Exams Flashcards by Ashley Graef

When an individual has a respiratory quotient of 1 they are oxidizing glucose over protein and lipids.

True

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The __________________ allows for pyruvate to be decarboxylated to form acetyl CoA.

pyruvate dehydrogenase complex

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Which of the following downregulates the pyruvate dehydrogenase complex?

Acetyl CoA

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The citric acid cycle generates 3 NADH and 1 FADH2 as reducing equivalents and 1 GTP (or ATP) by substrate level phosphorylation.

True

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NADH forms more ATP than FADH2 during oxidative phosphorylation because NADH donates its electrons to Complex 3 allowing for larger generation of the electrochemical gradient.

False

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Amphibolic reactions serve both anabolic and catabolic functions.

True

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The major fuels used by the body during the postabsorptive phase (between meals or at an overnight fast) include all of the following except

liver glycogen, non-esterified FA from adipose tissue, glycerol from adipose tissue, MUSCLE GLYCOGEN

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Non-esterified fatty acids are higher during starvation than the fed state.

True

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Which of the following is false regarding glucokinase (or hexokinase 2)?

IT IS SUBJECT OF FEEDBACK INHIBITION BY ITS PRODUCTS, It responds to a high influx of glucose, It traps glucose in the cell , It has a high Michalis Menton constant

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Digestive enzymes are secreted from which cells in the pancreas?

acinar cells

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Which of the following is not a function of insulin?

increases lipogenesis
increases glycogen storage
increases net protein synthesis
INCREASES HORMONE SENSITIVE LIPASE

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The presence of cyclic AMP in the cell upregulates all of the following except

glycogenolysis, gluconeogenesis,
beta-oxidation, CHOLESTEROL BIOSYNTHESIS

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Malonyl CoA is an important regulator of lipid metabolism. Which of the following is not true about malonyl CoA?

It can be used for ketone body synthesis

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Which of the following is a key stimulator of muscle protein synthesis?

mechanistic target of rapamycin complexes

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Glucose metabolism can be regulated in the liver by sequestering glucokinase (hexokinase 2) into the nucleus when glucose concentrations are elevated (~5 mmol/L)

FALSE

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Which is not a gluconeogenic precursor?

ACETYL COA
alanine
glycerol
lactate

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The monosaccharides galactose and fructose from the diet are converted into glucose in the small intestine.

FALSE

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In the pancreas, hexokinase 4 “senses” glucose which facilitates insulin release in the blood.

TRUE

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Which glucose transporter (GLUT) requires insulin before glucose can enter the cell?

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Which glucose transporter (GLUT) requires insulin before glucose can enter the cell?

erythrocytes

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The direct fate of glucose 6 phosphate in the liver includes all of the following except

-removal of the phosphate to enter the blood
-enter the pentose phosphate pathway
-form glucose 1 phosphate for glycogen synthesis
**form glycerol 3 phosphate for triacylglycerol synthesis

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The step the “commits” glucose to glycolysis is

6 phosphofructo-1 kinase

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The formation of 2-fructo-6-bisphosphate (or fructose 2,6 bisphosphate) by insulin stimulates the activity of 6-phosphofructo-1-kinase (or phosphofructokinase 1 or PFK-1) to keep glycolysis active.

True

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The formation of pyruvate to lactate via lactate dehydrogenase is important to maintain NAD+ concentrations in the cell to be used by glyceraldehyde-3-phosphate dehydrogenase in glycolysis.

True

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The liver can store more glycogen by weight than muscle, but whole-body muscle content is greater than the liver, thus provides more glycogen stores.

true

Which of the following stimulates glycogen synthase?

Insulin

List the 2 main functions of the pentose phosphate pathway.

1. Generate ribulose 5 phosphate (or ribose 5 phosphate) for ribonucleotide synthesis 2. Generate NADPH as a reducing agent for anabolic processes

Glycogen phosphorylase is inactive when phosphorylated.

False

To form new glucose via gluconeogenesis, _________ , ___________ , and ____________________ in glycolysis are irreversible and must be bypassed.

hexokinase PFK-1 pyruvate kinase

Gluconeogenesis can occur in which 2 tissues?

liver and kidney

What transports long chain fatty acids into the cell from the blood?

cluster of differentiation 36

What is necessary for long chain fatty acids to be transported from the mitochondrial intermembrane space to the matrix for beta-oxidation?

carnitine

The oxidation of saturated fatty acids produces less ATP than monounsaturated fatty acids with the same number of carbons.

False, Saturated fatty acids produce more ATP than MUFA of the same carbon length.

Methylmalonyl CoA mutase requires _________________ to form succinyl CoA from propionyl CoA. Correct!

vitamin B12

Describe in 2-3 sentences how acetyl CoA moves from the mitochondria matrix to the cytosol for fatty acid synthesis.

In the matrix, Acetyl CoA combines with oxaloacetate (OAA) to form citrate. Citrate is then transported from the matrix to the cytosol via the citrate transporter. Then, citrate lyase (ATP-dependent) cleaves citrate to re-form OAA + Acetyl CoA. Now Acetyl CoA can be carboxylated by Acetyl CoA Carboxylase (ACC) the regulated enzyme for fatty acid synthesis.

Which of the following serves as a negative or down-regulator for acetyl CoA carboxylase (ACC)?

AMPK

Ketone bodies are made in the liver and can be oxidized by all tissues except the liver.

True

The predominant ketone body made is

3-hydroxybutyrate

In 1-2 sentences describe the primary purpose of using ketone bodies as a fuel source during starvation.

The main purpose is to reduce the brain’s dependence on glucose for energy. Another answer may include to reduce protein break down in the muscle, in which the AA would be used as gluconeogenic precursors.

The product of fatty acid synthesis is

palmitic acid

Catecholamines stimulate the de-phosphorylation of both perilipin and hormone sensitive lipase to break down triacylglycerol to fatty acids + glycerol in adipose tissue.

False

Which of the following is false regarding eicosanoids.

they have long half-lives

Proinflammatory eicosanoids are usually derived from arachidonic acid while anti-inflammatory eicosanoids are usually derived from eicosapentaenoic acid.

False - the anti inflammatory eicosanoids are derived from docosahexaenoic acid (DHA).

Chylomicrons are absorbed from the small intestine into the lymph because they are too large to enter the portal blood.

True

Which lipoprotein is the major source of cholesterol transport to the cells?

LDL

In the blood, HDL exchanges cholesterol esters for triacylglycerol (TAG) with other lipoproteins.

True

Describe in detail how cholesterol is regulated at the gene level in the cell when: a) endoplasmic reticulum (ER) cholesterol concentrations are at 0% mol. (4 points) b) endoplasmic reticulum (ER) cholesterol concentrations are at 100% mol. (3 points)

a) When ER cholesterol concentrations are DEPLETED, cholesterol is not associated with SCAPs cholesterol sensing domain (because levels are low). Thus, SCAP is associated with SREBP, and is transported from the ER via COP2 vesicles to the Golgi. In the Golgi, SREBP2 is cleaved, and the transcription factor is released. The transcription factor enters the nucleus and binds to the promotor region of the genes that transcribe enzymes to increase cholesterol synthesis (e.g., HMG-CoA reductase) b) When ER cholesterol concentrations are ADEQUATE, cholesterol binds to the SCAP/SREBP2 complex which associates with INSIG. INSIG prevents the complex from being transported from the ER to the Golgi for further processing. INSIG also binds to the reductase and tags it for ubiquination.

Which apolipoprotein activates the enzyme that cleaves fatty acids from triacylglycerol so they can be taken up by tissues?

Apo C2

After eating a high-fat meal, chylomicrons will peak in the blood

at 4 hours

HDL cholesterol is formed by which apolipoprotein?

Apo A1

7-dehydrocholesterol in the skin is a precursor to which steroid hormone?

1,25 di-hydroxyvitamin D3

List 2 reasons why cholesterol is esterified in the cell.

Maintain cholesterol homeostasis in the cell Free cholesterol is toxic Provides cholesterol to the cell when needed Can be incorporated into lipid droplets that eventually donates to lipoproteins for secretion

Why are bile acids conjugated in the liver?

To make them more amphipathic and able to act as an emulsifier and more soluble in the micelle.

Bile acids serve as a nuclear receptor so it can regulate the amount of bile that is synthesized and excreted.

True

Describe in 2-3 sentences how excreting bile acids in the feces lowers blood cholesterol levels.

Bile acids are efficiently reabsorbed in the ileum and returns to the liver for re-circulation (enterohepatic circulation). When less bile is absorbed, more must be made in the liver. Cholesterol is used to make new bile in the liver, thus, lowering blood cholesterol levels.

HDL can cross the arterial wall and provoke an inflammatory response, which can lead to plaque formation.

False

Ketone bodies can provide all of the brain’s requirement for glucose.

False

Long-chain fatty acids that cross the blood brain barrier are used for the generation of ATP in the brain.

False

The minimum amount of glucose consumed by the brain in energy-balanced individuals is

100 g/d

The Acceptable Macronutrient Distribution Range (AMDR) for carbohydrate is 45-65% and lipids is 20-35% .

Which of the following is not a reason to limit added sugars?

they can replenish glycogen stores for athletes after a long workout

The Adequate Intake (AI) for dietary fiber is

14 g/1,000 kcal/d

According to research by Miketinas and Patterson, 2021, US adults with diabetes consume more fiber than healthy adults.

True

One-third of the brain's essential fatty acid content consists of _________ and _________.

docosahexaenoic acid + arachidonic acid

Aspirin modifies the cyclooxygenase 2 enzyme; therefore, pro-inflammatory leukotrienes are epimerized to pro-resolving leukotrienes.

True

Saturated fatty acids intake should be replaced with the following:

polyunsaturated fatty acids

The conversion rate of alpha-linoleic acid to eicosapentaenoic acid and docosahexaenoic acid in our bodies is very efficient; therefore, the need to supplement eicosapentaenoic acid to docosahexaenoic acid in some populations is not necessary.

False

The majority of added sugars in the US diet come from which of the following?

sugar-sweetened beverages

Glucose is the preferred fuel for enterocytes.

Glutamine is the preferred fuel for enterocytes.

The recommended intake of dietary fiber is 15 g per 1,000 kcal daily.

False

Fructose is absorbed from the small intestinal lumen into the enterocyte by

GLUT 5

Highly fermented fibers include all of the following except

*cellulose pectin oat bran inulin

Digestion of starch by amylase begins in the mouth by hydrolysis of what type of linkage?

alpha (1-->4)

The function of fiber in the large intestine depends on which of the following

degree of fermentation type of fiber resident microflora * all of the above

Which of the following is NOT true when describing cholecystokinin (CCK)?

* it is released into the lumen of the small intestine it stimulates digestive enzyme release from the pancreas it functions as a hormone in the GI tract it stimulates bile release from the gallbladder

Which of the following is NOT a function of gel forming fibers?

binding bile and removing it from the body improved satiety attenuate nutrient absorption *increase gastric emptying

Which of the following sugars is NOT a disaccharide?

sucrose *amylose maltose lactose

Resistant starch escapes digestion in the small intestine and enters the large intestine to be fermented by microbiota.

True

Which of the following is not absorbed in the stomach?

AMINO ACIDS, alcohol, salts, butyrate

The duodenum absorbs most nutrients except Fe and Ca

False

Bile acids can be ______ with glycine and taurine making them more polar prior to form micelles that aid in emulsifying dietary fat

true

Major functions of stomach

secretion of HCl, zmogens, endocrine hormones, and intrinic factor regulation of chyme entry into SI temporarily storing food and liquid

Which stomach cells release HCL and intrinsic factor?

Parietal

Leptin is released from the stomach during fasting and stimulates food intake

false

The ileum absorbs ______ and _____

vitamin b12 and bile acids

zwitterion

AA has a net charge of zero

Type of reaction that occurs when two amino acids form a peptide bond

condensation

The primary structure of a protein directs the folding of the protein in its 3D shape

true

Vitamin C and zinc are necessary for the hydroxylation of lysine and proline so collagen can mature

false

Which of the following can lead to the impairment of starch digestion and cause GI distress?

Alpha-glucosidase inhibitors

Incretins do all of the following except

stimulate insulin release INHIBIT DIPEPTIDYL PEPTIDASE-4 proliferate pancreatic beta cells effect food intake via the vagus nerve

What is required for pancreatic lipase to break down triacylglycerides in the presence of bile acid

colipase

30% of phytosterols are absorbed in the enterocyte

false

apolipoprotein associated with chylomicrons

APO B48

The most appropriate way to classify dietary fiber by physiological function is by solubility

false

During the fed state, the brain uses _____ percent of glucose for energy

which of the following is not a gluconeogenic substrate

glycerol alanine lactate ACETYL COA

adipose tissue has glycerol kinase

false

which glut is expressed in the brain

GLUT3

Hexokinase primarily acts as a glucose sensor in which tissue

pancreas

gluconeogenisis occurs in which two tissues

liver, kidney

primary regulator of glycolysis

fructose 2-6 bisphosphate

glycogen synthase is activated when phosphorylated

false

glycogen contains amylose and amylopectin

false, contains 1-4 and 1-6 branches but not called amylose and amylopectin

glycogen synthase adds glucose to the non-reducing end of existing glycogen molecule

true

net ATP from glucose alanine cycle

Exams Flashcards

(106 cards)