Lipids

Question 1

What are the 2 structures that lipids can be broken down into?

Answer 1

fatty acids and isoprenoids

Question 2

How do we name fatty acids? 2 methods.

Answer 2

:D^123

#= number of carbons
D= number of double bonds (db)
^123= 1st carbon of each db, counting from the acid end

OR

#= “ “
D= “ “
(omega - 3) = first carbon of first db counting from the methyl end, each subsequent db is then 3 carbons away

Question 3

What are the 2 types of unsaturated fatty acids?

Answer 3

Cis and trans

Question 4

Which form of unsaturated fats create a “bend” in the structure?

Answer 4

Cis

Question 5

Does a bend in the structure increase or decrease membrane fluidity?

Answer 5

Increases

Question 6

Do cis bonds allow for tighter or looser packing of phospholipids?

Answer 6

looser

Question 7

Which type of unsaturated fats are mostly from naturally made fats?

Answer 7

cis

Question 8

What are the 2 sources of trans fats?

Answer 8

1.) Some made naturally by gut bacteria of ruminants, meat.
2.) Most made commercially as a by-product of partial hydrogenation

Question 9

Partially hydrogenation targets cis-bonds in fatty acids to:

A) Remove hydrogens and turn oils into solid fats
B) Remove hydrogens and turn solid fats into oils
C) Add hydrogens and turn oils into solid fats
D) Add hydrogens and turn solid fats into oils

Answer 9

C.) Add hydrogens and turn oils into solid fats

Question 10

What is the by product of partial hydrogenation?

Answer 10

trans bonds

Question 11

Less that how many grams per serving can be labelled as “0% trans fat”?

Answer 11

.5 g per serving

Question 12

Where are fatty acids synthesized?

Answer 12

cytoplasm

Question 13

Which fatty acid is usually synthesized? How many carbon?

Answer 13

16:0 palmitate

Question 14

What are fatty acid substrates?

Answer 14

Acetyl CoA and malonyl CoA

Question 15

Malonyl CoA is acetyl CoA with what extra group added?

Answer 15

CO2

Question 16

With fatty acid synthase, how many fatty acid chains can be made at once?

Answer 16

2

Question 17

What are 3 coenzymes that could be involved in FA synthesis?

Answer 17

B7, B5, B3

Question 18

What does B7 (biotin) do in FAS?

Answer 18

Helps add CO2 to acetyl CoA to make malonyl CoA

Question 19

What does B5 do in FAS?

Answer 19

Part of fatty acid synthase
Part of acetyl CoA and malonyl CoA

Question 20

What does B3 do in FAS?

Answer 20

Reduced the FA chain

Question 21

What are the steps of FA synthesis?

Answer 21

1.) acetyl group joins
2.) malonyl group joins
3.) acetyl and malonyl groups condense with loss of CO2
4.) O removed as water, NADPH donates H’s
5.) FA chain shifts over

Question 22

If we can only make 2 FA chains at once, how do we get a 16 carbon chain?

Answer 22

Keep repeating steps 2-4

Question 23

How do you separate the FA chain from the enzyme?

Answer 23

Use water to break the bond

Question 24

How do you make a chain bigger than 16C? Where does this happen?

Answer 24

Elongate using enzymes embedded in the ER membrane. ER. Similar steps, different enzymes

Question 25

How do you make odd-numbered fatty acid chains?

Answer 25

Start with propionyl CoA (3C) rather than acetyl CoA (2C) in step one can make odd number chains.

Question 26

How do you get unsaturated FAs? (2)

Answer 26

1.) Made in ER: Desaturase enzymes use NAD(P)H (B3) to create double bonds 2.) Others are essential, from diet. (linoleic acid), plants

Question 27

What do fatty acids support?

Answer 27

cardiovascular, immune, reproductive and nervous systems

Question 28

What kind of fatty acid is alpha- linolenic acid?

Answer 28

Omega-3

Question 29

What kind of fatty acid in linolenic acid?

Answer 29

Omega-6

Question 30

What kind of il has a high level of linoleic acid?

Answer 30

vegetable oils

Question 31

When is epinephrine released?

Answer 31

Sympathetic responses (flight or fight)

Question 32

Synthesis is oppositely regulated to ______________.

Answer 32

breakdown

Question 33

Glucagon promotes (beta ox / FA synthesis) and therefore (increases / decreases) FA synthesis.

Answer 33

beta ox decreases

Question 34

Insulin promotes (beta ox / FA synthesis) and therefore (increase / decrease) beta ox

Answer 34

FA synthesis, decreases

Question 35

Epinephrine promotes (beta ox/FAS) and therefore decreases/increases FAS.

Answer 35

beta ox decreases

Question 36

What are the 3 regulators of fatty acid synthesis? And what do they do?

Answer 36

Glucagon and epinephrine (inhibit acetyl CoA carboxylase) Insulin (activates acetyl CoA carboxylase)

Question 37

Acetyl CoA will be inhibited by phosphorus. True or False

Answer 37

True

Question 38

What are the 2 outcomes of the inhibition of acetyl CoA carboxylase, and the lowering of malonyl CoA

Answer 38

1.) decreased substrate for FA --> decreased FAS 2.) increased transport of FAs into the mitochondria --> increased beta oxidation

Question 39

Triglycerides are 3 fatty acids attached to a _____________ backbone via an _____________ link.

Answer 39

glycerol ester

Question 40

What do FAs provide?

Answer 40

energy and insulation

Question 41

True or False. TGs pack tighter and therefore store energy more efficienty.

Answer 41

TGs

Question 42

Where does lipogenesis take place?

Answer 42

cytosol

Question 43

Steps of lipogenesis

Answer 43

1.) Addition of 2 FAs to a glycerol backbone 2.) Make substrates (glycerol-3-phosphate backbone and 3 fatty acyl CoAs) 3.) Transfer 2 FA chains to the backbone sequentially 4.) Replace the phosphate on the backbone with the 3rd FA chain

Question 44

What enzyme adds a phosphate to glycerol?

Answer 44

glycerol kinase

Question 45

In adipose and liver, what enzyme is used to convert DHAP to glycerol-3-phosphate using what enzyme?

Answer 45

glycerol-3-phosphate dehydrogenase

Question 46

What acts to carry the FA chains to the backbone and transfer them over from FA to fatty acyl CoA?

Answer 46

ATP

Question 47

What do both phospholipids and glycosphingolipids both contain what 3 things?

Answer 47

1.) a backbone 2.) lipid 3.) head group

Question 48

Phosphoglycerides contain what 2 things?

Answer 48

1.) glycerol backbone 2.) 2 fatty acid chains

Question 49

What 2 things do sphingolipids?

Answer 49

1.) sphingosine backbone 2.) ceramide: sphingosine (includes a fatty chain), plus and additional FA chain

Question 50

What are 3 sphingolipids?

Answer 50

1.) sphingomyelin 2.) cerebrosides 3.) gangliosides

Question 51

What are 2 phosoholipids?

Answer 51

1.) phosphatidates 2.) sphingomyelin

Question 52

What structures have a polar phosphate-alcohol head?

Answer 52

phospholipids

Question 53

What structures have a carbohydrate head?

Answer 53

glycosphingolipids

Question 54

What are the 3 major kinds of cell membrane lipids in animals?

Answer 54

glycolipids, phospholipids and cholesterol

Question 55

Where are phospholipids synthesized?

Answer 55

cytosol

Question 56

What 2 ways is glycerol-3-P made?

Answer 56

1.) Glycerol-3-phosphate is made from dihydroxyacetone phosphate (DHAP) in liver and adipose tissue. 2.) The liver can also convert glycerol into glycerol-3-phosphate.

Question 57

Once you have phosphatidic acid, how do you get to other phopholipids? What is added then removed in this process? What substitution is necessary?

Answer 57

1.) Phosphatidic acid is dephosphorylated 2.) Additional head groups are added: Different head groups are added to the remaining diacylglycerol (DAG) backbone 3.) CMP 4.) Nucleophilic

Question 58

What is the difference between the 2 phosolipid groups, glycerophospholipids and sphingomyelin?

Answer 58

It has a sphingosine back bone, rather than a glycerol backbone.

Question 59

What is the same between the 2 phospholipid groups?

Answer 59

both have 2 fatty acid-like tails

Question 60

What group do cerebrosides and gangliosides belong to?

Answer 60

sphingolipids (glycosphingolipids)

Question 61

What differentiates sphingomyelin and cerebrosides/gangliosides?

Answer 61

sm has a phosphorous head group c/g have carbohydrate head group G: 1 or more sialic acid PLUS 1 or more additional monosaccharide C: monosaccharide head group ***sulfatide if additionally sulfated

Question 62

Which type of sphingolipid has a polar and nonpolar part?

Answer 62

Ganglioside

Question 63

What is sphingolipid storage disease (spingolipidases)? Most common example?

Answer 63

accumulation of sphingolipids usually fatal by 5 years old Tay-Sachs Disease GM2 accumulates in lysosome due to enzyme deficiency Most severe excesses occur in brain= neural cell damage

Question 64

What are eicosanoids derived from? (2)

Answer 64

1.) arachidonic acid (20:4) 2.) 20 C FAs

Question 65

What is a common eicosanoid?

Answer 65

prostaglandin

Question 66

What are 3 physiological functions of eicosanoids?

Answer 66

1.) vasodilation 2.) vasoconstriction 3.) platelet aggregation

Question 67

What is a mixture FAs linked to long-chain hydrocarbon alcohols via ester bonds?

Answer 67

wax (the simplest FA esters) non polar

Question 68

What is an isoprene unit linked together called?

Answer 68

isoprene

Question 69

What forms could terpenes be?

Answer 69

alcohol, aldehyde, ring

Question 70

What is the smallest terpene? How many isoprene units?

Answer 70

monoterpene, 2

Question 71

What is a sesqui (1.5) terpene called?

Answer 71

Farnescene

Question 72

What is a triperpene called?

Answer 72

squalene

Question 73

What is a tetraterpene called?

Answer 73

beta cartene

Question 74

What is a mixed terpene?

Answer 74

terpene + non- terpene ex: CoQ, vit K, farnesylated proteins

Question 75

How many isoprene units make up a steroid?

Answer 75

6 (4 fused rings with various substituents)

Question 76

What are steroids made from?

Answer 76

cholesterol

Question 77

Cholesterol synthesis starts with 3 of what molecule, making which intermediate?

Answer 77

acetyl-CoA into 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA)

Question 78

In cholesterol synthesis, what is the rate limiting enzyme? What does it do? What does high cholesterol do to this enzyme?

Answer 78

HMG-CoA reductase catalyzes the conversion of HMG-CoA to mevalonate, a key step in the pathway. Regulation of HMG-CoA reductase is vital for maintaining cholesterol homeostasis in the body. When cholesterol levels are elevated, it inhibits the activity of HMG-CoA reductase, thus reducing the production of cholesterol. This regulatory mechanism helps prevent excessive accumulation of cholesterol in cells.

Question 79

What class of pharma drugs inhibits this enzyme?

Answer 79

statins

Question 80

What isoprenoid is formed that is ultimately converted to the cyclic structure of cholesterol?

Answer 80

In the pathway of cholesterol synthesis, an isoprenoid called farnesyl pyrophosphate (FPP) is formed. FPP serves as a precursor for various molecules, including squalene. Squalene is then converted to lanosterol, which eventually leads to the formation of the cyclic structure of cholesterol.

Question 81

Cholesterol synthesis

Answer 81

1.) 3 A-COA 2.)HMG CoA a.) ketogenesis b.) rate limiting step i.) HMG-CoA reductase begins synthesis ii.) HMG- CoA r. blocked by high cholesterol levels or statin drugs 3.) mevalonate 4.) isopentenyl pyrophosphate (isoprene units) 5.) squalene 6.) cholesterol

Question 82

Where does most cholesterol synthesis occur?

Answer 82

liver

Question 83

What does the liver do with cholesterol?

Answer 83

1.) make bile 2.) make lipoproteins (LDL) to carry cholesterol to the tissues --> binds on cell and taken in --> broken down inside --> chol. released

Question 84

What is familial hypercholesteremia?

Answer 84

inherited defect in LDL-receptors (increase circulated LDL, therefore cholesterol in the blood increase risk of myocardial infarction

Question 85

What is the precursor to steroid hormones?

Answer 85

cholesterol

Question 86

What is cholesterol first converted to, which is then converted to various other steroid hormones?

Answer 86

pregnenolone

Question 87

What can compete with intestinal cholesterol absorption? What do they help?

Answer 87

plant sterols lower LDL cholesterol levels

Question 88

Cardiac glycosides are derivatives of what?

Answer 88

plant sterols

Question 89

What does digoxin do? (cardiac glycoside)

Answer 89

Increase heart contractility and decrease rate