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What Are We?
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Eukaryotic Cell Biology
In this course, Professor Jake Baum (Imperial College London) introduces us to eukaryotic cells, that is animal and plant cells. To do this, we begin by: (i) asking what we are made of, and what scientists decades and centuries ago thought about this very same questions; before (ii) discussing how microscopy revolutionised our ability to understand ourselves to a much higher complexity; and then (iii) looking at the key players in cell biology, before beginning to understand the size and complexity of this field of science; which then follows onto (iv) cell compartmentalisation, and how this compartmentalisation enables the cell to carry out many different functions efficiently; and finally (v) looking at cell dynamism and seeing how this dynamism has enormous complexity but enables the most vital processes in our bodies such as growth and repair and cell division.
What Are We?
In the first mini-lecture, we ask the question “What am I?”. It’s a question that has interested scientists for centuries. Without access to modern tools such as microscopes, it was impossible to see what we were made of. This first mini-lecture introduces some of the prevailing theories that dominated scientific discussion over the centuries. Who were the key thinkers of this field, and what did they propose? We learn about the camera obscura, the first thinkers to understand how light behaved, including Ibn al-Haytham, Kepler, Descartes, as well as theories of self such as the homunculus, and continuity of form.
Hi. My name is Jake Baum.
00:00:06I'm professor of cell biology and infectious disease at Imperial College,
00:00:08London in the Department of Life Sciences.
00:00:11And today, what I'd like to do is to talk to you about cell biology,
00:00:13which is one of my passions, um, and in particular, the life of the Eukaryotic cell,
00:00:17which I'll explain in detail.
00:00:23What I like to do with the first mini lecture is
00:00:24really to get us thinking about the concept of a cell,
00:00:27which maybe you've never thought of as something abstract.
00:00:30But if you think about it,
00:00:33it's quite a wild idea that were made up of cells in the first place.
00:00:34So what I'd like you to do is think about what are you Who am I? What am I,
00:00:39um, am I some, uh, celestial being? Um
00:00:45and that's not not to sort of put any religious spin on it.
00:00:49But, you know,
00:00:52a lot of people kind of just can't deal with the
00:00:53fact that they are anything other than some kind of miracle.
00:00:56Or maybe you're at the other end of the spectrum,
00:00:58just a vehicle for self replicating bits of DNA
00:01:01and your only purpose in life is to pass on this strand of DNA,
00:01:03which is going to just carry on the sort of selfish DNA idea that
00:01:06you may have heard from people like Richard Dawkins or others in that kind of
00:01:09genre. Or maybe you're some neurological phenomenon.
00:01:14You're actually a sort of a product of some wild coding exercise that is,
00:01:17all the brain the cells are going in your brain.
00:01:21There are many different definitions of self that you might want to
00:01:23think about that might get you through a day to day existence.
00:01:26But for the purpose of these mini lectures,
00:01:29what I'd like you to do is to think about yourself as a sell.
00:01:31Now. It's not that you're one cell. In reality, you're more like 13 trillion cells.
00:01:35I think you know 37 trillion cells.
00:01:40That was one of the estimates I found in the literature.
00:01:42So you're just this moving macro structure made
00:01:44up of trillions and trillions of cells,
00:01:49and that's what I'd like you to think about.
00:01:51Um, it's not an obvious thought to think of yourself as a cell, Um,
00:01:54and even more miraculously, you came from a single cell,
00:02:00obviously a sperm and then came together and made that original cell, which is you.
00:02:03And then that grew into that multi cellular organism, which is the big you.
00:02:07So you're a multi cellular entity that came from cells.
00:02:12Now already, that's kind of quite a hard thing to get your head around. Um,
00:02:16and I think one thing we take for granted for granted,
00:02:21especially in the sort of digital and very you know,
00:02:24we all deal very easily with the scales from Nano through the macro.
00:02:27But it's not obvious to think of yourself as a cell.
00:02:32And then this first mini lecture I would really like to think about.
00:02:35You know, imagine if you've never seen or even heard of a cell.
00:02:38Um,
00:02:42what did people what did people think of
00:02:42life when they didn't know that sells existed?
00:02:45Now you may think
00:02:48it's quite a hard concept to get your head around,
00:02:51but in reality you've all come across single cells.
00:02:54So you've all come across an egg, maybe have an egg for breakfast.
00:02:57An egg is actually an unfertilised eggs, a single cell.
00:02:59Um, it's just, uh, well, it's a single cell.
00:03:02There are some single cells that you can see along with eggs.
00:03:07Um, those, uh, sort of swelled bladders that you get in the Citrus fruit,
00:03:10the little piece of
00:03:15fruit that's actually the swelled portion of one cell.
00:03:16Obviously, that makes up the order change
00:03:18that you can
00:03:21obviously see.
00:03:22But the vast majority of cellular life is well beyond our perception.
00:03:23We can't see it. It's as if it's there. So we have to imagine
00:03:28that cells exist.
00:03:32And that's really when we get into that sort of philosophical space.
00:03:34So what I like to do in introducing cell biology to students, um,
00:03:37and to those trying to learn about cell biology is to really
00:03:41teach them a little bit about the history of cell biology,
00:03:43because I think that tells us a lot about what a cell is and how we, um,
00:03:45and how we think about cells in the context of cell biology.
00:03:50So for me, the first step in understanding
00:03:53how in history we we kind of came across this concept of a
00:03:57cell was actually the process of learning how to see and for well,
00:04:03forever.
00:04:07Basically, we've been humankind has been thinking about how do we actually see
00:04:07the early Greek philosophers felt that what happened
00:04:12is as we were walking around the world,
00:04:14we would send out these beams of light a bit like Superman
00:04:16and that that would then bounce off.
00:04:18And then we would see the world as if sort of some kind of radar sonar laser. I kind of
00:04:20effect.
00:04:26Um, it was, uh, an Arabian scholar, Ibn Al Haytham.
00:04:27I think from Egypt who really made some of the first major steps in
00:04:31terms of understanding how we see the world and what the process seeing is,
00:04:38um,
00:04:42and some wonderful drawings he made about the structure
00:04:42about how the eyes link up with the brain.
00:04:45And it was his work.
00:04:48He also was one of the first to use a camera obscura,
00:04:49a pinhole camera idea where you can sit in a darkened room and have a very small
00:04:51aperture. Light comes in, you can see the world.
00:04:55And it was his work about 1000 years ago or 4050 years ago,
00:04:59that really set the stage for understanding how light behaves.
00:05:04And when you understand how light behaves,
00:05:07you can start to play with it and start to see the world
00:05:08after Al Haytham,
00:05:12You have people like Kepler and China who also
00:05:15laid some of the foundations of how we see.
00:05:17Um, and for example, uh, based on the work of Kepler in China,
00:05:20we had this kind of first idea that when we receive information in the I,
00:05:24it actually goes through this
00:05:27structure at the front of the either lens and it gets projected upside down.
00:05:28So the first bits of theory about how light
00:05:31behaves started to take shape and then you had people
00:05:35like Dick are to really lay down the foundations
00:05:40of how we think we sort of see the world
00:05:42Now, up until about the 16 hundreds.
00:05:45So sort of 500 years ago, Um,
00:05:48whilst some of the foundations of how we see in the study
00:05:51of optics and the physics of light had started to be set,
00:05:54there was still very much a perception that there is this continuity form of life.
00:05:58So life starts tiny and get big.
00:06:02One of my favourite examples of this is the homunculus, um
00:06:05which is this idea that a sperm
00:06:09and of course, 500 years ago is very male dominated
00:06:11the idea that the sperm contained a little person
00:06:15and the egg just provided all these nutrients.
00:06:18And this little person in the sperm basically started
00:06:20to get bigger and bigger and bigger and bigger,
00:06:22and that became a human being.
00:06:23So this idea of continuity form that we just basically
00:06:24small lumps of clay to become big lumps of clay.
00:06:26And this is actually a Greek idea from, I think from Aristotle,
00:06:29this idea that we're all part of this continuum
00:06:33and in fact, the early people who are playing with lenses and microscopes,
00:06:36which I'll come to.
00:06:39They looked down the microscope to try and see if there was a little person in sperm.
00:06:40And there's this wonderful drawing
00:06:44that I have on one of my slides
00:06:47you can see of a sort of somebody has painstakingly drawn a person kind of curled up
00:06:49in a sperm.
00:06:55Philosophically,
00:06:57there's been this long view that this continuity of form didn't make any sense,
00:06:58and actually, life was more made up of units.
00:07:02This sort of atomic view,
00:07:04which now obviously dominates everything we think of
00:07:06there's always a always a physicist somewhere trying
00:07:09to find one more little more subatomic particle
00:07:11that makes up the other subatomic particle.
00:07:13That used to be
00:07:14that we only just discovered.
00:07:15So that atomic view was quite was quite revolutionary, really.
00:07:17And most of human history has been dominated more by this idea
00:07:20of the continuity of form and that idea of continuity of form.
00:07:24Whilst it's appealing,
00:07:27it's also quite stretching if you think about it in
00:07:28the context of something as massive as the sequoia trees,
00:07:31these giant redwoods that you find in America that they come from
00:07:33this tiny seed and yet they grow into some of the biggest,
00:07:36largest structures, biological structures.
00:07:40It's one organism, but it's just it's It's so enormous this idea.
00:07:42This tiny little tree would start out in the seed and grow.
00:07:45Um, I think you can already sense that there's that.
00:07:47There's something that doesn't quite work like that or doesn't work
00:07:51
Cite this Lecture
APA style
Baum, J. (2022, August 30). Eukaryotic Cell Biology - What Are We? [Video]. MASSOLIT. https://massolit.io/courses/eukaryotic-cell-biology/cell-dynamism
MLA style
Baum, J. "Eukaryotic Cell Biology – What Are We?." MASSOLIT, uploaded by MASSOLIT, 30 Aug 2022, https://massolit.io/courses/eukaryotic-cell-biology/cell-dynamism