Science is a Process, not an Object.

Advanced Honors Biology

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Intro to Enzyme Kinetics

Enzymes really are at the heart of how our bodies work. The brief definition is a "bio-catalyst." These are almost always proteins. They lower activation energy of a particular reaction and as such speed it up, both in the forward and backward direction. Almost all enzymes will be able to work either "backwards" or "forwards." Some are effectively one-directional because of large negative delta G0, for example involving ATP hydrolysis. But, even most of these can be reversed.
Enzyme function requires particular structures. Structures of proteins can be altered by the binding of other proteins or other smaller molecules, or the addition of a phosphate to the enzyme at a specific point, or the local pH or charge distribution…so, every step of enzyme function can be regulated.
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Cytoskeletal discussion

I have a little assignment for you. broken up by group. I want to discuss the cytoskeleton and it's applications when we next get together.
The cytoskeleton is often the worst represented of cellular structures. In the image above, microtubules (made of tubulin) are in green, microfilaments (actin) are in red. Intermediate filaments (Keratins) are not shown.
As the name implies, they are all involved in providing structure to cells. Microtubules are the largest in diameter and ALWAYS grow out from an MTOC (centriole). Microfilaments are the thinnest and can grow anywhere in the cell. Intermediate filaments are…well, intermediate. They also tend to be on the long axis of large cells and sort of make up "cross members" in cube shaped (cuboidal) cells.
They all have some superpower that allows them to be repurposed very broadly in cells and in multicellular organisms.
Two of them have "motor proteins" associated with them. Two can be assembled and disassembled rapidly from subunits. One is insanely stable under virtually all conditions.
For your assigned structure, identify its superpower (motor protein or insane stability), how it is used in a single cell (Some are used more than one way) and how it can be repurposed for other applications in single cells and in an organism.
Look forward to the discussion.
You can start with the wikipedia entry on cytoskeleton and go on from there. Don't go crazy on this. I want you to see how they can be used.


Ryan, Lucius, Ethan, Evan: Actin: This one has a really dramatic use in animals
Dolce, Mira, Clare, Bella: Tubulin: This one has many uses in the cell…
Andrea, Ha Ha, Miller: intermediate filaments. Also repurposed dramatically in animals.
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Transport Proteins

One of the main things a membrane has to be able to do is control what flows through it. Sometime, that's just opening a channel and letting the dissolved thing flow "down gradient." But, sometime the cell has to do active work to pump ions to one side or the other of a membrane.
Once that gradient is established, it can be used to do work…and in fact used in myriad ways you can hardly imagine. Since it is so important, we will spend some time on it.
By the way, the figure is a cartoon of a protein called "aquaporin." Guess what it transports. It's a fascinating protein. Think about how you can make a protein that allows water…and only water…to pass through.
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Lipids

While almost all the reactions in your body take place in, and even include interactions with, water, there are some that require a hydrophobic milieu. Moreover, you need something to keep the outside out, and the inside in…a membrane…which is made of something called lipids.
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