Lipids and Membrane Structure

Question 1

What is a Lipid?

Answer 1

They comprise a very large class of compounds that are mostly insoluble in water. 
They are waxy, oily or greasy compounds which coat and protect plants and animals.
They serve as structural components in biological membranes and as a source of stored chemical energy.

Question 2

What are the two classes of Lipids?

Answer 2

Saponifiable and nonsaponifiable lipids.

Question 3

What are Saponifiable lipids? What are the two kinds?

Answer 3

They undergo a chemical hydrolysis when reacted with a strong base.
Simple: waxes and triglycerides (fats and oils)
Complex: Phospholipids and sphingolipids

Question 4

What are Nonsaponifiable lipids? What are the two kinds?

Answer 4

Do not react with a strong base.
Steroids (sterol ring structure)
Prostaglandins (compounds derived from fatty acids)

Question 5

What are fatty acids?

Answer 5

Long chain of carboxylic acids that ranch from about 8-26 carbons in length usually found in even numbered chains.

Question 6

Palmitic Acid

Answer 6

Draw structure. Its saturated. 5 carbon

Question 7

Saturated fatty acids contain how many double bonds?

Answer 7

none

Question 8

Unsaturated fatty acids contain how many double bonds?

Answer 8

one or more

Question 9

What lowers the melting point for a lipid?

Answer 9

• cis configuration called a kink
• one double bond drops melting point 60 degrees
• presence of another double bond drops an additional 10 to 20 degrees.

Question 10

What highers the melting point?

Answer 10

Every two additional carbon atoms adds 7-10 degrees.

Question 11

Saturated fatty acids are abundant in ____ and are _____ at room temperature.

Answer 11

fats, solids

Question 12

Unsaturated fatty acids are found in ____ and so are _____ at room temperature.

Answer 12

oils, liquids

Question 13

The carboxylate end of a fatty acid is _________ and is called the _________.

Answer 13

hydrophilic (water loving), polar head

Question 14

In fatty acids, the long chain of a carbon is _________ and is called the _________.

Answer 14

hydrophobic (water fearing), nonpolar tail

Question 15

What is a micelles?

Answer 15

spherical clusters that come together from nonpolar tails of fatty acids being exposed to water

Question 16

What are soaps?

Answer 16

Fatty acids derived by saponification of fats.

Question 17

What is a Linolenic Acid?

Answer 17

Omega 3 fatty acid. The last double bond is found 3 carbons away from the end of the nonpolar tail.

Question 18

What is a Linoleic acid?

Answer 18

Omega 6 fatty acid. Last double bond is found 6 carbons away from the end of the nonpolar tail.

Question 19

The term fat includes what two components?

Answer 19

3 fatty acids

Glycerol

Question 20

Hydrolysis

Answer 20

Treatment of a triglyceride with strong acid results in the hydrolysis of the three ester bonds holding the fatty acids to the glycerol backbone.

Question 21

Lipase

Answer 21

Natural enzymes which catalyze the hydrolysis of triglycerides in plant and animal tissues through general acid hydrolysis.

Question 22

Saponification

Answer 22

Treatment of a triglyceride with a strong base such as NaOH or KOH

Question 23

Hydrogenation

Answer 23

A simple organic reaction which reduces double bonded carbon atoms to all single bonds. The result: convert unsaturated fatty acids into more saturated species.

Question 24

Waxes

Answer 24

Second group of simple lipids. Structurally different than fats and oils because they do not have a glycerol backbone.

Question 25

Waxes are made up of what two components?

Answer 25

1 fatty acid | 1 long chained alcohol

Question 26

Phosphoglycerides or Phospholipids

Answer 26

Complex lipids which serve as the major structural components of cell membranes.

Question 27

Core structure in a Phospholipid is called...

Answer 27

phosphatidate

Question 28

Difference in Phosphatidates and Tryglycerides is...

Answer 28

1. Phospholipids have DAG's: two fatty acids that occupy the first and second position of the glycerol backbone. 2. Has a different modifying group attached to the phosphate. (contain amine & alcohol group)

Question 29

What are the 5 modifying groups in a phospholipid?

Answer 29

``` Ethanolamine Choline Serine Glycerol Inositol ```

Question 30

What is a lecithin?

Answer 30

Phosphatidyl choline or in other words a phosphoglycerides containing choline.

Question 31

What is a cephalin?

Answer 31

Phosphosglycerides found in the brain tissue that contain either serine or ethanolamine.

Question 32

What is a liposome?

Answer 32

The favored structure of phospho and glycolipids in aqueous solution is a sheet structure. Structures which mimic cellular membranes.

Question 33

What is the sheet structure?

Answer 33

A bi-layer of phospholipids only two molecules thick.

Question 34

Sphingolipids is different from phos and tri how?

Answer 34

1. Contain a backbone called sphingosine 2. One fatty acid attached to the sphingosine backbone called ceramide. 3. Modifying group is attached to the first OH

Question 35

Two types of sphingolipids are:

Answer 35

sphingomyelin and glycolipids

Question 36

What is a Sphingomyelin and where is it found?

Answer 36

Contains a phosphate and a choline like a lecithins. Found in membranes of brain and nerve tissue, also in fast nerves called myelin.

Question 37

What are the two glycolipids?

Answer 37

Simple one is cerebrosides and the complex is gangliosides.

Question 38

What is a cerebroside?

Answer 38

Found in brain tissue. Simple form of glycolipid. Contain sphingosine, fatty acid, and monosaccharide (glucose or galactose)

Question 39

What is a ganglioside?

Answer 39

Similar to cerbroside except more complex small branched sugar attached to the sphingosine.

Question 40

What is a membrane?

Answer 40

Biological structures which separate the cell factory from the environment and are comprised of mostly phospholipid that form sheet like structures only a few molecules thick.

Question 41

Biological membranes are asymmetrical with respect to both ________ and ________.

Answer 41

structure and function

Question 42

__________ and __________ move laterally in the membrane structure but do not readily flip/flop from one side to the other.

Answer 42

Phospholipids and Proteins

Question 43

Phospholipids and Proteins move ________ in the membrane structure and ________ readily flip/flop from one side to the other.

Answer 43

laterally, do not

Question 44

Membranes are ______ structures which allow movement of _______ across the surface.

Answer 44

fluid, proteins

Question 45

Most membranes are polarized by ______ species and so have a net ________ charge.

Answer 45

ionic, negative