H2O Soluble Vitamins (Test ?)
What is the symptom of pantothenic acid deficiency?
Burning Feet Syndrome
A major role for thiamin is:
Energy transformation.
Vitamin B12 is absorbed in the:
Ileum
Vitamin C is related to carnitine synthesis. Which amino acid metabolism does vitamin C involved in carnitine synthesis?
Lysine
Large amounts of folic acid can mask a vitamin B12 deficiency and prevent ________ from resulting. Over time the symptoms unique to a vitamin B12 deficiency will occur, and these are related to the _________.
Macrocytic anemia, nervous system
Folate is vitally important for dividing cells during growth and cancer because of its essential role in the synthesis of.
Purines and pyrimidines
Which of the following is an aitithiamin factor that is abundant in raw fish?
Thiaminase
A deficiency of which vitamin is commonly associated with rickets?
Vitamin D
For which vitamin is the Tolerable Upper Intake Level set because of increased tendency for bleeding?
Vitamin D
Which vitamin has as its primary function the maintenance of calcium homeostasis?
Vitamin D
What is the criteria for a genetic difference to be called a "polymorphism"?
a. It has to be lethal within 6 months of life. b. It causes a miscarriage 50% of the time. c. More men than women have the genetic difference. d. More than 1% of the population has the variation.***
Which of the following would you find under B12-deficient conditions and the methyl trap hypothesis?
a. accumulation of 5-methylene THF b. depletion of homocysteine c. accumulation of THF d. accumulation of 5-methyl THF*** e. more than one of the above
A good source of vitamin B6 is muscle meats because PLP is predominantly bound to the enzyme _____.
a. alanine aminotransferase b. cystathionine synthase c. glycogen phosphorylase*** d. aspartic aminotransferase
In the enzyme methionine synthase, vitamin B12 acts by accepting a _____ group from _____ and donating this group to _____ to form methionine.
a. carbon, methionine, folate b. methyl, 5-methyltetrahydrofolate, homocysteine*** c. methyl, formiminoglutamic acid, succinyl-CoA d. carbon, serine, glycine
Vitamin C acts as a cofactor by maintaining iron in a reduced state in:
a. collagen synthesis.*** b. methylation of homocysteine. c. release of energy from nutrients. d. red blood cell synthesis.
A major role for thiamin is:
a. energy transformation.*** b. blood coagulation. c. collagen formation. d. erythrocyte synthesis.
Most animals synthesize their own ascorbic acid from _____. a. glucose b. glutamine c. glycogen d. alanine
a. glucose***
Because vitamin B6 is involved in heme synthesis, a deficiency symptom is
a. hypochromic, microcytic anemia.*** b. seizures. c. hyperhomocysteinemia. d. impaired calcium metabolism.
Which is NOT a fate of homocysteine in the cell?
a. methylated to methionine b. used to restore tetrahydrofolate c. used to synthesize cysteine d. used in the synthesis of leucine***
Without enough vitamin C, collagen would _____. a. be too tightly coiled b. be over-hydroxylated c. be under-hydroxylated d. too strong and less flexible
c. be under-hydroxylated***
associated phrase: UL = 2000 mg/d
vitamin C
Which of the following is needed for the visual cycle?
11-cis retinal
Vitamin A functions in the visual cycle. This mechanism involves a vitamin A molecule called ________, combining with _________ to form ________. When photon energy strikes this molecule. It splits and causes a conformational change in the molecule, causing an electrical signal to be sent to the brain.
11-cis retinal, opsin, rhodopsin
How many ATPs will be produced by FADH2 at electron transport sytem?
2
What amount of supplemental folic acid is recommended daily for women of childbearing age in the United States?
400 ug DFE
In what type of tissue is the largest amount of vitamin E stored?
Adipose
The majority of vitamin A is stored in the liver, while carotenoids are stored mainly in the ________ tissue.
Adipose
A primary function of vitamin C is to act as an:
Antioxidant
Discuss niacin equivalents and how they are calculated based on protein intake.
Assume that 1 g of complete, high-quality protein = 10 mg of tryptophan. This estimate means that an intake of 60 g of complete protein, for example, would provide 600 mg of tryptophan (10 mg tryptophan/1 g protein × 60 g protein = 600 mg tryptophan). Then, because it takes 60 mg of tryptophan to generate 1 mg of NE, 600 mg of tryptophan would generate 10 NEs (600 mg tryptophan × 1 mg NE/60 mg tryptophan = 10 NEs).
How will retinol, once secreted from the liver, be found in the blood?
Attached to RBP and transthyretin
5-methyl THF requires the action of which vitamin in order to form THF?
B12
Intrinsic factor is required for the majority of absorption of which vitamin?
B12
Which of the water-soluble vitamins is able to be stored and retained in the body for long periods of time?
B12
Vitamins and Hematology. Folate and B12 have an important role in hematology ("blood-related" processes) such that a deficiency of either of these vitamins can result in anemia. Discuss the interrelationship between these vitamins and why a deficiency of either of them results in megaloblastic anemia. Your answer will likely need to talk to some extent about the methyl trap hypothesis. Make sure to relate any metabolic description of folate and B12 to the basis for anemia resulting from a deficiency.
B12 is required for homocysteine methylation to generate methionine. The methyl group comes from 5-methyl THF and THF is left over. Thus, without B12, folate accumulates as 5-methyl THF because it cannot be used for homocysteine remethylation, and it cannot be metabolized back to 5,10-methylene THF (one-way pathway). The result is that all other (besides 5-methyl THF) forms of folate decrease, including 5,10-methyhlene THF—the methylene group is used for DNA synthesis. Without DNA synthesis, RBCs cannot replicate and divide (hence, megaloblastic anemia).
A consequence of thiamin deficiency is:
Beriberi
Which of the carotenoid pigments has the greatest vitamin A activity?
Beta-carotene
A deficiency of what vitamin is associated with these symptoms: hallucinations, lethargy, skin rash, alopecia, and muscle pain?
Biotin
Vitamins - One-sentence Descriptions. For each vitamin listed below, indicate: (1) the active form of the vitamin, (2) the general function for the vitamin, and (3) an example of the general function (this could be a specific reaction or simply indicate a pathway/ process where it occurs). An example is provided; as you can see, your answers do not need to be long! Vitamins: Biotin, pantothenate, riboflavin, vitamin B6, thiamin, vitamin C, folate, niacin
Biotin (1) Biotin (2) Carboxylation (3) Acetyl-CoA carboxylase (FA synthesis), pyruvate carboxylase (gluconeogenesis), propionyl-CoA carboxylase (odd-chain FA degradation/ oxidation) Pantothenate (1) CoA (2) Activates substrates/ intermediates; protein acetylation (3) Many examples (acetyl-CoA, malonyl-CoA, etc.) in glycolysis/ TCA; FA synthesis and oxidation, etc. Riboflavin (1) FAD(H2) (2) Oxidation-reduction reactions (3) TCA cycle; FA β-oxidation B6 (1) PLP (2) Transamination; decarboxylation; transsulfuration; glycogenolysis (3) AA to KA (gluconeogenesis); heme synthesis; neurotransmitter synthesis; homocysteine to cystathionine and then to cysteine Thiamin (1) TPP or TDP (2) Oxidative decarboxylation (3) Pyruvate to acetyl-CoA; α-ketoglutarate to succinyl-CoA; HMS as transketolase Vitamin C (1) Vitamin C or ascorbic acid (2) Hydroxylation (3) Collagen synthesis (OH of pro and lys in collagen); carnitine synthesis; neurotransmitter synthesis Folate (1) Tetrahydrofolate (polyglutamates) (2) One-carbon transfer (3) DNA synthesis (uridylate to thymnidylate); homocysteine to methionine Niacin (1) NAD(H) or NADP(H) (2) Oxidation-reduction reactions (3) TCA Cycle reaction or.... (3) α-ketoglutarate succinyl-CoA NAD NADH
When water-soluble vitamins are consumed in excess of body needs, generally the excess is: a. excreted in the feces. b. stored in liver, bone, and adipose tissue. c. excreted in the urine. d. not absorbed.
C. excrete in the urine
Vitamins and Energy Metabolism. Vitamins play a big role in our ability to acquire energy from macronutrients. Pick one macronutrient and discuss how vitamins are involved in procuring energy; choose from: (1) carbohydrates (glycolysis/ TCA); (2) lipids (lipolysis/ β-oxidation); or (3) protein/ amino acids (gluconeogenesis). Your answer should be as specific as possible: names of vitamins and what they do with respect to the macronutrient you've chosen to help generate energy. A diagram may be especially useful. there are 4 vitamins for (1), 3-5 vitamins for (2), and 2-4 vitamins for (3)—the range for (2) and (3) is because it depends on the FA or AA you start with.
CHOs: Vitamins involved are thiamin (TPP; pyruvate dehydrogenase and α-ketoglutarate dehydrogenase; transketolase is with the pentose phosphate pathway); niacin (NADH, glycolysis/TCA; NADPH from HMS); riboflavin (FADH2 from TCA); and pantothenate as CoA. Lipids: For FA oxidation you use niacin and riboflavin (NADH and FADH2) and get acetyl-CoA (pantothenate). For odd-chain FA oxidation, you again generate acetyl-CoA and have those three vitamins, as well as biotin (propionyl-CoA carboxylase) and B12 (methylmalonyl-CoA mutase). You could also include TPP here in the TCA cycle. Protein: For amino acid metabolism, you need B6 (transamination of amino acids to ketoacids), and if the ketoacid obtained is pyruvate, biotin for pyruvate carboxylase; all of this is for gluconeogenesis. However, if the amino acid has more than 3 carbons, it will feed into the TCA cycle at the corresponding carbon length ketoacid; thus, NAD, FAD, and TPP all come into play (as well as CoA with succinyl-CoA).
The necessity of ascorbic acid for its role in is believed to be the reason that people with scurvy have no energy and are very tired.
Carnitine synthesis
Choose the food that is high in beta carotene.
Carrots
Vitamin C acts as a cofactor by maintaining iron in a reduced state in:
Collagen Synthesis
One method to assess vitamin status is using a "load test." Explain how this works—first in a conceptual way, and then specifically using one example. Your specific example can be chosen from either tryptophan or histidine (pick one). Do you think this is a good assessment method? Why or why not?
Conceptual: If it is known that a vitamin is required at a given step in a metabolic pathway, one can challenge that pathway by providing a large load of substrate. If the vitamin is present, it will be metabolized normally. If not, the substrate will either be metabolized down a different pathway and products of that will appear in the urine, or the intermediate compound just before the vitamin-requiring step will build up and be excreted in the urine. Specific: Trp - B6 is required to convert trp to niacin. Without sufficient B6, trp cannot be converted to niacin and follows an alternative pathway to xanthurenic acid, which can be found in the urine. Histidine loading will cause elevated FIGLU in urine because folate is required for the degradation of histidine.
One method to assess nutrient status is to measure the activity of an enzyme that requires the vitamin as a cofactor. Explain how this works—first in a conceptual way, and then specifically using an example. Your specific example choices are thiamin, riboflavin, or folate (pick one). Do you think this is a good assessment method? Why or why not?
Conceptual: If one knows of a specific enzyme that requires a vitamin as a cofactor to be active, its activity can be measured in an individual. Then, exogenous vitamin is provided (in the test tube, not to the person), and the activity is measured again. If the activity increases with extra vitamin provided, that tells you that the enzyme must have been deficient to begin with. Specific: Thiamin - transketolase requires TPP to be active. It can be measured in red blood cells as is, and in the presence of extra TPP added to the assay. An increase of >25% indicates deficiency. Called erythrocyte transketolase activity (ETKA) test. Riboflavin - glutathione reductase requires FAD. The enzyme is measured with and without extra FAD and a ratio of the two is determined (i.e., ratio of activity with versus without). A ratio greater than 1.4 (that's an increase of 40%) indicates deficiency. Folate - thymidylate synthetase is measured in cultured lymphoctyes or bone marrow cells with and without folate. If vitamin B12 is deficient, that also diminishes thymidylate synthetase. If a person were folate deficient, adding folate—but not vitamin B12—would normalize enzyme activity. Likewise, if a person were vitamin B12 deficient, adding vitamin B12—and not folate—would normalize thymidylate synthetase activity.
Folate in foods can only be absorbed in the monoglutamate form; therefore. Digestive enzymes called __________ are important for folate nutriture.
Conjugases
T/F: Vitamin C is a good reducing agent, meaning it keeps things reduced by undergoing irreversible oxidation; thus, it must continuously be replaced by dietary sources.
F: It's oxidation is not irreversible—it can be recycled back to its reduced form.
T/F: The active form of a vitamin is usually the form that has the greatest bioavailability.
F: Opposite—usually the active form must be modified to its parent form for absorption (e.g., TPP to thiamin; THF polyglutamates to monoglutamate).
T/F: Urinary excretion of xanthurenic acid may be an indication of niacin deficiency.
F: PLP, not niacin.
T/F: Pernicious anemia can be due to folate or B12 deficiency.
F: Pernicious anemia refers to megaloblastic anemia owing to lack of intrinsic factor.
T/F: Water-soluble vitamins are not stored, but readily excreted—the one exception is that we can store folate in the liver.
F: The exception is not folate, but B12¸which can be stored in the liver.
T/F: Biotin and B12 are both required for the synthesis of odd-chain fatty acids.
F: They are both required for the oxidation, not synthesis, of odd-chain FAs.
T/F: An increase in blood pyruvate and lactate levels may be due to a deficiency of riboflavin.
F: Thiamin, not riboflavin.
A good source of vitamin D is milk, because It is fortified with l,25-(OH)- vitamin D3.
FALSE
Gut bacteria can produce some vitamins, but this rarely contributes to our requirements because they are not absorbed.
FALSE
Pernicious Anemia can be due to folate or B12 deficiency.
FALSE
Water-soluble vitamins are not stored, but readily excreted—the one exception is that we can store folate in the liver.
FALSE
Metabolism of vitamin B6 to the primary coenzyme form, pyridoxal phosphate, requires the action of what other B vitamin?
FMN
Ascorbic acid provides a reducing equivalent so that iron is in the _________ form in lysyl hydroxylase.
Ferrous
Riboflavin coenzymes remain bound to their enzymes during the oxidation-reduction reactions and the complexes are called _____.
Flavoenzymes
Riboflavin coenzymes remain bound to their enzymes during the oxidationreduction reactions and the complexes are called:
Flavoproteins
Although for micronutrients increasing the amount of a protein by directly inducing gene expression is certainly a common mechanism, we have encountered other mechanisms by which vitamins can regulate proteins. Pick either posttranslational modification or allosteric regulation and provide one example—be as specific as possible.
For posttranslational modification (altering the function of an existing protein by forming a covalent bond without changing its abundance), pantothenic acid, as CoA, is involved in the acetylation of proteins. This means to "make a covalent bond" that consists of adding an acetate group (CH3COO-) to a protein to activate it. Another PTM example is the role of vitamin C in collagen synthesis. Really, this should be called collagen modification—we are not increasing the synthesis of collagen, we are modifying its structure so that it can form cross-links with other collagen molecules. Hydroxylation of the lysine or proline residues in collagen allows collagen to form cross-links (making it strong), and this process requires vitamin C. Vitamin C is not required directly in the hydroxylation step (which is why it is not considered a cofactor), but rather it is required to regenerate the enzyme that performs the actual hydroxylation. This enzyme contains Fe++ as a cofactor, which is oxidized to Fe+++ following the reaction; vitamin C functions to reduce the Fe+++ back to Fe++, thus allowing the enzyme to function again. Other vitamin C-dependent hydroxylation reactions are identical to this, with the exception that the substrate that is being hydroxylated is not a protein; thus, by definition it does not constitute posttranslational modification. Allosteric regulation refers to substances (like ATP or a metabolite) binding to an enzyme in a given pathway, resulting in the inhibition or activation of that enzyme. For example, as the concentration of ATP increases (a sign of energy being produced), there is no need for more glycolysis; thus, ATP binds to phosphofructokinase (PFK), a key enzyme in the glycolytic pathway, and inhibits it. Other examples include niacin and pantothenic acid. For niacin, when the concentration of NADH increases (such as in the fed state), it inhibits enzymes involved in producing energy, like PFK or pyruvate dehydrogenase or α-ketoglutarate dehydrogenase. Likewise, pyruvate can "make choices" metabolically, that is be oxidized to acetyl-CoA by pyruvate dehyrogenase (TPP-dependent) or go to OAA via pyruvate carboxylase (biotin-dependent). The level of acetyl-CoA can play an allosteric role in that it promotes/ activates pyruvate carboxylase when its concentration reaches a certain level. This makes sense, because the level of acetyl-CoA will be high when there is plenty of glycolysis going on and the resulting pyruvate is being metabolized by pyruvate dehydrogenase to acetyl-CoA—thus, it is diverting pyruvate to the opposing pathway of gluconeogenesis by stimulating pyruvate carboxylase. [This is a valid example because CoA is derived from pantothenic acid. Stating that glucagon does the same thing is not valid, because glucagon is a hormone, not a vitamin.]
Most animals syntithesize their own ascorbic acid from _______.
Glucose
To absorb folate consumed from green, leafy vegetables.
Glutamic acid molecules must be removed
Which is NOT related to the functions of vitamin A?
Growth
The digestion and absorption of cobalamin requires pepsin and _____; the presence of 2 nonenzymatic proteins: _____ and _____; and a receptor located in the _____.
HCl, R protein, intrinsic factor, ileum
Elevated homocysteine levels can be due to all the following:
High folacin. Low cobalamin. Low pyridoxine.
Immediately following a balanced meal that contained vitamin E (such as fortified milk), where would you most likely find most of the vitamin E in the body?
In chylomicrons In the lymphatic vessels and general circulation
Describe the process by which vitamin B12 is digested and absorbed
Ingested cobalamins are released from the proteins/polypeptides to which they are linked in foods through the actions of pepsin and hydrochloric acid in the stomach. Free vitamin B12 binds to an R protein that is found in saliva and gastric juice. Within the alkaline environment of the small intestine, the R protein is hydrolyzed by pancreatic proteases, and free vitamin B12 is released and binds to intrinsic factor (IF). The vitamin B12-IF complex travels from the duodenum to the ileum, where it interacts with a protein receptor (called cubilin, IF receptor, or cubam). Cubilin then interacts with another protein, amnionless, which facilitates cubilin's attachment to the ileal cell's plasma membrane. Binding of the vitamin B12-IF complex to the receptor triggers active endocytotic internalization. Vitamin B12 is absorbed throughout the ileum, especially the distal third. Within the enterocyte, the vitamin is released from the IF complex. Next, in or before it is transported across the ileum's basolateral membrane, vitamin B12 binds to the protein transcobalamin II for transport in portal blood.
Which vitamin has a reduced coenzyme form important for fatty acid and cholesterol synthesis that is a product of the hexose monophosphate shunt?
Niacin
Which vitamin has a reduced coenzyme form important for fatty acid and cholesterol synthesis that is a product of the pentose phosphate pathway?
Niacin
Which three vitamins are involved in the synthesis of fatty acids?
Niacin, biotin, pantothenic acid
Synthesis of coenzyme A starts with the phosphorylation of which vitamin?
Pantothenic acid
Which of the water-soluble vitamins is found widely distributed in all plant and animal foods, which makes a deficiency unlikely?
Pantothenic acid
The normal digestion and absorption of cobalamin requires adequate protein digestion in the stomach; the presence of 2 nonenzymatic proteins: ________; and a receptor located in the ________.
R protein and intrinsic factor, ileum
Which of the following reflects long-term folate status?
Red blood cell folate
Cheilosis is a symptom of a dietary deficiency of which vitamin?
Riboflavin
Which of the following vitamin requires digestion process to be free form specifically before being absorbed?
Riboflavin (B2)
Pernicious anemia is identified by the _____ test, which involves using radioactive _____.
Schilling, vitamin B12
In what cells will you find most of the retinol and vitamin A stored?
Stellate
T/F: Circulating concentrations of a vitamin typically reflect diet, whereas intracellular (e.g., RBCs, leukocytes) concentrations reflect body pools.
T
T/F: High circulating levels of homocysteine (i.e., hyperhomocysteinemia) have been implicated in a number of pathologies including cardiovascular disease.
T
T/F: In the folate-dependent one-carbon pool, a carbon unit in the methyl form (i.e., 5-methyl THF) is used in the conversion of homocysteine to methionine, whereas a carbon unit in the methylene form (i.e., 5,10-methylene THF) is used in DNA synthesis.
T
T/F: Pellagra symptoms may appear during B6 deficiency, because this vitamin is required in the process of obtaining niacin from tryptophan.
T
T/F: The primary role of vitamin C is as a reducing agent, particularly for the mineral component of a number of enzymes that becomes oxidized following catalysis of a reaction.
T
T/F: The reason we use equivalents when discussing the RDA for some vitamins is that there are different forms of the vitamin that, by weight, are not equal in terms of vitamin activity—this is due to differences in absorption and/or metabolism.
T
High-circulating levels of homocysteine (i.e., hyperhomocysteinernia) ave been implicated in a number of pathologies including cardiovascular disease.
TRUE
Many anticoagulants Inhibit the vitamin K cycle, thereby preventing activation of clotting proteins.
TRUE
Pellagra symptoms may appear during B6 deficiency, because this vitamin is required in the process of obtaining niacin from tryptophan.
TRUE
Production of active vitamin D requires skin, sunlight, cholesterol Production liver, and the kidneys.
TRUE
Rhodopsin is simply the opsin protein after it has been activated by 11-cis-retinal.
TRUE
The reason we use equivalents when discussing the RDA for some vitamins is that there are different forms of the vitamin that, by weight, are not equal in terms of vitamin activity—this is due to differences In absorption and/or metabolism.
TRUE
Erythrocyte transketolase activity is an assay to assess the status of:
Thiamin
Thiamin is important to fatty acid synthesis due to its requirement as a coenzyme for the hexose monophosphate shunt enzyme _____.
Transketolase
When the diet is adequate in protein, the body can synthesize niacin from which amino acid?
Tryptophan
Which vitamin directs cellular differentiation of epithelial cells?
Vitamin A
Which vitamin is said to be essential for growth and immune system function?
Vitamin A
Which of the following vitamins has a Tolerable Upper Intake Level established?
Vitamin B6
Which vitamin is most involved in amino acid metabolism?
Vitamin B6
Which water-soluble vitamin contributes to "Intracellular cement" in the formation of scar tissue and wound healing?
Vitamin C
What is the significance of vitamin C to carnitine and fat metabolism?
Vitamin C functions as a reducing agent, specifically reducing the iron atom from the ferric state (Fe3+) back to the ferrous state (Fe2+) for the reactions catalyzed by trimethyllysine hydroxylase and 4-butyrobetaine hydroxylase in the synthesis of carnitine. The carnitine shuttle is required for fatty acid oxidation by allowing entry of long-chain fatty acids into the mitochondria for beta-oxidation.
A consequence of thiamin deficiency mainly caused by alcoholism is:
Wernicke-Korsakoff syndrome
Explain the relationship of folate to vitamin B12 in the various anemias
Without vitamin B12, folate coenzymes are reduced to 5-methyl folate (the methyl-folate trap) and cannot be converted to the coenzyme forms 10-formyl THF and 5,10-methylene THF, which are needed for synthesis of the purine ring and thymidylate, respectively. Consequently, DNA synthesis becomes deranged, along with cell differentiation and maturation, and this negatively impacts cells, especially those with rapid turnover such as blood cells. Megaloblastic, macrocytic anemia results.
A major function of B vitamins is to serve as:
a part of a coenzyme.
What amount of supplemental folic acid is recommended daily for women of childbearing age in the United States?
a. 200 ug DFE b. 400 ug DFE*** c. 600 ug DFE d. 800 ug DFE
What amount of supplemental folic acid is recommended daily for women of childbearing age in the United States? a. 200 ug DFE b. 400 ug DFE c. 600 ug DFE d. 800 ug DFE
a. 200 ug DFE b. 400 ug DFE*** c. 600 ug DFE d. 800 ug DFE
Although excess absorbed ascorbic acid is excreted in urine, the body has an estimated maximal body pool of about _____, which can be maintained with intakes of 100-200 mg vitamin C per day.
a. 500 mg b. 1000 mg c. 1500 mg d. 2000 mg***
The RDA for vitamin C for adult men is _____ and the UL is _____.
a. 75 mg, 500 mg b. 100 mg, 500 mg c. 90 mg, 2000 mg*** d. 200 mg, 2000 mg
The RDA for vitamin C for adult men is _____ and the UL is _____. a. 75 mg, 500 mg b. 100 mg, 500 mg c. 90 mg, 2000 mg d. 200 mg, 2000 mg
a. 75 mg, 500 mg b. 100 mg, 500 mg c. 90 mg, 2000 mg*** d. 200 mg, 2000 mg
Ascorbic acid can reduce the oxidized form of vitamin E. Choose the phrase that describes this.
a. Ascorbic acid reduces the tocopheroxy radical to the quinone form; ascorbic acid is oxidized to dehydroascorbic acid. b. Ascorbic acid reduces the hydroquinone form to the quinone form; ascorbic acid is reduced to semi-dehydroascorbic acid. c. Ascorbic acid reduces the tochopheroxy radical to the tocopherol form; ascorbic acid is oxidized to semi-dehydroascorbate.***
Ascorbic acid can reduce the oxidized form of vitamin E. Choose the phrase that describes this: a. Ascorbic acid reduces the tocopheroxy radical to the quinone form; ascorbic acid is oxidized to dehydroascorbic acid. b. Ascorbic acid reduces the hydroquinone form to the quinone form; ascorbic acid is reduced to semi-dehydroascorbic acid. c. Ascorbic acid reduces the tochopheroxy radical to the tocopherol form; ascorbic acid is oxidized to semi-dehydroascorbate.
a. Ascorbic acid reduces the tocopheroxy radical to the quinone form; ascorbic acid is oxidized to dehydroascorbic acid. b. Ascorbic acid reduces the hydroquinone form to the quinone form; ascorbic acid is reduced to semi-dehydroascorbic acid. c. Ascorbic acid reduces the tochopheroxy radical to the tocopherol form; ascorbic acid is oxidized to semi-dehydroascorbate.***
5-methyl THF requires the action of which vitamin in order to form THF?
a. B12*** b. B2 c. niacin d. C
5-methyl THF requires the action of which vitamin in order to form THF? a. B12 b. B2 c. niacin d. C
a. B12*** b. B2 c. niacin d. C
Carbon in the one-carbon pool can be in the 5-methyl-THF form or the 5,10-methylene-THF form. Which statement is FALSE?
a. Both forms of carbon (methyl and methylene) can be used directly for thymidylate synthesis. b. The methylene group of 5,10-methylene-THF can be oxidized to generate 5-methyl-THF and vice versa. c. B12 is a cofactor for utilization of the methyl group in the conversion of homocysteine to methionine d. More than one is false.***
Carbon in the one-carbon pool can be in the 5-methyl-THF form or the 5,10-methylene-THF form. Which statement is FALSE? a. Both forms of carbon (methyl and methylene) can be used directly for thymidylate synthesis. b. The methylene group of 5,10-methylene-THF can be oxidized to generate 5-methyl-THF and vice versa. c. B12 is a cofactor for utilization of the methyl group in the conversion of homocysteine to methionine d. More than one is false.
a. Both forms of carbon (methyl and methylene) can be used directly for thymidylate synthesis. b. The methylene group of 5,10-methylene-THF can be oxidized to generate 5-methyl-THF and vice versa. c. B12 is a cofactor for utilization of the methyl group in the conversion of homocysteine to methionine d. More than one is false.***
Intrinsic factor is required for the majority of absorption of which vitamin?
a. C b. B6 c. B12*** d. B2
Intrinsic factor is required for the majority of absorption of which vitamin? a. C b. B6 c. B12 d. B2
a. C b. B6 c. B12*** d. B2
Vitamin C's actual participation in biochemical reactions usually involves its antioxidant ability. Choose the description of this activity.
a. Donates an electron or electrons to oxidize a mineral cofactor b. Accepts an electron or electrons to reduce a mineral cofactor c. Donates an electron or electrons to reduce a mineral cofactor*** d. Accepts an electron from the quinone form of vitamin E
Metabolism of vitamin B6 to the primary coenzyme form, pyridoxal phosphate, requires the action of what other B vitamin?
a. GSH b. NAD c. THF d. FMN***
Metabolism of vitamin B6 to the primary coenzyme form, pyridoxal phosphate, requires the action of what other B vitamin? a. GSH b. NAD c. THF d. FMN
a. GSH b. NAD c. THF d. FMN***
Nutrients can be used to compensate for some gaps in our DNA. For example:
a. Individuals with a change in the base sequence for the phenylalanine hydroxylase gene can correct the sequence of bases by eating a lot of phenylalanine. b. Obese individuals can lose body weight by eating fewer calories than they expend. c. Omega-3 fatty acids can up-regulate genes encoding for fat oxidation. d. Individuals with a polymorphism that decreases activity of a folate-metabolizing enzyme, methylene tetrahydrofolate reductase, may have more elevated plasma homocysteine than those with a normal enzyme while more folate intake can normalize plasma homocysteine for those with this polymorphism.***
What is the criteria for a genetic difference to be called a "polymorphism"? a. It has to be lethal within 6 months of life. b. It causes a miscarriage 50% of the time. c. More men than women have the genetic difference. d. More than 1% of the population has the variation.
a. It has to be lethal within 6 months of life. b. It causes a miscarriage 50% of the time. c. More men than women have the genetic difference. d. More than 1% of the population has the variation.***
The normal digestion and absorption of cobalamin requires adequate protein digestion in the stomach; the presence of 2 nonenzymatic proteins: _____; and a receptor located in the _____.
a. R binders and hydrochloric acid, colon b. pepsin and hydrochloric acid, ileum c. R protein and intrinsic factor, ileum*** d. R protein and intrinsic factor, duodenum
The normal digestion and absorption of cobalamin requires adequate protein digestion in the stomach; the presence of 2 nonenzymatic proteins: _____; and a receptor located in the _____. a. R binders and hydrochloric acid, colon b. pepsin and hydrochloric acid, ileum c. R protein and intrinsic factor, ileum d. R protein and intrinsic factor, duodenum
a. R binders and hydrochloric acid, colon b. pepsin and hydrochloric acid, ileum c. R protein and intrinsic factor, ileum*** d. R protein and intrinsic factor, duodenum
Which of the following would you find under B12-deficient conditions and the methyl trap hypothesis? a. accumulation of 5-methylene THF b. depletion of homocysteine c. accumulation of THF d. accumulation of 5-methyl THF e. more than one of the above
a. accumulation of 5-methylene THF b. depletion of homocysteine c. accumulation of THF d. accumulation of 5-methyl THF*** e. more than one of the above
A good source of vitamin B6 is muscle meats because PLP is predominantly bound to the enzyme _____. a. alanine aminotransferase b. cystathionine synthase c. glycogen phosphorylase d. aspartic aminotransferase
a. alanine aminotransferase b. cystathionine synthase c. glycogen phosphorylase*** d. aspartic aminotransferase
A genetic polymorphism that decreases the activity of N5,N10 methylene tetrahydrofolate reductase has been identified. This would cause _____.
a. an accumulation of 5-methyl THF b. an increase in the homocysteine concentration in the cell*** c. a decreased risk for megaloblastic anemia d. a decreased risk for heart disease
A genetic polymorphism that decreases the activity of N5,N10 methylene tetrahydrofolate reductase has been identified. This would cause _____. a. an accumulation of 5-methyl THF b. an increase in the homocysteine concentration in the cell c. a decreased risk for megaloblastic anemia d. a decreased risk for heart disease
a. an accumulation of 5-methyl THF b. an increase in the homocysteine concentration in the cell*** c. a decreased risk for megaloblastic anemia d. a decreased risk for heart disease
A major function of B vitamins is to serve as:
a. antibodies. b. a source of energy. c. a part of a coenzyme.*** d. electrolytes.
A primary function of vitamin C is to act as an:
a. antiviral agent. b. antioxidant.*** c. antirachitic agent. d. acyl transferase.
Riboflavin coenzymes remain bound to their enzymes during the oxidation-reduction reactions and the complexes are called _____.
a. apoenzymes b. flavokinases c. bound enzymes d. flavoproteins***
Riboflavin coenzymes remain bound to their enzymes during the oxidation-reduction reactions and the complexes are called _____. a. apoenzymes b. flavokinases c. bound enzymes d. flavoproteins
a. apoenzymes b. flavokinases c. bound enzymes d. flavoproteins***
Without enough vitamin C, collagen would _____.
a. be too tightly coiled b. be over-hydroxylated c. be under-hydroxylated*** d. too strong and less flexible
Which vitamin is most involved in amino acid metabolism?
a. biotin b. vitamin E c. vitamin A d. vitamin B6***
Which vitamin is most involved in amino acid metabolism? a. biotin b. vitamin E c. vitamin A d. vitamin B6
a. biotin b. vitamin E c. vitamin A d. vitamin B6***
A deficiency of what vitamin is associated with these symptoms: hallucinations, lethargy, skin rash, alopecia, and muscle pain?
a. biotin*** b. thiamin c. vitamin C d. vitamin B12
A deficiency of what vitamin is associated with these symptoms: hallucinations, lethargy, skin rash, alopecia, and muscle pain? a. biotin b. thiamin c. vitamin C d. vitamin B12
a. biotin*** b. thiamin c. vitamin C d. vitamin B12
Which three vitamins are involved in the synthesis of fatty acids?
a. biotin, vitamin D, thiamin b. thiamin, riboflavin, niacin c. niacin, biotin, pantothenic acid*** d. riboflavin, B12, folate
Which three vitamins are involved in the synthesis of fatty acids? a. biotin, vitamin D, thiamin b. thiamin, riboflavin, niacin c. niacin, biotin, pantothenic acid d. riboflavin, B12, folate
a. biotin, vitamin D, thiamin b. thiamin, riboflavin, niacin c. niacin, biotin, pantothenic acid*** d. riboflavin, B12, folate
In the enzyme methionine synthase, vitamin B12 acts by accepting a _____ group from _____ and donating this group to _____ to form methionine. a. carbon, methionine, folate b. methyl, 5-methyltetrahydrofolate, homocysteine c. methyl, formiminoglutamic acid, succinyl-CoA d. carbon, serine, glycine
a. carbon, methionine, folate b. methyl, 5-methyltetrahydrofolate, homocysteine*** c. methyl, formiminoglutamic acid, succinyl-CoA d. carbon, serine, glycine
Which of the following molecules synthesized with the help of vitamin C underscores the importance of vitamin C to fat metabolism? a. carnitine b. collagen c. tyrosine d. norepinephrine
a. carnitine***
Which of the following molecules synthesized with the help of vitamin C underscores the importance of vitamin C to fat metabolism?
a. carnitine*** b. collagen c. tyrosine d. norepinephrine
The necessity of ascorbic acid for its role in _____ is believed to be the reason that people with scurvy have no energy and are very tired.
a. collagen synthesis b. creatine synthesis c. hormone activation d. carnitine synthesis***
The necessity of ascorbic acid for its role in _____ is believed to be the reason that people with scurvy have no energy and are very tired. a. collagen synthesis b. creatine synthesis c. hormone activation d. carnitine synthesis
a. collagen synthesis b. creatine synthesis c. hormone activation d. carnitine synthesis***
Vitamin C acts as a cofactor by maintaining iron in a reduced state in: a. collagen synthesis. b. methylation of homocysteine. c. release of energy from nutrients. d. red blood cell synthesis.
a. collagen synthesis.***
Biotin must be covalently bound to each of four different enzymes in order for them to carry out _____.
a. decarboxylations b. oxidation-reduction reactions c. transfer of acetate groups d. carboxylations***
Biotin must be covalently bound to each of four different enzymes in order for them to carry out _____. a. decarboxylations b. oxidation-reduction reactions c. transfer of acetate groups d. carboxylations
a. decarboxylations b. oxidation-reduction reactions c. transfer of acetate groups d. carboxylations***
Thiamin is important to fatty acid synthesis due to its requirement as a coenzyme for the pentose phosphate pathway enzyme _____.
a. dopamine monooxygenase b. transketolase*** c. alpha-ketoglutarate dehydrogenase d. phenylalanine hydroxylase
Thiamin is important to fatty acid synthesis due to its requirement as a coenzyme for the pentose phosphate pathway enzyme _____. a. dopamine monooxygenase b. transketolase c. alpha-ketoglutarate dehydrogenase d. phenylalanine hydroxylase
a. dopamine monooxygenase b. transketolase*** c. alpha-ketoglutarate dehydrogenase d. phenylalanine hydroxylase
Vitamin B12 is absorbed in the _____.
a. duodenum b. jejunum c. ileum*** d. colon
Vitamin B12 is absorbed in the _____. a. duodenum b. jejunum c. ileum d. colon
a. duodenum b. jejunum c. ileum*** d. colon
A major role for thiamin is: a. energy transformation b. blood coagulation. c. collagen formation. d. erythrocyte synthesis.
a. energy transformation.*** b. blood coagulation. c. collagen formation. d. erythrocyte synthesis.
When water-soluble vitamins are consumed in excess of body needs, generally the excess is:
a. excreted in the feces. b. stored in liver, bone, and adipose tissue. c. excreted in the urine.*** d. not absorbed.
Ascorbic acid provides a reducing equivalent so that iron is in the _____ form in lysyl hydroxylase.
a. ferric b. ferrous***
Which of the water-soluble vitamins is able to be stored and retained in the body for long periods of time?
a. folic acid b. niacin c. thiamin d. B12***
Which of the water-soluble vitamins is able to be stored and retained in the body for long periods of time? a. folic acid b. niacin c. thiamin d. B12
a. folic acid b. niacin c. thiamin d. B12***
Tetrahydrofolate is vitally important for dividing cells during growth and cancer and knowledge of this need is used in cancer treatment by giving the drug methotrexate to inhibit the enzyme _____.
a. folylpolyglutamate synthetase b. dihydrofolate reductase*** c. formimino glutamate d. conjugase
Tetrahydrofolate is vitally important for dividing cells during growth and cancer and knowledge of this need is used in cancer treatment by giving the drug methotrexate to inhibit the enzyme _____. a. folylpolyglutamate synthetase b. dihydrofolate reductase c. formimino glutamate d. conjugase
a. folylpolyglutamate synthetase b. dihydrofolate reductase*** c. formimino glutamate d. conjugase
Most animals synthesize their own ascorbic acid from _____.
a. glucose*** b. glutamine c. glycogen d. alanine
B6-dependent transamination reactions are important in which process?
a. glyconeogenesis b. gluconeogenesis*** c. heme synthesis d. more than one of the above
B6-dependent transamination reactions are important in which process? a. glyconeogenesis b. gluconeogenesis c. heme synthesis d. more than one of the above
a. glyconeogenesis b. gluconeogenesis*** c. heme synthesis d. more than one of the above
Folate in foods can only be absorbed in the monoglutamate form; therefore, digestive enzymes called _____ are important for folate nutriture.
a. hydrolases b. lipases c. conjugases*** d. legumes
Folate in foods can only be absorbed in the monoglutamate form; therefore, digestive enzymes called _____ are important for folate nutriture. a. hydrolases b. lipases c. conjugases d. legumes
a. hydrolases b. lipases c. conjugases*** d. legumes
Because vitamin B6 is involved in heme synthesis, a deficiency symptom is _____. a. hypochromic, microcytic anemia. b. seizures. c. hyperhomocysteinemia. d. impaired calcium metabolism.
a. hypochromic, microcytic anemia.*** b. seizures. c. hyperhomocysteinemia. d. impaired calcium metabolism.
Folate is vitally important for dividing cells during growth and cancer because of its essential role in the synthesis of _____.
a. lipid bilayers b. mitochondria c. lysosomes and peroxisomes d. purines and pyrimidines***
Folate is vitally important for dividing cells during growth and cancer because of its essential role in the synthesis of _____. a. lipid bilayers b. mitochondria c. lysosomes and peroxisomes d. purines and pyrimidines
a. lipid bilayers b. mitochondria c. lysosomes and peroxisomes d. purines and pyrimidines***
When ascorbic acid becomes dehydroascorbic acid it has _____. a. lost 2 electrons b. lost 1 electron c. gained 2 electrons d. gained 1 electron
a. lost 2 electrons***
When ascorbic acid becomes dehydroascorbic acid it has _____.
a. lost 2 electrons*** b. lost 1 electron c. gained 2 electrons d. gained 1 electron
Elevated homocysteine levels can be due to all the following EXCEPT:
a. low ascorbic acid.*** b. low folacin. c. low cobalamin. d. low pyridoxine.
Elevated homocysteine levels can be due to all the following EXCEPT: a. low ascorbic acid. b. low folacin. c. low cobalamin. d. low pyridoxine.
a. low ascorbic acid.*** b. low folacin. c. low cobalamin. d. low pyridoxine.
The degradation of _____ provides the majority of one-carbon groups for pyrimidine synthesis. In this process _____ is formed.
a. methionine, tetrahydrofolate b. serine, 5,10-methylene tetrahydrofolate*** c. uridine, tetrahydrofolate d. homocysteine, 5-methyl tetrahydrofolate
The degradation of _____ provides the majority of one-carbon groups for pyrimidine synthesis. In this process _____ is formed. a. methionine, tetrahydrofolate b. serine, 5,10-methylene tetrahydrofolate c. uridine, tetrahydrofolate d. homocysteine, 5-methyl tetrahydrofolate
a. methionine, tetrahydrofolate b. serine, 5,10-methylene tetrahydrofolate*** c. uridine, tetrahydrofolate d. homocysteine, 5-methyl tetrahydrofolate
Which is NOT a fate of homocysteine in the cell? a. methylated to methionine b. used to restore tetrahydrofolate c. used to synthesize cysteine d. used in the synthesis of leucine
a. methylated to methionine b. used to restore tetrahydrofolate c. used to synthesize cysteine d. used in the synthesis of leucine***
Large amounts of folic acid can mask a vitamin B12 deficiency and prevent _____ from resulting. Over time the symptoms unique to a vitamin B12 deficiency will occur, and these are related to the _____.
a. microcytic anemia, muscular system b. DNA and RNA synthesis, vascular system c. one-carbon transfer, nervous system d. macrocytic anemia, nervous system***
Large amounts of folic acid can mask a vitamin B12 deficiency and prevent _____ from resulting. Over time the symptoms unique to a vitamin B12 deficiency will occur, and these are related to the _____. a. microcytic anemia, muscular system b. DNA and RNA synthesis, vascular system c. one-carbon transfer, nervous system d. macrocytic anemia, nervous system
a. microcytic anemia, muscular system b. DNA and RNA synthesis, vascular system c. one-carbon transfer, nervous system d. macrocytic anemia, nervous system***
How do we know that folate fortification has improved the biochemical folate status of Americans?
a. more folate is being consumed b. Americans are more aware of folate's importance c. there is a decline in NTDs*** d. RBC folate levels have increased
How do we know that folate fortification has improved the biochemical folate status of Americans? a. more folate is being consumed b. Americans are more aware of folate's importance c. there is a decline in NTDs d. RBC folate levels have increased
a. more folate is being consumed b. Americans are more aware of folate's importance c. there is a decline in NTDs*** d. RBC folate levels have increased
Cheilosis is a symptom of a dietary deficiency of which vitamin?
a. niacin b. ascorbic acid c. riboflavin*** d. biotin
Cheilosis is a symptom of a dietary deficiency of which vitamin? a. niacin b. ascorbic acid c. riboflavin d. biotin
a. niacin b. ascorbic acid c. riboflavin*** d. biotin
Which vitamin has a reduced coenzyme form important for fatty acid and cholesterol synthesis that is a product of the pentose phosphate pathway?
a. niacin*** b. thiamin c. riboflavin d. vitamin C
Which vitamin has a reduced coenzyme form important for fatty acid and cholesterol synthesis that is a product of the pentose phosphate pathway? a. niacin b. thiamin c. riboflavin d. vitamin C
a. niacin*** b. thiamin c. riboflavin d. vitamin C
Folic acid fortification has _____.
a. not caused the decrease in NTDs that was expected b. had no effect on the number of NTDs in this country c. caused a greater decrease in NTDs than was expected d. reduced the number of various NTDs by 11% to 50% in different studies***
Folic acid fortification has _____. a. not caused the decrease in NTDs that was expected b. had no effect on the number of NTDs in this country c. caused a greater decrease in NTDs than was expected d. reduced the number of various NTDs by 11% to 50% in different studies
a. not caused the decrease in NTDs that was expected b. had no effect on the number of NTDs in this country c. caused a greater decrease in NTDs than was expected d. reduced the number of various NTDs by 11% to 50% in different studies***
A consequence of thiamin deficiency is:
a. pellagra. b. megaloblastic anemia. c. beriberi.*** d. rickets.
A consequence of thiamin deficiency is: a. pellagra. b. megaloblastic anemia. c. beriberi. d. rickets.
a. pellagra. b. megaloblastic anemia. c. beriberi.*** d. rickets.
When the diet is adequate in protein, the body can synthesize niacin from which amino acid?
a. phenylalanine b. valine c. tyrosine d. tryptophan***
When the diet is adequate in protein, the body can synthesize niacin from which amino acid? a. phenylalanine b. valine c. tyrosine d. tryptophan
a. phenylalanine b. valine c. tyrosine d. tryptophan***
To absorb folate consumed from green, leafy vegetables, _____.
a. phosphate groups much be removed by the action of alkaline phosphatase b. glutamate must be transaminated to form alpha-ketoglutarate c. glutamic acid molecules must be removed*** d. glutamic acid molecules must be added
To absorb folate consumed from green, leafy vegetables, _____. a. phosphate groups much be removed by the action of alkaline phosphatase b. glutamate must be transaminated to form alpha-ketoglutarate c. glutamic acid molecules must be removed d. glutamic acid molecules must be added
a. phosphate groups much be removed by the action of alkaline phosphatase b. glutamate must be transaminated to form alpha-ketoglutarate c. glutamic acid molecules must be removed*** d. glutamic acid molecules must be added
Synthesis of coenzyme A starts with the phosphorylation of which vitamin?
a. pyridoxal phosphate b. pantothenic acid*** c. vitamin E d. folic acid
Synthesis of coenzyme A starts with the phosphorylation of which vitamin? a. pyridoxal phosphate b. pantothenic acid c. vitamin E d. folic acid
a. pyridoxal phosphate b. pantothenic acid*** c. vitamin E d. folic acid
Ascorbic acid may act as a pro-oxidant by:
a. reducing ferrous iron. b. mobilizing ferric iron from storage.*** c. reacting with transferrin-bound iron. d. reducing dehydroascorbic acid.
Ascorbic acid may act as a pro-oxidant by: a. reducing ferrous iron. b. mobilizing ferric iron from storage c. reacting with transferrin-bound iron. d. reducing dehydroascorbic acid.
a. reducing ferrous iron. b. mobilizing ferric iron from storage.*** c. reacting with transferrin-bound iron. d. reducing dehydroascorbic acid.
Which of the water-soluble vitamins is found widely distributed in all plant and animal foods, which makes a deficiency unlikely?
a. riboflavin b. folic acid c. pantothenic acid*** d. pyridoxine
Which of the water-soluble vitamins is found widely distributed in all plant and animal foods, which makes a deficiency unlikely? a. riboflavin b. folic acid c. pantothenic acid d. pyridoxine
a. riboflavin b. folic acid c. pantothenic acid*** d. pyridoxine
Which of the following reflects long-term folate status?
a. serum folate b. red blood cell folate*** c. homocysteine concentration in blood d. serum methylmalonic acid
Which of the following reflects long-term folate status? a. serum folate b. red blood cell folate c. homocysteine concentration in blood d. serum methylmalonic acid
a. serum folate b. red blood cell folate*** c. homocysteine concentration in blood d. serum methylmalonic acid
Methionine is used to synthesize S-adenosylmethionine (SAM). Why is this important?
a. so that 5-methyl THF is formed b. so that dUMP is catalyzed to dTMP c. so that fatty acids with an odd-numbered chain can be metabolized d. so that methyl groups are available***
Methionine is used to synthesize S-adenosylmethionine (SAM). Why is this important? a. so that 5-methyl THF is formed b. so that dUMP is catalyzed to dTMP c. so that fatty acids with an odd-numbered chain can be metabolized d. so that methyl groups are available
a. so that 5-methyl THF is formed b. so that dUMP is catalyzed to dTMP c. so that fatty acids with an odd-numbered chain can be metabolized d. so that methyl groups are available***
The most common tests of thiamin status include all the following EXCEPT:
a. static tests of urinary thiamin metabolites. b. a static test of serum thiamin. c. an in vitro functional test of RBC enzyme. d. in vivo functional tests.***
The most common tests of thiamin status include all the following EXCEPT: a. static tests of urinary thiamin metabolites. b. a static test of serum thiamin. c. an in vitro functional test of RBC enzyme. d. in vivo functional tests.
a. static tests of urinary thiamin metabolites. b. a static test of serum thiamin. c. an in vitro functional test of RBC enzyme. d. in vivo functional tests.***
Which classical vitamin deficiency is known for the four Ds: dermatitis, dementia, diarrhea, and death?
a. thiamin b. niacin*** c. biotin d. folic acid
Which classical vitamin deficiency is known for the four Ds: dermatitis, dementia, diarrhea, and death? a. thiamin b. niacin c. biotin d. folic acid
a. thiamin b. niacin*** c. biotin d. folic acid
Which of the following vitamins has a Tolerable Upper Intake Level established?
a. thiamin b. riboflavin c. vitamin B6*** d. vitamin B12
Which of the following vitamins has a Tolerable Upper Intake Level established? a. thiamin b. riboflavin c. vitamin B6 d. vitamin B12
a. thiamin b. riboflavin c. vitamin B6*** d. vitamin B12
Which water-soluble vitamin contributes to "intracellular cement" in the formation of scar tissue and wound healing?
a. thiamin b. riboflavin c. vitamin C*** d. vitamin B12
Erythrocyte transketolase activity is an assay to assess the status of:
a. thiamin.*** b. B6. c. riboflavin. d. B12.
Erythrocyte transketolase activity is an assay to assess the status of: a. thiamin. b. B6. c. riboflavin. d. B12.
a. thiamin.*** b. B6. c. riboflavin. d. B12.
Vitamin B6 functions importantly in all of the following EXCEPT _____.
a. transamination of amino acids b. synthesis of fatty acids*** c. synthesis of niacin d. glycogen breakdown
Vitamin B6 functions importantly in all of the following EXCEPT _____. a. transamination of amino acids b. synthesis of fatty acids c. synthesis of niacin d. glycogen breakdown
a. transamination of amino acids b. synthesis of fatty acids*** c. synthesis of niacin d. glycogen breakdown
PLP functions as a coenzyme for _____ when alanine enters the liver. Alanine becomes its α-keto acid, _____.
a. transamination, pyruvic acid*** b. transamination, α-ketoglutaric acid c. transmethylation, histidine d. desulfation, methioninie
PLP functions as a coenzyme for _____ when alanine enters the liver. Alanine becomes its α-keto acid, _____. a. transamination, pyruvic acid b. transamination, α-ketoglutaric acid c. transmethylation, histidine d. desulfation, methioninie
a. transamination, pyruvic acid*** b. transamination, α-ketoglutaric acid c. transmethylation, histidine d. desulfation, methioninie
associated phrase: edema and cardiac insufficiency
a. vitamin B12 b. vitamin B6 c. folate or folic acid d. vitamin C e. none of these***
associated phrase: edema and cardiac insufficiency a. vitamin B12 b. vitamin B6 c. folate or folic acid d. vitamin C e. none of these
a. vitamin B12 b. vitamin B6 c. folate or folic acid d. vitamin C e. none of these***
A primary function of vitamin C is to act as an: a. antiviral agent. b. antioxidant. c. antirachitic agent. d. acyl transferase.
b. antioxidant.***
Ascorbic acid provides a reducing equivalent so that iron is in the _____ form in lysyl hydroxylase. a. ferric b. ferrous
b. ferrous***
acetyl-CoA carboxylase; important to form malonyl-CoA and commit acetyl-CoA to fatty acid synthesis
biotin
Vitamin C's actual participation in biochemical reactions usually involves its antioxidant ability. Choose the description of this activity. a. Donates an electron or electrons to oxidize a mineral cofactor b. Accepts an electron or electrons to reduce a mineral cofactor c. Donates an electron or electrons to reduce a mineral cofactor d. Accepts an electron from the quinone form of vitamin E
c. Donates an electron or electrons to reduce a mineral cofactor***
A major function of B vitamins is to serve as: a. antibodies. b. a source of energy. c. a part of a coenzyme. d. electrolytes.
c. a part of a coenzyme.
Which water-soluble vitamin contributes to "intracellular cement" in the formation of scar tissue and wound healing? a. thiamin b. riboflavin c. vitamin C d. vitamin B12
c. vitamin C***
Vitamin C acts as is a cofactor by maintaining iron In a reduced state in:
collagen synthesis.
Sun exposure does not cause hypervitaminosis D because:
cutaneous production of the vitamin reaches a maximum
Although excess absorbed ascorbic acid is excreted in urine, the body has an estimated maximal body pool of about _____, which can be maintained with intakes of 100-200 mg vitamin C per day. a. 500 mg b. 1000 mg c. 1500 mg d. 2000 mg
d. 2000 mg***
When water-soluble vitamins are consumed in excess of body needs, generally the excess is:
excreted in the urine.
glutathione reductase; important for red blood cell antioxidant integrity and a sensitive measure of riboflavin nutriture
flavin adenine dinucleotide
associated phrase: Latin word means "leaf"; Italian word means "foliage"
folate or folic acid
associated phrase: a vitamin whose supplement form has MORE biologic action than the form found in nature
folate or folic acid
associated phrase: coenzyme carries one-carbon groups in metabolism
folate or folic acid
A good source of vitamin B6 is muscle meats because PLP is predominantly bound to the enzyme __________.
glycogen phosphorylase
The only test that will differentiate between a folic acid and cobalamin deficiency is the determination of the urinary metabolite _____, which is due to a lack of the coenzyme _____.
methylmalonic acid, 5' deoxyadenosyl cobalamin
aldehyde dehydrogenase; important for catabolism of vitamin B6 (pyridoxal to pyridoxic acid)
nicotinamide adenine dinucleotide
Pharmacologic doses of 2 vitamins, _____ and _____, are used therapeutically to lower serum cholesterol and alleviate premenstrual syndrome, respectively.
nicotinic acid, pyridoxine
alanine aminotransferase; important in amino acid transaminations for facilitating protein synthesis
pyridoxal phosphate
Microcytic hypochromic anemia may result from a deficiency of the vitamin _____ because its coenzyme is involved in the synthesis of _____.
pyridoxine or B6, heme
The continuation of the Kreb's cycle is ensured by the replenishment of oxaloacetate, which is formed by the carboxylation of _____ with a biotin-containing coenzyme, _____.
pyruvate , pyruvate carboxylase
Retinol must be __________ to be carried in the chylomicron.
re-esterified
pyruvate dehydrogenase; important for decarboxylations in carbohydrate catabolism
thiamin diphosphate
Which is NOT a fate of homocysteine in the cell?
used in the synthesis of leucine
associated phrase: pernicious anemia is a lack of absorption of this
vitamin B12
Associated phrase: hypochromic, microcytic anemia
vitamin B6
associated phrase: PLP is coenzyme form
vitamin B6
associated phrase: coenzyme labilizes covalent bonds around the alpha-carbon of an amino acid
vitamin B6
associated phrase: hemoglobin synthesis
vitamin B6
associated phrase: serine hydroxymethyltransferase
vitamin B6
associated phrase: a water-soluble vitamin that is not a coenzyme
vitamin C
associated phrase: gulonolactone oxidase
vitamin C
associated phrase: potatoes and broccoli are good sources
vitamin C
associated phrase: prolyl hydroxylase
vitamin C
