45 Questions
What happens to acetyl-CoA when NADH is high?
It is converted into ketone bodies
What is the impact of high NADH on gluconeogenesis?
It converts oxaloacetate into malate
What is the consequence of high NADH on pyruvate?
It is converted into lactate
What is the clinical consequence of lactate accumulation?
Impaired uric acid excretion
What is the role of PEPCK in gluconeogenesis?
It converts oxaloacetate to PEP
What is the consequence of high NADH on glucose oxidation?
It decreases glucose oxidation
What is the effect of chronic alcoholism on glucose metabolism?
It induces hyperglycemia
What is the consequence of high NADH on malate?
It increases malate levels
What is the role of GA3P DH in gluconeogenesis?
It requires NAD+ as a cofactor
Where does the MEOS produce acetaldehyde and NADP+?
Endoplasmic reticulum
What is the committed enzyme of cholesterol de novo synthesis?
HMG-CoA Reductase
What is the source of Acetyl CoA in cholesterol synthesis?
Glycolysis
How many NADPH molecules are required for cholesterol synthesis?
16
In which state does endogenous de novo synthesis of cholesterol occur?
Fed state
What is the source of exogenous cholesterol in the diet?
Animal source
How many stages are involved in cholesterol biosynthesis?
5
What is the product of the condensation of six isoprene units?
Squalene
What is the final product of cholesterol biosynthesis?
Cholesterol
What happens to SREBP-1 when there is an abundance of cholesterol?
It forms a complex with SCAP and Insig-1, becoming biologically inactive
What is the result of step 8 in cholesterol formation?
Formation of 27-carbon cholesterol
What happens to SREBP-1 when there is a depletion of cholesterol?
It translocates into the golgi apparatus and becomes biologically active
What is the end product of step 12 in cholesterol formation?
Cholesterol
What is the function of Insig-1 in the regulation of SREBP-1?
It inhibits the activity of SREBP-1
What is the intermediate formed in step 9 of cholesterol formation?
1,4-Demethyl lanosterol
What is the function of SREBP-1 in the nucleus?
It enhances gene transcription
What is the intermediate formed in step 10 of cholesterol formation?
7,24-Cholestadienol
What is the role of the golgi apparatus in SREBP-1 activation?
It activates SREBP-1
What is the product of the decarboxylation of lanosterol?
Cholesterol
What is the substrate for the isomerization reaction in Step 10?
Zymosterol
What is the result of high sterol molecules in the ER?
The complex of SREBP 1 and SCAP remains in the ER membrane
What happens to the complex of SREBP 1 and SCAP when sterol molecules are low in the ER?
It translocates to the Golgi complex
What is the role of Insig in the regulation of SREBP 1?
It escorts SREBP 1 to the Golgi complex
What is the primary function of LPL?
To extract free fatty acids or TAGs from VLDL
What is the result of SREBP 1 translocating to the nucleus?
It enhances gene expression of HMGR
What is the fate of excess LDL?
It gets oxidized by macrophages, forming foam cells
What is the function of the DNA binding domain of SREBP 1?
It enhances gene transcription
What is the role of the liver in the transportation of TAGs?
It transports TAGs out of the liver by VLDL
What is the purpose of the regulation of HMG-CoA reductase?
To regulate cholesterol levels in the cell
What is the result of low sterol molecules in the ER?
The complex of SREBP 1 and SCAP translocates to the Golgi complex
What is the function of HTGL?
To hydrolyze IDL into LDL
What is the location of the carboxy terminal domain of the LDL receptor?
Intracellularly
What is the function of the O-linked oligosaccharide domain of the LDL receptor?
To extend the receptor away from the membrane
What is the function of the LDL-binding region of the LDL receptor?
To bind LDL
What is unique about the structure of the LDL receptor?
It is composed of multiple domains
What is the significance of the cysteine sequences joined by disulfide bonds in the LDL receptor?
They contribute to the structural stability of the receptor
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