CH 5 concept check and questions

Question 1

Which components of membrane lipids contribute to their structural role in membranes and which components contribute to function

Answer 1

membrane lipids are amphipathic
polar heads: hydrophilic
fatty acid tails: hydrophobic
allows them to form bilayers in aqueous solutions

fatty acid tails form the majority of the of the phospholipid bilayer: predominately structural

polar head: functional difference are determined, because of the constant exposure of the exterior environment, can be either the inside or the outside of the cell

structural: fatty acid tails
functional: polar head, and the degree of saturation/unsaturation of the fatty acid tails

Question 2

What is the difference between a sphingolipid that is also a phospholipid and one that is not

Answer 2

difference is between the bond that linked the sphingosine backbone and the polar head group

a sphingolipid that is a phospholipid has a phosphodiester bond

a sphingolipids that is not a phospholipid but instead a glycolipid contain a glycosidic linkage to a sugar

Question 3

Name the three major categories of sphingolipids and their characteristics

Answer 3

sphingomyelin: phospholipid with a phosphatidylethanolamine or phosphatidylcholine functional polar head
glycosphingolipids: glycolipid with sugars (mono or polysaccharide) functional polar head
ganglioside: glycolipid with oligosaccharides and N-acetylneuraminic acid (NANA) aka sialic acid functional polar head

Question 4

What would happen if an amphipathic molecule were placed in a non polar solvent rather than an aqueous solution

Answer 4

it would become soluble in a non-polar solvent

the opposite of what would happen if it was placed into a polar solvent

the hydrophilic polar part of the molecules would be sequestered inside while the non polar hydrophobic part of the molecule would be found on the exterior and exposed to the solvent

Question 5

How many carbons are in diterpene

Answer 5

20

one terpene unit has 2 isoprene units that contain 5 carbons

Question 6

What is the difference between a steroid and a steroid hormone

Answer 6

steroid: defined by its structure, which includes three cyclohexane rings and a cyclopentane ring

steroid hormone: molecule within the steroid class that also functions as a hormone, meaning it travels the bloodstream, is active in low concentrations, has high-affinity receptors, and affects gene expression and metabolism

Question 7

NSAIDS block prostaglandin production in order to reduce pain and inflammation. what do prostaglandins do to bring about these symptoms

Answer 7

prostaglandins regulate the synthesis of cAMP which is involved in many pathways, including those that drive pain and inflammation

prostaglandins synthesis cAMP which is an umbiquotis cell messenger to trigger downstream events such as temperature in fevers, pain, smooth muscle inflammation

Question 8

Name and function of the four fat soluble vitamins

Answer 8

Vitamin A, carotene:
as retinal: vision
as retinoic acid: epithelial development

Vitamin D, cholecalciferol: as calcitriol: calcium and phosphate regulation

Vitamin E, tocopherols: antioxidants, using an aromatic ring

Vitamin K, phylloquinone and menaquiones:
post translational modifications of prothrombin which is a clotting factor
addition of calcium binding sites on many proteins

Question 9

3. Which of the following best describes the structure of steroids

A. three cyclopentane rings, one cyclohexane ring
B. three cyclohexane rings, one cyclopentane ring
C. four carbon rings, differing in structure of each steroid
D. three cyclic carbon rings and a functional group

Answer 9

B. three cyclohexane rings and one cyclopentane ring

the overall structure of each steroid does not differ but the oxidation state of the rings does differ

Question 10

4. Soap bubbles form because fatty acid salts organize into…

A. lysosomes
B. micelles
C. phospholipid bilayers
D. hydrogen bonds

Answer 10

B. micelles

the fatty acids in soap are free fatty acids not phospholipids

fatty acid salt micelles are responsible for the formation of soap bubbles

Question 11

5. Steroid hormones are steroid that:

I: have specific high-affinity receptors
II: travel in the bloodstream from endocrine glands to distant sites
III: affect gene transcription by binding directly to DNA

A. I only
B. III only
C. I and II only
D. I and III only

Answer 11

C. I and III only

steroid hormones are produced in endocrine glands and travel in the bloodstream to bind high-affinity receptors in the nucleus

the hormones receptors binds to DNA as part of the hormone-receptor complex, but the hormone itself does not bind directly to DNA

Question 12

7. Which of the following is correct about fat-soluble vitamins

I: vitamin E is important for calcium regulation
II: vitamin D protects against cancer because it is a biological antioxidants
III: vitamin K is necessary for the post translational introduction of calcium binding sites
IV: vitamin A is metabolized to retinal which is important for site

A. III only
B. I and II only
C. III and IV only
D. II, III, and IV only

Answer 12

C. III and IV only

III: vitamin K is necessary for the post translational introduction of calcium binding sites

IV: vitamin A is metabolized to retinal which is important for site

vitamin E is biological antioxidants

vitamin D is important for calcium regulation

Question 13

8. Which of the following is true of amphipathic molecules

A. they form protective spheres in any solvent, with hydrophobic molecules interior and hydrophilic molecules exterior
B. they have two fatty acid chains and a polar head group
C. they are important to the formation of the phospholipid bilayer and soap bubbles
D. they have a glycerol base

Answer 13

C. they are important for the formation of the phospholipid bilayer and soap bubbles

phospholipids, triacylclylcerols, and fatty acids salts all form amphipathic molecules

only form spheres in an aqueous solution the opposite is true in non polar solvent

phospholipids and sphinoglids are the ones that have two fatty acid chains and a polar head group

triacylglycerols and phospholipids have a glycerol backbone, but fatty acid salts do not

Question 14

9. Which of the following is/ are true about sphingolipids

I: they are all phospholipids
II: they all contain a sphingosine backbone
III: they can have either a phosphodiester or glycosidic linkages to their polar head groups

A. I only
B. III only
C. II and III only
D. I, II, and III only

Answer 14

B. III only, they can have either a phosphodiester or glycosidic linkages to their polar head groups

sphingolipids can either have a phosphodiester bond and therefore are phospholipids or have a glycosidic linkage and therefore can be glycolipids

not all sphingolipids have a sphingosine backbone, they can also have sphingoid backbone

Question 15

10. Which of the following statements about saturation is false

A. it can describe the number of double or triple bonds in a fatty acid tail
B. it determines at least one of the membrane properties
C. more saturated fatty acids make for a more fluid solution
D. fully saturated fatty acids only have single bonds

Answer 15

C. more saturated fatty acids make for a more fluid solution is false

more saturated fatty acids is more solid
more unsaturated fatty acids is more fluid

Question 16

How does the human body store spare energy and why doesn’t the human body store energy as sugar

Answer 16

human body stores energy as glycogen and triacylglycerols

triacylglycerols are preferred because their carbons are more reduced, resulting in a larger amount of energy yield per unit weight

due to their hydrophobic nature, triacylglycerols do not need to carry extra weight from hydration (water)

Question 17

Describe the structure and function of triacylglycerols

Answer 17

triacylglycerols are also called triglycerides

composed of a glycerol backbone esterified to three fatty acids

the fatty acid tails are usually all different

used for energy storage

Question 18

What bonds are broken during saponification

Answer 18

ester bonds of triglycerides are broken to form a glycerol molecule and the salts fo fatty acids (soap)

Question 19

Why does soap appear to dissolve in water and how is this important for cleaning

Answer 19

soap appears to dissolve in water because amphipathic free fatty acid salts form micelles, with hydrophobic fatty acid tails toward the center and carboxylate groups facing outward toward the water

fat soluble particles can then dissolve inside the micelles, in soap and water solution and then wash away

water soluble compounds can freely dissolve in the water

Question 20

1. Which of the following is NOT a type of glycolipid

A. Cerebroside
B. Globoside
C. Ganglioside
D. Sphingomyelin

Answer 20

D. Sphingomyelin

glycolipids contain sugar moieties connected to their backbone

sphingomyelin is not a glycolipid but is a phospholipid because it has a phosphate backbone, can have a phosphatidylcholine or phosphatidylethanolamine as a head group and therefore contains a phosphodiester, not glycosidic bond

Question 21

2. During saponification…

A. triacylglycerols undergo a condensation reaction
B. triacylglycerols undergo ester hydrolysis
C. fatty acid salts are produced using a strong acid
D. fatty acid salts are bound to albumin

Answer 21

B. triacylglycerols undergo ester hydrolysis

saponification is the ester hydrolysis of triacylglycerol using a strong base like sodium or potassium hydroxide to form glycerol and fatty acid salts

not a condensation reaction

fatty acids do travel in the bloodstream bound to serum albumin but this is irrelevant to saponification

Question 22

6. Why are triacylglycerols used in the human body for energy storage

A. they are highly hydrated and therefore can store lots of energy
B. they always have short fatty acid chains for easy access by metabolic enzymes
C. the carbon atoms of the fatty acid chains are highly reduced and therefore yield more energy upon oxidation
D. polysaccharides, which would actually be a better energy storage form, would dissolve in the body

Answer 22

C. the carbon atoms of the fatty acid chains are highly reduced and therefore yield more energy upon oxidation

triacylglycerols are highly hydrophobic so are not hydrated, making them lighter and less heavy, they are more energy dense

fatty acid chains produce twice as much energy as polysaccharides during oxidation because they are highly reduced

fatty acids chains vary in length and saturation

Question 23

11. Which of the following is true about glycerophospholipids

A. glycerophospholipids can sometimes be sphingolipids, depending on the bonds in their head group
B. glycerophospholipids are merely a subset of phospholipids
C. glycerophospholipids are used in the ABO blood typing system
D. glycerophospholipids have one glycerol, one polar head group, and one fatty acid

Answer 23

B. glycerophospholipids are merely a subset of phospholipids

sphingomyelins are a subset of phospholipids as well

glycerophospholipids are never sphingolipids because they contain a glycerol backbone rather than a sphingosine or sphingoid backbone

sphingolipids are used in ABO blood typing tests

glycerophospholipids have a polar head group, glycerol, and two fatty acid tails not just one

Question 24

12. Which of the following statements about terpenes is FALSE

A. terpenes are strongly scented molecules that sometimes form protective functions
B. terpenes are steroid precursors
C. a triterpenes is made of three isoprene moieties and therefore has fifteen carbons
D. terpenes are made by plants and insects

Answer 24

C. a triterpenes is made of three isoprene moieties and therefore has fifteen carbons

a triterpene is made of six isoprene moieties not three so therefore it has a 30 carbon backbone

one terpene unit contains two isoprene units and each isoprene unit has 5 carbons

Question 25

13. Which of the following is TRUE about cholesterol

A. cholesterol always increases membrane fluidity in cells
B. cholesterol is a steroid hormone precursor
C. cholesterol is a precursor for vitamin A, which is produced in the skin
D. cholesterol interacts with only the hydrophobic tails of phospholipids

Answer 25

B. cholesterol is a steroid hormone precursor

cholesterol is a steroid hormone precursor that has variable effects on membrane fluidity depending on the temperature

interacts with both the hydrophobic and hydrophilic parts of the membrane

precursor for vitamin D, which can be produced in the skin in a UV-driven reaction

Question 26

14. Which of the following statements regarding prostaglandins is FALSE

A. prostaglandins regulate the synthesis is cAMP
B. prostaglandin synthesis is inhibited by NSAIDS
C. prostaglandins affect pain, inflammation, and smooth muscle functions
D. prostaglandins are endocrine hormones, like steroid hormones

Answer 26

D. prostaglandins are endocrine hormones, like steroid hormones

prostaglandins are paracrine or autocrine signaling molecules, not endocrine

they affect regions close to where they are produced, rather than affecting the whole body

example is when you knee gets hit on something and swelling occurs in your knee but not everywhere in the body

Question 27

15. Which of the following statements regarding waxes is FALSE

A. waxes generally have melting points above room temperature
B. waxes are produced only in plants and insets and therefore must be consumed by humans
C. waxes protect against dehydration and parasites
D. waxes are esters of long-chain fatty acid and long-chain alcohols

Answer 27

B. waxes are produced only in plants and insets and therefore must be consumed by humans

waxes are also produced in animals for similar protective functions and example in humans is earwax