120 201 Foundations of BiologyrSpring 2018 Practice questions for Exam 3 36. Pre

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120 201 Foundations of BiologyrSpring 2018 Practice questions for Exam 3 36. Predict which of the following organisms will have the highest percentage df Page 6 of 15 their membranes. Explain your answer. Antarctic fish unsaturated phospholipids in c) Humans living in a tomperate forest d) Thermophilic bacterium that lives in hot springs near 100'c 37. New membrane phospholipids are synthesized by enzymes bound to the side of the lumenal, Golg cytosolic, endoplasmic reticulum d) extracelular, plasma 38. Three different membrane components are shown in the figure below. Using the list below identity the three molecules, and label the chemical groups indicated a) Glycerol b) Sugar d) Glycolipid e) Sterol f Unsaturated g) h) Saturated hydrocarbon Sterol polar head group 39. Match the columns a) symport b) facilitated dilusion c) pump d) uniport e) antiport Expense of ATP; extrusion of ions or small molecules Solute enters the cell through a specific channel Coupled transport in which two solutes enter or exit the ce single molecule or ion passes through a carrier A 40. Porin proteins form large, barrel-like channels in the membrane. Which of the tolowing is not true about hese channels? a) They are made primarily of a-helices b) They are made primarily of p-pleated sheets c) Proteins cannot form narrow channels. d) They have alternating hydrophobic and hydrophilic amino acids. below. Not all words or phrases will be used; each word or phrase should be used only once There are several ways that membrane proteins can associate with the cel membrane. Membrane proteins that extend through the lipid bilayer are called 41. For each of the folowing sentences, fill in the blanks with the best word or phrase selected from the lst proteins and have regions that are exposed to the interior of the bilayer. On the other hand, membrane- associated proteins do not span the bilayer and instead associate with the membrane through an a-helix that is inserted in the membrane. Other proteins areattached to lipid molecules that are membrane proteins are linked to the membrane through noncovalently hydrophilic cortical integral (intrinsic) unfolded

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Answere :

Question 36 : The option (a) is correct i.e. Antartcic fish becauses cells of organism living at low temprature have high proportion of unsaturated fatty acids in thier membrane to maintain fluidity of the membrane. Double bonds in unsaturated hydrocarbon able to increase the fluidity of phospholipid bilayer by making it more difficult to pack the chains together.

Question 37 : The option (c) is correct i.e. cytosolic, endoplasmic reticulum. New membrane phospholipids are synthesized by enzymes bound to the cytosolic side of endoplasmic reticulum membrane.

Question 38 :

I. The first membrane component is a glycolipid consist of sugar moiety and saturated hydrocarbon chain.

II. The middle one is a sterol molecule consisting of sterol polar head group.

III. The last one is a phospholipid molecule consisting of glycerol to which attached a unsaturated hydrocarbon chain

Question 39 : The exact match is given below

c) pump - expanse of ATP, extrusion of ions and small molecules.

b) facilitated diffusion - solutes enters the cell through a specific channel.

e) antiport - coupled transport, one solute enter, another one exits the cell.

a) symport - coupled transport in which two solutes enter or exit the cell.

d) uniport - a single molecule or ion passes through the carrier.

Question 40 : The option (c) is false i.e. porins proteins cannot form narrow channel because these proteins form narrow channel through which allow free diffusion of molecules smaller than about 1000 daltons.

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