Biochemistry II Chapter 9 Lipids Practice Questions/MC

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17. Which of the following statements describes integral membrane proteins? I. They protect the contents of the cell from chaotropic agents such as urea. II. They are easily dissociated from the membrane by changes in pH or high salt concentration. III. They are held tightly in place by hydrophobic effects between the membrane and hydrophobic amino acids. A) I, II, III B) I, III C) I D) II E) III

2. Saturated fatty acids have C-C single bonds and unsaturated fatty acids have one or more unsequential C=C double bonds in cis configuration. Saturated fatty acids are waxy solids at room temperature while unsaturated fatty acids are oily liquids. This is because: A. Unsaturated fatty acids form salts but saturated fatty acids cannot. B. Saturated fatty acids pack together to form solids but unsaturated fatty acids cannot because the cis C=C double bonds form kinks. C. C=C double bonds in unsaturated fatty acids form H bonds with other unsaturated fatty acids. D. Unsaturated fatty acids form micelles but saturated fatty acids do not.

24 4 32 I-cell disease results in psychomotor retardation, skeletal deformities and death. Which of the following is true regarding this disease? A) The disease results in inclusion of glycosaminoglycans and glycolipids due the absence of an essential carbohydrate marker that directs the lysosomal hydrolases to the lysosome. B) The disease results in inclusion of glycolipids due mutations in the lysosomal hydrolases that render them inactive. C) The disease results in increased expression of SNARE proteins that result in vesicle fusion and exchange of glycosaminoglycans. D) The disease results from the lack of KDEL sequences which would normally signal their return to the ER following Golgi processing. E) All of the above are true.

7. All of the following are true of cholesterol except: A. It attaches to glycerophospholipids and sphingolipids in membranes. B. It is transported through the blood by lipoproteins. C. It is derived from isoprene. D. It is found in both plant and animal tissue. E. It is a building block for hormones. F. It is a building block of bile salts. Incorrect, cholesterol is derived from isoprene.

B, A, E, G, C, F, D

8. Label the parts of the membrane by entering the letter of the part shown in the schematic below: ___ Lipid tail ___ Polar head ___ Peripheral membrane protein ___ Carbohydrate ___ Lipid bilayer ___ Cholesterol ___ Integral membrane protein

phosphatidylcholine

A derivative of _________ is the major lipid in lung surfactant.

plasmalogen

A glycerophospholipid in which the C1 substituent linkage forms a vinyl ether that is more easily oxidized than its ester counterpart is called a _______

A researcher is developing a new drug for the treatment of influenza. Based on the information presented in the text about the influenza virus, which of the following drug reactions describes the action of this new drug? A) A drug which specifically interrupts the conformational change that results from the pH change in the endosome. B) A drug which enhances the function of a normally quiescent enzyme responsible for cleavage of the carbohydrate component on glycophorin A proteins. C) A drug which readily binds the hemagglutinin tag and results in conformational change. D) All of the above are potential actions of this new drug. E) None of the above is a plausible reaction for this new drug.

vitamin D

A steroid-derived hormone that must be activated by hydroxylation, _______ regulates Ca2+ metabolism.

A suspension of which of the following is most likely to form a liposome? I. fatty acids II. triacylglycerols III. glycerophospholipids IV. sphingomyelins A) I, II B) II, III C) III, IV D) II, IV E) I, IV

Adipocytes A) are specialized cells for the synthesis of triglycerides. B) are specialized cells for short term energy storage. C) provide compartments for efficient membrane bilayer synthesis. D) exist primarily in a thin layer surrounding major muscle groups as a rapid high energy source. E) All of the above characterize adipocytes

Adipocytes are fat storage cells in animals. These cells contain the enzyme lipase, which catalyzes the release of fatty acids. This reaction is called: A. Esterification B. Saponification C. Hydrolysis D. Hydrogenation

Botox is used cosmetically to reduce wrinkles for a limited time interval. The function of Botox is described by which of the following? A) Botox inhibits function of the hemagglutinin tag. B) Botox relaxes small muscles by cleaving the leader peptide prior protein folding. C) Botox functions by inhibiting function of the SNARE protein. D) Botox functions by inhibiting the lysosomal protease cathepsin D. E) None of the above describes the function of Botox.

Cholesterol A) incorporation into the membrane results in increased rigidity. B) functions as a precursor to cerebrosides. C) is synthesized in two-carbon units. D) is synthesized from steroid hormones. E) all of the above

Coated vesicles are used to ensure that the enclosed protein maintains its proper orientation. Clathrin is one type of protein used to coat vesicles. Which of the following is true regarding clathrin vesicles? A) They transport proteins between successive components of the Golgi compartments. B) They transport transmembrane proteins and GPI-linked proteins from the Golgi to the plasma membrane. C) They transport proteins from the ER to the Golgi. D) They form a rigid complex capable of protecting protein structure and orientation as it is passed from hydrophobic to hydrophilic environments. E) None of the above

Cold blooded animals modulate the fatty acid composition of their membranes as a function of temperature in order to A) adjust the membrane thickness and increase thermal insulation. B) maximize available fatty acids for metabolic use. C) ensure consistent membrane fluidity. D) compensate for decreasing cholesterol solubility. E) all of the above

B, G, S, G, G, S

Designate each group below as a possible constituent of the glycerophospholipids (G) or sphingolipids (S) or both (B) by entering G, S, or B in each blank. ___ H ___ Serine ___ Glucose ___ Inositol ___ Choline ___ Phosphocholine

arachidonic acid

Eicosanoids are 20-carbon compounds derived from ________

gangliosides

Glycosphingolipids with complex carbohydrate head groups that often serve as cellular receptors are _______

In bacteria, phospholipids are synthesized: A) on the cytoplasmic face of cell membranes B) at the rough endoplasmic reticulum C) on the extracellular face of the cell membrane D) on site at the endoplasmic reticulum. E) nonenzymatically at the site of the membrane.

Lipid bilayers with high concentrations of gangliosides are rare. Which of the following explanations is correct? A) The hydrophobic tails on gangliosides form a conical shape rather than a cylindrical shape making close packing difficult. B) Gangliosides contain large headgroups making close packing difficult. C) Gangliosides contain trans fatty acids resulting in a bent hydrophobic tail making close packing difficult. D) All of the above are correct. E) None of the above is correct.

Lung surfactants function to decrease the likelihood of collapse of the alveoli when air is expired. Based on your knowledge of lipids and amphipathic molecules, which of the following explains the mechanism by which the dipalmitoyl phosphatidylcholine (DPPC) can accomplish this task? A) The hydrophilic head groups are bulky and expand the surface area of the alveoli. B) The inclusion of saturated fatty acids on the glycerophospholipid allows close packing of tail groups which are fully extended and prevent collapse upon expiration. C) The hydrophobic portion of the DPPC repel air, forcing the alveoli space open. D) The choline portion of the molecule is bulky, thus increasing surface area of alveoli. E) None of the above explain the mechanism.

sterol

Members of the ______ family have four fused, nonplanar rings and a C3-OH group.

Membranes serve as a selective barrier for the cell. Small, non-polar molecules such as H2O go through the membrane via simple diffusion. Facilitated diffusion is a protein-mediated process wherein particular integral membrane proteins, called permeases, form channels for certain molecules. In what ways are permeases similar to enzymes? A. They obey Michaelis-Menten kinetics B. They lower activation energy. C. They are nonspecific for many types of molecules. D. They catalyze reverse reactions.

Micelles of fatty acids in water are organized such that the ___ face the solvent and the ___ are directed toward the interior. A. hydrophilic heads; hydrophobic tails B. carboxylic acid groups; hydrocarbon chains C. hydrocarbon chains; carboxylic acid groups D. hydrophobic tails; hydrophilic heads E. The first and second answers are both correct.

N-terminal signal peptides function to direct proteins A) destined for secretion. B) to the endoplasmic reticulum. C) destined to be part of the lysosomes. D) all of the above E) none of the aboveD

Phospholipids are molecules that contain: A. positively charged functional groups. B. long water-soluble carbon chains. C. cholesterol. D. hydrophilic heads and hydrophobic tails. E. The third and fourth answers are both correct.

Proteins which are passed from one Golgi compartment to the next in a successive fashion do so via a mechanism called____. A) maturation B) cisternal progression C) retrograde transport D) anterograde transport E) medialgrade transport

Receptor-mediated endocytosis: A) is comparable to the activities of vesicle fusion. B) superficially resembles binding of a clathrin coated vesicle to the plasma membrane. C) superficially resembles the reverse of vesicle fusion to the plasma membrane. D) mimics the function of the Golgi apparatus. E) functions much like the SNARE mediated fusion process.

Sphingolipids I. contain a glycerol core with a phosphocholine headgroup. II. contain a modified sphingosine. III. often function as receptor components of membranes. IV. function as a precursor to sterols. A) I, II, IV B) II, IV C) I, II, III D) II, III E) II, III, IV

The C=C bond in fatty acids: A. Is inert B. Is subject to autooxidation C. Reacts with NaOH to form lye D. Cannot be converted from cis to trans configuration

The _________ model describes the cell membrane as an assortment of integral proteins suspended freely in a lipid bilayer. A) FRAP B) cellular fusion C) transverse diffusion D) lateral diffusion E) fluid mosaic

The _________, which is found embedded in the endoplasmic reticulum, is a _______ protein. A) SRP receptor...signal B) ribosome...transmembrane pore C) translocon...transmembrane pore D) translocon...peripheral E) ribosome...signal

The glycerophospholipids are composed of two fatty acids attached to glycerol and one of the following head groups: A. ethanolamine. B. choline. C. serine. D. threonine. E. All but the fourth choice are correct.

The levels of Na+ and K+ in a cell are maintained by the Na+-K+ ATPase pump. This is an example of active transport across a membrane. This pump: A. Creates ATP B. Pumps K+ and Na+ in C. Is an example of antiport. D. Requires light absorption

The main difference between saturated and unsaturated fatty acids is A. the number of carbons. B. the presence of keto groups. C. the presence of double bonds. E. that one is absent from phospholipids. F. none of the above.

spectrin

The major protein in the erthrocyte (RBC) membrane skeleton is ______________

The melting properties of fatty acids and lipid bilayers is due primarily to A. hydrogen bonds. B. the hydrophobic effect. C. van der Waals forces. D. electrostatic interactions. E. covalent bonds.

sphingomyelins

The myelin sheath contains high levels of

The protein that forms a transmembrane pore that allows growing polypeptides to pass through the RER membrane is called the ______. A) signal recognition particle B) signal peptide C) docking protein D) translocon E) none of the above

The signal peptide sequence I. is often used to direct proteins to the lysosome for incorporation into the lysosome. II. is usually not used for small eukaryotic proteins. III. of some transmembrane proteins is embedded into the membrane as an anchor. IV. is usually cleaved off the completed protein. A) I, IV B) I, II, IV C) II, III, IV D) I, III, IV E) I, II, III, IV

Transmembrane proteins I. are predominantly constructed of a single hydrophobic α-helix. II. are often constructed from bundles of hydrophobic -helices. III. are sometimes constructed from β-barrels with hydrophobic interiors and exteriors. IV. may have transmembrane helices identified by the free energy of transfer to water. A) I, III, IV B) II, III C) II, III, IV D) I, IV E) II, IV

Triacylglycerols are a cellular metabolic fuel. Which of the following are true of triacylglycerols? A. They are polar, hydrophobic molecules. B. Most triacylglycerols have three fatty acid groups that are identical. C. They should be completely eliminated from the human diet. D. Triacylglycerols from animals are solids at room temperature while those from plants are liquid.

Triglycerides contain more metabolic energy per unit weight than glycogen because: I. Glycogen has greater polarity than fatty acids. II. Fatty acids predominate in an anhydrous form III. Fatty acids are less oxidized than carbohydrates. IV. Triglycerides have a higher average molecular mass. A) I, II, III, IV B) I, II, III C) I, II D) II, III E) III

Unsaturated fatty acids: A) are commonly found in plants and animals B) usually contain a double bond with cis stereochemistry C) sometimes contain multiple double bonds D) have lower melting points than the analogous saturated fatty acids E) all of the above

triacylglycerol

What classification of lipid is 1-palmitoyl-2-linoleoyl-3-stearoyl-glycerol

steroid

What classification of lipid is cholesterol

unsaturated fatty acid

What classification of lipid is oleic acid

glycerophospholipid

What classification of lipid is phosphatidylcholine

eicosanoid

What classification of lipid is prostaglandin H2

sphingolipid

What classification of lipid is sphingomyelin

saturated fatty acid

What classification of lipid is steraric acid

lysophospholipid

When snake venom phophalipase A2 acts on a glycerolphospholipid, the main product is ______________

Which experiment listed below did NOT verify the fluid mosaic model of membranes? A) observation of lateral movement of membrane across the cell while anchored to a microscope slide. B) monitoring the transverse diffusion of human proteins within a mouse cell membrane. C) membrane fusion between mouse and human cells. D) monitoring the lateral diffusion of fluorphores both bleached and unbleached. E) All of the above describe experiments that verified the fluid mosaic model of membrane

Which of the following amino acids from an integral membrane protein would likely contact the membrane? A) Asn B) Gln C) Glu D) Ala E) Asp

Which of the following classes of proteins associates with the membrane bilayer with the lowest energy and would therefore be most difficult to separate from the membrane? A) extrinsic proteins B) lipid-linked proteins C) transmembrane proteins D) peripheral proteins E) hydrophilic proteins

Which of the following correctly describes the usefulness of SNAREs? I. They are essential for proper post-translation processing. II. They are a critical element in the function of the secretory pathway. III. They are effective at overcoming electrostatic repulsion between vesicle membranes. IV. They facilitate anchoring between vesicle membranes. A) I, II, III, IV B) II, III C) III D) IV E) III, IV

Which of the following correctly ranks the steps in the secretory pathway? 1. Synthesis occurs with a leading signal peptide 2. The SRP-ribosome complex binds the SRP receptor-translocon complex 3. The signal peptide binds the SRP and GDP is replaced with GTP 4. GTP hydrolysis results in dissociation of SRP and SR 5. SRP changes in conformation arresting peptide growth 6. The nascent protein begins to fold and post-translational modification is initiated 7. Signal peptidase cleaves the protein from the signal peptide A) 1, 2, 5, 4, 6, 7, 3 B) 1, 3, 5, 2, 4, 7, 6 C) 2, 4, 1, 3, 5, 6, 7 D) 2, 4, 3, 5, 4, 6, 7 E) 1, 3, 4, 2, 5, 7, 6

Which of the following fatty acids would have the lowest CMC (critical miscellar concentration) A. C4-COOH. B. C5-COOH. C. C6-COOH. D. C7-COOH. E. C8-COOH.

Which of the following is (are) NOT found as covalently attached anchors in lipid-linked proteins? A) isoprenoid groups B) fatty acids C) cholesterol and other sterols D) glycosylphosphatidyl inositol groups E) All of the above are found as covalently attached anchors in lipid-linked proteins.

Which of the following is comprised primarily of fatty acids and other single tailed amphiphiles? A) lipid bilayers B) two-dimensional membranes C) liposomes D) micelles E) solvent-filled vesicles

Which of the following is true about membrane proteins embedded within the lipid bilayer? A) An increased temperature of the bilayer decreases the rate of transverse diffusion of the membrane protein. B) They undergo transverse diffusion approximately every 5 seconds at body temperature. C) They undergo transverse diffusion readily at body temperature unless their movement is restricted by other cellular components. D) As the temperature decreases, lateral diffusion of the membrane protein is restricted in bilayers with lipids which have longer chain fatty acids and fewer double bonds. E) Lateral diffusion of the membrane protein occurs independent of bilayer composition and temperature.

Which of the following lipid types is the least polar? A) triacylglycerols B) glycerophospholipids C) sphingolipids D) gangliosides E) glycolipids

Which of the following lipids would NOT likely be found in a lipid raft? I. glycosphingolipids II. glycerophospholipids III. cholesterol IV. palmitoleic acid A) I, IV B) I, II, IV C) II, IV D) III, IV E) IV

Which of the following processes presented in this chapter is (are) readily reversible with the help of enzymes known as thioesterases? A) myristoylation B) glycosylphosphotidylinositalation C) palmitoylation D) all of the above E) none of the above

Which of the following proteins are synthesized on free ribosomes? A) mitochondrial proteins B) secretory proteins C) signal peptides D) lysosomal proteins E) transmembrane proteins

Which of the following statements describes one reason that plant oils are generally healthier for human consumption than animal fats? A) Plant oils usually contain more unsaturated fatty acids than animal fats. B) Plant oils usually contain more trans fatty acids than animal fats. C) Plant oils usually have a higher degree of saturation than animal fats. D) Plant oils are glycerol based rather than phospholipid based. E) Plant oils have shorter chain fatty acids than animal fats.

Which would be most likely to be found in the membranes of mouse brain cells? A) cholesterol B) glycerolphospholipids C) GM1, GM2, or GM3 D) all of the above E) none of the above

Why are fatty acids amphiphilic molecules? A. They have both (+) and (-) charges. B. They contain saturated and unsaturated groups. C. They are water-soluble. D. They have polar heads and non-polar tails. E. They are unbranched.

amiphiphiles

With respect to polarity, membrane lipids can be described as ________

triacylglycerols

________ are the lipids that are most abundant even though they are not components of membranes.

eicosanoid

a class of fatty acids that regulate blood vessel vasodilation, temperature elevation, WBC activation, and other physiologic processes involved in immunity

porins

channel-forming proteins found in the outer membranes of bacteria, with a beta-barrel motif

micelles

detergents aggregate to fomr _____________

integral membrane proteins

general class of proteins that are tightly bound to membranes by hydrophobic interactions

lipid-linked proteins

membrane associated proteins that have covalently-bonded lipids

fatty

palmitic acid is a _______ acid

hydrolysis

phospholipases are enzymes that catalyze ___________ of glycerophospholipids

peripheral (extrinsic) proteins

proteins that are associated with membranes, but can be dissociated by relatively mild procedures

transmembrane proteins

proteins that completely span the membrane

phosphatidylethanolamine

what lipid is this?

cerebroside

what type of lipid is this?

eicosanoids

what type of lipid is this?

gangliosides

what type of lipid is this?

glycerophospholipids

what type of lipid is this?

phosphatidylcholine

what type of lipid is this?

phosphatidylglycerol

what type of lipid is this?

sphingomyelin

what type of lipid is this?

triacylglycerols

what type of lipid is this?

ceramide