Liver Biochemistry

Question 1

What protein made by the liver is a inflammatory marker and a marker for heart disease?

Answer 1

C reactive protein

Question 2

What liver cells protect against viruses and tumors?

Answer 2

Pit cells (Lymphocytes)

Question 3

What comes together to form IPP?

Answer 3

3 acetyl CoA’s

Question 4

What are the sources of acetyl CoA?

Answer 4

• oxidative decarboxylation of pyruvate
• Beta oxidation of fatty acids
• Breakdown of amino acids

Question 5

Acetyl CoA is transported into the cytoplasm via what?

Answer 5

Citrate shuttle

Question 6

How many units of IPP form the tetracyclic (4 ring) sterane backbone of most steroids?

Answer 6

6

Question 7

What carbon on cholesterol has a hydroxyl group?

Answer 7

C3

Question 8

Where is the double bond on cholesterol?

Answer 8

Between C5 and C6

Question 9

The liver packages cholesterol into what?

Answer 9

VLDL molecules

Question 10

Enzyme from Acetyl CoA –> Acetoacetyl CoA

Answer 10

Acetyl CoA acetyltransferase

Question 11

Enzyme for Acetoacetyl CoA –> HMG CoA

Answer 11

HMG CoA synthase

Question 12

Enzyme for HMG CoA –> Mevalonate

Answer 12

HMG CoA reductase

Question 13

What step is the rate limiting step in cholesterol biosynthesis?

Answer 13

HMG CoA –> Mevalonate using HMG CoA reductase

Question 14

Name all the intermediates in cholesterol biosynthesis in order

Answer 14

Acetyl CoA –>Acetoacetyl CoA –> HMG CoA –> Mevalonate –> IPP –> Squalene –> Lanosterol –> Cholesterol

Question 15

What 2 things accelerate or promote the reaction of HMG CoA to Mevalonate?

Answer 15

Insulin and thyroxine

Question 16

What things inhibit or slow down the reaction of HMG CoA to Mevalonate?

Answer 16

Glucagon, Sterols, high AMP, Vitamin E, and statins

Question 17

What inhibits conversion of Lanosterol to cholesterol?

Answer 17

Antifungal agents

Question 18

What things are formed from side reactions from intermediates of cholesterol synthesis?

Answer 18

Ubiquitous and Heme A (in cytochromes)

Question 19

Long term statin use for cholesterol regulation will inhibit the formation of what?

Answer 19

Ubiquinone which will mess up TCA cycle

Question 20

Local centers for signal transduction processes and sites for abnormal processing of proteins in neurodegenerative disorders?

Answer 20

Lipid rafts

Question 21

Where are the ubiquitination sites on HMG CoA reductase?

Answer 21

Lysine 89 and Lysine 248

Question 22

What membrane is HMG reductase on?

Answer 22

ER

Question 23

The catalytic domain of HMG CoA reductase faces what?

Answer 23

The cytosol

Question 24

HMG CoA reductase is directly inhibited by what?

Answer 24

Free Fatty acids, Bile Acids, and oxysterols

Question 25

These are pharmacological molecules that are competitive inhibitors and sit in the active site of HMG CoA reductase

Answer 25

Statins

Question 26

Referring to covalent modifications, HMG CoA reductase is Active in what form?

Answer 26

Dephosphorylated

Question 27

Low energy state does what to HMG CoA reductase?

Answer 27

Causes phosphorylation thus inactivation

Question 28

Translation of HMG CoA reductase is reduced by what?

Answer 28

Gamma-tocotrienol (vitamin E family) and oxylanosterols

Question 29

In the presence of high cholesterol, HMG CoA interacts with INSIG which causes what?

Answer 29

Polyubiquitination of HMG CoA reductase

Question 30

Polyubiquitination of HMG CoA reductase leads to removal from the ER and degradation by what?

Answer 30

26S protea some

Question 31

While synthesized cholesterol is packaged into VLDLs, dietary cholesterol is delivered to the liver via what?

Answer 31

Chylomicron remnants

Question 32

In the synthesis of Bile Acids, cholesterol is converted to ________ by the enzyme ________.

Answer 32

7-alpha- hydroxycholesterol; 7-alpha-hydroxylase

Question 33

Name the intermediates in bile acid synthesis in order.

Answer 33

Cholesterol –> 7-alpha-hydroxycholesterol –> chenocholic acid –> cholinergic acid