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Definition
| Amphipathic proteins with a stretch of nonpolar amino acids; they can integrate into the lipid bilayer; as measured by mass, they are equal to the phospholipids in the membrane |
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Definition
| Some proteins are inserted into the lipid bilayer, making the membrane a fluid, dynamic mosaic of phospholipids and proteins |
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Term
| Freeze-fracture electron microscopy |
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Definition
Used to examine the membrane; it supports the fluid-mosaic model. The process:
-Freeze cell
-Strike frozen cell with a knife
-Fracture splits the lipid bilayer (half still on the cell and half on the frozen part)
-The cell surface can then be scanned, which reveals that the middle of the membrane contains pits and mounds; the exterior contains only mounds |
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Definition
| Used to remove proteins from a cell membrane by insertion into the membrane. Their hydrophobic tails interact with the phospholipids and the hydrophobic parts of membrane proteins to form complexes |
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Term
| Isolating membrane proteins |
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Definition
| 1. Detergents break up plasma membranes by coating hydrophobic portions of membrane proteins and phospholipids |
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Term
| How can membrane proteins affect ions and molecules? |
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Definition
| They form membrane channels, transporters, and pumps that affect membrane permeability |
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Term
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Definition
| Ions move in response to an electrochemical gradient. |
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Term
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Definition
| Solutes move from an area of higher concentration to an area of lower concentration. If positive ions move across, that side becomes positive, repelling more positive ions |
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Term
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Definition
| Forms a channel permeable to cations but not anions; the interior of the channel is hydrophilic and the exterior hydrophobic, which allows it to interact with phospholipid tails |
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Term
| Facilitated diffusion/passive transport |
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Definition
| Ions and large molecules traveling down the electrochemical gradient through transport proteins. This requires no energy and decreases the charge and concentration differences between the cell interior and exterior |
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Term
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Definition
| Ion carriers that bind to an ion on one side of the membrane, diffuse across the membrane as they react with the ion, and release it on the other side; this is also a type of facilitated transport that takes no energy |
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Term
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Definition
The transport protein that increases membrane permeability to glucose
1. The binding side of GLUT-1 faces outside the cell
2. Glucose binds to GLUT-1
3. A conformational change results, transporting glucose to the interior
4. Glucose is released inside the cell
It takes no energy as it is still down the concentration gradient, and so still decreases the difference between the inside and outside of the cell. |
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Term
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Definition
| Uses ATP to transport molecules against the electrochemical gradient. Increases the difference between the inside and outside of the cell |
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Term
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Definition
Uses ATP to transport Na+ and K+
1. Three sodium ions enter the enzyme from within the cell
2. ATP phosphorolates the enzyme, causing it to pump the Na+ out of the cell
3. Two potassium ions are pumped into the cell by the now-unphosphorolated enzyme |
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Term
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Definition
| Provides structural support for the cell; it is dynamic in that it changes to alter the cell's shape, transport materials in the cell, or move the cell itself |
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Term
| Three cytoskeletal elements |
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Definition
| Actin filaments (microfilaments), intermediate filaments, microtubules |
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Term
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Definition
| Grouped together in large bundles or dense networks that are usually found just inside the plasma membrane and help define the cell's shape by resisting tension. They also assist in motility by muscle contraction or cell crawling, cell division in animals, and movement of organelles and cytoplasm in plants, fungi, and animals. They are strands wound in a double helix. |
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Term
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Definition
| A motor protein whose head attaches to actin, causing the actin filament to slide and inducing movement. This causes movements like cell crawling, cytokinesis, and cytoplasmic streaming |
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Term
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Definition
| Actin-myosin interactions push the cytoplasm forward; actin polymerization creates pseudopodia |
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Term
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Definition
| Actin-myosin interaction split the membranes in two in the final step of cell division |
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Term
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Definition
| In plants, this helps things circumvent the large central vacuole, which often gets in the way |
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Term
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Definition
Provide structural support for the cell; they are defined by size rather than composition. They are made of fibers wound into thicker cables.
They maintain shape by resisting tension (pull) and anchor the nucleus and some organelles. |
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Term
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Definition
Large, hollow tubes made of alpha and beta tubulin dimers. They maintain cell shape by resisting compression (push), cause motility in a flagellum or cilium, move chromosomes during cell division, form the cell plate during plant cell division, move organelles, and help in the growth of plant cell walls.
Unlike the other two, microtubules are not involved in physical cell division but still move chromosomes. |
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Definition
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Definition
| Structure from which microtubules emanate in animal and fungi chromosome movement |
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Term
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Definition
| 9x3 structures of microtubules found in chromosomes |
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Term
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Definition
| Transport vesicles move through the cell via these tracks; this process requires ATP and kinesin |
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Definition
A motor protein which converts chemical energy into mechanical work.
It has a tail, which carries a vesicle, a stalk, and a head, which "walks" along a microtubule track with the help of ATP |
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Term
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Definition
| Long projections that move cells. |
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Term
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Definition
| Made of flagellin and rotate like a propeller |
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Term
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Definition
| Made of microtubules and wave back and forth |
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Term
| Construction of cilia and flagella |
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Definition
| Their axonemes have a complex 9+2 arrangement of microtubules connected by spokes and bridges (made of dynein) |
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Term
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Definition
| The hair-like structure that is the basis of flagella and cilia |
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Term
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Definition
| A motor protein that forms the arms between doublets and changes shape when ATP is hydrolyzed to walk up the molecule. When the dynein arms on just one side of the flagellum or cilium walk, the structure bends rather than elongating because of the restrictions of the spokes and bridges of the microtubule doublets |
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