Lipids

Question 1

*What are lipids? List the 5 types of lipids and their functions

Answer 1

Lipids- molecules that are not soluble in water; but soluble in organic solvents.
5 types of Lipids:
1. Free Fatty acids- a common fuel (source of energy)
2. Triacylglycerols - storage form of fatty acids
3. Phospholipids- membrane lipids
4. Glycolipids- membrane lipids composed in part of carbohydrates
5. Steroids- polycyclic hydrocarbons with a variety of functions (hormones, ex: cholesterol)

Question 2

*Differentiate between saturated and unsaturated fatty acids?

Answer 2

Unsaturated fatty acids have double bonds, meanwhile, saturated fatty acids have no double bonds (single c-c bonds)
ex: Palmitate- saturated fatty acid (16 C, COO-, methyl)
Oleate- unsaturated fatty acid (18 c, Coo-, methyl) that contains cis double bond.

Question 3

*Describe the nomenclature of fatty acids. What is the omega carbon ?

Answer 3

Fatty acids carbon atoms are usually numbered beginning from the carboxyl terminal carbon (1st position).
Carbon atoms 2 and 3 are referred to as alpha and Beta.
Fatty acids can also be numbered from Omega carbon, which is the methyl carbon atom that is usually seen at end of chain.

Question 4

*Explain what is meant by the melting temperature of fatty acids
What structural characteristic of these fatty acids account for differences in melting points?

Answer 4

The temperature at at which the fatty acids change from solid to liquid form.

Fatty acid chain length and degree of unsaturation (number of cis bonds).
Longer fatty acid chain allows for more Van der Waals interactions between chains. increase in chain length, increases melting point.
As the number of cis double bond increases (higher unsaturation), the melting point decreases.

Question 5

*Why are ω-3 fatty acids important for the human health?

Answer 5

Omega- 3 fatty acids are important for human health because it is good for brain health, prevents thrombosis (inhibit blood clotting), lowers bp and prevent and reduces risk of cardiovascular disease.

Question 6

*What is a triacylglycerol?

Answer 6

Triacylglycerol are the storage form of fatty acids. They are composed of 3 fatty acids and one glycerol backbone that is attached to FA’s through ester bonds.
Triacylglycerols are energy-rich

Question 7

*Explain the relationship between anhydrous fat stores and hydrated glycogen. Which
one lasts longer? For how long?
How are migratory birds able to travel long distances, long journeys without any food.

Answer 7

Anhydrous fat stores are hydrophobic and reduced, so they will store more than 6 times the energy of a gram of hydrated glycogen.
last longer
Migratory birds use fat stores to power long flights without opportunity to feed.

Question 8

*Where are triacylglycerols stored?

Answer 8

In mammals, most triacylglycerols are stored in adipose tissue. Each adipocyte (adipose cell or fat cell) contains large droplet in which triacyclglycerols are housed.

Question 9

*What are the common types of membrane lipids?

Answer 9

1. Phospholipids
2. Glycolipids
3. Cholesterol

Question 10

*Explain the special role cholesterol plays in the cell

Answer 10

Steroid that maintains fluidity in the membrane

Question 11

*what is meant by the phrase “membrane lipids are amphipathic molecules”? Also discern between which part of membrane displays each propery.

Answer 11

amphiphatic- molecules containing both hydrophobic and hydrophilic properties.
Fatty acid components- hydrophobic properties
Alcohol and phosphate components called polar head group- hydrophilic properties.

Question 12

*What is the cause of “Hutchinson-Gilford progeria syndrome”?

Answer 12

Inappropriate farnesylation is the cause of Hutchinson-Gilford progeria.
Failure to remove a farnesyl group from nuclear protein Lamin- resulting in deformed nuclear membrane and impaired nuclear function.

Question 13

Why are cis polyunsaturated fatty acids essential in human diet, and what role do they play?

Answer 13

Cis poly unsaturated acids are essential components of our diet because humans cannot synthesize them.
These fatty acids are precursors to a variety of hormones and offer protection from coronary heart disease.
ex:omega-3 fatty acids like alpha-Lineolate (walnuts, vegetable oil), eiscospentaneoate (EPA, fish oil), Docasahexaenoate (DHA, salmon)

Question 14

What is soap made from and how is it generated?

Answer 14

Soaps are sodium or potassium salts of fatty acids, that are generated by treating triacyclglycerols with a strong base.

Question 15

Why are proteins sometimes modified by covalent attachments?

Answer 15

proteins are covalently bonded to lipids to localize protein to cell membrane.

Question 16

What are the composition of membrane lipids of extremophiles and what role do these structures play?

Answer 16

Membrane lipids are made of ESTER linkages and BRANCHING structures of membrane lipids.
They prevent hydrolysis and oxidation of membrane in harsh environments.

Question 17

What is the most common steroid and what role does it play?

What kind of structures play role of cholesterol in plants, and prokaryotes?

Answer 17

Most common steroid- cholesterol
cholesterol maintains membrane fluidity.
Hopanoids like and various sterols play role of cholesterol in plants and prokaryotes.
ex: Sitosterol (plant sterol; 1 more methyl than cholesterol) and Diplopterol (hopanoid)

Question 18

What is the most common steroid and what role does it play?

What kind of structures play role of cholesterol in plants, and prokaryotes?

Answer 18

Most common steroid- cholesterol
cholesterol maintains membrane fluidity.
Cholesterols are also precursor to steroid hormones
Hopanoids like and various sterols play role of cholesterol in plants and prokaryotes.
ex: Sitosterol (plant sterol; 1 more methyl than cholesterol) and Diplopterol (hopanoid)

Question 19

What are steroids and what structures do they consist of?

Answer 19

Steroids are lipids that have a variety of roles

They are built on tetracyclic platforms that consist of 3 cyclohexane rings and a cyclopentane ring fused together.

Question 20

Describe what glycolipids are. its component roles and provide an example.

Answer 20

Glycolipids are carbohydrate-containing lipids.
The carbohydrate components are on extracellular surface of cell membrane, where they play a role in cell-cell interactions.
Ex: cerebrosides (neurons and muscle cells) are simplest glycolipids.

Question 21

Name the components of phospholipids and where the major phospholipids are derived from.
What are the platforms of phospholipids and what do you call phospholipid with glycerol?

Answer 21

Phospholipids are composed of 4 components:
fatty acids (2 or more), a platform, a phosphate and an alcohol.
the 2 common platforms of phospholipids are glycerol and sphingosine
phospholipids with a glycerol platform are called phosphogylcerides or phosphoglycerols.
major phospholipids are derived from phosphatidate.

Question 22

What are the composition of membrane lipids of extremophiles and what role do these structures play?

Answer 22

Membrane lipids are made of ETHER linkages and BRANCHING structures of membrane lipids.
They prevent hydrolysis and oxidation of membrane in harsh environments.

Question 23

What is the most common steroid and what role does it play?

What kind of structures play role of cholesterol in plants, and prokaryotes?

Answer 23

Most common steroid- cholesterol
cholesterol maintains membrane fluidity.
Cholesterols are also precursor to steroid hormones
Hopanoids and various sterols play role of cholesterol in plants and prokaryotes.
ex: Sitosterol (plant sterol; 1 more methyl than cholesterol) and Diplopterol (hopanoid)

Question 24

Explain what Diabetic Retinopathy is and what may possibly cause the disease. Also discuss the uses of DHA (docosahexaneoate) and other compounds involved.

Answer 24

Diabetic retinopathy- complications of diabetes (both type 1, and type 2), where the blood vessels in retina are damaged leading to impaired vision or eventual blindness.
inappropriate DHA metabolism may result in diabetic retinopathy.
DHA (docosahexaeoate)- fatty acid known to provide protection from cardiovascular disease and maintenance of brain and eye function. some of health benefits may be due to actions of metabolites of DHA like epoxydocasapentaenoate (19, 20 EDP)

The overproduction of 19, 20 EDP may lead to development of diabetic retinopathy.
soluble epoxide hydrolase that processes EDP may be therapeutic target for treatment of the retinopathy.
Genetic suppression of the expression of hydrolase gene or pharmalogical inhibition of enzyme activity prevents blindness.

Question 25

Explain what Diabetic Retinopathy is and what may possibly cause the disease. Also discuss the uses of DHA (docosahexaneoate) and other compounds involved.

What is a form of treatment for this retinopathy?

Answer 25

Diabetic retinopathy- complications of diabetes (both type 1, and type 2), where the blood vessels in retina are damaged leading to impaired vision or eventual blindness.
inappropriate DHA metabolism may result in diabetic retinopathy.
DHA (docosahexaeoate)- fatty acid known to provide protection from cardiovascular disease and maintenance of brain and eye function. some of health benefits may be due to actions of metabolites of DHA like epoxydocasapentaenoate (19, 20 EDP)

The overproduction of 19, 20 EDP may lead to development of diabetic retinopathy.
soluble epoxide hydrolase that processes EDP may be therapeutic target for treatment of the retinopathy.
Genetic suppression of the expression of hydrolase gene or pharmalogical inhibition of enzyme activity prevents blindness.