Bio2 Exam 1 Flashcards
cytoplasm
In eukaryotic cells, the cytoplasm is that part of the cell between the cell membrane and the nuclear envelope. It is the jelly-like substance in a cell that contains the cytosol, organelles, and inclusions, but not including the nucleus. In fact, the cytoplasm and the nucleus make up the protoplasm of a eukaryotic cell.
P Face and E Face
E face is the tail view/side of the phospholipid bilayer that faces the extracellular material. The P face is the tail view/side of the phospholipid bilayer that faces the protoplasm.
Integral Proteins
Integral membrane proteins contain one or more hydrophobic regions that are embedded within the lipid bilayer.
Peripheral Proteins
Peripheral membrane proteins are too hydrophilic to penetrate into the membrane but are attached to the membrane by electrostatic and hydrogen bonds that link them to adjacent membrane proteins or to phospholipid head groups.
Lipid Anchored Proteins
Lipid-anchored proteins are hydrophilic and do not penetrate into the membrane; they are covalently bound to lipid molecules that are embedded in the lipid bilayer. Proteins on the inner surface of the membrane are usually anchored by either a fatty acid or an isoprenyl group. On the outer membrane surface, the most common lipid anchor is glycosylphosphatidylinositol (GPI). (Becker 7-19)
Extra Cellular Matrix
Tissues are not made up solely of cells. A substantial part of their volume is extracellular space, which is largely filled by an intricate network of macromolecules constituting the extracellular matrix. This matrix is composed of a variety of proteins and polysaccharides that are secreted locally and assembled into an organized meshwork in close association with the surface of the cell that produced them.
What are the three major structural elements of the cytoskeleton?
Microtubules, Microfilaments, Intermediate Filaments.
Microtubules
Made of tubulin, form a hollow cylinder that has polar ends, largest of tubules, makes the axoneme of flagella and cilia, 25nm in diameter. Provide track to move vesicles.
Microfilament
made of actin, solid, 5-9nm in diameter, polar ends, assembly proceeds more readily from one end and disassembly more readily from another. makes cleavage furrow that separates cells during mitosis.
How is actin made?
G-actin (globular) polymerizes into long strands of F-actin (filamentous).
Intermediate Filaments
found in cells of multi-cellular organisms only, 8-12nm in diameter, varying protein composition
Desmosomes
Spot Junctions (with IF)
Adherens Junction
belt junctions (with MF).
what is the function of gap junctions? What protein are they made from?
made from the protein called connexons. Allows passage of small molecules and ions (for signaling & nutrition). It’s a small gap between cells, 2-4nm. It forms a gated channel or pore.
What protein makes the “tight junction” and what is the junction’s function?
Made by claudins. Provides water-tight seal between cells; divides membrane in one cell into regions. It forms a fusion of ridges of protein in membrane.
what are the structural features, protein and function of adhesive, or anchoring, junctions.
Made from protein called cadherins, they add strength and are used for larger gaps between cells (25-30nm). They are classified by shape (spot or belt) and type of filament (IF or MF). IF = desmosomes. MF = adherens junction.
Dynein vs kinesin
both motor molecules. Dynein carries things into the MTOC (centrosome) and Kinesin carries things out (to the Korners).
Gap Junction: what are they made from, their function and size?
connexins make the connexon which is a gated channel used for transport. Small gap between cells, 2-4nm
Tight Junction: what are they made from, their function and size?
fusion of ridges of protein, form tight seal. Made from claudins. Function: structure.
Adhesive Junctions: what are they made from, their function and size?
Intracellular plaques with filaments, made from cadherins. Larger gap (25-35nm). Function: strength
Plaques used in cell to cell junction: what are the shapes and names, and what sort of filament do they attach to?
- spot, IF, desmosomes
2. belt, MF, adherens
what is the function of hemi-desmosomes?
Cell-basal lamina adhesion.
