BC 351- Unit 3
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| shape of detergent molecule | cone
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| shape of membrane lipid | cylinder
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| when a lipid bilayer is torn it does not seal by forming a hemi micelle cap because | membrane lipids are cylindrical
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| why do lipid bilayers form? | lipids point inside to lower the energy
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| two membrane lipid backbones | glycerol or sphingosine
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| where does one find sphingolipids? | neuronal cells
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| are negatively charged membrane lipids found inside or outside of cells? | inside
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| 3 structural components of membrane lipids | fatty acyl tails, backbone (sphingosine/glycerol), head group (may be charged)/phosphate
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| how are membrane lipids classified? | 1) spingosine/glycerol
2) head group; charged/uncharged?
3) phosphate or no phosphate
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| 3 classes of membrane lipids | cholesterol, glycophospholipids, sphingolipids
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| 2 negatively charged glycerophospholipid head groups | inositol, serine
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| lipid rafts | regions of more sphingolipids/cholesterol found on the outside of the membrane
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| rotational diffusion | membrane lipid spins
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| translational diffusion | membrane lipid moves around
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| transmembrane diffusion | membrane lipid "flips"
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| phospholipid crucial in intracellular signaling is | phosphatidylinositol
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| flippase | outer to inner translocation
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| floppase | inner to outer translocation
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| scramblase | moves lipids toward equilibrium w/ the concentration gradient
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| Phosphatidylserine, normally found primarily only in the cytoplasmic side of the plasma membrane, is found at high levels on outer side in apoptotic cells; why? | the phospholipid translocators are inactivated
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| cholesterol is essential for lipid raft formation because | sphingolipids have large head groups
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| the mass ratio of lipids to proteins in membranes | varies widely in different membranes
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| 3 classes of membrane proteins | lipid anchored, peripheral, integral
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| which class of membrane proteins can be removed w/ salt or urea? | peripheral membrane proteins
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| constitutive membrane protein | always part of the membrane
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| amphitrophic membrane protein | regulated (sometimes expressed, sometimes not)
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| The forces that hold a membrane protein in the lipid bilayer and those that lead to protein folding into their tertiary structure | both involve the minimization of the interact of hydrophobic R groups w/ the aqueous environment
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| hydropathy plot of hydrophobic alpha helices | one high region of hydrophobicity
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| hydropathy plot of amphipathic alpha helices | stays about static b/c hydrophobic and hydrophilic
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| why does a hydrophobic alpha helix only span once? | to minimize interactions w/ the lipid bilayer (must be hydrophobic on all sides)
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| advantage of using amphipathic alpha helices for channel | polar inside, hydrophobic outside
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| how do mild detergents isolate membrane proteins? | hydrophobic ends stick to it to maintain its shape
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| A bacterial small protein causes red blood cell lysis. It also make artificial liposomes very permeable; it is likely | a B barrel protein that forms a pore
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| transporter vs channel | channel= goes right through; transporter= binds the solute
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| Na/K atpase | 3Na+ flow out; 2K+ flow in (against gradient)
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| If the plasma membrane becomes permeable to Na+ and K+, the Na+/K+ pump would | continue to pump ions and to hydrolyze ATP, but only generate heat in the process.
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| Secondary Active Transport | uses energy source indirectly
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| glucose transport into blood | Na/glucose cotransporter; glut-2; na/k atpase
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| Warburg Effect | upregulated lactate production; down regulated acetyl coA production
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| 2 examples of normal cells undergoing warburg effect | early embryogenesis (1st 3 cell divisions); astrocytes/neurons
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| neurons convert ___ to ___ | glutamine to glutamate
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| astrocytes convert ___ to ____ | glutamate to glutamine
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| 3 main types of metabolic pathways | anabolic, catabolic, amphibolic
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| three main "energy currency" molecules | ATP, NADH, acetyl coA
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| why is ATP-> ADP + Pi so negative? | pH of cells (neutral)
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| ΔG'° vs. ΔG | ΔG depends on temperature and concentrations
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| when would a rxn with ΔG'° that is positive still proceed? | high concentration of reactants
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| ΔE'°= | E'° (electron acceptor) + E'° (electron donor)
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| E'° (electron acceptor) | more positive
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| E'° (electron donator) | more negative (think NADH or FADH-> NAD+ or FAD+)
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| For ATP hydrolysis, ATP ADP + Pi, what is the effect of changing the reaction conditions from standard chemical conditions to biochemical standard conditions on ΔG of the reaction? | The ΔG of the reaction will be more negative at a given ADP/ATP ratio.
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| a ΔE ̊’ that is favorable (-ΔG ̊’) is | positive
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| The structure of NAD+ does not include | a flavin nucleotide
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| Glycolysis occurs in essentially all cells because | it evolved in an ancestor common to nearly all cells present on earth today.
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| In the breakdown of what you had for breakfast, the stage that generated the most ATP is | oxidative phosphorylation
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| The purpose of phosphorylation of glucose to glucose 6-phosphate by the enzyme hexokinase as the first step in glycolysis is | to help keep glucose in the cytoplasm
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| The conversion of 1 mol of fructose 1,6-bisphosphate to 2 mol of pyruvate by the glycolytic pathway results in a net formation of | 2 mol of NADH and 4 mol of ATP
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| what happens to NADH in anaerobic tissues? | it's used up to make lactate
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| The lipid bilayer of biological membranes | is self sealing in an aqueous environment
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| Membrane lipids are classified | first by backbone and second by head group.
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| Amphipathic α-helical structures | can form a hydrophilic pore within a lipid bilayer
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| A hydropathy plot indicates | a stretch of amino acids forming a single-pass transmembrane domain
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| Sodium (Na+) transport across a membrane | uses ~30% of the ATP hydrolyzed in mammalian cells
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| Aerobic glycolysis or the Warburg Effect | can be visualized through PET scans
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| NAD+ carries | only one hydride anion (1 H+ and 2 e-s)
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| metabolism | consists of metabolic pathways that are linear, cyclic and spiral
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| Anabolic and catabolic pathways are related by | anabolic pathways synthesizing more complex organic molecules using the energy derived from catabolic pathways
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| Energy requiring metabolic pathways that yield complex molecules from simpler precursors are | anabolic
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| Life is thermodynamically possible because living cells | release heat to the environment
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| If you mixed succinate, fumarate, FAD, and FADH2 together, all at l M concentrations and in the presence of succinate dehydrogenase, which of the following would happen initially? | Fumarate would become reduced, FADH2 would become oxidized.
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| The most important reaction involved in the reoxidation of NADH is: | pyruvate → lactate
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| The anaerobic conversion of 1 mol of glucose to 2 mol of lactate by fermentation is accompanied by a net gain of | 2 mol of ATP (2 used up; NADH converted back to NAD+)
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| what is true of sphingolipids? | cerebrosides and ganliosides are sphingolipids
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| how to draw hydropathy plot | N->C; peaks at transmembrane regions; +/- on y axis
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| which types of transmembrane proteins are energy dependent | all (facilitated diffusion, simple diffusion, active transport)
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| which types of transmembrane proteins can be saturated by substrate | facilitated diffusion
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| which types of transmembrane proteins can establish a concentration gradient | active transport only
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| Warburg and glutamate | dependent on it (more so than other cells)
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| aerobic re-generation of NAD+ | in electron transport chain!
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