Lecture 15 - Lipids

Question 1

Fatty acids are water _______ (insoluble/soluble) biomolecules that are highly ______ (insoluble/soluble) in organic solvents

Answer 1

insoluble, soluble

Question 2

What properties of lipids are due to fatty acids?

Answer 2

Hydrophobic properties

Question 3

As the fatty acid tail gets longer, what happen to the solubility?

Answer 3

It becomes more insoluble

Question 4

What are the most biologically significant properties of lipids?

Answer 4

the hydrophobic properties (contributed by fatty acids)

Question 5

What makes up a fatty acid?

Answer 5

Hydrocarbon chains of various length and degrees of unsaturation that terminate with carboxylic acid group

Question 6

Fatty Acids are the building blocks of what two biological membrane components?

Answer 6

Phospholipids and glycolipids

Question 7

Many proteins can be modified. What is one way that involves fatty acids?

Answer 7

Covalent attach of fatty acid to the protein, allowing it to target membranes

Question 8

How are fuel molecules stores?

Answer 8

As Triacylglycerols

Question 9

Derivatives of fatty acids serve as:

Answer 9

Hormones Signal Molecules Intracellular messengers

Question 10

Review nomenclature

Answer 10

Slide 6

Question 11

Steps for Numbering the Carbon Atoms

Answer 11

Start at the carboxyl terminus Carbon 2 and 3 are also referred to alpha and beta The methyl carbon atom at the distal end of the chain is called the omega carbon

Question 12

Numbering Double Bonds

Answer 12

Position of double bound is represented by ∆ followed by a superscript number Position can also be denoted by counting from the distal end (methyl group), with the omega carbon atom as number one

Question 13

Do fatty acids typically contain an even or odd amount of C atoms and typically how many?

Answer 13

Even 14 and 24

Question 14

What are the lengths of the most common fatty acids?

Answer 14

16 and 18

Question 15

What is the configuration of the double bonds in most unsaturated fatty acids?

Answer 15

cis

Question 16

What happens to a fatty acid at physiological pH?

Answer 16

It is ionized

Question 17

Unsaturated fatty acids have a _____ melting point than saturated fatty acids of the same length

Answer 17

lower

Question 18

What happens to the melting point of saturated fatty acids as the chain length increases?

Answer 18

The melting point also increases longer chain = higher melting point

Question 19

Name the essential fatty acids

Answer 19

Omega-6: Linoleate and Arachidonate Omega-3: Linolenate

Question 20

Linoleate # of C’s, # of double bonds, and systemic name

Answer 20

C’s = 18 Double bonds = 2 Systemic name: cis,cis-∆9,∆12 or octadecadienoate

Question 21

Arachidonate # of C’s, # of double bonds, and systemic name

Answer 21

C’s = 20 DB’s = 4 Systemic name: all-cis ∆5,∆8,∆11,-∆14 Eicosatetraenoate

Question 22

Linolenate # of C’s, # of double bonds, and systemic name

Answer 22

C’s = 18 DB’s = 3 Systemic name: all-cis ∆9,∆12,∆15 Octadecatrienoate

Question 23

Name the two non-essential fatty acids

Answer 23

Palmitate and Stearate

Question 24

Palmitate # of C’s and systemic name

Answer 24

16 n-Hexadecanoate

Question 25

Stearate # of C's and systemic name

Answer 25

18 n-Octadecanoate

Question 26

Why is the archaeon membrane lipid able to withstand such an extreme environment?

Answer 26

The ether linkage is more resistant to hydrolysis The branched and saturated hydrocarbons are more resistant to oxidation

Question 27

What are the three major membrane lipids?

Answer 27

Phospholipids Glycolipids Cholesterol

Question 28

Give two examples of phospholipid

Answer 28

Phosphoglyceride and Sphingomyelin

Question 29

Give one example of a Glycolipid

Answer 29

Cerebroside

Question 30

What are the 4 components of a phospholipid?

Answer 30

Fatty Acid A backbone to which fatty acids are attached A phosphate An alcohol attached to phosphate

Question 31

What is the backbone of a phospholipid made up of?

Answer 31

Glycerol (3-C alcohol; phosphoglycerides) or a sphingosine (a more complex alcohol; sphingomyelin)

Question 32

Identify this Phosphoglyceride

Answer 32

Phosphatidate or diacylglycerol 3-phosphate A key intermediate in the biolsynthesis or other phosphoglycerides \*only a small amount of phosphatidate are present in membranes

Question 33

Identify this structure and its function

Answer 33

Phosphatidylserine Important for memory and cognition

Question 34

Identify this structure and its function

Answer 34

Phosphatidylcholine Major constituent of cell membrane and pulmonary surfactant

Question 35

Identify this structure and its function

Answer 35

Phosphatidylethanolamine Composing 25% of all phospholipids Found in nervous tissue (white matter of the brain)

Question 36

Identify this structure and its function

Answer 36

Phosphatidylinositol Important for signaling and other functional activities in eukaryotic cell

Question 37

Identify this structure and its function

Answer 37

Diphosphatidylglycerol (cardiolipin) Important component of inner mitochondrial membrane

Question 38

What is a Sphingosine?

Answer 38

An amino alcohol that contains a long, unsaturate hydrocarbon chain

Question 39

What is Sphingomyelin?

Answer 39

Phospholipid with the sphingosine as the backbone. The amino group of the sphingosine backbone is linked to a fatty acid by an amide bond

Question 40

Where can you find Sphingomyelin?

Answer 40

In animal cell membranes, especially in the membranous myelin sheat that surrounds some nerve cell axons

Question 41

What are Glycolipids?

Answer 41

Sugar containing lipids

Question 42

What are glycolipids derived from?

Answer 42

Sphingosine

Question 43

How do glycolipids differ from sphingomyelin?

Answer 43

Differ in the identity of the unit that is linked to the primary hydroxyl group of the sphingosine background

Question 44

How are Glycolipids oriented?

Answer 44

Oriented with the sugar residues on the extracellurlar side of the membrane

Question 45

What is the simplest Glycolipid?

Answer 45

Cerebroside

Question 46

What two sugar residues might a cerebroside contain?

Answer 46

Glucose or Galactose

Question 47

Cerebroside is the common name for what group of glycosphingolipids?

Answer 47

Monoglycosylceramides

Question 48

Monoglycosylceramides are important components in what?

Answer 48

Animal muscle and nerve cell membranes

Question 49

The more complex glycolipids called _________ contain a branched chain of as many as _____ sugar residues

Answer 49

Gangliosides Seven

Question 50

Define Cholesterol

Answer 50

A steroid, present in eukaryotes but not in most of prokaryotes, built from 4 fused saturated hydrocarbon rings

Question 51

Why can Cholesterol be further classified as a sterol?

Answer 51

Because of its C3-OH group and its branched aliphatic side chain of 8 to 10 C atoms at C-17

Question 52

What is the most abundant steroid in animals?

Answer 52

Cholesterol

Question 53

Explain how cholesterol is oriented in a membrane

Answer 53

Cholesterol is oriented parallel to the fatty acid chains of the phospholipids, and the hydroxyl group interacts with the nearby phospholipid head group

Question 54

What is the metabolic precursor of steroid hormones?

Answer 54

Cholesterol