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169 Cards in this Set
- Front
- Back
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fibrous protein that forms the intermediate filaments
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tubulin
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subunit in microtubules
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tubulin
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subunit in actin filaments
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actin
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provide cells with mechanical strength
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intermediate filaments
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main function is to enable cells to withstand mechanical stress that occurs when cells are stretched
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intermediate filaments
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made of actin, microtubules, intermediate filaments
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cytoskeleton
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fibrous network all over the cell
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cytoskeleton
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toughest and most durable filament
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intermediate
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anchored to plasma membrane at cell-cell junctions such as desmosomes
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intermediate
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found within nucleus in a mesh of filaments known as the nuclear lamina
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intermediate
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rope-like structures with N-terminal globular heads and C-terminal globular tain and a central elongated rod domain
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intermediate
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has an alpha helical region that enable pairs of intermediate filaments to form stable dimers by wrapping around each other
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rod domain
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abundant on the axons of nerve cells, muscle cells, and epithelial cells
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intermediate
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class of intermediate filament found in epithelial cells
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keratin
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class of intermediate filament found in connective tissue cells, muscle cells, and supporting cells of nervous system
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vimentin and vimentin related filaments
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class of intermediate filaments found in nerve cells
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neurofilaments
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class of intermediate filaments that strengthen nuclear membrane
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nuclear lamins
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have crucial organizing role
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microtubules
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long, stiff hollow tubes that can disassemble in one location and reassemble in another
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microtubules
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grow out from one centrosome and extend toward cell preiphery
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microtubule
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creates a system of tracks within cell that move vesicles and organelles
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microtubules
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segregates chromosomes equally into daughter cells
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mitotic spindle
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build from subunites called tubulin that have an alpha-tubulin and a beta-tubulin bound tightly together
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microtubules
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stack together to make hollow cylindrical microtubule which is made of 13 parallel protofilaments
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tubulin dimers
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plus end of microtubule
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Beta-tubulin
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minus end of microtubule
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alpha-tubulin
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organizes the array of microtubules that radiates outward from it through the cytoplasm
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centrosome
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contains hundres of ring shaped structures (y-tubulin) that form nucleation site for growth of one microtubule
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centrosome
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add to the y-tubulin ring in specific orientation with the minus end embedded in the centrosome
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alphabeta-tubulin
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suddenly undergoes a transition that causes it to shrink rapidly inward losing subunits from free end
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microtubules
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can shrink partially, grow suddenly again, or disappear altogether
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dynamic instability
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contain tightly bound GTP molecule that is hydrolyzed to GDP
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tubulin dimers
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add to end of microtubule faster than GTP can be hydrolyzed which makes the end composed entirely of GTP-tubulin forming a GTP cap which are more tightly bound causing continuous growth
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tubulin molecules
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point the same direction in axon with plus end toward axon terminal
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microtubule
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mitochondria and smaller membrane-enclosed organelles have small, jerky movements known as...
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saltatory movement
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motor protein that moves toward plus end in microtubule
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kinesin
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motor protein that moves toward minus end in microtubule
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dyneins
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have two globular ATP-binding heads and a tail
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kinesins and dyneins
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enzymes with ATP-hydrolyzing activity that cause conformational changes in the head that enable it to move along microtubule by cycle of binding and release
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heads of kinesins and dyneins
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depend on microtubules for alignment and positioning
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ER and Golgi
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attach to outside of ER membrane and pull outward along microtubule
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kinesins
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pull golgi inward toward cell center along microtubules
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dyneins
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stable microtubules
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cilia and flagella
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hairlike structures, covered by plasma membranes; contain a core of stable microtubules
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cilia
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primary function is to move fluid over surface of a cell, or to propel single cells through a fluid
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cilia
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propel sperm and many protozoa, very long, designed to move entire cell
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flagella
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generates the bending motion of the core of motor proteins
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ciliary dynein
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essential for movements involving cell surface
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actin
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unstable
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actin
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stable structure is contractile apparatus of the muscle
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actin
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on brush-border cells lining the intestin
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microvilli
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contractile bundles in cytoplasm in two during division
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actin
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contractile ring pinches cytoplasm in two during division
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actin
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threads of a twisted chain of identical globular filaments that are polar
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actin
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thinner, flexible, shorter but found in cross-linked or bundled networks
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actin
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add monomers at either end but faster on plus end
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actin and microtubule
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monomers carry tightly bound ATP which hydrolyze to ADP
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actin
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when reduced it decreases stability of polymer
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actin and microtubule
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bind to actin monomers in cytosol preventing them from adding to ends of actin filaments
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thymosin and profiln
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create meshwork that supports the outersurface of the cell
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cell cortex
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cell pushes out protrusions at its fron
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actin movements
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protrusions adhere to surface over which the cell is crawling
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actin movements
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cell drags itself forward by traction on anchorage points
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actin movements
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thin, sheetlike, extended by fibroblast, contain dense meshwork of actin
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lamellipodia
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stiff protrusions extended
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filopodia
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promote formation of branched actin filaments
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ARPs
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transmembrane proteins that adhere to molecules
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integrins
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motor protein in actin
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myosin
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monomeric GTP-binding proteins that cycle between an active GTP state and an inactive GTP-bound state
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Rho protein family
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two ATPase heads and long rodlike tail
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myosin II
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molecule is a dimer composed of a pair of identical myosin molecules held together by their tains
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myosin II
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they form clusters of coiled-coil tails called myosin filaments
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myosin II
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double headed arrow with two heads pointing in opposite direction
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myosin II
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one head binds to actin and moves it one way and the other head binds to a different actin filament and moves it the opposite way
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myosin II
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contractile elements of the muscle cell
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myofibrils
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chain of identical tiny contractile units
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sarcomeres
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contraction is caused by simultaneous shortening of all the _______ which in turn is caused by the actin filaments sliding past each other
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sarcomeres
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walks along the actin hydrolyzing ATP to cause conformational changes of attachment and detachment
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myosin head
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contains high levels of Calcium ion
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sarcoplasmic reticulum
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electrical exitation releases.....
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calcium ion
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interacts with tropomyosin that overlaps seven actin monomers and prevents myosin heads from associating with actin filament
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calcium ion
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has a calcium ion sensitive protein and is associate with the end of tropomyosis molecule
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troponin
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abundant calcium ion pumps in...
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sarcoplasmic reticulum
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triggered by adrenaline, serotonin, prostaglandins, etc.
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smooth muscle
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membrane enclosed organelles
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ER, golgi apparatus, lysosome, endosome, peroxisomes, mitochondria, chloroplasts
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site of steroid hormone synthesis
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smooth ER
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sequesters Calcium ion from cytosol and release and reuptake from ER of Calcium ion is a rapid response to many extracellular signals
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smooth ER
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ribosomes attached to ER surface synthesize proteins
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rough ER
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degrade worn-out organelles, macromolecules and particles taken into the cell by endocytosis
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lysosome
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receives proteins and lipids from the ER, modifies them, then takes them to other designations
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golgi apparatus
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sort ingested molecules and recycle some back to plasma membrane
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endosome
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break down lipids and destroy toxic molecules
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peroxisome
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site of oxidative phosphorylation and produces ATP
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mitochondria
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site of photosynthesis and produces ATP
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chloroplast
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attached by the cytoskeleton especially to microtubules
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ER, golgi, mitochondria, and chloroplast
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have small size and high surface-to-volume ratio or which helps the plasma membrane sustain all the vital functions
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bacteria
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membrane grows inside the cell
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membrane invagination
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directs proteins to the organelle in which it is required
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sorting signal
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proteins going from cytosol to nucleus are transported by....
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nuclear pores
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proteins moving from cytosol to ER, mitochondria, chloroplasts, peroxisomes are transported by...
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protein translocators
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proteins moving from ER onward are transported by
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transport vesicle
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removed from finished protein once the sorting has been executed
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signal sequence
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cross linking protein
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plectin
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proteins are all made where
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out in the cytoplasm
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proteins from where are encoded by genes in the nucleus and are imported from the cytosol
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mitochondria and chloroplast
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have signal sequence on their N-terminus that allows proteins to enter
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mitochondria and chloroplast
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protein must unfold before entering the...
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mitochondria
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proteins inside organelles that pull protein across two membranes and refold the protein once its inside
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chaperone
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transported individually to these organelles by water-soluble lipid-carrying proteins
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phospholipids
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two kinds of proteins that are transferred from cytosol to ER
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water-soluble proteins and prospective transmembrane proteins
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internal engulfing of a structure
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autophagy
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attached to cytosolic side of the ER membrane
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membrane-bound ribosomes
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unattached to any membrane and make other proteins encoded by nuclear DNA
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free ribosomes
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binds to ER signal sequence when exposed on the ribosome
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signal-recognition particle
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embedded in ER membrane and is a receptor for the signal recognition particle
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SRP receptor
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initiates translocation
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N-terminal sequence
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halts translocation
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stop transfer sequences
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internal signal sequence; starts protein transfer
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start transfer sequence
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go outward from ER to plasma membrane and inward from plasma membrane to lysosomes
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transport vesicles
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start with biosynthesis of proteins on ER and entry into ER, lead through the golgi to cell surface. a golgi side branch leads off through endosomes to lysosome
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outward secretory pathways
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responsible for the ingestion and degradation of extracellular molecules; moves materials from the plasma membrane through endosomes to lysosomes
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inward endocytic pathway
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vesicles with a distinctive protein coat
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coated-vesicles
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when does a vesicle shed its coat, allowing its membrane to interact directly with the membrane to which it will fuse?
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after budding
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purpose of this is to shape the membrane into a bud, and help capture molecules for onward transport
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coat
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bud from golgi on outward secretory pathway and from plasma membrane on inward endocytic pathway
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clathrin coated vesicles
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small GTP-binding protein that assembles as a ring around the neck of each deeply invaginated coated pit and causes the ring to constrict pinching off vesicle from membrane
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dynamin
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secure clathrin coat to the vesicle membrane and help select cargo molecules for transport
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adaptins
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transport molecules between ER and Golgi and from one part of the golgi to another
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COP-coated vesicles
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transmembrane proteins
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SNARES
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surface of target membrane transmembrane protein
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t-SNARES
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surface of vesicle membrane transmembrane protein
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v-SNARES
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catalyzed by specialized proteins that assemble at a fusion site to form a fusion complex
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membrane fusions
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play a central role in fusion process because after v-SNARES pair with t-SNARES, they wrap around each other and act like a winch that pulls the two membranes into close proximity
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SNARE
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fuse with plasma membrane
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exocytosis
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proteins that enter the ER lumen or membrane are converted to glycoproteins in the ER by the covalent attachment of short oligosaccharide chains
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glycosylation
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small GTP-binding protein that assembles as a ring around the neck of each deeply invaginated coated pit and causes the ring to constrict pinching off vesicle from membrane
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dynamin
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secure clathrin coat to the vesicle membrane and help select cargo molecules for transport
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adaptins
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transport molecules between ER and Golgi and from one part of the golgi to another
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COP-coated vesicles
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transmembrane proteins
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SNARES
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surface of target membrane transmembrane protein
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t-SNARES
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surface of vesicle membrane transmembrane protein
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v-SNARES
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catalyzed by specialized proteins that assemble at a fusion site to form a fusion complex
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membrane fusions
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play a central role in fusion process because after v-SNARES pair with t-SNARES, they wrap around each other and act like a winch that pulls the two membranes into close proximity
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SNARE
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fuse with plasma membrane
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exocytosis
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proteins that enter the ER lumen or membrane are converted to glycoproteins in the ER by the covalent attachment of short oligosaccharide chains
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glycosylation
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protect the protein from degradation, hold it in the ER until it is properly folded, or help guide it to appropriate organelle by serving as a transport signal
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oligosaccharides
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1st step in series of modifications in ER
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addition of 14-sugar oligosaccharides
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proteins that are made in ER and are destined to function there..they are retained by C-terminal sequence of four amino acids called....
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ER retention signal
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these pathways stream vesicles from trans golgi and fuse with plasma membrane and operates continuously..supplies newly made lipids and proteins to plasma membrane
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constitutive exocytosis pathways
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this pathway only operates in cells specialized for secretion
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regulated exocytosis pathway
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these cells produce large quantities of hormones, mucus, and digestive enzymes
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secretory cells
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hormones, digestive enzymes and mucus are stored in....
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secretory vesicles
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what pathway secretes proteins but does not aggregate them and automaticaly carries them to the plasma membrane by transport vesicles?
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constitutive pathways
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involves ingestion of fluid via small vesicles
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pinocytosis
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ingestion of large particles such as microorganisms and cell debris via large vesicles called phagosomes
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phagocytosis
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defend us against infection by ingesting invading microorganisms
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phagocytic cells
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sheetlike projections of plasma membrane
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pseudopods
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when pseudopods fuse at tip
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phagosome
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selective concentrating mechanism that increases efficiency of internalization of particular macromolecules
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receptor mediated endocytosis
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insoluble
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cholesterol
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dissociates in acidic endosome from its receptor and is delivered to lysosome where it is broken down and available for new membrane synthesis
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low-density lipoproteins
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kept acidic by ATP driven proton pump
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interior of endosome
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return to plasma membrane from which they came
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receptors
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can travel to lysosomes where they are degraded but not always
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receptors
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proceed to different domain of plasma membrane
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receptors
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transferring cargo from one extracellular space to another is....
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transcytosis
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membranous sacs of hydrolytic enzymes that carry out the controlled intracellular digestion of both extracellular materials and worn-out organelles
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lysosome
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degrade proteins, nucleic acids, oligosaccharides, and phospholipids
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lysosome
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has ATP driven proton pump along with the endosomes in its membrane
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lysosome
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