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