What is the product of glycolysis in red blood cells and exercising muscle?

Lactate

A modified B oxidation leads to the formation of acetyl-CoA and H2O2 and occurs in what organelle?

Peroxisome

Which reducing equivalents are generated and used to form ATP during B oxidation of fatty acids?

FADH2 and NADH

What do adipose TAGs supply during a fasting state?

Fatty Acids

Why can red blood cells use only glucose as a form of energy?

They lack mitochondria

What compounds are used in gluconeogenesis as carbon sources

Lactate, glycerol, amino acids

During starvation, carbohydrates are depleted and free fatty acids are mobilized, which leads to what process?

Ketosis

Urea is formed from amino acids by which organ?

Liver

The last step in the B oxidation of fatty acids involves the conversion of 3-ketoacyl-CoA to acyl-CoA and acetyl-CoA by which enzyme?

Thiolase

In a state of starvation, what organ increases it use of ketone bodies as a major energy source?

Brain

When glucose is produced from non-carb compounds, it is called what?

Gluconeogenesis

What part of TAG is converted to glucose during periods of prolonged fasting?

Glycerol

The catabolism of fatty acids requires what form of energy?

ATP

In the B oxidation of fatty acids, carbons are cleaved from acyl-CoA molecules on which end?

Carboxyl

What are the insulin and glucagon levels of a person in a basal state?

Insulin low, glucagon high

What enzyme is used to form acylcarnitine?

Carnitine palmitoyltransferase-I (CPT-I)

The formation of ketone bodies primarily occurs in what organ?

Liver

After at least one day of fasting, what is the sole source of blood glucose?

gluconeogenesis

After how many days of fasting does the body begin producing ketone bodies for fuel?

3 days

How many mols of ATP are produced in the citric acid cycle for every 8 mol of acetyl-CoA formed?

10

What are the three types of ketone bodies?

B-hydroxybutyrate, acetoacetate, acetone

Which amino acid remains in the muscles in a state of starvation

Leucine

When partially digested food enters the intestine, the hormone ______________ is secreted by the intestine, which signals the gallbladder to contract and release bile acids, and then the pancreas to release digestive enzymes.

Cholecystokinin

Laboratory results for a patient with uncontrolled Type I diabetes mellitus reveal hyperglycemia (634 mg/dL) and hypertriglyceridemia (498 mg/dL). The most likely cause of the hypertriglyceridemia in this patient is which of the following?

Decreased lipoprotein lipase activity

Bile slats must reach a particular concentration within the intestinal lumen before they are effective agents for lipid digestion. This is because of which of the following?

The bile salts solubility in the lumen is a critical factor

What are the components of chylomicrons?

Chylomicrons are formed by triglycerides, phospholipids, cholesterol and apoB48

The apoproteins B-48 and B-100 are similar with respect to which of the following?

They are synthesized from the same gene

LCAT is a plasma enzyme and its substrate is cholesterol contained in _____.

HDL

Elevated serum TG levels can occur due to a number of factors. which one of the following factors reduces TG levels?

Under production of apo B-100

The major enzyme that digests dietary TAGs is ______________ produced in the pancreas. Pancreatic lipase is secreted along with another protein, colipase, in response to the release of the cholecystokinin from the intestine.

Lipase

Which cells produce LPL?

Adipose, Muscle, and Lactating mammary gland cells

Which hormone stimulates the synthesis of lipoprotein lipase?

Insulin

What is the starting point for the LCAT pathway?

Lecithin

In a fasting state, what is released from adipose stores for gluconeogenesis?

Fatty acids and glycerol

What is the optimal pH for digestive enzymes in the intestine?

6

What protein activates lipoprotein lipase?

Apoprotein CII

Chylomicron remnants are taken up by which receptors found in the liver?

Apoprotein E receptors

Which apoprotein is responsible for activating the LCAT pathway?

ApoAI

Which apoprotein inhibits lipoprotein lipase?

ApoCIII

Which of the following is produced in the blood?

LDL

Which is the largest of the lipoproteins?

Chylomicrons

In the LCAT pathway, what is cholesterol converted to?

Cholesterol ester

Fatty acids released from triacylglycerols must form complexes with what molecule to travel in the blood?

Albumin

The synthesis of chylomicrons occurs in which intestinal cellular organelle?

Smooth ER

Where are chylomicrons secreted?

Lymph

What is lipogenesis stimulated by to convert glucose to fatty acids?

Insulin

Which apoprotein is a ligand for the LDL receptor?

ApoB100

What lipoprotein contains triacylglycerol, apolipoprotein B-48, phospholipids, and cholesterol esters?

Chylomicron

Chylomicron remnants are taken up by which receptors found in the liver?

Apoprotein E receptors

What is lipogenesis stimulated by to convert glucose to fatty acids?

Insulin

Lingual and gastric lipases preferentially hydrolyze fatty acid chains of what size?

Short and medium chains

How long after the start of a meal do nascent chylomicrons enter the bloodstream?

1 to 2 hours

The high solubility of cholesterol in blood is due to plasma lipoprotein(s).

VLDL and LDL

What percent of cholesterol in plasma lipoproteins exists in the form of cholesterol esters?

70%

What percent of the cholesterol in plasma exists in the form of free cholesterol?

30%

Bile becomes a very efficient detergent when conjugated to:

Amino acids (glycine and taurine)

Can cholesterol be metabolized to CO2 and water in humans?

No

Which one of the following conditions can induce the formation of gallstones?

Excess HMG-CoA reductase activity, Reduced levels of cholesterol & a-hydroxylase, High levels of deoxycholate that inhibit CYP7A1 enzyme activity (all of the above)

The cholesterol pool of the body is derived from the absorption of dietary cholesterol and biosynthesis primarily in:

Liver and intestine

You decide to treat a patient who has very high levels of serum cholesterol with the statin drug Lipitor (atorvastatin). You know that this drug acts in the metabolic pathway leading to the synthesis of cholesterol. The substrate for the enzyme inhibited by the statin d

HMG-CoA

The initial and rate-limiting step of bile synthesis is achieved by:

7 a-hydroxylase, CYP7A1

Excretion of cholesterol is by way of the liver and gallbladder through the intestine in the form of bile acids

True

Which disease is a result of abnormal, deficient, or inactive LPL?

Familial lipoprotein lipase deficiency

HDL transfers which proteins to chylomicrons and VLDL?

ApoE and apoCII

How does HDL transport cholesterol or cholesterol esters to the liver?

CETP

HDL converts cholesterol to cholesterol esters via which pathway?

LCAT

High levels of which cholesterol are especially atherogenic?

LDL

Which of the following diseases is believed to be both genetic and environmental?

Hypercholesterolemia

How is cholesterol packaged when in the intestines?

Chylomicrons

What is the precursor for cholesterol synthesis?

Acetyl-CoA

Which lipoprotein returns dietary lipids to the liver?

Chylomicron remnants

What adds stability to the phospholipid bilayer of membranes?

Cholesterol

What occurs to the LDL receptors in people with familial hypercholesterolemia?

Lack LDL receptor protein

A majority of synthesized cholesterol is secreted from which type of cell?

Hepatocytes

Which disease leads to premature coronary heart disease due to atherosclerosis and thrombosis due to the inhibition of fibrinolysis?

Familial lipoprotein A excess

Which proteins are responsible for moving unwanted or excess cholesterol from enterocytes to the gut lumen?

ABCG5 and ABCG8

What enzyme is responsible for releasing free fatty acids for milk production?

LPL

What member of the ABC family is required for reverse cholesterol transport and HDL biogenesis?

A1

The presence of a fatty streak is early gross evidence of what type of formation?

Atherosclerotic plaque

What do nascent VLDL particles accept from HDL particles to form mature VLDL particles?

Apolipoproteins

What does VLDL convert to initially?

IDL

After digestion by lipase, LDL returns to the liver and enters cells via what process?

Endocytosis

Cholestyramine leads to excretion of what product?

Bile acids

The second pathway of biosynthesis and degradation of bile acids may occur in what organelle?

Mitochondria

What structural part of bile salts makes them well suited for micelle formation?

Hydrophobic, hydroxyl group

Which of the following is a primary bile acid?

Taurocholic acid

What forms micelles with fatty acids released from dietary triglycerides?

Bile salts

Which of the following is a secondary bile acid?

Lithocholic acid

What effect does rising levels of cholesterol and bile acids have on HMG-CoA reductase?

Proteolysis susceptibility

What does the lipase/colipase complex promote the degradation of?

Triacylglycerol

Bile acids improve the absorption of which vitamins?

A,D,E,K

Where does fat emulsification and micelle formation occur?

Small intestine

How does cholestyramine lower cholesterol levels in the blood?

Binds bile acids to limit reabsorption

Once micelles transport degradation products to the mucosa, what occurs to the products?

Reassembly into triacylglycerols

The production of secondary bile acids occurs in which organ?

Intestines

In what organ is bile synthesized?

Liver

Primary and secondary bile acids are absorbed in the intestines and returned to which organ?

Liver

The presence of bile and fatty acids in the duodenum increases the level of which hormone?

Secretin

What is the rate-limiting step in the synthesis of bile acids?

CYP7A1 reaction

What property do bile acids have that promotes the encircling and degradation of triglycerides and phospholipid fat particles in food?

Detergent

Bile salts generated with α-hydroxyl groups at the 3 and 7 positions form which set of bile salts?

Chenocholate

The conjugation of glycine and taurine occurs in what part of the cell?

Peroxisome

What are the four classes of plasma lipoproteins in normal fasting humans?

HDL, LDL, IDL, VLDL

The protein component of a lipoprotein particle is called

apolipoproteins

True or False: The HDL particle has higher percentage of protein than VLDL particle

True

True or False: VLDL is synthesized in the intestine and liver

False

Lipoprotein lipase is located on the surface of-

endothelial cells of capillaries

Which apo protein is required for activation of lipoprotein lipase?

ApoC-II

The pKa of the bile acids is approximately 6. The intestinal lumen has a pH of 6. That means-

Half of the bile molecules are present in the protonated (acid) and the other half are ionized (salt).

When bile salts form conjugates with taurine or glycine their pKa values decrease to as low as 2. What would you expect to see in the intestinal lumen that has a pH of 6?

Majority of bile molecules are in ionized form (salt)

What role does intestinal bacteria play regarding bile salt molecules?

Deconjugate and Dehydroxylate bile salts

Which type of secondary bile salt/acid has the least solubility in the intestinal lumen and its major fate is excretion?

Lithocholic acid

What is the rate of HMG-CoA reductase mRNA synthesis controlled by?

SREBP

The synthesis of all steroid hormones begins with the conversion of cholesterol to what compound?

Progesterone

All the carbons of cholesterol are derived from which precursor?

Acetyl-CoA

SREBPs are integral proteins of what cellular organelle?

Endoplasmic reticulum

How many condensed molecules of acetyl-CoA are required to form HMG-CoA?

3

How do statins lower cholesterol?

Inhibit HMG-CoA reductase

In what part of the cell does cholesterol synthesis occur?

Cytosol

At what point is the SREBP:SCAP complex transported to the Golgi apparatus?

decrease in cholesterol

What are the three main organs, aside from the liver, in which significant quantities of cholesterol are biosynthesized?

Gut, adrenal cortex, gonads (ballz)

How does hyperinsulinemia change the molecule of HMG-CoA reductase?

Leads to dephosphorylation

What effect does increased glucagon levels have on HMG-CoA reductase?

Inactivation

How many fused cyclic rings does the cholesterol molecule contain?

4

What is the precursor for glucocorticoids, androgens, and estrogens?

Cholesterol

The conversion of HMG-CoA to mevalonic acid is catalyzed by which enzyme?

HMG-CoA reductase

What class of steroid hormones contains 21 carbons?

Glucocorticoids

Two molecules of farnesyl pyrophosphate undergo a fusion reaction to yield what compound?

Squalene

Cholesterol is stored as cholesterol esters in the cells of what organ?

Adrenal cortex

What is the energy source for cholesterol synthesis?

ATP

In order for mevalonate to form, what compound must be reduced via catalyzation?

HMG-CoA

The synthesis of what compound is considered the rate-limiting step in cholesterol formation?

Mevalonate

What type of bond helps nucleotide molecules form RNA and DNA strands?

Phosphodiester

Gout is a metabolic disorder of which of the following?

Purine catabolism

The uric acid pathway occurs in what organ?

GI tract

What is the end product of purine catabolism in humans?

Uric acid

Why does abnormal catabolism of pyrimidines not form as many serious diseases as catabolism of purines?

Pyrimidines form highly water soluble products

Which of the following is produced by the catabolism of pyrimidines?

CO2

How many ring structures does adenine have?

2

What is formed from ribose, glycine, aspartate, glutamine, tetrahydrofolate, and CO2?

IMP

Disorders of β-alanine and β-aminoisobutyrate metabolism arise from defects in which enzymes?

Pyrimidine catabolism

Which component of nucleosides and nucleotides is important in energy storage and signaling?

Phosphate group

Which purine molecule is converted into uric acid and excreted in the urine?

Xanthine

Which molecules have a pyrimidine ring in their structures?

Cytosine, thymine and uracil

Adenosine is converted to what compound via adenosine deaminase in the uric acid pathway?

Inosine

Which molecules have a purine ring in their structures?

Adenine and guanine

Nucleotides are similar in structure to nucleosides except for the addition of what molecule?

Phosphate

What medical conditions could result from mistakes or deficiencies in nucleosides or nucleotides?

Death

How many ring structures does thymine have?

1

One of the many functions of nucleosides and nucleotides includes which of the following?

Maintaining/transferring genetic information

Which molecule has a nitrogenous base and a five-carbon carbohydrate?

Nuceloside

How does allopurinol work as a treatment for gout?

Reduces production of uric acid

What enzyme is activated by increased glutamate, N-acetylglutamic acid, and/or arginine concentrations?

Carbamoyl phosphate synthetase

Conversion from citrulline to argininosuccinate requires?

a single ATP molecule is required for the reaction of citrulline to argininosuccinate

Glutamate donates the first amino group for urea; which molecule donates the second?

Aspartate

Nitrogen-based waste products are excreted as what compound?

Urea

Which of the following is an essential amino acid?

Lysine

Amino acids are metabolized via which pathway?

Citric acid cycle, glycolysis

The enzyme argininosuccinate lyase is used during which reaction?

Argininosuccinate to arginine

The reaction of CO2 and NH4 is catalyzed by CPS-I and forms carbamoyl phosphate in the urea cycle. Where does this reaction occur?

Mitochondria

The urea cycle occurs mostly in what bodily organ?

Liver

What characteristic of amino acids makes them useful for making a variety of fuels for the body?

Carbon skeleton

How many ATP molecules are required in the urea cycle?

3

What does glutamate donate for the conversion to urea?

NH3

The production of urea occurs in what part of the cell?

Cytosol

The conversion of what molecule allows for the utilization, generation, and/or storage of ammonia?

Α-ketoglutarate to glutamate

What does carbamoyl phosphate combine with to form citrulline?

Ornithine

What is used as building blocks for proteins, nucleic acids, hormones, neurotransmitters, antioxidants, and signaling molecules

Amino Acids

Which of the following is in the correct order for the urea cycle?

Carbamoyl phosphate, citrulline, argininosuccinate

What does α-ketoglutarate convert to?

Glutamate

How many amino groups are used for the conversion of products to urea?

2

What is the function of Argininosuccinate synthetase?

Conversion from citrulline to arginiosuccinate

Urea is produced in the

Liver

Which amino acid donates the second nitrogen atom during the Urea Cycle?

Aspartate

Ammonia formed in muscle and other organs is transported through the blood circulation in nontoxic form as-

Glutamine and Alanine

Fumarate from urea cycle is a source for-

Glucose, Aspartate, ATP energy

How is the urea cycle regulated?

by CPS-I

A 9-month-old infant was admitted to the hospital in a coma and a temperature of 103°F. His pulse was elevated, his liver was enlarged, and an electroencephalogram was grossly abnormal. Intravenous glucose was administered. He improved rapidly and came out of the coma in 24hrs. Analysis of his urine showed abnormally high amounts of glutamine, which suggested a high blood ammonium ion concentration.

Which enzyme may be defective in this patient?

Glutaminase

The most important amino acids as a source of fuel that generate a large amount of NADH and FADH2 are:

Valine, Leucine, and Isoleucine

The amount of fumarate used to form ATP is approximately equal to that required for the urea cycle and gluconeogenesis, meaning that-

The liver gains no net energy

Why do caloric restriction and low blood glucose increase the activities of glutamate dehydrogenase?

The activity is raised in order to increase the amount of a-ketoglutarate produced, which can be used to provide energy.

(True or False) Any urea that enters the intestinal tract is cleaved by urease-containing bacteria in the intestinal lumen and the ammonia is absorbed back into the body

True