Biochem Exam 18Dec2008 (Added)

Front 1

What is the key regulated enzyme in the synthesis of heme?

Back 1

ALA Synthase
(aminolevulinic acid synthase)

Front 2

What increases ALAS (aminolevulinic synthase activity) in the synthesis of heme? What inhibits ALAS activity in the synthesis of heme?

Back 2

-Falling hemin levels (activation of P450 pathway, steroid synthesis, drug detox, etc) stimulates ALAS.
-Hemin (formed by spontaneous oxidation of extra heme in the absence of globin) inhibits.

Front 3

What does ALAS (aminolevulinic acid synthase) require as a cofactor in the synthesis of heme?

Back 3

Pyridoxal phosphate (Vit B6)

Front 4

What two molecules come together to form ALA (aminolevulinic acid) as the first compound in the heme pathway?

Back 4

Glycine and Succinyl CoA

Front 5

What enzyme is used in the condensation reaction of two ALA (aminolevulinic acid) to porphobilinogen? What is a required cofactor?

Back 5

-ALAD (aminolevulinic acid dehydratase).
-Requires Zn+

Front 6

What blocks ALAD (aminolevulinic acid dehydratase) and stops it from creating a porphobilinogen?

Back 6

-Pb2+

Front 7

Describe the basis of tissue damage in light sensitive porphyrias.

Back 7

-Porphyringogens in excess oxidize to porphyrins
-UV light excites porphyrins
-Excited porphyrins create ROS

Front 8

There is just enough enzyme present in some porphyrias for normal functioning. What kind of stressors would increase symptoms on porphyria?

Back 8

-Steroid drug production
-Drug detox (4-15)

Front 9

Heme-->bilirubin (carried on albumin)-->bilirubin diglucuronide-->excretion. What step and where does bilirubin get conjugated for excretion?

Back 9

-bilirubin-->bilirubin diglucuronide
-Liver

Front 10

Babies have low levels of Bilirubin-gluconyl transferase that conjugates bilirubin and makes it more easily excreted. How is this treated in babies until they kick up enough Bilirubin-glucuronyl transferase?

Back 10

-Blue light helps to isomerize bilirubin to be more water soluble

Front 11

Would you have in increase in conjugated or unconjugated bilirubin in a blockage of a bile duct?

Back 11

Conjugated bilirubin

Front 12

Would you have in increase in conjugated or unconjugated bilirubin in hepatitis?

Back 12

Unconjugated bilirubin

Front 13

Would you have in increase in conjugated or unconjugated bilirubin in hemolytic diseases?

Back 13

Unconjugated bilirubin

Front 14

How does fatty acid synthesis get kicked into gear in the TCA cycle?

Back 14

-Insulin switches on pyruvate dehydrogenase
-Citrate piles up
-Citrate spills over into cytosol and does FA synthesis

Front 15

Differences between FA synthesis and beta-oxidation?

Back 15

Synthesis vs catabolism:
-uses NADPH vs produces FADH2 and NADH
-occurs in cytosol/smooth ER vs mitochondria

Front 16

When doing FA synthesis, where do the 2 new carbons get added?

Back 16

They're added at the head. Carbon 1 and 2

Front 17

What are substrates of FA synthesis?

Back 17

AcCoA

Front 18

What is needed for the creation of an activated building block in FA synthesis (turning AcCoA into Malonyl CoA)?

Back 18

Biotin

Front 19

Why are linoleate and linolenate essential in the diet?

Back 19

Necessary for conversion to arachidonic acid, which is necessary for synthesis of eicosanoids (signaling molecules like inflammation and immunity and messengers in CNS) and phospholipids

Front 20

What can't humans synthesize arachidonic acid?

Back 20

Humans can't place double bonds any farther down than position 9 and arachidonic acid has double bonds as far down as position 14.

Front 21

Where is this process occuring?
Glycerol --> Glycerol-3P --> Phosphatidic acid --> Diacylglycerol --> Triacylglycerol

Back 21

Liver, only liver has glycerol kinase.
THIS PROCESS IS THE CREATION OF A TG.

Front 22

Where is this process occuring?
Glucose --> DHAP --> Glycerol-3P --> Phosphatidic acid --> Diacylglycerol --> Triacylglycerol

Back 22

Adipose tissue doesn't have glycerol kinase.
THIS PROCESS IS THE CREATION OF A TG.

Front 23

What is the main carrier of TG from liver to the tissues?

Back 23

VLDL

Front 24

What is the main carrier of TG's from the gut to the tissues?

Back 24

Chylomicron

Front 25

What role does insulin play in the role of synthesis of triglycerols in adipose tissue?

Back 25

-Increases movement of glucose into adipose tissue
-Increases number and activity of lipoprotein lipases to get FAs into the cell to build TG's.

Front 26

How are FA's mobilized in the fasting state?
How are free FA's transported in the blood?

Back 26

-Glucagon triggers hormone sensitive hormone sensitive lipases to break down TG's into free FA's.
-Carried by albumin

Front 27

What is the fate of glycerol that has been released with free FA's from adipose during fasting states?

Back 27

Goes to the liver

Front 28

What is the fate of the free FA's that are broken down in adipose tissue during a fast?

Back 28

40% goes out to the tissues and 60% is put back into TG's! This is known as the TG-free FA futile cycle.

Front 29

What are 3 things that affect membrane fluidity?

Back 29

-Tail saturation
-C=C rigidity
-Cholesterol

Front 30

Where are phospholipids synthesized?

Back 30

-Smooth ER

Front 31

What are the 3 components of Glycero-phospholipids?

Back 31

-Glycerol (hydrophobic)
-Polar head group
-Fatty acids

Front 32

What are the two activation strategies to attach a head group to make a phospholipid?

Back 32

-Activate the head group using CTP. Reacts with 1,2 diacylgrycerol.
-Activate phosphatidic acid using CTP. Reacts with head group.

Front 33

What 3 phospholipids are created using an activated head group?

Back 33

-Phosphotidylcholine
-Phosphotidylethanolamine
-Phosphotidyserine

Front 34

What 3 phospholipids are created using an activated phosphatidic acid?

Back 34

-Phosphotidylinositol
-Cardiolipin
-Phosphotidylgycerol

Front 35

How is phosphotidylethanolamine converted to phosphotidylcholine?

Back 35

Requires SAM (S-adenyl methionine) for a triple methylation

Front 36

How is phosphotidylethanolamine converted to phosphotidylserine?

Back 36

Simple displacement reaction.

Front 37

What phospholipid is being described?
"Important in signaling -- protein kinase C activation"

Back 37

Phosphotidylinositol

Front 38

What phospholipid is being described?
"Stabilizes respiratory complexes, affects membrane permeability"

Back 38

Cardiolipin

Front 39

What phospholipid is most important in RDS, asthma? (Makes up lung surfactant)

Back 39

Dipalmitoylphosphotidylcholine