Biochem Final Exam

Front 1

What are the 2 subunits of ATP synthase? What does each do?

Back 1

Fo (oligomycin) is the proton channel.
F1 is the ATP synthesis part.

Front 2

Why does it take 4 protons to make ATP instead of 3?

Back 2

3 are required to turn the synthase 360 degrees. However, free Pi must be in matrix to create ATP. A proton is co-transported with Pi into the matrix. This is why 4 protons make 1ATP.

Front 3

What does E° tell you?

Back 3

The more negative E°, the more likely a compound will release/transfer electrons.

Front 4

What is the function of ubiquinone?

Back 4

It transfers either 1 or 2 electrons from complex I/II to complex III.

Front 5

What is the function of cytochrome C? Which membrane is it found on?

Back 5

Transfer electrons between complex III and IV.
Outer mitochondrial membrane

Front 6

What is the name of complex I? What about complex II? What accounts for the fact that FADH2 only gets you 1.5ATP whereas NADH gets you 2.5?

Back 6

Complex I or NADH dehydrogenase.
Complex II or Succinate dehydrogenase
FADH2 feeds into complex II which doesn't pump protons.
NADH feeds into complex I which pumps 4 protons.

Front 7

What are the components of the electron transport chain?

Back 7

Complex I pumps 4 protons, passes electrons to Ubiquinone.
Complex II pumps no protons, also passes to Ubiquinone.
Ubiquinone passes to complex III which pumps 4 protons. Complex III (cytochrome reductase) passes to cytochrome c and reduces it.
Cytochrome c then is oxidized by complex IV which pumps 2 protons.
Finally the electrons are given to Oxygen.

Front 8

Which 2 compounds inhibit complex I?
What compound inhibits complex III?
What compound inhibits complex IV?

Back 8

Rotenone and amytal
Antimycin
Cyanide

Front 9

How does dinitrophenol work?

Back 9

Binds protons on the outer surface of the mitochondria. Moves through into matrix and releases protons. As a result, it kind of uncouples the gradient.

Front 10

Name the 3 hormones that adipose tissue releases? What are their functions?

Back 10

Adiponectin, resistin - peptide hormones assoc. with insulin resistance.
Leptin - controls appetite.

Front 11

What type of enzyme is the insulin receptor? How does it function?

Back 11

Tyrosine kinase.
It has 2 alpha and 2 beta subunits. The alpha subunits inhibit the beta subunits from phosphorylating. When insulin binds, the alpha subunits are changed so their inhibition is removed.

Front 12

Name the 4 targets that the insulin receptor phosphorylates? Which 2 are the main ones?

Back 12

IRS protein - main
CBL/Cap protein
Shc protein - main
Gab protein

Front 13

What do the Sh2 proteins do?

Back 13

The Sh2 proteins bind to phosphorylated tyrosine residues on the IRS protein. They are either kinases, phosphatases or activate G-protein cascades.

Front 14

What are the roles of IRS1-IRS4?

Back 14

IRS-1 is involved in cell differentiation and division due to insulin stimulus.
IRS-2 is involved in glucose uptake by the cell.
3 and 4 are unknown.

Front 15

What is different about the way that the Cbl/Cap protein sends it's message?

Back 15

It does not work through phosphorylation dependant kinase mechanisms. It activates lipid rafts and caveolae which increase glucose uptake in response to insulin.

Front 16

What is PI3K? WHy is it called that? What happens when it does it's job?

Back 16

PI3K is phosphatidylinositol 3 kinase and it is called that because it phosphorylates PIP2 at the 3' OH position.
When PIP2 is phosphorylated, it activates phosphorylation dependant kinases (PDK1). PDK1 increases glycogen synthesis, movement of GLUT4 to surface and cell division.

Front 17

How do I activate PDK1?
What does it do?

Back 17

Insulin binds to it's receptor
Beta subunit phosphorylates tyr residues on IRS protein which activates PI3K
PI3K phosphorylates PIP2 at the 3' position which activates PDK1
PDK1 increases glycogen synthesis, moves GLUT4 to the surface for increased glucose uptake and stimulates cell differentiation and division.

Front 18

Other than activating PDK, how does PIP2 have an effect?

Back 18

When it is activated by PI3K, it can activate phospholipase C which cleaves PIP2 into DAG and IP3. Both of these are 2nd messengers.

Front 19

What mechanisms do the following proteins work through? IRS, Cbl/CAP, Shc and Gab.
What cellular changes can these make?

Back 19

IRS works through PI3K to increase either PDK activity or phospholipase C activity. This stimulates glucose transport, glycogen synthesis and cell division.
Cbl/CAP works through lipid rafts/caveolae to increase glucose uptake.
Shc and Gab work through Mitogen activated protein kinases (MAPK) which stimulates cell division.

Front 20

What are the 3 ways that IRS proteins are controlled?

Back 20

Proteosome degradation
Dephosphorylation
Ser/thr phosphorylation

Front 21

How does TNFa and ffa's cause insulin resistance in obese patients?

Back 21

TNFa and ffa's stimulate ser/thr kinases which phosphorylate the IRS protein preventing it from being phosphorylated at tyr residues.
THIS DECREASES INSULIN SIGNAL

Front 22

What is mTOR and how does it work?

Back 22

mTOR is a protein product of the IRS PI3K cascade. It phosphorylates ser residues on the IRS protein which specifically prevents PI3K from binding to IRS.
This dampens the insulin signal through feedback inhibition.

Front 23

How does PKCξ work?

Back 23

It phosphorylates the IRS protein which causes it to release from the insulin receptor. IkB kinase β is the instigator that starts the whole process.

Front 24

How do the protein tyrosine phosphatases relate to insulin sensitivity?

Back 24

The PTPases are coded for by PTPB1. They dephosphorylate the IRS protein to decrease insulin signaling. KO mice for PTPB1 show increased insulin sensitivity.
An inhibitor PTPB1 is a potential drug therapy for obesity induced Type II.

Front 25

How does the SHIP2 protein work?

Back 25

It does exactly the opposite of PI3K, it dephosphorylates PIP2 at the 3' position.

Front 26

What are potential treatments for insulin resistance?

Back 26

Inhibitors of mTOR, PKCξ and IKKβ.
Salicylates have been shown to block IKKβ for treatment of type II.

Front 27

What is the PPARγ? What do they do? What drug blocks them?

Back 27

Peroxisome proliferator activated receptors.
They increase CAP protein function thereby increasing glucose uptake.
They stimulate release of adipokines from adipose to cause liver to increase fat storage and production.
Thaizolidinedione

Front 28

What are the relative melting points of fatty acids?

Back 28

Unsaturated fats have very low melting points - often liquids at room temperature.
Short chain saturated fats have lower MP's than longer chain saturated fats.

Front 29

What is structure of palmitic acid?

Back 29

16:0

Front 30

What is structure of stearic acid?

Back 30

18:0

Front 31

What is structure of oleic acid?

Back 31

18:1Δ9

Front 32

What is structure of linoleic acid?

Back 32

18:2Δ9,12

Front 33

What is structure of linolenic acid?

Back 33

18:3Δ9,12,15

Front 34

What is structure of arachidonic acid?

Back 34

20:4Δ5,8,11,14

Front 35

Which fatty acid bond is more prevalent in our bodies cis or trans?

Back 35

Cis is more prevalent. Trans are found in plant fats

Front 36

How does the omega system differ in nomenclature?

Back 36

You number the carbons from the CH3 end instead of the COOH end.

Front 37

Are most polyunsaturated fats conjugated or non-conjugated? What does this mean?

Back 37

They are non-conjugated
Conjugated means that every carbon is involved in 1 double bond.
Non-conjugated means there is a methylene group between C=C

Front 38

When would you use phosphatidal instead of phosphatidyl?

Back 38

In the case of plasmalogens when the bond between fatty acid and glycerol is an ether bond not an ester bond.

Front 39

What is saponification?

Back 39

The formation of soap when fatty acid of longer than 20 carbons reacts with heat and base.

Front 40

What do we need to get fatty acids into the mitochondria?

Back 40

We need to activate them with HSCoA, the enzyme acyl-CoA synthetase and ATP.
Acyl-CoA synthetase can also be called thiokinase.

Front 41

What do we do with Acyl-CoA once we have formed it in the cytosol?

Back 41

We esterify it with carnitine and the enzyme carnitine palmitoyl transferase 1. The product is acylcarnitine.
We can now move it into the intermembrane space.

Front 42

What enzyme is needed to move acylcarnitine into the matrix of the mitochondria?

Back 42

Carnitine acylcarnitine translocase because it exchanges carnitine in the matrix for acylcarnitine from the space.

Front 43

Where is CPTII found? What does it do?

Back 43

Carnitine palmitoyl transferase II is found on the matrix side of the inner mitochondrial membrane.
It cleaves the acyl-CoA off of carnitine for β oxidation.

Front 44

What inhibits CPT1?

Back 44

Malonyl-CoA which is the substrate required for fa synthesis

Front 45

What is the 1st step in β oxidation? What enzyme and cofactor are used?

Back 45

Create a double bond btw alpha and beta carbons.
Enzyme is acyl-CoA dehydrogenase and the cofactor is FAD

Front 46

Which step in β oxidation requires FAD?

Back 46

The first step of creating a double bond between alpha and beta carbons.

Front 47

What type of double bond is formed in the 1st step of β oxidation?

Back 47

A trans double bond btw alpha and beta carbons.

Front 48

What enzyme does the 2nd step of β oxidation use and what does it do?

Back 48

Enoyl-CoA hydratase and it adds water across the double bond to form a hydroxyl group on the β carbon (3-hydroxyacyl-CoA)

Front 49

What enzyme does the 3rd step of β oxidation and what does it do?

Back 49

3-hydroxyacyl-CoA dehydrogenase and it converts the OH group on the β carbon into a C=O to form 3-ketoacyl-CoA

Front 50

What is the 4th step of β oxidation? What enzyme catalyzes this reaction?

Back 50

Thiolase adds HSCoA to the β carbon and cleaves off acetyl-CoA. The products are an acyl-CoA product 2 carbons shorter and acetyl-CoA.
Thiolase can also be known as acetyl-CoA acetyltransferase

Front 51

How many acetyl-CoA do you get from β oxidation of an 18 carbon fatty acid?
How many FADH2, NADH, ATP, H20?

Back 51

18/2 = 9 Acetyl-CoA
9-1 = 8FADH2, 8NADH, 8H20
7x1.5 = 12 (FADH2)
8x2.5 = 20 (NADH)
9x10 = 90 (acetyl-CoA)
Total ATP 122 - 2 (activation) = 120

Front 52

What is the first step in ketone body formation? What enzyme is involved?

Back 52

Add acetyl-CoA to acetoacetyl-CoA (the last 4 carbons of β oxidation) to form HMG-CoA.
HMG-CoA synthase

Front 53

In ketone body generation instead of adding acetyl-CoA to acetoacetyl-CoA to form HMG-CoA why not just leave a 6 carbon fragment from β oxidation?

Back 53

Because the acetyl-CoA is not added in a straight chain. It is added to the C=O on the β carbon where a OH group has now formed.

Front 54

What do we do with HMG-CoA when we are making ketones?

Back 54

Using HMG-CoA lyase, we remove acetyl-CoA leaving us with acetoacetate.

Front 55

T/F the acetyl-CoA added to form HMG-CoA is the same acetyl-CoA that gets kicked off when formed ketone bodies?

Back 55

False, it is a different 2C fragment.

Front 56

What enzyme and cofactor are required for formation of β-hydroxybutyrate from acetoacetate?

Back 56

β-hydroxybutyrate dehydrogenase and NADH is oxidized to NAD.

Front 57

What is the difference in structure between β-hydroxybutyrate and acetoacetate?

Back 57

β-hydroxybutyrate is a straight chain whereas acetoacetate is branched. The β carbon also has a hydroxyl instead of C=O which is why we need NADH.

Front 58

How do we form acetone?

Back 58

It is spontaneous decarboxylation from acetoacetate

Front 59

What happens to ketones once they get to other tissues?

Back 59

The β hydroxybutarate is converted into acetoacetate. This generates 1 NADH.
Succinyl-CoA gives up CoA to acetoacetate to form acetoacetyl-CoA.
Due to this, acetoacetyl-CoA bypasses the first 3 steps of β oxidation.
Finally thiolase cuts the acetoacetyl-CoA into 2 acetyl-CoA.
Ketones do not generate the same amount of ATP as normal β oxidation of a 4C fragment.

Front 60

What is the difference between fasting, prolonged fasting and DM in terms of tissue usage?

Back 60

Fasting - protein provides a lot of glucose for brain and RBC's. Adipose provides ketones and ffa's for heart, kidney and muscle.
Prolonged fasting - protein no longer provides glucose. Adipose provides ketones for brain and ffa's for muscle, heart and kidney. Ketone bodies end up in urine.
DM - Muscle breakdown is huge and brain uses glucose from this. Heart, kidney and muscle use ketones and ffa's. Ketones and glucose end up in urine.

Front 61

How do you breakdown odd carbon unsaturated fatty acids? How do you change ATP yield calculation?

Back 61

β oxidation is run until the cis double bond is at 3 position. Enoyl-CoA isomerase converts this into a trans double bond at 2 position which is now the normal acyl-CoA structure for β oxidation.
It yields 1.5 less ATP because FADH not generated in forming double bond.

Front 62

How do you breakdown even carbon unsaturated fatty acids?

Back 62

β oxidation is run until your trans double bond exist at 2 position and the existing cis double bond at 4 position. Using dienoyl-CoA reductase, you combine the 2 bonds into a 3 position trans bond and then using enoyl-CoA isomerase, you move the trans double bond to the 2 position. Now β oxidation can run as usual.

Front 63

What happens if you have to degrade an odd numbered fatty acid? What enzymes and cofactors are used?

Back 63

You use β oxidation until proprionyl-CoA exists. Using proprionyl-CoA carboxylase, ATP and biotin you add a carbon to form methylmalonyl-CoA. Then with methylmalonyl-CoA mutase and B12, you form succinyl-CoA.

Front 64

What is the similarity between pyruvate carboxylase and proprionyl-CoA carboxylase?

Back 64

Both use ATP and biotin.

Front 65

How do you breakdown branched chain fatty acids?

Back 65

Using alpha oxidation. The alpha carbon in this case is COOH and the β is CH2. You add OH to B carbon, you then convert it into C=O and then decarboxylate the compound to give CO2 and RCOOH.

Front 66

What enzymes and cofactors are used in alpha oxidation?

Back 66

Monooxygenase, O2, Fe2+ and ascorbate are used to form OH group on β carbon.
Then the OH is oxidized and NAD is reduced with a dehydrogenase enzyme.
Finally, ATP, NAD+ and ascorbate are used to decarboxylate the compound.

Front 67

What genetic disease results when alpha oxidation is deficient?

Back 67

Refsum's disease.

Front 68

How do we form bile acids? What cofactors and enzymes are used?

Back 68

We use ω oxidation to convert CH3 to COOH forming a dicarboxylic acid.
Monooxygenase and NADPH - notice NADPH

Front 69

Where does fa synthesis occur? What about elongation of fatty acids and desaturation?

Back 69

Synthesis occurs in the cytosol.
Elongation occurs in the mitochondria
Desaturation occurs in the ER.

Front 70

What is the rate limiting step in fa synthesis? What enzyme and cofactors are required?

Back 70

The formation of malonyl-CoA from acetyl-CoA.
Acetyl-CoA carboxylase, biotin, ATP and HCO3- are required for the formation.

Front 71

How do we control fa synthesis? What are the control molecules?

Back 71

We control acetyl-CoA carboxylase.
Citrate allosterically activates ACC.
Palmitoyl-CoA inhibits it for feedback inhibition.
Glucagon increases cAMP which phosphorylates the enzyme inactivating it.

Front 72

What allows fatty acid synthetase to have 2 binding sites?

Back 72

ACP is attached which has an SH binding site. FAS has it's own SH binding site.

Front 73

How do you prep for fa synthesis?

Back 73

Attach acetyl-CoA to FAS SH with acetyl transferase
Attach malonyl-CoA to ACP SH with malonyl-CoA.

Front 74

What is the 1st step of fa synthesis? What enzyme is required?

Back 74

Transfer the acetyl-CoA group on the FAS protein to malonyl-CoA on the ACP protein. Lose COOH to form β-ketoacyl.
Enzyme: β-ketoacyl synthetase.

Front 75

How many CO2 are encorporated into a fatty acid?

Back 75

None, the CO2 added in forming malonyl-CoA is lost when transferring acetyl-CoA to malonyl-CoA on the ACP protein.

Front 76

What is the 2nd step of fa synthesis? What enzyme is required? What cofactor is required?

Back 76

You convert the β carbon C=O to C-OH.
Enzyme: β-ketoacyl reductase
IMPORTANT: NADPH is used here for the first time.

Front 77

What is the 3rd step of fa synthesis? What structure is formed? What type of double bond is formed?

Back 77

Use a hydratase enzyme to take H2O off the C-OH and form a double bond btw alpha and β carbon.
Crotonyl-S-ACP
Trans double bond.

Front 78

What is the 4th step of fa synthesis? What enzyme and cofactors are used?

Back 78

Reduce the double bond btw α and β carbons to a single bond.
Enzyme: Enoyl reductase
NADPH is once again used right here

Front 79

What 2 steps of fa synthesis do we use NADPH?

Back 79

Reducing the β C=O to an OH (step 2)
Reducing the C=C to single bond (step 4).

Front 80

What is the last step of fa synthesis?

Back 80

Using a transferase, we move the acyl fragment from the ACP protein to the FAS protein so that a new malonyl-CoA can join at the ACP protein

Front 81

How many acetyl-CoA, malonyl-CoA, NADPH, ATP and CO2 do we need to make palmitic acid?

Back 81

8 acetyl-CoA
7 malonyl-CoA
14 NADPH (2 for each cycle, except for the first kind of)
7 ATP to form malonyl-CoA
7 CO2 to add to malonyl-CoA but none of these are encorporated, just used.

Front 82

What is the source of NADPH for the following tissues?
Liver, brain, muscle

Back 82

Liver gets it from the pentose phosphate shunt.
Brain gets it from cytosolic isocitrate dehydrogenase
Muscle gets it from malic enzyme, converting OAA into malate.

Front 83

What is C75? How does it work?

Back 83

It is a new drug for obesity. It blocks FAS which increases malonyl-CoA which inhibits certain neuropeptides responsible for appetite.

Front 84

What are the steps of fatty acid elongation?

Back 84

Reverse of β oxidation.
Thiolase to add acetyl-CoA to palmitic acid.
Dehydrogenase (EXCEPT WITH NADPH) to create OH group.
Hydratase to convert OH to a double bond.
Finally dehydrogenase (ONCE AGAIN WITH NADPH INSTEAD) to form a single bond.

Front 85

How do you make unsaturated fatty acids? What enzyme is needed? What are the contraints?

Back 85

You use the desaturase (monooxygenase) enzyme to create a cis double bond anywhere except past carbon 9.

Front 86

Why do we need linoleic and linolenic acid in the diet?

Back 86

Because both have double bonds past carbon 9 which our desaturase enzyme can't make.

Front 87

How do we make arachidonic acid? What about docosahexaenoic acid?

Back 87

Take linoleic acid 18:2∆9,12.
Add a 6C double bond to form
18:3∆6,9,12.
Then add 2C to give you 20:3∆8,11,14 (arachidonic acid)
Similar process except use linolenic acid.

Front 88

When are linoleic and linolenic acid not required in the diet?

Back 88

When arachidonic and docosahexaenoic acid are provided.

Front 89

What method can only the intestines use to make TGLs? What enzymes are required?

Back 89

Taking monoglyceride and adding acyl groups to form TGL.
Monoacylglycerol acyl transferase and Diacylglycerol acyl transferase

Front 90

What method can only liver and intestines use to make TGL's?

Back 90

Take glycerol, phosphorylate it with glycerokinase to form α-Glycerophosphate.
Add 2Acyl-CoA to form 1,2-Diacylglycerol (phosphatidic acid).
Use phosphatidate phosphohydrolase to remove the phosphate to form diglyceride.
Add acyl-CoA to form TGL (COMMON TO ALL PATHWAYS)

Front 91

What method can all liver, adipose and intestines all use to make TGL's?

Back 91

Take DHAP
Use α-Glycerophosphate dehydrogenase and NADH to convert C=O in middle to CH2-OH.
Now you have α-Glycerophosphate.
Convert this to phosphatidic acid and the rest is easy.

Front 92

Why do alcoholics develop fatty livers?

Back 92

Alcohol dehydrogenase generates NADH when converting ethanol to acetaldehyde.
Acetaldehyde is then converted into acetate by acetaldehyde dehydrogenase which also generates NADH.
Increases in NADH stimulate α-Glycerophosphate dehydrogenase which converts DHAP into α-Glycerophosphate. This increases TGL formation.

Front 93

What enzyme breaks down TGL's in adipose tissue and what are the products formed?

Back 93

Triglyceride lipase converts TGLs into diglycerides and ffa's.
Diglycerides are further broken down into glycerol and ffa's.

Front 94

Why can't adipose tissue make TGL's out of glycerol?

Back 94

Because it lacks glycerokinase which is required to convert glycerol into α-Glycerophosphate.
This is also why during fa breakdown in adipose tissue, the glycerol cannot be used and is sent to the liver for processing.

Front 95

Where does the formation of glycerophospholipids occur?
What is a precursor to their formation?

Back 95

In the ER.
1,2-diacylglycerol phosphate (phosphatidic acid)

Front 96

When forming PC or PE, which compound is CDP activated?

Back 96

The choline or ethanolamine is CDP activated and then added to the 1,2-diacylglycerol (diglyceride)

Front 97

When forming PC or PE, do you use phosphatidic acid or diglyceride? What about PI?

Back 97

You use diglyceride for PC and PE and you use phosphatidic acid for PI

Front 98

When forming PI, which compound is CDP activated?

Back 98

The phosphatidic acid is CDP activated in this case

Front 99

How do you attach the CDP to ethanolamine or choline? What about CDP-phosphatidic acid?

Back 99

The choline or ethanolamine is phosphorylated with ATP. Then CTP adds to the phosphorylated portion kicking off PPi and yielding CMP.
Well phosphatidic acid is already phosphorylated, so just add the CTP.

Front 100

Which 2 phospholipids can you easily interconvert? How do you do this?

Back 100

Phosphatidylethanolamine and phosphatidylserine.
To form PS, you just exchange the serine for ethanolamine.
To form PE from PS, you have to decarboxylate.

Front 101

Name 2 ways to make phosphatidylcholine?

Back 101

Add CDP-choline to diglyceride or use SAM to triple methylate PE.

Front 102

What happens to the position of PE in the membrane as you methylate it?

Back 102

PE moves to the outside, the more methyls you add to form PC.

Front 103

Name 3 functions of phospholipids?

Back 103

They form membranes for cellular structural support
PIP2 can be cleaved by phospholipase C to yield 2nd messengers IP3 and DAG.
You can cleave PI with phospholipase A2 to yield arachidonic acid for prostaglandin synthesis.

Front 104

How does DAG cause it's 2nd messenger effects?

Back 104

It activates protein kinase C which phosphorylates a number of protein products (including IRS proteins for insulin signalling)

Front 105

How does IP3 cause it's 2nd messenger effects?

Back 105

It binds to the ER and causes Ca2+ release which activates certain proteins and other protein kinases.

Front 106

What is the precursor to all sphingolipids?
How do you make this?

Back 106

Ceramide
Add serine to palmitic acid to form dehydrosphinganine. Then reduce with NADPH to form sphinganine and introduce a double bond for sphingosine.
Finally, the most important step, add a fatty acyl to the serine residue in an AMIDE BOND to form ceramide.

Front 107

How do you make sphingomyelin? What about cerebrosides? What about sulfatide and gangliosides?

Back 107

Add CDP choline to ceramide
Add UDP-gal or UDP-glu to ceramide
For sulfatide add the activated sulfur compound PAPS to cerebroside.
For gangliosides add a number of sugar residues and sialic acid.

Front 108

What is wrong in Niemann-Pick's disease?

Back 108

Sphingomyelinase is missing so sphingomyelin builds up

Front 109

What is wrong in Gaucher's disease?

Back 109

Lack of glucocerebrosidase
As a result glu-ceramide increases.

Front 110

What is wrong in Tay-Sachs disease?

Back 110

Lack of hexosaminidase A
Normally breaks down N-acetylgalactosamine ceramide to ceramide
N-acetyl builds up in cells.

Front 111

Which organelles contain high levels of PC, sphingomyelin, cholesterol and cardiolipin

Back 111

ER contains high PC
Plasma membrane contains high sphingomyelin and cholesterol
Mitochondrial membranes contain high cardiolipin

Front 112

What is a way to tell that an RBC is old by looking at the phospholipids?

Back 112

Normally PC, sphingomyelin and cholesterol are high on the outside of the membrane and PE is high on the inside.
When an RBC is diseased, PC and sphingomyelin are on the inside.

Front 113

What are 2 markers of apoptosis?

Back 113

PS shifts to the outside of the membrane because ATP is usually required to keep it on the inside.
Cytochrome C is released from the mitochondria and the nucleus becomes pyknotic.

Front 114

What is the difference between membrane bound proteins and cytoplasmic proteins?

Back 114

They DO NOT contain more hydrophobic residues but do have hydrophobic residues every 3 aa's or so.

Front 115

List the 5 functions of membrane proteins

Back 115

Act as transporters (GLUT)
Act as communication between cells (receptors)
Act as markers (ABO blood)
Hormone receptors
Enzymatic activity

Front 116

How do spleen macrophages detect aging RBC's?
How could you mimic the action?

Back 116

RBC's normally have sialic acid attached to their surface proteins. This sialic acid has a negative charge and allows them to repel one another. When RBC's age, they lose this sialic acid as it breaks off. Macrophages can recognize this missing sialic acid and destroy the RBC.
If you use neuraminidase, you can remove the sialic acid enzymatically.

Front 117

What is the very first step in cholesterol synthesis? What enzyme is used?

Back 117

Take 2 acetyl-CoA and combine them into acetoacetyl-CoA in the reverse of the last step of B-oxidation.
The enzyme is thiolase which is actually named for the reverse reaction.

Front 118

What is the second step of cholesterol synthesis? What enzyme is used?

Back 118

The second step is adding another acetyl-CoA to acetoacetyl-CoA to form HMG-CoA.
The enzyme that does this is HMG-CoA synthase (same in ketone body formation)

Front 119

What is the rate limiting step of cholesterol formation?
What enzyme is it?
What cofactors are used?
What control do we have of this enzyme?
Where does this reaction take place?

Back 119

The rate limiting step is HMG-CoA reductase converting HMG-CoA into mevalonate.
HMG-CoA reductase uses NADPH and it controlled by cholesterol through negative feedback. In addition, this is where the statin drugs work.
This reaction takes place in the ER.

Front 120

Discuss the formation of cholesterol from mevalonate including numbers?

Back 120

6 x Mevalonate = Isopentenyl pyrophosphate
2 x Isopentenyl pyrophosphate = Geranyl pyrophosphate
Geranyl pyrophosphate + Isopentenyl pyrophosphate = Farnesyl pyrophosphate
Farnesyl pyrophosphate X 2 = Squalene X 1 = cholesterol

Front 121

Name all the controls of HMG-CoA reductase including
Genetic, covalent and allosteric controls

Back 121

Cholesterol and farnesyl pyrophosphate inhibit transcription and translation of the HMG-CoA enzyme. They also increase protease activity to degrade it.
Cholesterol allosterically inhibits the enzyme
Glucagon increase cellular cAMP which phosphorylates the protein. THIS INACTIVATES IT
Insulin lowers cAMP which dephosphorylates HMG-CoA reductase which ACTIVATES IT.

Front 122

What type of inhibition do statin drugs have on HMG-CoA reductase?

Back 122

They are competitive inhibitors of HMG-CoA.

Front 123

What are the uses of Farnesyl pyrophosphate?

Back 123

Forming ubiquinone, dolichyl, anchor proteins and geranyl geranylated proteins

Front 124

How do you make a cholesterol ester? What enzymes can be used?

Back 124

Attach a fatty acid to the OH group on the A ring in the form of acyl-CoA.
Either ACAT (acylcholesterol acyl transferase) or LCAT (lecithin cholesterol acyl transferase).

Front 125

Where are ACAT and LCAT found?

Back 125

ACAT is found in the tissues and LCAT in the plasma.

Front 126

Where does LCAT get it's substrate from?

Back 126

LCAT cuts a monounsaturated fatty acid off of lecithin (PC) and transfers it to cholesterol.

Front 127

What is the relationship with oleic acid and LCAT?

Back 127

If you eat a diet rich in oleic acid, PC will have oleic acid at the R2 position.
LCAT will then take this oleic acid and transfer it to cholesterol and store the oleic acid. This is good.

Front 128

What does a deficiency in LCAT cause?

Back 128

It causes the serum free cholesterol to rise in the blood and the CholE to drop. Normally the ratio is 25% free, 75% CholE.

Front 129

T/F ACAT uses lecithin to form cholesterol esters in the tissues?

Back 129

False, ACAT can add any fatty acyl-CoA to cholesterol for storage.

Front 130

What are the two major bile acids?
What is the main difference between them and cholesterol?

Back 130

Cholic acid and chenodeoxycholic acid
The proprionic group of cholesterol was cleaved by ω and β oxidation. This left a COOH group at this position.
Other than that, numerous positions are hydroxylated.

Front 131

What is the normal ratio of cholic acid to chenodeoxycholic acid?

Back 131

80% cholic
20% chenodeoxycholic acid.

Front 132

What are the steps of bile formation? Include rate limiting step and enzyme

Back 132

Cholesterol is converted into 7-a-hydroxycholesterol by cholesterol 7-a-hydroxlase. THIS IS THE RATE LIMITING STEP.
The 7-a-hydroxycholesterol is then converted into 7-a-hydroxy-4-cholestene-3-one by a dehydrogenase, isomerase and NAD is needed. This step involves moving the double bond from the B to the A ring and oxidizing the OH group to C=O
This last compound is then converted into cholic acid and chenodeoxycholic acid.

Front 133

What enzyme do we control when we control bile synthesis? What can we control it with?

Back 133

7-a-hydroxylase which starts the conversion of cholesterol into bile acids.
Cholesterol is a positive stimulus for this enzyme and bile acids are a negative feedback.

Front 134

How do we convert cholic acid to primary bile acids? Which primary bile acid is more common?
What happens if we shift this balance?

Back 134

Using CoASH and ATP, we attach the CoA to the COOH group on cholic acid. Then with either glycine or taurine, we attach the aa to this same area kicking off the CoA. We now have primary bile acids like taurocholic acid or glycocholic acid.
(Note, you can do this with chenodeoxycholic acid too).
Glycocholic acid is 75% and Taurocholic acid is 25%.
You develop gall stones.

Front 135

What time of bond exists between taurine/glycine and cholic acid? Why is this important?
What other compound has an amide bond between a fat and an aa?

Back 135

An AMIDE bond
Bacteria can break this bond to help with excretion.
Ceramide - serine and palmitic acid or additional fatty acid added.

Front 136

What is a secondary bile acid?

Back 136

Bacteria remove OH groups on primary bile acids and amide linkage to form secondary bile acid.

Front 137

How do you form cholestanol and coprosterol? Can you absorb these?

Back 137

Bacteria reduce the double bond of the B ring of cholesterol to allow for excretion.
These compounds are not reabsorbable bile acids.

Front 138

What are the functions of bile acids?

Back 138

Accelerate action of p.lipase
Aid in emulsification
Help absorb ADEK vitamins
Keep cholesterol in solution allowing excretion.
Bile acid excretion stimulates intestinal motility
Major route of cholesterol removal from the body.

Front 139

What are the 3 drugs for lowering cholesterol and how do they work?

Back 139

1) Statin drugs block HMG-CoA reductase preventing the formation of cholesterol
2) Cholestyramine blocks reabsorption of bile acids thereby stimulating 7-a-hydroxylase to make more and use up cholesterol.
3) Vitorin also blocks bile acid reabsorption.

Front 140

How do you absorb diet cholesterol?

Back 140

Cholesterol esters are broken down by esterases into cholesterol and ffa's and both are absorbed.

Front 141

What is the main way we absorb TGL's?

Back 141

P. lipase cuts fatty acids off either side of the TGL and yields a monoglyceride and 2 fatty acids. These are then absorbed.

Front 142

How do we absorb phospholipids?

Back 142

Prophospholipase is released from the pancreas and trypsin activates it. This then cuts off the middle fatty acid to yield lysophospholipid which is absorbed.

Front 143

What are the 2 ways to separate lipoproteins in the lab? What is the order the elute in both cases?

Back 143

Ultracentrifugation
Top to bottom: Chylomicrons, VLDLs, IDLs, LDLs, HDLs
Electrophoresis.
Source to end: Chylomicrons, LDLs, VLDLs and HDLs

Front 144

What are the main compositions for the lipoproteins and what are their alternate names?

Back 144

HDL (a-lipoproteins) mostly protein (their fat is phospholipid)
LDL (B-lipoproteins) mostly cholesterol
VLDL (preB-lipoproteins) mostly TGL's
Chylomicrons mostly TGL's

Front 145

What apolipoprotein is specific to chylomicrons?
What is the disease called if you are missing it?

Back 145

B-48
A betalipoproteinemia

Front 146

What are endogenous and exogenous lipoproteins?

Back 146

Endogenous - VLDL's
Exogenous - Chylomicrons

Front 147

What enzyme is needed to convert a VLDL into an IDL?
What about converting IDL into LDL?

Back 147

Lipoprotein lipase to remove TGL's from the VLDL
LCAT to transfer the cholesterol ester from HDL to IDL to form LDL. In the process cholesterol is given to the HDL.

Front 148

What are the important apolipoproteins, where are they found and what is their function?

Back 148

A-1 on HDLs and VLDLs. It 'A'ctivates LCAT
B-48 on chylomicrons. Needed for synthesis in intestines.
B-100 on LDLs, IDLs and VLDLs. 'B'inds to liver for remnant uptake.
C-1 is found on chylomicrons and VLDLs. Activates LCAT like A-1
C-11 is found on chylomicrons and VLDL's. Activation lipoprotein lipase.
E found on VLDLs, IDLs and chylomicrons. Also for liver recognition.

Front 149

Discuss LDL receptor control in tissues

Back 149

LDL binds to receptor.
Is taken up by cell by receptor mediated endocytosis
The cholesterol ester inside is broken down into free cholesterol and fatty acids.
This free cholesterol inhibits HMG-CoA reductase and also binds to ER to reduce LDL receptor synthesis.
The free cholesterol is then esterified with ACAT to be stored.

Front 150

4 reasons why HDLs are good for you

Back 150

1) Speed the formation of LDL's by cholesterol ester transfer with IDLs. This allows quicker storage of cholesterol.
2) They remove TGL's from chylomicrons quickly to leave the cholesterol rich remnant which is taken up by the liver.
3) They tranfer ApoCII and E to VLDLs and chylomicrons to cause faster activation of lipoprotein lipase and quicker uptake of remnants.
4) They take cholesterol from dead tissue and membranes back to the liver for excretion.

Front 151

What is elevated in Type I hyperlipoproteinemia? What is the problem? Treatment?

Back 151

It is a genetic deficiency in lipoprotein lipase so chylomicrons and serum TGL's are elevated. There is minor cholesterol elevation.
Reduce dietary fats

Front 152

What is elevated in Type IIa hyperlipoproteinemia? What is the problem? Treatment?

Back 152

IIa is an LDL receptor deficiency. Increased LDLs and cholesterol in the serum.
Statins, resins and diet.

Front 153

What is elevated in Type IIb hyperlipoproteinemia? What is the problem? Treatment?

Back 153

Also a defective LDL receptor. Increased LDLs, VLDLs, serum cholesterol and TGLs
Statins, resins and diet.

Front 154

What is elevated in Type III hyperlipoproteinemia? What is the problem? Treatment?

Back 154

A block converting IDLs into LDLs. IDLs, serum cholesterol and TGLs are increased.
Reduce weight, fat and CHO intake

Front 155

What is the deficiency in Type IV hyperlipoproteinemia? What is increased? Treatment?

Back 155

Has no external symptoms
No deficiency, caused by American diet, DM and obesity.
VLDLs and serum TGLs are increased. Serum cholesterol is slightly increased.
Alcohol and CHO's increase VLDLs significantly.
Watch your diet

Front 156

What is the deficiency in Type V hyperlipoproteinemia? What is increased? Treatment?

Back 156

Secondary to DKA and nephrosis.
Increased VLDLs, chylomicrons and serum TGLs. Slight serum cholesterol increase.
Treatment not known

Front 157

What are the 2 stages of atherosclerosis?

Back 157

1) Formation of fatty streaks which is deposition in macrophages and smooth cells of the blood vessel.
2) Cholesterol esters, dermatin sulfate and platelets form calcified plaques which cause hardening of the arteries and clot formation.

Front 158

What level of serum cholesterol predisposes you to an MI? What else does it predispose you to? What is the recommended level to stay below?

Back 158

> 250mg/dl
Death from the 1st MI
200mg/dl

Front 159

What are the primary factors increasing your risk for MI? What about secondary factors?

Back 159

Primary factors
Smoking, serum cholesterol and hypertension
Secondary factors
Decreased exercise, stress, diabetes, obesity, OCD

Front 160

What 2 ratios are you interested in for your atherosclerosis risk?

Back 160

LDL/HDL < 3
Total cholesterol/HDL < 5

Front 161

How do foam cells form?

Back 161

Cholesterol deposits in the tunica intima of the artery. This cholesterol gets oxidized and is taken up by macrophages, these are foam cells.
T-cells can also secrete cytokines which attract smooth muscle cells to ingest the oxidized LDL and form foam cells.

Front 162

Why do alcohol and statin drugs help with reduced atherosclerosis?

Back 162

Alcohol and statin drugs are both antioxidants that prevent oxidation of the B ring double bond of cholesterol.
In addition, statins block HMG-CoA reductase lowering the de novo synthesis of cholesterol.

Front 163

What is the new marker for heart disease? Where does it come from? Does it correlate with serum cholesterol?

Back 163

C-reactive protein (CRP) comes from the liver in response to vascular cells releasing interleukin-6 after damage.
It does not correlate well with serum cholesterol

Front 164

What are the new MI risk factors?

Back 164

[chol] > 200mg/dl
HDL < 40mg/dl
CRP > 3mg/dl

Front 165

What is the rate limiting step for the formation of prostaglandins?

Back 165

Cyclooxygenase converting arachidonic acid (or other 20C fatty acids) into PGG2.

Front 166

What are the 2 enzymes of the PGH synthase complex?

Back 166

Cyclooxygenase converts arachidonic acid into PGG2.
Hydroperoxidase converts PGG2 into PGH2

Front 167

Does aspirin block COXI or II better? How does it work?

Back 167

It blocks COXI best but is also able to block COXII
Aspirin acetylates a serine residue in the active site of COXI. This is an irreversible chemical reaction.

Front 168

What does tylenol block?

Back 168

COXII

Front 169

What enzymes do I use to make prostacyclin and thromboxane A2 from PGH2?

Back 169

Prostacyclin synthase
Thromboxane synthase

Front 170

Discuss how platelets aggregate? How does aspirin stop this?

Back 170

Thrombin binds to the platelet and activates phospholipase A2.
This cuts arachidonic acid from PIP2 and COXI converts the arachidonic acid into PGG2 and then hydroperoxidase converts PGG2 into PGH2.
PGH2 is converted into thromboxane A2 by thromboxane synthase.
Thromboxane A2 causes platelets to become sticky.
Aspirin blocks the COXI step.

Front 171

How does prostacyclin work? Where is it made and how?

Back 171

PGI2 (prostacyclin) is made in the endothelium.
COXII converts arachidonic acid into PGG2 and then hydroperoxidase converts that into PGH2.
PGH2 is converted into PGI2 by prostacyclin synthase.
PGI2 binds to platelets and activates adenylate cyclase. This lowers cAMP which inhibits Phospholipase A2. No arachidonic acid, no thromboxane A2 preventing platelets from sticking.

Front 172

Name 2 functions of thromboxane A2 and prostacyclin

Back 172

TXA2 is a vasoconstrictor and platelet aggregator.
Prostacyclin is a vasodilator and causes platelets to repel.

Front 173

How do I make leukotrienes?

Back 173

Lipooxygenase converts arachidonic acid into either LTA4, LTB4 or LTC4. These are inflammatory mediators.
Lipooxygenase can also convert arachidonic acid into 5 or 10-HPETE - these are vasoconstrictors

Front 174

What can I use to block leukotrienes?

Back 174

Singulair blocks the action of leukotrienes.

Front 175

What is saponification?

Back 175

Using alkaline hydrolysis to break fatty esters into soap.
If the fat doesn't have any esters then it is non-saponifiable

Front 176

What is the difference btw cis and trans fatty acids?

Back 176

Cis lower the melting point because it creates a kink in the fatty acid.

Front 177

What is the function of ∆3 cis-∆2 trans enoyl-CoA isomerase?

Back 177

It is needed to break down unsaturated fatty acids because B-oxidation requires a trans double bond at the 2 position. The enzyme converts the cis double bond at the 3 position to the 2' trans double bond.

Front 178

What does a deficiency in LCAT cause?

Back 178

Low levels of serum cholesterol esters and lysolecithin.
High levels of serum cholesterol and lecithin.

Front 179

How does a-ketoglutarate dehydrogenase differ from pyruvate dehydrogenase?

Back 179

Pyruvate dehydrogenase has protein phosphatase activity

Front 180

Why is oxygen still used when amytal is applied to mitochondria?

Back 180

Amytal blocks complex I but complex II is still able to feed protons into Ubiquinone

Front 181

What cofactor does acetyl-CoA carboxylase require?

Back 181

Biotin

Front 182

How do you know how many methylene groups there are in a fatty acid?

Back 182

There are 2 less than the carbon count unless it is unsaturated.

Front 183

What cofactor does HMG-CoA reductase need?

Back 183

NADPH to form mevalonic acid.