Lecture 1 Notes 7/5
Possible Q's
What are the origins of cell biology? Was there agreement among all scientists in early Cell Biology? If not, what were the differences? What are significant characteristics?
What am I saying when I say there are limits to technology? What are some examples of this? How are some ways we work around these?
What types of "technology" do cells employ? What do these technologies tell us about cellular evolution?
Tell me something about dimensionality? What does this have to do with cells?
Define PHENOMENOLOGY. What does it have to do with the study of cells?
3) Why was is lucky for cell culture studies that many of the early efforts at cell cultures were attempted with cells from rodents such as mice?
If I said: Because rodents cells grow readily in culture and much more easily when little was know about cell cultures. Also they become cancerous at a higher rate than the cells of larger mammals. IS THIS ENOUGH - OR DO I NEED TO BREAK DOWN 'CANCEROUS' into "IMMORTAL" and "TRANSFORMED"?
4) What survives better in cell culture systems, cells from adults or cells from early developmental stages such as embryos? Explain your answer.
5) Starting with a chunk of tissue removed from an organism, explain how a cell line is obtained. In this answer you should list a complete, detailed procedure including all the elements discussed in class.
6) Concering your answer to number 5 - what would happen if instead of using serum to provide growth factors to the culture medium I instead added the exact growth factors to promote growth of the cells I specifically wanted to obtain. NOTE: be cautions in your answer because this question is a bit tricky.
Assume you have a suspension culture of cells growing from a tumore. You start the culture with 10 cells in it and the suspension culture has 100 mLs of medium in it. (In case you don't remember a suspension culture is s culture where the cells are gently mixed so that they are floating around.The currents in the mdeium prevent them from settling down onto the bottom of the culture plate). Answer the following questions below (9-12) with regard to this experiement.
9) How many cells will be present in the plate 3 days later? WHAT"S THE ANSWER? DID WE EVER GET A RATE OF GROWTH? CANCER CELLS DIVIDE in 18 HRS. IS THAT IT?
4 x 18 = 72 hrs. 10 > 20 > 40 > = 80 ?
10) If you wanted to isolate 1 cell out of the suspension culture to start a new suspension culture from a single cell, describe two methods discussed in class to perform this task.
11) What would you predict would happen if you took the initial suspension culture and turned off the mechanism that gently mixed the cells?
12) How would you test your prediction?
13) Assume that you have a cell walking on a substrate. With regard to that cell, describe the various parts of the cells and how these structures give you information about the directionality of the cell. IF I DREW A PICTURE OF THE NON-WALKING CELL TO SHOW NO MOVEMENT - WOULD THIS BE INCORRECT? Or INCORRECT WITHOUT?
14) Describe the process that has to occur in a normal cell if it is to become both anchorage-independent for growth and immotal? I suggest you use a diagram to answer this question.
-----------------------
Outline:
- Intro
- Origin of Cell Biology
- Biomolecular mechanisms / machines
- Problems with Dimenstionality
- Behavior of Cells
- Cell Walking - Culture + in Biology
- Cells as organisms
- How do you look at cells?
------------------------------
Cell Biology
-----------------
It can be seen through 2 historical perspectives
1) Biochemical perspective:
Biochemists were one group of researches who began CB. They homogenized cells first and tested these parts of cells
2) Morphologists:
Used ELETRON MICROSCOPY - they fixed and viewed cells under a microscope to find out more about them.
In the 1950's CB had groups involved like the (ASM) Microbiologists - wanted to understand "how cells work"
--They were trying to understand what cells DO. Cells were NOT intuitive - scientists didn't know how they worked
"Evolution designed cells" - if cells had desirable characteristics, they lived. If they didn't, they died
What are "Biomolecular machines" and what do they do? How do we understand biomolecular machines?
First approach is DESCRIPTIVE:
If we want to describe anything, what do we do? We look at it, look at its structures. Macroscopic observation means looking at something overall and describing what we know empirically by observing with our eyes, senses.
BUT - this doesn't work with CELLS. Why not? Not because:
- Cells are small, TINY - we can't actually see them - so we have to use MACHINES to do this.
- Electron Microscopy is a technology we use - BUT - our view are only FREEZE FRAME picutres
- It took 40+ years to figure out some basic structures.
SO - Cells are THEORETICAL because of out limits of observation
Given all this, since we have to have indirect approaches to study cells - theoretical ways - scientists came up with approaches to do so.
Cliques arose between the BIOCHEMISTS and MICROBIOLOGISTS camps and the didn't agree upon which approach was best - do we study the minute details - the individual pieces because we couldn't look at the parts in an intact cells, or did we look without a lot of detail at whole cells?
- Example: Microfilaments, a basic structure in cells - was huge source of contention. I remember going to a conference where grown men called each other names and used four-letter words over whether microfilaments exisited. MIC's insisted that they could look right at cells and see them. BCHs laughed and said "you're crazy"- when we break the cells up, there is absolutely no evidence they exist.
Biochemists like to isolate single, pure parts of a cells or molecules and study, test these. They take a tube with a receptacle and a plunger, and plunge, plunge to break cells apart and then centifuge. At the bottom of the tube you get "gemisch" and plasma above that. So they take these cells parts from the bottom and study them. What might be a limitation for this? It's one approach, BUT - "all cells come from cells". When you do this - are you studying a live cell any more? Can you tell exactly what it's doing? Can you tell by observing - what the cell is doing? NO - it's DEAD!
REVIEW THIS - CAN YOU CLARIFY WHAT YOU MEANT BY THE LIGHT SWITCH and MARKERS?
So - to see a live, or at least entatct, cell, you put it under a Microscope, you look at it. What do you see [refers to a drawing on board] let's say we have these structures and parts. What is "uniform" vs. "non-uniform" - what are separate distinct stuctures? What do they do? We cam to realize over time that these were separate "machines" with specific functions.
Example: let's say you come into a room you've never been in before. You see the light switch. Even if you've never seen one like this before, could you guess at what is does? Could you guess that it at least does something specific because it is discrete and it's there? You walked into the room, and you turned it on. It is distinct and has a function. You did these in sequence. The same with these board markers.
This is the same thing with cells. We look at cells and we can tell that because there are structures, organization, distinct or discrete characteristics, that these parts and stuctures have function. We may not know what they do - we still don't know what some of these things do - but we know that the cells have evolved to have them as "machines".
This is the same as biotechnology - they take these machines, the mechanisms of cells and do tasks - like the light switch - ON DEMAND and OUT OF SEQUENCE, to meet the needs the researchers are looking for.
DIMENSIONALITY
-----------------------------
WHICH EM IS THE BEST? SEM? TEM?
- Cells are SMALL
- Our understanding of cells is ABSTRACT
- ELECTRON MICROSCOPY is in STILL FRAMES (DEAD CELLS)
- Thin 2-D slices is what we see in Trasnmission Electron Microscopy. So it would be like you looked at me through thin slices - would you be able to get a good idea of how I looked if this is what you saw?
- Cytologic FIXATION KILLS Cell
- Scanning Electon Microscopy is another method that was developed and it addressed some of the drawbacks of TEM - it shows 3-D views of cells at the surface but at one time was not as high resolution as now. SEM is better, higher resolution than LIGHT MICROSCOPY - you can see filaments such as FILIPODIA which are only 0.2 x 10 micrometers - much smaller structures than can be seen with LM. So - SEM has about a 0.2 micrometer resolution.
Drawbacks to SEM:
- Can't see within cells
- Can't see motion
LIGHT MICROSCOPY (LIVING CELLS):
- Bright field - use stained slides
- Phase constast
- Differential Interferometry?!?! Contrast
---------------------------------------------------------------
CELL BEHAVIOR - phenomenological behavior, involves how cells are predicted to act, based on what we've observed of their behavior. For example, if I see a cell moving and it stops, I can predict with good accuracy what the cell will do next.
So - if we drop cells into a culture, and they are suspended and free to move about - what shape will they assume?
- SPHERE!!! Why is this? Because the sphere is a shape has the smallest sruface area with the largest volume. All cells in culture assuma SPHERICAL shape and fall to the bottom of their container. What's interesting is that when they hit that bottom, they being to explore. Let me explain....
First, though - tell me, what are some examples of cell types? [From stus: hepatocytes, hempcytes. These react DIFFERENTLY to their enrivonment. For example - if I put a rabbit into a box - what happens? It will go to the middle of the box. If I do the same with a rat - what do you predict will happen? It will run to the corner and cower. These are different species, but just by knowing what they are and having observed them, I can predict with great certainty what they will do]
So - we have cells, say our heptocytes that hit the botton of the container - what do they do? They are sphereical as they fall - but look at the picture [Has a Sphere, half-sphere, half-flat, and somewhat flat cells]
They touch the bottom, and:
FILIPODIA: - the cell initially extends these in all directions. They are tiny hair-like, like fingers to "feel" their environment. 0.2 micometers in diameter, 2-10 micrometers in length. So, the cell extends these out to feel. As it does this, the cell begins to touch the bottom of the container. The cells does this for a while and then stops 2-3 minutes - a pause. Then...
LAMELLIPODIA: once the cell senses the surface with FILIPODIA and pauses, it extends a larger stucture like a leg, engulfing "swallowing" the FILIPODIA as it extends. As the cell extends a LAMELLIPODIA, is secretes a substances onto the surface of the container - the "cellular equivalent of superglue" so that it sticks and continues extending until FLAT and like a pancake. It may stay there, or it may begin to "WALK". [Note the drawings of a "pancake" with a hump in the middle - NONW WALKING and one with the hump to a side - WALKING.] The lamellipodia then assembles actin and miosin filaments together to form the "cellular equivalent of a muscle" which contracts to MOVE THE CELL?!?!? then sends another lamellipodia out in the direction it wants to go. It will only do this in the direction of the surface of the container. The cell won't waste ATP trying to extend lamellipodia in a diection it won't be able to move in.
As the cell contracts and WALKS, it leaves behind RETRACTION FIBERS - which are the superglue form where the lamellipodia attached and small blebs of plasma membrane that trail behind. Eventually these release and merge (mostly) back into the cell's membrane and cytoplasm. After the retraction fiber releases, there will still be traces of superglue and membrane left - MICROEXUDATES.
As the cell moves, it "drags" the Nucleus (which causes the bulge) using ATP ONLY in the lamellipodia. (The cell doesn't waste ATP by forming and contracting "muscles" in the part of the cell around the trailing Nucleus.)
What are the origins of cell biology? Was there agreement among all scientists in early Cell Biology? If not, what were the differences? What are significant characteristics?
What am I saying when I say there are limits to technology? What are some examples of this? How are some ways we work around these?
What types of "technology" do cells employ? What do these technologies tell us about cellular evolution?
Tell me something about dimensionality? What does this have to do with cells?
Define PHENOMENOLOGY. What does it have to do with the study of cells?
3) Why was is lucky for cell culture studies that many of the early efforts at cell cultures were attempted with cells from rodents such as mice?
If I said: Because rodents cells grow readily in culture and much more easily when little was know about cell cultures. Also they become cancerous at a higher rate than the cells of larger mammals. IS THIS ENOUGH - OR DO I NEED TO BREAK DOWN 'CANCEROUS' into "IMMORTAL" and "TRANSFORMED"?
4) What survives better in cell culture systems, cells from adults or cells from early developmental stages such as embryos? Explain your answer.
5) Starting with a chunk of tissue removed from an organism, explain how a cell line is obtained. In this answer you should list a complete, detailed procedure including all the elements discussed in class.
6) Concering your answer to number 5 - what would happen if instead of using serum to provide growth factors to the culture medium I instead added the exact growth factors to promote growth of the cells I specifically wanted to obtain. NOTE: be cautions in your answer because this question is a bit tricky.
Assume you have a suspension culture of cells growing from a tumore. You start the culture with 10 cells in it and the suspension culture has 100 mLs of medium in it. (In case you don't remember a suspension culture is s culture where the cells are gently mixed so that they are floating around.The currents in the mdeium prevent them from settling down onto the bottom of the culture plate). Answer the following questions below (9-12) with regard to this experiement.
9) How many cells will be present in the plate 3 days later? WHAT"S THE ANSWER? DID WE EVER GET A RATE OF GROWTH? CANCER CELLS DIVIDE in 18 HRS. IS THAT IT?
4 x 18 = 72 hrs. 10 > 20 > 40 > = 80 ?
10) If you wanted to isolate 1 cell out of the suspension culture to start a new suspension culture from a single cell, describe two methods discussed in class to perform this task.
11) What would you predict would happen if you took the initial suspension culture and turned off the mechanism that gently mixed the cells?
12) How would you test your prediction?
13) Assume that you have a cell walking on a substrate. With regard to that cell, describe the various parts of the cells and how these structures give you information about the directionality of the cell. IF I DREW A PICTURE OF THE NON-WALKING CELL TO SHOW NO MOVEMENT - WOULD THIS BE INCORRECT? Or INCORRECT WITHOUT?
14) Describe the process that has to occur in a normal cell if it is to become both anchorage-independent for growth and immotal? I suggest you use a diagram to answer this question.
-----------------------
Outline:
- Intro
- Origin of Cell Biology
- Biomolecular mechanisms / machines
- Problems with Dimenstionality
- Behavior of Cells
- Cell Walking - Culture + in Biology
- Cells as organisms
- How do you look at cells?
------------------------------
Cell Biology
-----------------
It can be seen through 2 historical perspectives
1) Biochemical perspective:
Biochemists were one group of researches who began CB. They homogenized cells first and tested these parts of cells
2) Morphologists:
Used ELETRON MICROSCOPY - they fixed and viewed cells under a microscope to find out more about them.
In the 1950's CB had groups involved like the (ASM) Microbiologists - wanted to understand "how cells work"
--They were trying to understand what cells DO. Cells were NOT intuitive - scientists didn't know how they worked
"Evolution designed cells" - if cells had desirable characteristics, they lived. If they didn't, they died
What are "Biomolecular machines" and what do they do? How do we understand biomolecular machines?
First approach is DESCRIPTIVE:
If we want to describe anything, what do we do? We look at it, look at its structures. Macroscopic observation means looking at something overall and describing what we know empirically by observing with our eyes, senses.
BUT - this doesn't work with CELLS. Why not? Not because:
- Cells are small, TINY - we can't actually see them - so we have to use MACHINES to do this.
- Electron Microscopy is a technology we use - BUT - our view are only FREEZE FRAME picutres
- It took 40+ years to figure out some basic structures.
SO - Cells are THEORETICAL because of out limits of observation
Given all this, since we have to have indirect approaches to study cells - theoretical ways - scientists came up with approaches to do so.
Cliques arose between the BIOCHEMISTS and MICROBIOLOGISTS camps and the didn't agree upon which approach was best - do we study the minute details - the individual pieces because we couldn't look at the parts in an intact cells, or did we look without a lot of detail at whole cells?
- Example: Microfilaments, a basic structure in cells - was huge source of contention. I remember going to a conference where grown men called each other names and used four-letter words over whether microfilaments exisited. MIC's insisted that they could look right at cells and see them. BCHs laughed and said "you're crazy"- when we break the cells up, there is absolutely no evidence they exist.
Biochemists like to isolate single, pure parts of a cells or molecules and study, test these. They take a tube with a receptacle and a plunger, and plunge, plunge to break cells apart and then centifuge. At the bottom of the tube you get "gemisch" and plasma above that. So they take these cells parts from the bottom and study them. What might be a limitation for this? It's one approach, BUT - "all cells come from cells". When you do this - are you studying a live cell any more? Can you tell exactly what it's doing? Can you tell by observing - what the cell is doing? NO - it's DEAD!
REVIEW THIS - CAN YOU CLARIFY WHAT YOU MEANT BY THE LIGHT SWITCH and MARKERS?
So - to see a live, or at least entatct, cell, you put it under a Microscope, you look at it. What do you see [refers to a drawing on board] let's say we have these structures and parts. What is "uniform" vs. "non-uniform" - what are separate distinct stuctures? What do they do? We cam to realize over time that these were separate "machines" with specific functions.
Example: let's say you come into a room you've never been in before. You see the light switch. Even if you've never seen one like this before, could you guess at what is does? Could you guess that it at least does something specific because it is discrete and it's there? You walked into the room, and you turned it on. It is distinct and has a function. You did these in sequence. The same with these board markers.
This is the same thing with cells. We look at cells and we can tell that because there are structures, organization, distinct or discrete characteristics, that these parts and stuctures have function. We may not know what they do - we still don't know what some of these things do - but we know that the cells have evolved to have them as "machines".
This is the same as biotechnology - they take these machines, the mechanisms of cells and do tasks - like the light switch - ON DEMAND and OUT OF SEQUENCE, to meet the needs the researchers are looking for.
DIMENSIONALITY
-----------------------------
WHICH EM IS THE BEST? SEM? TEM?
- Cells are SMALL
- Our understanding of cells is ABSTRACT
- ELECTRON MICROSCOPY is in STILL FRAMES (DEAD CELLS)
- Thin 2-D slices is what we see in Trasnmission Electron Microscopy. So it would be like you looked at me through thin slices - would you be able to get a good idea of how I looked if this is what you saw?
- Cytologic FIXATION KILLS Cell
- Scanning Electon Microscopy is another method that was developed and it addressed some of the drawbacks of TEM - it shows 3-D views of cells at the surface but at one time was not as high resolution as now. SEM is better, higher resolution than LIGHT MICROSCOPY - you can see filaments such as FILIPODIA which are only 0.2 x 10 micrometers - much smaller structures than can be seen with LM. So - SEM has about a 0.2 micrometer resolution.
Drawbacks to SEM:
- Can't see within cells
- Can't see motion
LIGHT MICROSCOPY (LIVING CELLS):
- Bright field - use stained slides
- Phase constast
- Differential Interferometry?!?! Contrast
---------------------------------------------------------------
CELL BEHAVIOR - phenomenological behavior, involves how cells are predicted to act, based on what we've observed of their behavior. For example, if I see a cell moving and it stops, I can predict with good accuracy what the cell will do next.
So - if we drop cells into a culture, and they are suspended and free to move about - what shape will they assume?
- SPHERE!!! Why is this? Because the sphere is a shape has the smallest sruface area with the largest volume. All cells in culture assuma SPHERICAL shape and fall to the bottom of their container. What's interesting is that when they hit that bottom, they being to explore. Let me explain....
First, though - tell me, what are some examples of cell types? [From stus: hepatocytes, hempcytes. These react DIFFERENTLY to their enrivonment. For example - if I put a rabbit into a box - what happens? It will go to the middle of the box. If I do the same with a rat - what do you predict will happen? It will run to the corner and cower. These are different species, but just by knowing what they are and having observed them, I can predict with great certainty what they will do]
So - we have cells, say our heptocytes that hit the botton of the container - what do they do? They are sphereical as they fall - but look at the picture [Has a Sphere, half-sphere, half-flat, and somewhat flat cells]
They touch the bottom, and:
FILIPODIA: - the cell initially extends these in all directions. They are tiny hair-like, like fingers to "feel" their environment. 0.2 micometers in diameter, 2-10 micrometers in length. So, the cell extends these out to feel. As it does this, the cell begins to touch the bottom of the container. The cells does this for a while and then stops 2-3 minutes - a pause. Then...
LAMELLIPODIA: once the cell senses the surface with FILIPODIA and pauses, it extends a larger stucture like a leg, engulfing "swallowing" the FILIPODIA as it extends. As the cell extends a LAMELLIPODIA, is secretes a substances onto the surface of the container - the "cellular equivalent of superglue" so that it sticks and continues extending until FLAT and like a pancake. It may stay there, or it may begin to "WALK". [Note the drawings of a "pancake" with a hump in the middle - NONW WALKING and one with the hump to a side - WALKING.] The lamellipodia then assembles actin and miosin filaments together to form the "cellular equivalent of a muscle" which contracts to MOVE THE CELL?!?!? then sends another lamellipodia out in the direction it wants to go. It will only do this in the direction of the surface of the container. The cell won't waste ATP trying to extend lamellipodia in a diection it won't be able to move in.
As the cell contracts and WALKS, it leaves behind RETRACTION FIBERS - which are the superglue form where the lamellipodia attached and small blebs of plasma membrane that trail behind. Eventually these release and merge (mostly) back into the cell's membrane and cytoplasm. After the retraction fiber releases, there will still be traces of superglue and membrane left - MICROEXUDATES.
As the cell moves, it "drags" the Nucleus (which causes the bulge) using ATP ONLY in the lamellipodia. (The cell doesn't waste ATP by forming and contracting "muscles" in the part of the cell around the trailing Nucleus.)
posted by Ari at 9:55 PM
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