Lipids

Example of trans-fatty acid derived from partial hydrogenation of vegetable oils is ___________________.

MARAGINE

Explain the biochemical mechanism of the toxicity of snake venom.

Snake venom contains phospholipases that break down phospholipids which results in lysolecithin which acts as a detergent and dissolves the membranes of red blood cells.

What is the source of Benecol developed by the Pharmaceutical company, and what is the claim made?

Source; pine wood, claim; reduced blood cholesterol by 14%

Why are some plant sterols considered as natural cholesterol fighters?

not absorbed into body, block absorption in the intestines.

What are cardiac glycosides or cardiotonic steroids - what do they inhibit and why are they called so?

plant and animal steroids that inhibit NA, K-ATPase and ion transport causing potent effects on heart.

Bacillus thuringeinsis is a biological pest control and accounts for more than 90% of sales among the biological pest control systems available. What is the mechanism by which this works, for exterminating mosquitoes and other pests?

produce proteins in digestive system causing them to leak Na, K and H leading to starvation of insect.

Platelet Activating Factor- an ether glycerophospholipid, has both deleterious effects when over-induced and beneficial effects in certain processes. Explain this with examples.

-:TSS +:implantation of egg in uterine wall.

n male hermaphrotidism (see section on page 171), which enzyme has been implicated and in the pathway of synthesis of which steroid hormone?

17 beta-hydroxysteroid, testosterone.

All are characteristic of the gastric proton pump EXCEPT: a. Gastric proton pump requires high levels of dietary K+ to create a K+ gradient. b. Gastric proton pump is a H+, K+-ATPase. c. Gastric proton pump maintains a pH gradient of about 6.6 across the mucosal cell membrane. d. Gastric proton pump is electroneutral. e. Gastric proton pump produces a net influx of HCl into the stomach.

A

Membrane transport includes all of the following EXCEPT: a. Transport of the lipid bilayer from one organelle to the other as needed b. Transport of Na+ , H+, K+ and Ca2+ c. Transport of Cl- and HCO3- and phosphates d. Transport of glucose, amino acids and complex sugars e. Transport of peptides and drugs

A

Steroid hormones include all of the following EXCEPT: a. dolichol b. progesterone c. cortisol d. estradiol e. testosterone

A

Which of the following are essential fatty acids but cannot be synthesized by mammals? a. Linoleic acid and α-linoleic acids are "essential" fatty acids. b. Palmitic acid c. Stearic acid d. Trigylcerides

A

Which of the following is a Fatty acid lipid? a. Triglyceride b. Terpenes c. Steroids d. Isoprenoids. e. None of the above.

A

Which of the following is a phosphatidate? a. Lecithin b. Platelet Activating Factor c. Cardiolipin d. Plasmalogen e. Both a and c.

A

Which of the following is a sphingomyelin? a. A sphingolipid that has a phosphate containing side group attached to the ceramide hydroxyl group, b. A ceramide containing one or more sugar residues in a beta-glyocosidic linkage at the hydroxyl moiety of the ceramide c. Ceramide with three or more sugars esterified d. A ceramide with multiple chains of fatty acids.

A

Which of the following is applicable to fatty acids? a. They have acyl carbon (carboxyl group) at the head b. They have long hydrocarbon chain tail that cannot have double bonds c. The carboxyl group is not deprotonated/ionized in physiological conditions d. They occur as free molecules just as fatty acids e. A nomenclature which shows the numbers 18:2 (9, 12) indicates that that there are 18 carbons in the hydrocarbon tail, 2 chains and there are 9 double bonds in one chain, 12 double bonds in second chain.

A

Which of the following steroids regulate salt balances in tissues? a. Androgens, b. Progestins c. Glucocorticoids d. Mineralocoritcoids e. Bile acids

D

All of the following is true for waxes EXCEPT: a. Waxes are esters of long-chain alcohols with long-chain fatty acids b. The fatty acid part in the waxes are unsaturated fatty acids c. The alcohols found in waxes may be saturated or unsaturated d. The alcohol may also include sterol such as cholesterol e. Waxes are water-repellent and are found on animal skin, plant leaves, bird feathers.

B

Although present in small amounts in most membranes, glycosphingolipids have a number of cellular functions EXCEPT: a. involvement in nerve impulse transmission. b. water-repellant properties of animal skin. c. tissue and organ specificity. d. cell-cell recognition. e. tissue immunity.

B

Integral membrane proteins (intrinsic proteins) have the following properties, EXCEPT: a. have hydrophobic surfaces as well as hydrophilic surfaces b. Easily dissociate from the membrane by treatment with salt solutions. c. get exposed to one or both aqueous surfaces of the membrane. d. insert into the membrane. e. Can also extend all the way across the membrane.

B

Lipids such as triglycerides are the biomolecules of choice for storage of metabolic energy because they: a. are soluble in nonpolar solvents. b. Are rich in reduced carbons and yield large amounts of energy upon oxidation. c. are highly saturated. d. are easily hydrolyzed. e. are amphipathic.

B

Platelet activating factor (PAF) has all of the characteristics EXCEPT: a. PAF is a potential mediator in inflammation, allergic responses and shock. b. PAF is a sphingolipid. c. PAF is an ether glycerophospholipid. d. PAF is involved in implantation of the egg in the uterine wall. e. PAF stimulates production of fetal lung surfactant.

B

Which of the following is NOT true about proton pumps? a. In addition to gastric proton pump, other types of proton pumps exist that maintain proton gradients in other organs. b. Proton pumps V-type ATPases are found in osteoclasts that break down bone during normal bone remodeling c. Proton pumps of osteoclast membranes pump protons into the extracellular space attached to the bone, creating an acidic pH d. Bone mineral is made of calcium carbonate and calcium phosphate (hydroxyapatite) and can therefore dissolve in the acidic pH created, and thus provides circulating calcium. e. All of our bone mineral gets dissolved away in this fashion, to provide the circulating calcium.

B

Which of the following is a cerebroside? a. A sphinghosine joined to a fatty acid via an amide link b. A ceramide containing one or more sugar residues in a beta-glyocosidic linkage at the hydroxyl moiety of the ceramide c. A ceramide with a single glucose or galactose as the sugar linked d. A ceramide with three or more sugars esterified.

B

Which of the following steroid hormones participate in control of pregnancy? a. Androgens, b. Progestins c. Glucocorticoids d. Mineralocoritcoids e. Bile acids

B

Calcium transport properties are all of the following EXCEPT: a. Are involved in several cellular signaling processes in almost all cells b. Have special role in muscles for signaling muscles to contract c. Levels of Ca2+ in resting phase of muscles is very high at 10uM. d. Calcium ions in the muscles are sequestered in a complex network of vesicles called sarcoplasmic reticulum. e. The Ca2+-ATPase has ten transmembrane α- helical segments with two Ca2+ ions buried deep in the membrane-spanning portion

C

In the Na+, K+-ATPase mechanism, ATP is involved in all EXCEPT: a. Binding to the protein conformation type E2 to change conformation to E1 and release of K+. b. Binding E2 to facilitate affinity to K+ c. transferring a phosphate group to make sodium phosphate to facilitate pH maintenance. d. hydrolysis of ADP and E1-P. e. Phosphorylation of the enzyme by transferring a phosphate group

C

Lipids that spontaneously form micelles, monolayers and bilayers have what property? a. waxy b. Negative polarity c. amphipathic d. bipolar e. polyisoprenoid

C

Melittin is a 26-residue peptide in honeybee venom that: a. has ionophore antibiotic properties. b. is a phospholipase that attacks red blood cells causing hemolysis. c. Forms transmembrane ion channels that create Cl- pores that causes flow of Cl- out of the cells in nerve endings that diminishes the transmembrane potential and triggers a pain response. d. inhibits Na+, K+-ATPase. e. discharges mitochondrial proton gradients and ATP synthesis.

C

Which of the following does not apply to Terpenes?: a. Terpenes are fatty-acid containing lipids b. They have isoprene units c. An isoprene is a 2-methyl-1,3-butadiene d. A diterpene will have 20 carbons e. Monoterpenes occur in all higher plants

C

Which of the following does not represent lipid-anchoring motifs in lipid-anchored integral proteins?: a. amine-linked myristoyl anchors. b. thioester-linked fatty acyl anchors. c. amide-linked prenyl anchors. d. thioether-linked prenyl anchors. e. Glycosyl phosphatidylinositol anchors.

C

Which of the following is NOT applicable to proteins associated with membranes? a. Proteins embedded in the membranes do so, through interactions of their hydrophobic groups exposed to the membrane. b. Proteins on the periphery of the membrane are associated to the membrane through electrostatic interactions of ionic charges c. Proteins anchored to the membrane are through non-covalently linked lipids which are on the surface d. None of the above are applicable.

C

Which of the following pairs are NOT exchanged one-for-one? a. Cl- and HCO3- b. H+ and K+ c. Na+ and K+ d. None of the above e. All of the above

C

Which of the following transports is NOT thermodynamically favored and needs energy input? a. Passive diffusion b. Facilitated diffusion c. Active Transport d. All of the above

C

Yeast a-factor ATPase (in yeast) and MDR ATPase (in eukaryotic cells) are two members of a superfamily of transport proteins that actively transport: a. H+ to dissolve bone mineral. b. Ca2+ into the sarcoplasm. c. a broad group of diverse organic molecules such as drugs across membranes creating drug resistance in many human malignancies. d. Mg2+ against a concentration gradient. e. None of the above.

C

he type of proteins that are associated with the membrane by means of covalent linked lipids are: a. Peripheral proteins b. Integral proteins c. Lipid Anchored proteins d. Membrane transformation proteins

C

A 12-TMS would represent: a. 12-transmethyl synthase. b. 12-tris-methyl sulfate. c. 12-transmodel symmetry. d. 12-transmembrane segments. e. 12-trimethyl stearate.

D

According to Fluid Mosaic Model, Lipid Bilayer exhibit all but not the following property: a. Hydrocarbon tails of the phosphopholipids may tilt, bend and adopt a variety of orientations b. Lipids and proteins can move along the membranes c. Lipids and proteins can form clusters in the membranes can undergo phase separation, and can also undergo physical change causing phase transition at transition temperatures d. The two sides of the membrane in the lipid bilayer are exactly similar in terms of orientation and distribution of proteins and lipids e. The phoshoplipids can get flipped from one side of the bilayer to the other side at a faster rate with help of flippases. .

D

Active transport is uniquely characterized by: a. transport of hydrophobic molecules. b. transport of hydrophilic molecules. c. transport of a molecule or ion across a membrane, with the species going from a greater concentration to a lesser concentration. d. the linkage of an input of energy to drive a thermodynamically unfavorable reaction. e. absolute requirement for ATP hydrolysis, no other energy sources such as light energy or ion gradient energy will work.

D

Diets aimed at reducing coronary heart disease should be: a. low in trans-fatty acids and high in saturated fatty acids. b. high in trans-fatty acids and high in saturated fatty acids. c. high in trans-fatty acids and low in saturated fatty acids. d. low in trans-fatty acids and low in saturated fatty acids. e. low in trans-fatty acids and low in unsaturated fatty acids.

D

Which of the following applies to Cortisol? a. It is a glycocorticoid b. It is a steroid hormone c. It participates in the metabolism of carbohydrates, lipids and proteins. d. All of the above apply

D

Which of the following is NOT mediated by membrane proteins on erythrocytes? a. Glucose transport b. Cl- transport c. HCO3- transport d. Gastric H+

D

Which of the following is NOT true about Secondary active transport : a. It is a transport process driven by ion gradients. b. Requires establishment of a cation or anion gradient with an ATPase that subsequently drives transport of other molecules. c. Amino acid and sugar transport against a concentration gradient is a consequence of initial Na+ or H+ gradients driven by ATPases. d. Symport means same concentrations of the ions and the transported amino acids or sugars are transported and antiport means different concentrations are transported. e. There are different different transport systems for different types of amino acids depending on acid, versus basic versus neutral amino acids, or branched-chain and aromatic.

D

Which of the following is true? a. All lipids are fatty acids containing. b. Saturated fatty acids have double bonds at some carbon atoms c. Monounsaturated means the fatty acid is made of one chain of hydrocarbons. d. Most fatty acids in nature are cis-configuration for double bonds. e. Unsaturated fatty acids can pack close together to form close packing to form ordered, rigid arrays as in membranes

D

What is the significance of digitalis, and why does its dosage need careful controlling?

Digitalis is a genus of herbal plants that contain cardiac glycosides named Digitalin (or Digitalis). Because of its narrow therapeutic range ( in other words, high toxicity), its dosage must be monitored carefully.

A Sphingosine does all of the following EXCEPT: a. Forms a ceramide via amide linkage with a fatty acid b. Forms a sphingomyelin by further esterification of the hydroxyl group of a ceramide c. Forms glycosphingolipids important in muscle and nerve membranes by having one or more sugars to the ceramide d. Forms Gangliosides with three or more sugars attached to the ceramide backbone e. Can form Lanolin and cetyl palmitate

E

A fatty acid linked to a sphingosine a. Through acyl carbon linkage b. Through amide linkage c. Gives a ceramide d. Has a glycerol backbone e. Both b and c are correct.

E

All of the following are terpenes EXCEPT: a. Squalene and lanostrerol, the precursors of cholesterol b. side chains of vitamin-K, vitamin-E, α-tocopherol (vitamin E) and β-carotene the precursor of Vitamin A c. Retinal the essential pigment in the eye and lycopene found in tomatoes d. The flavor and odor-giving compounds limonene, citronelle, menthol, etc in flowers and fruits e. cetyl palmitate (spermaceti) in whales

E

Lipid Bilayers are characterized by all of the following EXCEPT: a. Back-to-back arrangements of monolayers b. Phospholipids are the major components of the lipid bilayers c. bilayers form unilamellar liposomes or multilamellar vesicles d. Have a polar surface and nonpolar hydrophobic core e. Proteins and lipids in the lipid bilayer cannot traverse in the lipid bilayer of biological membranes

E

Muscle Ca2+-ATPase resembles Na+, K+-ATPase in many ways EXCEPT: a. Both have α-subunits of similar size. b. Both form covalent E-P intermediates during ATP hydrolysis. c. Both have similar mechanisms of ATP hydrolysis. d. Both have similar ion transport mechanisms. e. Both have residence on the sarcoplasmic reticulum.

E

Transport processes directly driven by ATP does NOT include: a. Na+ and K+ transports b. Ca2+ transport c. Gastric H+ and K+ transports d. Osteoclast H+ V-type transports e. secondary transport of amino acid and sugars

E

Which of the following Does Not apply to steroids? a. Steroids are terpene-based lipids. b. Cholesterol is a steroid . c. Steroids contain methyl groups at some of the carbons in the rings as well as side chains in their structure. d. Plant sterols are steroids which are considered to be effective in blocking the absorption of cholesterol by intestinal cells. e. For humans, all the cholesterol in the body is obtained through diet rich in cholesterol

E

Which of the following applies to integral proteins with multiple TMS? a. The primary sequence of several TMS proteins contain numerous hydrophobic α-helical segments b. Bacteriorhodopsin of halobacterium is an example of multi-TMS with α-helical segments c. Porins are examples of multiple TMS proteins with β-sheets and β-turns. d. Membrane proteins with multiple TMS are often transport proteins e. All of the above

E

Which of the following does not apply to Glycophorin? a. It is an integral membrane protein b. It has only one transmembrane segment c. The transmembrane segment is an α-helix d. The oligosaccharide (sugar) hydrophilic groups of the protein constitute the ABO and MN blood group antigen specificities of the red blood cells, and act as receptors for influenza virus e. The oligosaccaharide hydrophilic groups form the intracellular domain oriented towards the inner cytoplasmic fluid

E

Which of the following does not apply to the Na+, K+-ATPase active transport mechanism? a. Na+, K+-ATPase is an integral membrane protein b. This active transport helps maintain cell volume, shape, for neurons to communicate, for secondary transport of amino acids, sugars, and other substances. c. This sodium pump actively pumps three Na+ ions out of the cell and two K+ ions into the cell for every ATP hydrolysis d. ATP hydrolysis occurs on the cytoplasmic side of the membrane instead of in the extracellular domain e. The net movement of number of Na+ ions per cycl makes the sodium pump process electrical neutrality.

E

Which of the following is False for biological membranes? a. They are uniquely organized arrays of lipids and proteins b. They constitute boundaries of cells and organelles c. They provide a surface for many important biological processes to occur d. Membranes have proteins that regulate and transport many important molecules e. All proteins of the biological membranes are deeply embedded in the membrane.

E

Which of the following is NOT a fatty acid lipid? a. Glycerophospholipids b. Ether Glycerophospholipids c. Sphingolipids d. Waxes e. Steroids

E

Which of the following is false about glycerophospholipids? a. It is a 1,2-diglycerol, that has a phosphate esterified at carbon atom 3 of the glycerol backbone b. Number 2 carbon of a phoshpholipid is asymmetric (chiral), whereas the carbons in the regular glycerol is only prochiral c. Phosphatidic acid is the parent compound of glycerol-based phospholipids d. The phosphate group of the phosphatidic acid becomes further esterified with other organic molecules to form phosphatidates e. None of the above is false.

E

Which of the following is false about lipids? a. They are poorly soluble in water and aggregate making them suitable for membrane formation b. Largely hydrocarbon in nature and can form bilayers c. Represent highly reduced forms of carbon d. Lipids found in biological membranes are amphipathic e. None of the above

E

Which of the following is false about triglycerides? a. Body fat is mainly stored as triglycerides b. Oxidation yields large amount of energy as compared to carbohydrates and proteins c. Body fat in the form of triglycerides also has high insulation properties. d. Has glycerol backbone where the hydroxyl groups are esterified with three fatty acids e. All three fatty acid chains in the triglycerides must be the same.

E

Which of the following transport proteins are involved in Facilitated Diffusion? a. Glucose Transport Protein b. Anion Transport Protein c. Na+,K+-ATPase d. Ca2+ - ATPase e. Both a and b are involved in facilitated diffusion

E

What are the uses of sphingolipids such as sphingomyelins?

IMPORTANT IN NERVOUS TISSUE IN ANIMALS

Trans fatty acids are considered to have deleterious effects on heart because, they raise plasma _________________________ and _________________________ levels and lower the _______________________levels.

LDL, CHOLESTEROL, TRIGLYCERIDES

Give an example of a cardiac glycoside.

Ouabain

Although vegetable oils are generally higher in proportion of unsaturated fatty acids than animal fats and oils, several plant oils have very high saturated fats. Examples include _____________________ and _______________________oils.

PALM, COCONUT

If you were a researcher trying to come up with an antidote for this venom poison, what would be the most likely antidote that you should think of?

PHOSPHOLIPASE INHIBITORS

Terpenes and terpene derived molecules are found in a variety of fruits and vegetables, and they have several uses in our body giving rise to vitamins and steriods. Explain with examples .

Squalene and lanosterol are precursors to cholesterol, beta carotinoid is precursor to vitamin A.

The type of lipids stored by polar bears for their survival during long periods of fasting is ___________________________

TRIGLYCEROLS

Although glycosphingolipids are useful at low concentration, accumulation of these molecules can have deleterious effects. Given an example of a genetically transmitted disease that results in accumulation of glycophospholipds; explain the mechanism and what are the outcomes of such a disease.

Tay-Sachs- lack of lysosomal hydrolytic enzymes in brain leads to accumulation of non-degraded lipids which leads to cell swelling (due to osmosis) and eventually cell death.

What are the uses of glycosphingolipids?

Tissue and organ specificity, cell-cell recognition, tissue immunity, nerve impulse transmission.

Why do birds avoid eating both monarch and viceroy butterflies?

Viceroy butterflies mimic monarchs in appearance; monarchs store cardiac glycosides in their exoskeleton.

Discuss the uses of waxes not only for human applications but in other living organisms as well.

WATERPROOF COATING

From the "Deeper look" section on page 180 answer the following question. In addition to the glycoporin protein there are other single TMS proteins that play important roles in human body. Explain this from the point of immune system (in your own words) and give examples.

act as recognition sites to differentiate host vs foreign antigens/cells/viruses..

How do the antiallergy medications Allegra, Claritin, Zyrtec, etc. work? What is the biochemical mechanism, based on involvement of cell membrane proteins, and what molecule is involved in triggering the allergic reactions?

bind to histamine receptors to prevent response to allergens.

This molecule can either be a rodent poison, or can also be an anticoagulant to reduce the risk of heart disease and strokes. How can it be used for such two disparate purposes? Explain in your own words, the mechanisms by which these two applications are possible.

depends on dosage. right dosage gives anticoagulant function, overdose leads to hemorrhage and death.

Why is of Na+,K+-ATPase implicated in hypertension (high blood pressure) and which inhibitor of this transport system in thought to be involved?

inhibitors of NA K-ATPase and are narrow blood vessels (vasocontriction).

What is Coumadin (also known as Warfarin) in terms of its structure?

isoprene-derived molecule

Lipid bilayers form liposomes which are useful in many ways in healthcare. Explain this in terms of drug delivery and diagnostic imaging purposes.

target specific cells for drug delivery, used for contrast agents for diagnostic imaging.