Biology Notes

Essay by kaytg17College, UndergraduateA+, October 2009

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19/25/09•CytoskeletonoMaintains cell shape and provides supportoGives cells mechanisms for movementoSets up tracks for motor proteins to carry things in the cello3 types of components:1. Microfilaments (7 nanometers):a. Made of proteins such as actin and myosinb. May exist as a single fiberc. May be in a bundled. May form a large networke. Important for cell contractionsf. Give the plasma membrane its shapeg. Involved with cytoplasmic streamingi. Making the cytoplasm move and not stay stagnanth. Important for formation of pseudopodsi. Allow for the movement of smaller eukaryotesi. Important for bringing things into the cellj. Important for cell divisionk. Form microvilli2. Intermediate Filaments (8-12 nanometers)a. Found in multicellular organismsb. Form rope-like assemblagesc. Stabilize cell structured. Important for resisting tensione. Form nuclear laminaf. Hold organelles and nucleus in place3. Microtubules (Up to 25 nanometers)a. Hollow cylinders, made of tubulin proteinb. Provide rigid, interskeletal frameworkc. Act as a track for motor proteinsd. Motor proteins associate with tubulini.

Dynein: Moves a vesicle towards the negative end (interior)ii. Kinesin: Moves a vesicle towards the positive end (periforate)e. Associated with locomotion appendagesf. Help form the cilia and flagellai.9 on outside, 2 on insideg. Important for forming centriolesi. Centriole: Center of the cell during cell division. Helps move the chromosomes during cell division.

9/30/09•Cell Wall (Plant Cells)oMade of celluloseoComplex polysaccharides associated with proteinsoInsulates plasma membrane to prevent rupture==>Protects against turgor pressure•Turgor Pressure: Internal pressure exerted on the cell membrane•Extracellular Matrix (ECM)oComposed of fibrous proteins (collagen, elastic fibers)==>Allow for rigidnessoGlycoproteinsoIt holds cells together to form tissuesoIt contributes to the physical properties of the tissue==>Connective Tissue: Cells associated with the ECM•Bone•BloodoFilters material that passes between cellsoOrients cell movement==>Releases chemical signalsoEmbryonic developmentCh. 5•Cell membranes are bilayered and dynamicoDynamic: Membrane is continuously forming, it can move around, and it can fuse with other membranes•Fluid Mosaic ModeloInterior of membrane is fluid, allowing some...