l nó mə́tʃ mɔ́r ðǽn ðé wɪ́l,

ǽnd hópfəli sə́m tájm dáwn ðə ród,

wɛ́n jú bɪkə́m mɔ́r ǽnd mɔ́r ɪ̀nfluɛ́ntʃəl vɔ̀jsəz ɪn səsájəti,

jú llbe ébəl tú kəntrɪ́bjut wə́t jú ə̀ndərstʊ́d hɪ́r,

wə́t jú lə́rnd hɪ́r tú ðǽt dɪ̀skə́ʃən,

rájt náw mə́tʃ ə́v bioethical dɪ̀skə́ʃən ɪ́z fjúəld báj pípəl hú hévən tthe végɪ̀st ajdíə wə́t ə ribosome ɔ́r mitochondrion ɔ́r ívən ə dʒín ɪ́z,

ǽnd ðɛ́rfɔ̀r ɪ́z ɒ́fən ə dɪ̀skə́ʃən ə́v mjútʃuəli ʃɛ́rd ɪ́gnərəns wɪ́tʃ jú kǽn dəfjús báj lə́rnɪŋ sə́m bésɪks,

báj lə́rnɪŋ sə́m ə́v ðə əsɛ́ntʃəlz,

hɪ́r ɪ́z ðə kəmplɛ́ksəti ə́v ðə sɛ́l wí regoing tú fókəs ɑ́n lɑ́rdʒli ðɪ́s səmɛ́stər,

wɪ́tʃ ɪ́z tú sé ðə eukaryotic rǽðər ðǽn ðə prokaryotic sɛ́l,

ǽnd ðɪ́s ɪ́z dʒə́st tú gɪ́v jú ə fílɪŋ fɔ́r ðə óvərɒ̀l dɪ̀mɛ́nʃənz ə́v ðə sɛ́l ǽnd rəfə́r tú mɛ́ni ə́v ðə lǽndmɑ̀rks ðǽt wɪ́l rəpítədli bí brɒ́t ə́p dʊ́rɪŋ ðə kɔ́rs ə́v ðɪ́s səmɛ́stər,

hɪ́r ɪ́z ðə núkliəs,

ðə tə́rm karion kə́mz frə́m ðə grík mínɪŋ ə síd ɔ́r ə kə́rnəl,

ǽnd ðə núkliəs ɪ́z wə́t gɪ́vz ðə eukaryotic sɛ́l ɪ́ts ném,

wəðɪ́n ðə núkliəs,

ɒ̀lðó nɑ́t ʃón hɪ́r,

ɑ́r ðə króməzòmz wɪ́tʃ kǽri dna,

jú mé hǽv lə́rnd ðǽt ə lɒ́ŋ tájm əgó,

áwtsájd ə́v ðə núkliəs ɪ́z ðɪ́s ɛntájər vǽst əré ə́v ɔ̀rgənɛ́lz ðǽt góz frə́m ðə núkliər mɛ́mbrèn,

ǽnd áj mpoint tú ɪ́t rájt hɪ́r,

ɒ́l ðə wé áwt tú ðə áwtsájd ə́v ðə sɛ́l.

ðə áwtsájd lɪ́mətɪŋ mɛ́mbrèn,

ðə áwtər mɛ́mbrèn ə́v ðə sɛ́l ɪ́z kɒ́ld ðə plǽzmə mɛ́mbrèn,

ǽnd bətwín ðə núkliəs ǽnd ðə plǽzmə mɛ́mbrèn ðɛ́r ɪ́z ǽn ənɔ́rməs əmáwnt ə́v bɑ̀jəlɑ́dʒɪkəl ǽnd bɑ̀jokɛ́məkəl æktɪ́vəti tékɪŋ plés,

hɪ́r ɑ́r,

fɔ́r ɪgzǽmpəl,

ðə mitochondria,

ǽnd ðə mitochondria,

ǽz wə́n hǽz lə́rnd,

ɑ́r ðə sɔ́rsəz ə́v ɛ́nərdʒi prədə́kʃən ɪn ðə sɛ́l,



wí lltouch ɑ́n ðɛ́m vɛ́ri brífli,

ðɪ́s ɪ́z ǽn ɑ́rtəst sconception ə́v wə́t ə mitochondrion lʊ́ks lájk.

ɒ́lmòst ɒ́lwèz ɑ́rtəsts kənsɛ́pʃənz ə́v ðíz θɪ́ŋz hǽv ónli vég rəzɛ́mbləns tú ðə riǽləti,


ɪn ɛ́ni kés,

jú kǽn bɪgɪ́n tú gɛ́t ə fílɪŋ fɔ́r wə́t wə́n θɪ́ŋks əbáwt ðɛ́r əpɪ́rəns,

hɪ́r ɑ́r mitochondria slájst ópən báj ðə hǽnd ə́v ðə ɑ́rtəst,



mitochondria hǽv ðɛ́r ón dna ɪn ðɛ́m,

wə́n náw æksɛ́pts ðə fǽkt ðǽt mitochondria ɑ́r ðə dəsɛ́ndənts ə́v bæktɪ́riə wɪ́tʃ ɪ̀nsɪ́njuetəd ðɛmsɛ́lvz ɪ̀ntú ðə cytoplasms ə́v lɑ́rdʒər sɛ́lz,

rə́fli 1,

5 bɪ́ljən jɪ́rz əgó,

ǽnd bɪgǽn tú dú ə spɛ́ʃəlɑ̀jzd dʒɑ́b wɪ́tʃ ɪ̀nkrísɪŋli bɪkém ðə dʒɑ́b ə́v ɛ́nərdʒi prədə́kʃən wəðɪ́n sɛ́lz,

tú ðɪ́s dé,

mitochondria rətén sə́m vəstɪ́dʒiəl ǽtrəbjùts ə́v ðə bæktɪ́riəl ǽnsɛ̀stərz wɪ́tʃ ɪ̀nɪ́ʃəli kɑ́lənɑ̀jzd ɔ́r parasitized ðə sájtəplæ̀zəm ə́v ðə sɛ́l,

wɛ́n áj sé parasitized,

jú májt ɪ̀mǽdʒən ðǽt ðə mitochondria ɑ́r tékɪŋ ædvǽntɪdʒ ə́v ðə sɛ́l,