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Cell Bio Exam 3
Cellular Biology USD Fall 2018 Dr. Karen Koster
| Question | Answer |
|---|---|
| Where are V-class proton pumps found in plants, yeast, and fungi? | vacuolar membranes |
| Where are V-class proton pumps found in animal cells? | Endosomal and lysosmal membranes |
| Where are V-class proton pumps found in kidney tubule cells? | Plasma Membrane |
| What do Proton-ATPase and V-type pumps do? | They pump H+ out of cytosol and into organelles and vesicles |
| What does the movement of H+ protons into organelles and vesicles do? | regulates cytosolic pH, can acidify vesicles, and can affect membrane potential |
| What are F-type ATPase similar to? | structure of V-type ATPase |
| What do F-type Atpase move? | H+ |
| What does the F in F-type ATPase stand for? | Factor |
| How do F-type ATPase move protons? | they move protons by facilitated diffusion or actively using ATP |
| How does F-type ATPase use fac. diff? | energy released by diffusion is used to make ATP |
| Where are f-type ATPase found? | bacteria, mitochondria, and chloroplasts |
| What does ABC-Type ATPase stand for? | ATP-binding cassette |
| What are ABC-type ATPase? | large superfamily of related transporters in prokaryotes and eukaryotes |
| What are ABC-type ATPase made of? | usually 4 separate polypeptides, sometimes 1 large proteins |
| What ar the 4 domains of ABC-type ATPase? | 2 hydrophobic and 2 peripheral |
| What are the 2 hydorphobic domains of ABC-type ATPase made of? | each made of 6 transmembrane helices |
| What are the 2 peripheral domains of ABC-type ATPase for? | they biind and hydrolyze ATP |
| Where are ABC-type ATPase found? | plasma membrane and organelle membranes |
| What do ABC-type ATPase transport? | numerous small solutes such as lipids, sugars, peptides, amino acids |
| How does ABC-type ATPase use energy? | they bind ATP in conserved domain and then hydrolyze it to transport energy |
| How does indirect active transport work? | uses solutes (usually ions |
| What is chemiosmosis? | free energy released as molecules diffuse down their gradient can be used to do work |
| What do animal cells usually use to drive transport across plasma membranes? | Na+ gradients |
| What do other cells usually use to drive transport across membranes? | proton gradients |
| What is cotransport? | transport of two solutes symport or antiport |
| What is the endomembrane system? | a system of membrane compartents linked together by ontogeny and function |
| In simple terms, what is the endomembrane system? | membranes made in the ER, become golgi, plasma membrane, nuclear envelope, and lysosomes |
| What is not part of the endomembrane system? | proteosomes |
| What are the two types of endoplasmic reticulum? | smooth and rough |
| What are the 4 functions of the smooth ER? | steroid biosynthesis, assembly of most glycerolipids, calcium storage, and drug detoxification |
| What are the spaces of the ER called? | lumen |
| What are the membrane folds f the ER called? | cisternae |
| Which type of ER lacks ribosomes? | smooth ER |
| What is the shape of cisternae of the smooth ER? | tubular |
| What does the smooth ER store? | calcium and triacyclglycerols |
| What is the function of the rough ER? | biosynthesis and processing of proteins for EMS and secretion |
| How does the rough ER structure differ from the smooth ER? | rough ER has ribosomes and smooth doesn't, rough ER has flattened cisternae and smooth has tubular, smooth stores calcium and triacylglyceros and rough accumulates secretory proteins |
| Where are proteins for EMS translated? | on the rough ER |
| What guides polypeptide into membrane? | signal sequences on the N-terminus |
| What MAY occurin the ER | some glycosylation |
| Where does glycosylation of membrane roteins and lipids begin? | ER |
| What modification are done in the ER? (3) | Biosynthesis of core oligosaccharides, processing of core ologosaccharides, and removal of misfolded proteins |
| Where does biosynthesis of core ologsaccharides occur? | ER, protein |
| Where does atatchment of N-acetylgalactosamine occur? | Golgi, protein |
| Where does processing of core ologosaccharides occur? | ER, protein |
| Where does phosphorylation of lysosomal proteins occur? | Golgi, protein |
| Where does removal of misfolded proteins occur? | ER, protein |
| Where does removal of mannose occur? | Golgi, protein |
| Where does attachment of N-acetylglucosamine? | Golgi, protein |
| Where does addtion of galactose occur? | Golgi, protein |
| Where does addition of sialic acid occur? | Golgi, protein |
| Where does attachment of sulfate to tyrosine occur? | Golgi, protein |
| What varies in different golgi cisternae? | different enzymes in different cisternae, and idfferent things happen to different sugars as they move down the apparatus |
| What type of golgi faces ER? | cis |
| What type of golgi faces the plasma membrane? | trans |
| What is the first function of the golgi apparatus? | chemical modification of proteins and lipids |
| What are the three ways the golgi apparatus modifies proteins and lipids? | glycosylation, phosphorylation, and methylation |
| What is the shape of cisternae in the golgi apparatus? | flattened disks |
| what is the second function of the golgi apparatus? | sorting proteins and targeting to specific destinations |
| What is the target for proteins to the ER? | KDEL amino acid sequences |
| What is the target for proteins to the lysosome? | mannose-6-phosphate |
| What is the target for proteins for secretion? | extracellular sequences of aa |
| What may trap integral membrane proteins as they move through the EMS? | increasing membrane thickness |
| How does the golgi apparatus recognize these amino acid/sugar sequences? | the golgi recognizes the shape, structure, and properties of the amino acid sequences |
| Where do sugar polymers first assemble? | cytosol |
| What surface of the EMS are sugars added to proteins and further modified? | lumen surface |
| What acts as the carrier of oligosaccharides for protein glycosylation? | dolichol phosphate |
| Where does core oligosaccharide synthesis begin? | cytoplasm |
| What is the beginning step of oligosaccharide sythesis? | N-acetyl-glucosamine and mannose are added to dolichol phosphate |
| Where are N-acetyl-glucosamine added to oligosaccharides? | cytosol of ER |
| What does flippase catalyze? | the translocation of oligosaccharides from the cytosol of the ER to the lumen |
| What is flippase? | a phospholipid translocator |
| Where does completion of hte core oligosaccharide occur? | in the lumen of the ER |
| Wher are mannose and gluocse units added to oligosaccharides? | in the lumen of the ER |
| How does the targeting protein to lysosomes using mannose-6-phosphate work? | the lysosomal enzyme is snthesized and the carb is added in the ER, mannose is phosphorylated and sequential activity of two enzymes in teh Golgi, Mannose-6-phosphate binds to receptor and tagged enzyme packaged in transport vesicle, Low pH in endosome ca |
| What is an endosome? | organelles formed by fusion of vesicles from golgi and endocytotic vesicles from plasma membrane |
| How does endosomes mature? | addition of more vesicles/enzymes from the golgi |
| What is a late endosome? | more acidic than early endosomes |
| What does a late endosome develop into? | lysosome |
| When does a late endosome develop into a lysosome? | when they get more enzymes from the golgi |
| Lysosomes have low pH, how do they become acidic? | with V-type ATPase pumps because vesicle transport |
| What is a lysosome? | organelle that digests biological macromolecules |
| What is the purpose of vacuoles? | similar function to lysosomes, but in plants |
| What is the plasma membrane made of and where does it come from? | most lipids and protein constituents are derived from the ER via the Golgi |
| What is the nuclear envelope? | outer membrane that is continuous with the ER |
| How is nuclear envelope formed? | by fusion of the ER vesicles after mitosis |
| Where does the nuclear envelope get its lipids and proteins? | from the ER/Golgi |
| What is trafficking in the EMS? | directed movement of vesicles among compartments |
| What is the movement of transition vesicles? | ER to golgi |
| What is the movement of shuttle vesicles? | between golgi stacks |
| What are the two movements of shuttle vesicles? | anterograde and retrograde |
| What is anterograde shuttle vesicle movement? | cis to medial to trans golgi |
| What is retrograde shuttle vesicle movement? | trans to cis golgi to ER |
| What is the movement of secretory vesicles? | trans golgi to plasma membrane |
| What is the movement of endosomal vesicles? | trans golgi to endosomes to lysosomes |
| What is hte movement of endocytotic vesicles? | plasma membrane to endosome to lysosome |
| What are coated vesicles? | membranes surrounded by a protein coat |
| What does the protein coat do for coated vesicles? | gives them shape and helps target vesicle to the correct site |
| What is the first type of protein coat for coated vesicles? | clathrin |
| What is clathrin? | multimeric protein forms interlocking polygonal cages |
| Where do clathrin- coated vesicles form? | at the trans-golgi and plasma membrane |
| Where do clathrin-coated vesicles go? | to the endosomes |
| what is a triskelion subunit? | 6 polypeptic multimeric clathrin coated protein |
| what link clatherin coats to membranes? | adaptor proteins |
| What pinches the clathrin cage off membranes? | dynamin protein (GTPase) |
| wat are clathrin protein coats called when they come off the plasma membrane via endocytosis? | coated pits |
| what are the two options for clathrin coats? | dissociate or stay |
| When do clathrin coats dissociate? | after budding of vesicle |
| When do clathrin coats have to stay until? | fusion with target |
| What is the SNARE hypothesis? | rteins protruding from vesicle surface and target membrane link and pull the two membranes together |
| What is recognition in the SNARE hypothesis mediated by? | multimeric tethering complexes of proteins on target membranes |
| Explain the process of vesicle binding and fusion | recognition is mediated by multimeric tethering complexes of proteins on target membranes. These the nbind the incoming vesicle and pull it to the membrane surface and the SNAREs link |
| What is the structure before vesicle fusion? | a vesicle with Rab GTPase and a v-SNARE protiein hanging off of it and the target membrane has a coiled tethering complex, a multisubunit tethering complex, and a t-SNARE |
| What is the first step in vesicle fusion? | vesicle is recognized and bound by the memrante anchored thethering proteins (coiled and multisubunit) |
| What is the second step in vesicle fusion? | Rab GTPase bound to the vesicle stimulates association of v-SNARE with the t-SNARE |
| What is the third step in vesicle fusion? | Membrane fusion is promoted by the interaction of v-SNARE and t-SNARE |
| What is the last step in vesicle fusion? | NSF and SNAPs binding promotes dissociation of hte SNARE complex |
| What does v-SNARE stand for? | vesicle SNAP receptor |
| What does t-SNARE stand for? | target SNAP receptor |
| What does SNAP stand for? | soluble NSF attachment protein |
| What is NSF? | N-ethylmaleimide sensitive factor |
| What does RAB GTPase do? | it helps the SNARES connect |
| What is the first step in receptor-mediated endocytosis? | ligands bind to receptors in the plasma membrane and triggers the formation of clathrin-coated pits |
| What happens after the clathirn-coated pits are formed? | vesicles fuse to early endosomes and clathrin is released |
| What happens after clathrin is released? | contents are sorted |
| Explain clathrin-dependent receptor-mediated endocytosis | yolk particles accumulate in a coated pit with a clathrin coat on inner surface, as more clathrin is added a deeper pit forms and traps the additional particles of yolk, addition of curvature leads to formation of vesicle |
| What is secretion/exocytosis? | fusion of vesicle with plasma membrane and release of contents out of cell |
| What are the 2 types of secretion/exocytosis? | constitutive and regulated |
| What is constitutive secretion/exocytosis? | continuous |
| What are examples of things that undergo constitutive secretion/exocytosis? | mucus, glycoproteins for ECM |
| What is regulated secretion/exocytosis? | secretion/exocytosis that occurs in response to a signal |
| How is the type of secretion/exocytosis decided? | depends on targeting sequences of amino acids |
| Explain exocytosis/secretion | secretory vesicle approaches pm, the membranes fuse, the plasma membrane ruptures and the contents of the vesicle are discharged outside of the cell |
| What happens to the secretory vesicles after exocytosis/secretion? | the vesicle embrane becomes integrated into the plasma membrane |
| vesicle movement occurs along _________. | Cytoskeleton |
| What does vesicle moment use? | motor proteins |
| What do vesicles move along? | microtubules and actin microfilaments |
| What kinds of things undergo regulated secretion/exocytosis? | neurotransmitters and insulin |
| What is the nuclear envelope? | two concentric, fused membranes that separate transcription from translation |
| What are the components of the nuclear envelope? | outer membrane, inner membrane, pore complex |
| What is the outer membrane? | continuous with ER and has ribosomes |
| What is the inner membrane? | lacks ribosomes |
| What is the nuclear lamina? | network of lamin proteins linked to the membrane proteins |
| Where is the nuclear lamina found? | in the inner membrane |
| What is a lamin? | an intermediate filament (cytoskeleton) |
| WWhat is the function of the lamin? | structural support for the envelope |
| How do lamin help link to cytoskeleton in the cytoplasm? | via pores |
| What is the measurement related to nuclear lamina? | 10-40 nm thick |
| What gives structural support to the envelope and the nucleus? | nuclear lamina nad the matrix |
| What is the nuclear matrix? | fibrous structure that helps organize chromatin |
| what does the lamina connect to? | nuclear matrix |
| What is the perinuclear space? | the region between the inner and outer envelopes |
| What are nuclear pores? | transporters in the nuclear nevelope |
| Where is the nuclear pore located? | where the inner and outer envelopes fuse in the nuclear envelope |
| What does the nuclear pore enable? | transport between the nucleopasm and cytoplasm |
| What is the nuclear pore complex? | large complex |
| What is the size of the nuclear pore complex? | 120 nm in diameter |
| What is the size of a nuclear pore channel? | 80 nm |
| How many different proteins make up the nuclear pore complex? | 50 different proteins |
| What are the different proteins called in the nuclear pore? | nucleoporins |
| What is the symetry of the nuclear pore complex? | octagonal |
| What is an annulus? | proteins lining rim of pore, bound to membrane of envelope |
| What regulates transport in the nuclear pore? | spokes and fibers of proteins extend into the channel and into the cytoplasm, nucleus |
| What does abundance of pore complexes vary with? | activity of the cell in transcriptions |
| What is the general rule for abundance of pore complexes? | there are more nuclear pore complexes in closer proximity as the activity of the cell increases |
| What are the two types of transport through the nuclear pore complex? | unregulated and regulated |
| What size of molecules can diffuse freely through the NPC? | 9-10 nm |
| Why can smaller molecules diffuse faster in the NPC? | there is little to no electrical resistance, so ions can go through freely |
| What are large molecules regulated by in transport through the NPC? | regulated transport |
| how or molecules recognized by regulated transport via the NPC? | the nuclear localization signal which is 8-30 amino acids with special sequence |
| What does the NLS bind to? | importin, a carrier protein |
| How does importin bind? | it binds to fibers extending from the pore and moves along into the pore |
| What is found inside the nucleus? | Ran |
| What is Ran? | GTP-binding protein with bound GTP |
| How does protein cargo get released in regulated transport via NPC? | Ran (GTP binding protein) binds to importin and cargo is released |
| How does importin get out of the NPC? | ran-GTP-importin moves out |
| How is importin released? | GTP is hydrolyzed |
| What is the last step of import through regulated transport via the NPC? | ran-GDP re-enters nucleus and trades GDP for GTP |
| What is export through regulated transport via NPC cargo? | RNA boudn to adaptor protein with NES |
| What is NES? | nuclear export signal |
| How does cargo bind to export out of the NPC? | Ran-GTP binds to exportin which enables cargo to bind |
| How does the Ran_GTP-exportin/cargo move through pore? | the complex is recognized by the NPC |
| What happens when the complex moves out to cytoplasm during export via regulated transport from NPC? | GTP is hydrolyzed and the complex dissociates |
| HOw does more unsaturated fats affect Tm? | more unsaturated means more fluid |
| How does more saturated fats affect Tm? | more saturated means less fluid |
| How does number of carbon atoms affect Tm? | more carbon atoms means less fluid |
| How does number of carbon double bonds affect Tm? | more double bonds means more fluid |
| Why do more saturated fatty acids mean less fluid? | the saturated fatty acids are able to pack together more tightly |
| In biological membranes, what regulates fluidity and phase transitions? | lipid compositions |
| How do sterols affect fluidity? | sterols increase fluid at lower temps because they interupt the lipids ability to pack together tightly |
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