NST 103: MIDTERM 3 Flashcards
What is HMG-CoA ?
- HydroxyMethylGlutaryl-Coenzyme A
- it is an intermediate in ketone body synthesis
ketone bodies are synthesized in mitochondria
Why is it important that ketone bodies are synthesized in the mitochondria ?
- this is important because production of acetyl-CoA, the substrate for synthesis of ketone bodies, occurs in the mitochondria via β-oxidation of fatty acids
ketone bodies are synthesized in mitochondria
What is acetyl-CoA ?
- acetyl-CoA is a metabolite derived from glucose, fatty acid, and amino acid catabolism. During glycolysis, glucose is broken down into two three-carbon molecules of pyruvate.
How is acetyl-CoA carboxylase regulated ?
- activated by citrate
- inhibited by long chain acyl-CoA
- inhibited by AMPK
- activated by insulin
all are true
Which of the following is false about **chylomicron metabolism **?
A) Uptake by hepatocytes is via interaction of apoB-48 with the LRP
B) Uptake by hepatocytes is via interaction of **apoE **with **LDL receptor **
C) The majority of **TAG **in chylomicron is hydrolized in the capillary of adipose tissue
D) Chylomicron remnants does NOT contain ApoC-ll
E) Chylomicron is generated from LDL in the liver
E) Chylomicron is generated from LDL in the liver
A-D are true about chylomicron metabolism
apoB-48 = shorter form of apo B (chylomicrons and their remnants contain one molecule of apoB-48)
LRP = LDL receptor-like protein (Chylomicron remnant receptor)
apoE = apolipoprotein E
LDL = low-density lipoprotein
TAG = triacylglycerol
apoC-II = apolipoprotein C-II
Which lipoprotein particles have higher triaglycerol percentage ? Choose the right order.
choices: IDL, LDL, CM, HDL
CM > IDL > LDL > HDL
CM = chylomicron
IDL = intermediate density lipoprotein
LDL = low-density lipoprotein
HDL = high-density lipoprotein
Which particle delivers cholesterol to peripheral tissues ?
LDL (low-density lipoprotein)
They bind to a specific cell receptor (LDL-receptor), and after endocytosis the intracellular cholesterol will be used to build cell membranes and to synthesize other molecules (biliary acids, hormones). The cholesterol present in peripheral tissues is taken up by high-density lipoproteins (HDL) and transferred to LDL.
T/F: Activation of one fatty acid requires two ATP equivalents of energy.
TRUE
T/F: Entry of fatty acids into the mitochondria is regulated by malonyl-CoA.
TRUE
T/F: Glucagon can inhibit HSL activity in humans.
FALSE
HSL = hormone-sensitive lipase
Several hours after a meal, insulin levels decrease, resulting in:
Increased B-oxidation as the major source of energy in muscle and adipose tissue.
Which of the following are activator(s) of mTOR signaling ?
A) Insulin signaling
B) Glucose
C) Leucine
D) Cholesterol
E) Glucagon signaling
Select all that apply
**A) Insulin signaling
**B) Glucose **
C) Leucine
Which of the following is true in regards to the Ping Pong reaction ?
A) APALP is required as a coenzyme
B) The transaminase enzyme can bind to both substrates at the same time
C) A keto acid accepts the NH2 group to form a new amino acid
D) The purpose is to expend the energy after a high protein meal
E) Involves formation of a Schiff base
Select all that apply
A) APALP is required as a coenzyme
C) A keto acid accepts the NH2 group to form a new amino acid
E) Involves formation of a Schiff base
Which of the following is true ?
A) Reactions that produce ammonia are often coupled with reactions that reincorporate it
into an amino acid because our body has no way to excrete the toxic metabolite
B) Alanine and glutamine are favored as “nitrogen carriers” over glutamate, since glutamate can be neurotoxic at high levels
C) Citrulline and arginine combine to form Argininosuccinate in the third step of the urea cycle
D) Pyridoxine is a non-essential nutrient
B) Alanine and glutamine are favored as “nitrogen carriers” over glutamate, since glutamate can be neurotoxic at high levels
T/F: In the postprandial state HSL is active in adipose tissue.
**FALSE **
T/F: Biotin is involved in the generation of Acetyl-ACP.
FALSE
T/F: NADPH is used for ketone body synthesis
FALSE
T/F: Citrate is an allosteric inhibitor of Acetyl-CoA Carboxylase.
FALSE
T/F: During fasting, cAMP signaling results in phosphorylation of HSL by PKA activates
lipolysis
TRUE