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cell bio midterm 1
BIOL 288
Question | Answer |
---|---|
sucrose | glucose alpa 1,2 fructose |
lactose | galactose beta 1,4 glucose |
maltose | glucose alpha 1,4 glucose |
alpha helix | inter and intra H bonds. h bonds parellel to axis. r groups point outside 3.6 AA/turn to ensure peptide bonds close enough for H bonds |
beta sheet | antiparellel more stable, straight h bonds only intra H bonds central carbon at peaks and troughs R groups jut out |
what makes up phosphoglycerides | small, polar r group, phosphate, glycerol and 2FA |
what makes up phosphoceramide | small, polar r group, phosphate, sphingosine, and FA |
what makes up glycolipid | single, uncharged sugar, sphingosine and FA |
what makes up sterols | cholesterol |
what makes up fatty acids | phosphate head, glycerol (linker) and hydrocarbon tail |
what happens to membrane after TT | before: parellel and can rotate/move after: FA chain movement restricted and tightly packed |
bacterial KcsA K channel | homotetramer, each subunit has two membrane spanning domains (m1 and m2- helices) has pore region (forms selectivity filter) GYGVT |
euk voltage-sensing K channel | homotetramer, 6 helices. helices 1-4 are voltage sensing. S4 has pos (Glu, Arg) pore domain is helices 5 & 6 pore is GYGV/IT |
compare euk and bacterial k channels | both homotetramers (euk has 6 helices, not 2). euk is a true voltage gated, bacterial is pH mediated. euk has cytoplasmic domain, bacterial doesn't. |
how does K+ move through bacterial selectivity filter | 1,3 and 2,4 move two in filter at a time. energetically favourable to move through, stabilized by oxygen ring. |
how does gate open and close? (bacterial) | pH-mediated m2, glutamine gets protonated as H+ increases due to dec in pH. this causes the GLu to repel positively charged ARgininge which it had H bond with. open at glycine hinge |
what are GLUT transporters | 12 transmembrane proteins. tissue specific. 1-3 are insulin independent and 4 is dependent. 5 fructose dependent |
what kind of transport is GLUT 1 | facilitated diffusion |
what are the steps in GLUT 1 transport | glucose binds to transporter from outside, conformational change, transporter opens to inside, glucose released (gets phosphorylated into glucose-6-phosphate), transporter returns to original state |
what is/kind of transporter Na+/K+ ATPase pump | direct active maintains resting mp, creates a steep ion gradient that is important for indirect transport, maintains cell volume and resting mp) |
steps Na+/K+ ATPase | 3Na+ bind from inside cell, ATP phosphorlyates pump, conf change release Na+ to outside, 2K+ bind from outside, de-phosphorylates, releases K+ inside and returns to intial |
what is the initial state Na+/K+ | faces inside |
what is Na+/glucose symporter type of transport | indirect active |
what is Na+/glucose symporter steps | binds 2Na+ from outside, glucose binds soon after, conf change, symporter opens to inside, Na+ released to inside (soon pumped out byNa/K+ atpase. glucose released too. empty symporter returns to initial |
what is the intial state of Na/glucose | open to outside |
what causes cystic fibrosis | phenylalanine deletion in the first ATP binding site (that drive Cl- tansport) Cl- cannot pass, neither can water or Na+ |
what is cystic fibrosis transporter | 2 transmembrane domains for Cl- pore 2 ATP binding sites drive Cl- transport cytoplamic domain |
what kind of transport is cystic | active |
what are the basic properties of cells | life, highly organized, genetic program, produce more cells, use/acquire energy, carry out chemical rxns, engage mechanical activity, respond to stimuli, self-regulate, evolve |
what is the significance of van der waals and hydrophobic forces | weak individually, but collectively strong. universal, allow for protein shape/conformation,stable DNA strands when separated and bind'/interact btwn proteins and molecules (ES complex) |
properties of water | cohesive, temp stabilizing capacity, solvent properties, hydrophobic effect and acid-base chem |
what cohesiveness due to | h-bond network |
what temp stab capacity due to | H-bond network |
what solvent properties due to | polarity (hydration spheres) |
what hydrophobic due to | cohesivenss |
what is quinary structure of proteins | non-covalent interaction between molecules that organize the cellular interior. structural elements of the cell. substrate channelling |
what is substrate channeling | when multiple protons (metabolon) work together to move a substrate from one active site to the next seamlessly in an ordered fashion to speed up reactions. like finding friend in bar |
what are the membrane functions | boundary and permeability barrier, organization and localization of function, transport processes, signal detection, cell to cell communication |
what are the three classes of proteins | integral, peripheral and lipid-anchored |
what is abundant on the outer layer of the membrane | sphingomyelin, phosphatidylcholine, glycoproteins/lipids, some monotopic/peripheral proteins |
how membrane asymmetrical | in ER-Golgi-sent to PM. in ER(adds phopholipids, scramblase makes symmetrical. in golgi(flippase makes the proper proteins on each side-assym) |
what are the factors affecting transition temperature of the membrane | degree of saturation, fatty acid chain length, and sterols(cholesterol) |
what are the enzymes that remodel membranes to keep them fluid | a) desaturase enzymes to convert single bonds to double bonds and move with kinks. b)shuffling of fatty acyls chains-phospholipases (cut off chain)and acyltrandferases(move other chain into cleaved) |
what are the 4 types of transport ATPases | P-class pumps, V-class proton pumps, F-class proton pumps, ABC superfamily |
what is P-class pumps | reversible, phosphorylated by ATP. 8-10 transmemb protein, transport cations. sensitive to vandate (vo43-).eg=NA+/K+ and H+/K+ ATPases |
what is V-class proton pumps | on vacuole/lysozymes. 2 multisubunit components, v1- peripheral cytoplasmic component that gets phosphorylated by ATP |
what is F-class proton pumps | "factor", inner mito memb and chloroplast. 2 multisubunit components. f1-peripheral. protons move down conc grad. ATP binding site, can synthesize it via ATPase via proton movement b/c proton pore moves w/ grad. can pump other dir using ATP BIDIRECTIONAL |
what is ABC superfamily | 150 transporters. ATP binding cassette. 4 proton domains. 2 integral(t)-hydrophobic,6 transmemb, form channel. 2 peripheral(a)-bind ATP. heterotetramer. move ion, sugars, AA. medically relevant. |
what are the steps in citric acid cycle (substrate channeling) | L-malate--mMDH--> oxaloacetate--CS-->citrate--ACON-->isocitrate |