Term
| "What is the proportionality of lipids, proteins, and carbohydrates in MYELIN?" |
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Definition
| lipid >> protein >> carbohydrates. Lots of lipids for fast signal conduction |
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Term
| "What is the proportionality of lipids, proteins, and carbohydrates in RED BLOOD CELLS?" |
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Definition
| lipids = proteins >> carbohydrates |
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Term
| "What is the proportionality of lipids, proteins, and carbohydrates in the INNER MITOCHONDRIAL MEMBRANE?" |
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Definition
| "proteins >> lipids, NO carbohydrates. Lots of proteins for enzyme function and transport through the bilayer." |
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Term
| Describe the formation of an ester bond: |
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Definition
| R-OH + HOOC-R; example is glycerol reacting with a fatty acid |
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Term
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Definition
| A hydrocarbon chain with a carboxylic acid at one end; HOOC-R |
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Term
| Describe a phosphoglyceride: |
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Definition
| "Two hydrophobic chains attached to a glycerol (two ester linkages is normal, one ester and one ether with plasmologens) which is attached to a phosphate group which is attached to an amino acid OR a sugar" |
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Term
| What are the two types of phospholipids? |
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Definition
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Term
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Definition
| "A special type of phosphoglyceride that has a one fatty acid linked to glycerol via an ester linkage, and another hydrophobic chain linked to glycerol via an ether linkage" |
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Term
| What are the different amino acids/sugars that can be attached to the phosphate in a phosphoglyceride? |
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Definition
| "phosphotidyl - ETHANOLAMINE, CHOLINE, SERINE, or INOSITOL (sugar)" |
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Term
| Describe how phosphotidylcholine and phosphotidylethanolamine can form bends in a lipid bilayer: |
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Definition
| "PC has a cylindrical shape, PE has a conical shape; PE on the inside and PC on the outside will form a bend in a lipid bilayer" |
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Term
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Definition
| Two fatty acid chains linked to a SPHINGOSINE backbone which is attached to a phosphate and a CHOLINE amino acid; if it is attached to a sugar it will not have the phosphate and it will be a glycolipid! |
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Term
| What forces hold a lipid bilayer together? |
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Definition
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Term
| What is the difference between a MICELLE and a LIPOSOME? |
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Definition
| A micelle is only a single lipid layer with a hydrophobic interior and hydrophilic exterior. A liposome is a double lipid layer (bilayer) that has a hydrophilic interior and exterior |
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Term
| "What are the two states of a lipid bilayer, and which is present at normal physiological temperatures?" |
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Definition
| Fluid and Gel states; Fluid state is present at normal physiological temperatures |
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Term
| How does cholesterol affect membrane fluidity? |
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Definition
| "Cholesterol prevents lateral movement of phospholipids, therefore preventing transitions from gel to fluid state. It increases fluidity at cold temperatures and decreases fluidity at warm temperatures." |
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Term
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Definition
| "A microdomain enriched in cholesterol, sphingolipids, and cell-surface receptor proteins; involved in cell signalling" |
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Term
| Exoplasmic vs. Cytosolic membrane faces |
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Definition
| "Exoplasmic is the membrane face that is on the outside of the cell or the inner faces of a double-membrane organelle (far away from cytosol), Cytosolic is the inside face of the cell membrane or the inner and outer membrane faces of a double-membrane organelle (closest to cytosol)" |
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Term
| What are the three COVALENT ways a peripheral protein can be attached to a membrane? |
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Definition
| "(1) N-terminal is attached to a hydrocarbon chain in the membrane via a CYSTEINE residue, (2) C-terminal is attached to a hydrocarbon chain in the membrane via a GLYCINE residue, or (3) C-term is attached via a GPI anchor directly to the membrane" |
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Term
| What amino acids are sugars linked to in an O-linkage? Is this branched? |
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Definition
| "serine, threonine, hydroxylysine; short and unbranched" |
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Term
| What amino acids are sugars linked to in an N-linkage? Is this branched? |
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Definition
| asparagine; 3 mannose and 2 N-acetylglucosamine residues that are BRANCHED |
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Term
| What enzymes attache sugar residues to proteins on the exoplasmic face of a membrane? |
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Definition
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Term
| What are ABO blood types the result of? |
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Definition
| "carbohydrate modifications of antigens; everyone has the O-antigen, A-type adds a N-acetylgalactosamine, B-type adds a galactose" |
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Term
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Definition
| A membrane protein in RBC's. May be involved in transport of ammonium ion or CO2. |
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Term
| What is the order of permeability of substances through the plasma membrane? |
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Definition
| "gases, small uncharged polar molecules, large uncharged polar molecules, ions, charged polar molecules" |
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Term
| Describe the three types of transporters: |
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Definition
| All do not use ATP; Uniporter moves one substance down its conc. gradient; Symporter moves two substances down their conc. gradients in the opposite direction; Antiporter moves one substance down its conc. gradient and another up its conc. gradient (different directions) |
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Term
| How does the Km of a transporter describe its affinity for the substrate? |
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Definition
| Low Km = high affinity/transport rate and transporter is efficient; High Km = low affinity/transport rate and transporter is inefficient |
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Term
| Describe glucose uptake from the intestinal lumen to the blood: |
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Definition
| "Glucose uptake by epithelial cells in the intestine is COUPLED to the Na+/K+ ATPase pump in the basolateral membrane because the pump moves sodium out and potassium in using ATP to establish the Na+ gradient that drives the Glucose/2Na+ symporter, glucose leaves via facilitated diffusion" |
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Term
| Describe a P-class ATPase: |
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Definition
| "Two subunits, alpha and beta. Alpha is phosphorylated to activate the transport cycle. Na+/K+ pump is an example." |
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Term
| Describe a V-class ATPase: |
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Definition
| Proton pump. Multiple subunits involved in transport. No phosphoprotein intermediate like P-class. |
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Term
| Describe an F-class ATPase: |
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Definition
| Multiple subunits. Transports protons DOWN their concentration gradient in order to SYNTHESIZE ATP! No phosphoprotein intermediate like in P-class. Found in mitochondria and chloroplasts. |
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Term
| Describe the ABC superfamily of ATPases: |
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Definition
| ATP-Binding Complex; Have two ATP-binding domains and two transport domains. |
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Term
| Describe the Na+/K+ pump prior to ATP binding: |
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Definition
| "3 high affinity Na+ sites, 2 low affinity K+ sites" |
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Term
| Describe the Na+/K+ pump after ATP binding: |
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Definition
| "3 low affinity Na+ sites, 2 high affinity K+ sites; phosphorylates an aspartate residue" |
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Term
| Where are P-class ATPases found? |
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Definition
| "H+ pumps in plants and yeast, Na+K+ pump, Ca++ pump" |
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Term
| Where are V-class ATPases found? |
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Definition
| "lysosomes, endosomes, plant vacuoles" |
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Term
| Explain how the stomach is acidified: |
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Definition
| "H+ is taken from H20 inside the cell, H+/K+ ATPase pumps 1 K+ into the cell and 1 H+ out of the cell into the lumen, Bicarbonite/Cl- antiporter at the basolateral membrane gets rid of the bicarbonate produced when H+ is taken from water and OH- combines with CO2, Cl- is released via a transport channel at the lumen" |
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Term
| Explain how a nascent protein reaches the ER lumen for CO-TRANSLATIONAL TRANSLOCATION: |
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Definition
| "Signal sequence on N-term is recognized by SRP complex that carries the ribosome and protein to the SRP receptor on the ER membrane, 2 GTP's are used to bind the complex, ribosome is transferred to a translocon causing the translocon to open a channel for the nascent protein strand, a Signal Peptidase cleaves the N-term signal sequence and translation continues " |
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Term
| Explain how a nascent protein reaches the ER lumen for POST-TRANSLATIONAL TRANSLOCATION: |
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Definition
| "Protein is already translated, N-term signal sequence interacts directly with the translocon on the ER membrane (no SRP!), Sec63 Complex uses ATP to move the protein into the lumen and makes an ""ADP necklace"", ADP is later phosphorylated to ATP and the protein is allowed to fold" |
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Term
| Describe a Class 1 Integral Membrane Protein: |
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Definition
| "Spans the membrane one time, signal sequence is on the N-term and the N-term is hydrophilic (most of the protein is inside the lumen)" |
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Term
| Describe a Class 2 Integral Membrane Protein: |
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Definition
| "Spans the membrane one time, signal sequence is on the C-term and most of the protein is inside the lumen" |
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Term
| Describe a Class 3 Integral Membrane Protein: |
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Definition
| "Spans the membrane one time, signal sequence is on the N-term and the N-term is hydrophobic (most of the protein is outside the lumen)" |
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Term
| Describe a Class 4 Integral Membrane Protein: |
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Definition
| Multi-pass transmembrane protein |
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Term
| What are the 4 steps of protein modifications and where do they occur? |
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Definition
| "Covalent addition of carbohydrates (in ER lumen), Formation of disulfide bonds (in ER lumen), Proper folding and assembly of multisubunit proteins (in ER lumen), Proteolytic cleavage (anywhere!!!)" |
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Term
| What are the purposes of carbohydrate modification to proteins? |
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Definition
| "Assist in folding, protect mature proteins from proteolysis, help in cell-cell adhesion, functions as an antigen" |
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Term
| What types of proteins usually have disulfide bonds? |
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Definition
| secretory proteins and the exoplasmic domain of membrane proteins |
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Term
| What enzyme creates disulfide bonds? |
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Definition
| Protein Disulfide Isomerase (PDI) |
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Term
| What enzyme is involved in assembling multi-subunit proteins? |
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Definition
| Peptidyl-Prolyl Isomerase |
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Term
| Can improperly folded proteins exit the ER? |
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Definition
| "NO, they are targeted by protein folding catalysts or the ubiquitin/proteosome pathway" |
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Term
| Explain how a nascent protein reaches the mitochondria for POST-TRANSLATIONAL TRANSLOCATION: |
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Definition
| "N-term sequence designates the protein for a specific part of the mitochondria (matrix, intermembrane space, outer membrane, inner membrane), Proteins to matrix pass through both membranes simultaneously while a chaperone protein uses ATP at the surface membrane to stabilize the protein during transport" |
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Term
| How are non-nascent mitochondrial proteins kept from folding outside of the mitochondria before they are translocated? |
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Definition
| Chaperone proteins prevent them from folding |
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Term
| What proteins in humans are synthesized inside the mitochondria? |
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Definition
| "The ETC component proteins, synthesized on mitochondrial ribosomes" |
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Term
| What are two diseases caused by mutations in mtDNA? |
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Definition
| "Kearns-Sayre syndrome, Leber's hereditary optic neuropathy" |
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Term
| Explain the translocation of a protein to the peroxisome: |
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Definition
| "Post-translational translocation, signal sequence is on the C-term, requires GTP" |
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Term
| What is a disease caused by defective peroxisomal protein assembly? |
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Definition
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Term
| Describe the formation of peroxisomes de novo: |
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Definition
| "Precursor membrane can come from the ER, Golgi, cytosol synthesis.; Membrane proteins are inserted and matrix proteins are imported; Pex 11 is an enzyme that can divide one peroxisome into two!" |
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Term
| Where are all nuclear proteins synthesized and how do they end up in the nucleus (general)? |
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Definition
| "In the cytosol, they enter the nucleus through the nuclear pores because they have an INTERNAL nuclear localization sequence (NLS) which is not removed!" |
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Term
| Explain how proteins are imported into the nucleus: |
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Definition
| "Importin binds the protein and carries it across the nuclear membrane. Inside, it binds to GTP which causes it to release the protein inside the nucleus. On its way out of the nucleus, cytoplasmic filaments cause the GTP to be hydrolyzed to GDP which causes the Importin to bind another cargo protein" |
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Term
| What proteins coat vesicles moving from the RER to the Golgi? |
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Definition
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Term
| What proteins coat vesicles moving from the Golgi to the RER? |
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Definition
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Term
| What proteins coat vesicles that were endocytosed? |
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Definition
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Term
| "After vesicles bud off and coatings are removed, how do naked vesicles bind to their targets?" |
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Definition
| Interaction of the V-SNARE (vesicle) and T-SNARE (target) proteins |
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Term
| What are the two main pathways for translocating proteins to different organelles? |
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Definition
| "Secretory pathway (go to rough ER, either post-translational or co-translational translocation), Non-secretory pathway (synthesis of protein in cytosol and post-translational translocation to other organelles)" |
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