Unformatted text preview: 205} ‘v'aline. a nonpolar amino mid. shows up in the wrong place in the hemoglobin of sickle- cell
anemia. causingthedisease. This is dueto agenelic mutation.The result of this mutation is that
hemoglobin molecules—w hich tra'lsport oxygen in red blood cells—stick together. causing the red blood cells to become distorted. but without having any significant effect on oxygen binding. Bﬂed
on what you ltnow about protein structure and the polarity of an ino acids. predict where the mutated valine would most liltely befound.
A} along anonpoler region of aﬂ- pleded sheet B} on the surface of hemoglobin
G} in the oxygen binding site of hemoglobin D} in the deep interior of hemoglobin QUE} What isthe name of the currently azoepted model of membrane structure. and where does it plane
A} sandwich: em bedded within the membraneand on the surfacesof the membrane
B} sandw ich: on the outside and inside surfaces of the mem brane only
G} fluid- mosaic: on the surfaces of the mem brane only
D} fluid- mosaic: em bedded Within the membrane and on the surfacesof the membrane 29?]: Which of the follow ing observdio ns mate with freeze- fracture electron microscopy p royides
evidence for the fluid- mosaic model of mem brane structure? A} The exterior surfsme of the membrane contained pitsand mounds. B} The exterior surface of the membrane contained pits only.
G} The inner surfaces of the mem brane contained pits and mounds. D} The middle of the membrane viewed under the electron microscope was smooth and regular. 206} Integral membrane proteins stay in mem branes because of
A} diffusion of proteins from the cytoplasm to the membrane.
B} osmotic pressure from proteins outside the oell.
G} the lo-cﬂions of their poles and nonpola: anino acids
D} their small size. w hich does not allow them to pass through the mem brane. 209} Where would you most likely find an integral membrane protein?
A} on the outside surface of the cell mem brane B} on the inside surfaoe of the cell mem brane
G} spanning the oell membra1e,w ith parts of the protein visible from both the inside and the outside of the cell
D} floating freely in the cytoplasm 210} To determine if mem bra1e proteins affect membrane permeﬂlility. you oould isolﬂe the proteins
from the lipid components of the membra'le by using detergents. Then you oould sepaate the individual proteins and test each of them in a planet bilayer. What technique could you use to
sepa'ele the proteins from one another siter they have been isolated from the membra'le'? A} diffusion B} freeze fra:ture electron microscopy
G} amino a:id analysis D} gel electrophoresis 205} 203} 207} 2031' 2091' 2m} ...
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- Spring '07