Which cellular site is responsible for heme biosynthesis?

Occurs in erythroid cells and in the liver.

Which could be one of the major causes of thiamin deficiency?

A defect in thiamin transporter protein gene transcription.

Why do we require intrinsic factors?

For the absorption of vitamin B12 in small intestine.

Why is the consumption of raw eggs a problem?

It contains the protein avidin which prevents biotin absorption.

Why cytosolic carbamoyl phosphate synthetase II enzyme important?

This enzyme is the rate-limiting enzyme during pyrimidine biosynthesis.

Which is the rate limiting enzyme during purine biosynthesis?

Glutamine phosphoribosyl amido transferase

Which group of amino acids is required to synthesize purine nucleotide?

Glutamine, glycine, and aspartate.

What is the metabolic benefit of methionine synthase catalyzed conversion of homocysteine to methionine?

Regenerates methylcobalamin and maintains a store of tetrahydrofolate.

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BioChem3test

Question	Answer
Which amino acid is common precursor for the biosynthesis of heme, creatine, and purine bases?	Glycine
Which cellular site is responsible for heme biosynthesis?	Occurs in erythroid cells and in the liver.
Which amino acid is required for heme biosytheses?	Glycine
Which amino acid is the precursor of the neurotransmitter serotonin?	Tryptophan
Water soluble vitamin that can produce toxicity if taken in excessive quantities that is more than 1 gram per day for several weeks.	Ascorbic Acid
What is the function of glucagon during fasting condition?	Increases blood glucose level
Lack of which enzyme can prevent vitamen C biosynthesis?	Gulonolactone oxidase
Deficiency of which vitamin can cause a disease showing symptoms of bleeding gum?	Vitamin C
Which is the storage form of Vitamin B12 within the cytosol before it is converted to its active cofactor form?	Hydroxycobalamin
Which of the following is accumulated after several days of starvation?	Ketone Bodies
Deficiency of which of the following vitamin may cause Beriberi?	Thiamin or B1
Which amino acid is not used in pyrimidine synthesis	glycine
Which is active coenzyme form of B1	Thiamin pyrophosphate
Niacin deficiency can also be caused by deficiency of which of the following compound?	Tryptophan
Deficiency of which vitamin can cause misincorporation of the methyl group during DNA biosynthesis?	Folate
What is the enzyme which puts 2 ALA molecules together to form a pyrrole ring in heme synthesis?	S-ALA dehydratase
Which is the active cofactor form of the vitamin B12 within mitochondria?	Deoxycobalamin
Which could be one of the major causes of thiamin deficiency?	A defect in thiamin transporter protein gene transcription.
Which vitamin is an integral component of the acyl carrier protein(ACP)?	Pantothenic acid or vitamin B5
Amino acids, fatty acids and glucose are oxidized and enter citric acid cycle as...	Acetyl-COA
Which of the following compounds transfers methyl group to synthesize methionine from homocysteine in the methionine synthase catalyzed reaction?	Methylcobalamin
A diet very high in protein and fats, but very low in carbs. After two weeks, the excess amino acids being consumed can be stored as	As live glycogen
In which of the following reactions NAD+ is used as a substrate, but not as a cofactor?	ADP-ribosylation reaction
Deficiency of which of the following vitamins can interrupt with the biosynthesis of norepinephrine?	Vitamin C
Why do we require intrinsic factors?	For the absorption of vitamin B12 in small intestine.
NADH and NADPH participate in which of the following type of reactions?	Oxidation-reduction reaction.
What is the central ion in the center of the porphyrin ring of an OXIDIZED molecule of hemoglobin?	Fe3+
Why is the consumption of raw eggs a problem?	It contains the protein avidin which prevents biotin absorption.
Deficiency of which of the following vitamin can cause Pellegra?	Niacin
Which of the following form of folic acid is absorbed by the intestinal mucosal cells?	Pteroylmonoglutamate
Which vitamin functions as free radical scavenger?	Vitamin C
Why cytosolic carbamoyl phosphate synthetase II enzyme important?	This enzyme is the rate-limiting enzyme during pyrimidine biosynthesis.
Which is the rate limiting enzyme during purine biosynthesis?	Glutamine phosphoribosyl amido transferase
Which vitamin is required for the biosynthesis of glycine from serine?	Tetrahydrofolate
Which vitamin is used as a cofactor for the enzyme caralyzed conversion of a ketose sugar(ie xylulose 5-phosphate) into an aldose sugar(glyceraldehyde 3-phosphate)?	Thiamin
Which group of amino acids is required to synthesize purine nucleotide?	Glutamine, glycine, and aspartate.
Which of the following viatmins is required as a cofactor in the formation of (S-ALA)during heme biosynthesis?	Pyridoxal phosphate(PLP)
Which of the following amino acid is the precursor of the catecholamine neurotransmitters?	Tyrosine
Appropriate doses of which of the following vitamins can prevent lipid peroxidation?	Ascorbic Acid
Which compound would inhibit carbamoyl phosphate synthetase II by a negative feedback mechanism?	Uridine triphosphate
Deficiency of which vitamin can cause Pernicious anemia?	Malabsorption of vitamin B12
Which type of reactions are catalyzed by riboflavins?	Oxidation-Reduction reactions
Which of the following nutrients CAN NOT be utilized for cellular energy?	Vitamins
A person was clinically diagnosed to have megaloblastic anemia. Which vitamins deficiency can be the cause of anemia?	Vitamin B12 and Folic Acid
Which of the following molecules is NOT derived from glycine?	Melatonin
Amino acids	are precursors of nucleotides
Which tissue contributes for glucose to the blood?	Liver
Which of the following compound is the active coenzyme form of riboflavin?	FAD+
What is the metabolic benefit of methionine synthase catalyzed conversion of homocysteine to methionine?	Regenerates methylcobalamin and maintains a store of tetrahydrofolate.
Which functional group is transferred to guanidinoacetate to synthesize creatine?	Methyl
Which of the following vitamins is required by the enzyme dihydrofolate reductase to convert folic acid to its active coenzyme form?	NADPH
Deficiency of which amino acid can interrupt with the de novo biosynthesis of pyrimidine nucleotide?	Glutamine
High fat diet and no exercise	will increase triacylglycerol storage in adipose tissue.
Conversion of serine to glycine requires	Tetrahydrofolate(THF)
In creatine synthesis what type of reaction converts guanidinoacetate to creatine?	Methylation
What is the central ion in the center of the porphyrin ring of hemoglobin?	Fe2+
What are the two beginning precursors of heme synthesis?	Glycine and Succinyl-CoA
Which of the following is required as a coenzyme in the formation of (S-ALA) during heme biosynthesis?	Pyridoxal phosphate(PLP)
Which amino acid is the precursor of serotonin?	Tryptophan
Which of the following enzyme is the rate-limiting enzyme in the biosynthetic pathway of heme?	S-ALA synthase
Whyat type of reaction converts glutamate to the inhibitory neurotransmitter GABA?	decarboxylation
What is the enzyme which puts 2 ALA molecules together to form a pyrrole ring in heme synthesis?	S-ALA dehydratase
Which of the following amino acid is the precursor for the synthesis of thyroid hormones?	tyrosine
NADPH	required by dihydrofolate reductase to convert folic acid to its active coenzyme form.
Megaloblastic anemia	Vit B12 and Folic acid
amino acids are required to synthesize purine nucleotide?	glycine, glutamine, and aspartate
Nucleotide produced first in the biosynthetic pathway of purine nucleotides.	Inosine monophosphate(IMP)
Precursor for the synthesis of (RNAs) and (DNAs)	Inosine monophosphate(IMP)
Precursor of the catecholamine neurotransmitter	tyrosine
Vitamin essential for the conversion of dopamine to norepinephrine	vitamin C
Amino acid require for the synthesis of melantonin	tryptophan
Active coenzyme form of B1	tiamin phyrophosphate(TPP)
Defect in thimain pyrophosphate kinase	can cause thiamin deficiency conditions.
Defect in thiamin transporter protein gene transcription	can cause thiamin deficiency conditions.
Starts fatty acid biosynthesis	Biotin
Skeletal muscle cannot release	glucose from glycogen into the blood which can be used by other tissues in the body.
Source of energy in brain during a starved condition (more than 4 to 5 days)	ketone bodies
Glucagon during fasting condition	will increase blood glucose levels.
Integral component of the acyl carrier protein(ACP)	pantothenic acid or vitamin B5
NAD is used as a substrate, but not as a coenzyme in	ADP-ribosylation reaction
Pellegra	Niacin
Niacin deficiency can also be caused by	tryptophan deficiency
Active coenzyme form of B6	pyridoxal phosphate
Vitamin B6 can participate in	tansamination
Intrinsic factor is required for	absorption of B12 in small intestine.
Pernicious anemia	malabsorption of vitamin B12
Pteroylmonoglutamate	intestinal mucosal cells.
Deficiency of folate can cause	misincorporation of the methyl group during DNA biosynthesis.
Biotin favors	carboxylation reactions
Ascorbic acid is a water soluble vitamin	that can produce toxicity if more than 1 gram is taken for several weeks.
Vitamin C	functions as free radical scavenger
Lack of gulonolactone oxidase	can stop Vitamin C biosynthesis.
Ascorbic acid	can prevent lipid peroxidation.
De novo synthesis	glutamine and aspartate
Aspartate glutamine, and asparagine	pyrimidine synthesis
Deficiency of B6	would lead to an inability to synthesize heme.
Transketolase enzyme catalyzed reactions	require thiamin
FAD	active coenzyme form of riboflavin
NADH AND NADPH	oxidation-reduction reaction.
Heme biosynthesis happens	in the mitochondria
Which intermediate of the citric acid cycle is used for heme biosynthesis?	Succinyl CoA
How many pyrrole rings are required to construct the structure of heme?	4
Which enzyme incorporates ferrous in the center of the heme molecule?	ferrochelatase
How heme biosynthesis is regulated?	Production of heme inactivates the δ-ALA synthase (negative feedback)
How heme is degraded biochemically?	Heme is oxidized and yields CO (carbon monoxide) and biliverdin.Biliverdin is then reduced to bilirubin which is transported to theliver bound to serum albumin.
bile pigments	It is formed during biochemical degradation of heme
amino acids are required for creatine biosynthesis?	Glycine, Arginine, Methionine
Creatine synthesis	begins in kidney and it is completed in liver
Within the kidneys during Creatine synthesis	Glycine combines with arginine forming guanidinoacetate and ornithine which travels to liver
In the liver during creatine synthesis	guanidinoacetate is methylated by S-adenosyl-methionine(SAM) to form creatine and then it is released to bloodstream and enter into the cells.
What is the product when guanidinoacetate is methylated?	creatine
Which compound donates methyl group to guanidinoacetate to synthesize creatine?	S-adenosyl-methionine (SAM)
Which enzyme catalyzes the formation of creatine phosphate?	Creatine (Phospho) Kinase (CPK or CK)
How creatinine is produced from creatine phosphate?	Creatinine is the anhydride form of creatine. It is formed largely in muscle by irreversible nonenzymatic degradation of creatine phosphate
Which amino acids are required for purine biosynthesis?	Glycine, Glutamine, Aspartate
What is the role of 5-phosphoribosyl 1-pyrophosphate (PRPP) in purine biosynthesis?	5-Phosphoribosyl-1-pyrophosphate (PRPP) is the source of the ribose moiety
What is the precursor for PRPP synthesis?	ATP and ribose-5’-phosphate
Which enzyme catalyzes the synthesis of PRPP?	PRPP synthase
Which biochemical pathway is the source of ribose 5-phosphate?	Pentose phosphate pathway
Which reaction step in purine biosynthesis is the rate limiting step?	PRPP & glutamine to form phosphoribosylamine.
Which enzyme is the rate-limiting enzyme in purine biosynthesis?	PRPP glutamyl amidotransferase
What are the substrates for the first reaction in purine biosynthesis?	Glutamine and PRPP
What is the first product in purine biosynthesis?	phosphoribosylamine
Which nucleotide is formed first in purine biosynthetic pathway?	IMP
Which ribonucleotides are produced in purine biosynthetic pathway?	Adenine and Guanine
Which enzyme catalyzes the formation of deoxyribonucleotides from ribonucleotides?	Ribonucleotide Reductase
Which amino acids are used for pyrimidine biosynthesis?	Aspartate and Glutamine
What are the substrates in the first reaction step in pyrimidine biosynthesis?	glutamine reacts with CO2 and ATP to form carbamoyl phosphate
Which compound can inhibit this rate-limiting step of pyrimidine biosynthesis?	UTP
Which molecule activates the rate-limiting step of pyrimidine biosynthesis?	PRPP
At which cellular site the rate-limiting enzyme for pyrimidine biosynthesis is located?	Cytosol
Which is the first nucleotide produced in the pyrimidine biosynthetic pathway?	Uridine monophosphate (UMP)
Which ribonucleotides are produced in pyrimidine biosynthetic pathway?	Uracil and Cytosine
Which deoxyribonucleotides are produced in pyrimidine biosynthetic pathway?	Thymine and Cytosine
Which amino acid is used to produce CTP from UTP?	Glutamine
Which enzyme catalyzes the conversion of CDP to dCDP?	Ribonucleotide Reductase
Which one-carbon group containing intermediate of tetrahydrofolate is used to produce dTMP from dUMP?	5,10-Methylene-FH4
Why our body needs to synthesize purine and pyrimidine bases?	To make DNA and RNA
Which amino acid is the precursor of melanin?	Tyrosine
Which amino acid is the precursor of thyroid hormone biosynthesis?	Tyrosine
What is the decarboxylation product of L-dopa?	Dopamine
Which enzyme catalyzes the formation of L-dopamine? Which vitamin is the cofactor in this step?	Dopa decarboxylase. Cofactor=Vitamin B6
Which enzyme catalyzes the formation of L-norepinephrine? Which functional group isattached in this reaction?	Dopamine β-hydroxylase
Which enzyme catalyzes the formation of L-epinephrine? Which functional group is attachedin this reaction? Which compound is the donor of this functional group?	phenylethanol-amine N-methyl-transferase. A methyl group is attached. S-Adenosylmethionine (SAM) is the donor.
Which amino acid forms the cofactor NAD+/NADP+?	Tryptophan
Which amino acid is the precursor of histamine?	Histidine
Which amino acid is the precursor of nitric oxide?	Arginine
Which enzyme catalyzes the formation of nitric oxide?	NO synthase
metabolism	the sum of all chemical transformations taking place in a cell or organism through series of enzyme-catalyzed reactions.
What are the major nutrients in our diet?	carbohydrates, proteins, lipids, oils, nucleic acids, vitamins, minerals, water, dietary fibers, etc.
What is catabolism?	breakdown of the complex foods molecules to simplest form that can be absorbed by the cells.
What is anabolism?	simple monomer units participate to synthesize new complex molecules, such as proteins, carbohydrates, lipids, etc.
glucose is oxidized to pyruvate	in glycolyis cycle
pyruvate is then used to make acetyl-CoA	which enters the citric acid cycle to allow one full rotation
During glycolysis and the citric acid cycle	numerous NADH, NADPH, and FADH2 are produced which enter oxidative phosphorylation to produce ATP.
gluconeogenesis	Glucose synthesis from noncarbohydrate sources such as pyruvate, citric acid cycle intermediates, lactates, etc.
glycogenesis	formation of glycogen stores from glucose molecules. Glycogen is the storage form of glucose.
glycogenolysis	The breakdown of glycogen to release glucose molecules
fatty acid β-oxidation	Results in the formation of Acetyl-CoA
fatty acid biosynthesis	Synthesis of acetyl-CoA groups into acyl groups
triacylglycerols are synthesized	Three acyl groups are attatched to a glycerol backbone and stored for later use
the carbon skeletons of the 20 "standard" amino acids	amino acids can be entirely oxidesed to carbon dioxide and water.
Glucogenic amino acids are degraded to	pyruvate, α-ketoglutarate, succinyl-CoA, fumarate and oxaloacetate and can be used as a the precursor of glucose.
ketogenic amino acids can be degraded to	ketone bodies such as acetoacetate or acetyl-CoA, which can be used for fatty acid synthesis
urea cycle	Five enzyme-catalyzed steps in which the carbon of bicarbonate and the nitrogens of NH3 and aspartate are combined to form urea
The brain prefers	glucose as an energy source, but can also use ketone bodies.
Which hormone is released when blood glucose is higher than normal levels?	Insulin
Which hormone is released when blood glucose is below normal levels?	Glucagon
What is the effect of elevated levels of insulin in blood circulation?	Cellular uptake of glucose increases and blood glucose levels drop.
What is the effect of elevated levels of glucagon in blood circulation?	Cellular uptake of glucose decreases, glucose secretion into blood by liver increases, and the blood glucose levels rise.
largest source of fuel in a well-nourished human	triacylglycerols in adipose tissue
glucose 6-phosphate in the live	conversion to liver glycogen
glucose 6-phosphate in the live	dephosphorylation and release of glucose into bloodstream
glucose 6-phosphate in the live	oxidation via the pentose phosphate pathway
glucose 6-phosphate in the live	oxidation via glycolysis and the citric acid cycle
glucose 6-phosphate in the live	oxidation to acetyl-CoA, which thenserves as precursor for synthesis of triacylglycerols, phospholipids, and cholesterol
Describe metabolic fate of glucose in the skeletal muscle tissue.	It is broken down to pyruvate. Then to acetyl-CoA which enters the TCA cycle. Substrates created during TCA cycle are then sent through oxidative phosphoylation.
Describe the metabolic fate of glucose in the liver tissue.	in excess amounts, glucose is stored as glycogen.
Describe the metabolic fate of glucose in the brain tissue.	It is broken down to pyruvate. Then to acetyl-CoA which enters the TCA cycle. Substrates created during TCA cycle are then sent through oxidative phosphoylation.
Describe the metabolic fate of glucose in the red blood cells.	Glucose is broken down to pyruvate which is then broken down to lactate.
What is postprandial glucose level?	It is a test to determine how much glucose is in the blood after eating a meal.
metabolic fate of glucose oxidation during starved condition	Glycogen stores are broken down to glucose and utilized.
metabolic fate of glucose oxidation during starved condition	Fatty acids and glycerols from triglycerides are used and ketone bodies are used by the brain to make energy.
metabolic fate of glucose oxidation during starved condition	Once everything is depleted, proteins, amino acids and tissues such as muscle begin to be broken down.
vitamins	Organic compounds required in diet
general functions of vitamins	to maintain basic cellular function, but overall function- maintain body metabolism including overall growth, metabolism, and cell integrity
Why you think vitamins are not considered as major nutrients, but essential in nutrition?	Vitamins are usually cofactors and are needed by enzymes
water soluble vitamins	Vitamin B complexThiamin – B1Riboflavin – B2Niacin – Nicotinic acid, B3Pantothenic Acid –B5Pyridoxine – B6 Cobalamin – B12Folic Acid – Pterylglutamic acidBiotinVitamin C or Ascrobic Acid
fat soluble vitamins	Vitamin A,D,E,and K
major food sources of water soluble vitamins	They are mostly found in organic compounds in natural foods;Including…..cereal grains, meat, eggs, legumes (beans and grn. Beans), fruits, liver, peanuts, milk,;Vit B6- unrefined cereal grains, whole grains, enriched flours
What are the major effects of food processing, heat, and light exposure on the activities of vitamins?	Destroys them
Which enzyme can destroy thiamine?	Thiaminase
What are the dietary available forms of thiamine?	Thiamine phosphate or Thiamine Diphosphate
Which form of thiamine is the metabolically active form?	Thiamine disphosphate
Which enzyme catalyzes the formation of the active form of thiamine?	Thiamine pyrophosphokinase
What are the substrates in the formation of the active form of thiamine?	Thiamine --> Thiamine pyrophosphokinase or Thiamine disphosphate
Which tissue and cell type are involved in the absorption of dietary thiamine?	Intestinal mucosal cell
Which membrane protein is involved in the transportation of dietary thiamine across the intestinal mucosal membrane?	Thiamine Transporter Protein
Thiamin is absorbed by the intestinal mucosal cells	and transported by a thiamin transporter protein into the mucosal cells
Thiamin is converted to TPP and then	leave the intestinal mucosal cell by a Na+-dependent transport mechanism to the circulation.
Which are the two reaction types that use the activated thiamine molecule as cofactor?	1.Oxidative decarboxylation of α-keto acids 2.Transketolase reactions for interconversions of sugar phosphates
Oxidative decarboxylation of α-keto acids	α-Ketoglutarate → Succinyl CoA + CO2& Pyruvate → Acetyl CoA
Transketolase reactions for interconversions of sugar phosphates	Xylulose 5-phosphate + Erythrose 4-phosphate Glyceraldehyde 3-phosphate + Fructose 6-phosphate
Oxidative decarboxylation of -ketoglutarate	forms succinyl-CoA and carbon dioxide
Cofactor used in Oxidative decarboxylation of -ketoglutarate	Thiamine Pyrophosphatate
Oxidative decarboxylation of pyruvate	forms acetyl-CoA and carbon dioxide
Cofactor used in Oxidative decarboxylation of pyruvate	Thiamine Pyrophosphatate
Which cofactor is used in transketolase type of reaction?	Thiamine Pyrophosphatate
Which enzyme uses thiamin for the interconversion of ketose and aldose sugars phosphates?	Transketolase
What primary symptoms may be associated with thiamin deficiency?	Mental confusionMuscular weaknessParalysis of the motor nerves of the eyeMuscle wastingPeripheral paralysis, TachycardiaEnlarged heart
What is the recommended dietary allowance (RDA) value for thiamine for adult normal individual?	1.1-1.2 mg/day
What are the active coenzyme forms of riboflavin?	FAD and FMN
What type of reaction is catalyzed by riboflavins?	Oxidoreductase rxns
Deficiency of which vitamin can cause ariboflavinosis?	Riboflavin
What are the major symptoms of riboflavin deficiencies?	Stunted growthSeborrheic (secretion of fatty or oily fluid) dermatitisSoreness and burning of the lips, mouth and tonguePhotophobiaBurning and itching of the eyesNeuropathy
What are the metabolically active forms of niacin?	Coenzymes NAD+ and NADP+
What types of reactions are catalyzed by niacin?	Oxidation-reduction rxns
Give an example in which the active form of niacin is used as a substrate in that enzyme catalyzed reaction.	ADP-ribosylation rxns
Which amino acid can synthesize niacin?	Tryptophan
What are the major signs and symptoms of niacin deficiency?	Weight lossDigestive disordersDermatitisDepressionDementia
What are the metabolically active forms of the vitamin pantothenic acid or vitamin B5?	Coenzyme A and Acyl Carrier Protein ACP
Which vitamin is required to synthesize coenzyme A?	B5
Which vitamin is an integral part of acyl carrier protein?	B5
What are three naturally occurring dietary forms of vitamin B6 or pyridoxine?	PyridoxinePyridoxal phosphatePyridoxamine phosphate
What is the metabolically active form of vitamin B6?	Pyridoxal Phosphate
Which vitamin is required for transamination reaction?	Pyridoxal Phosphate
Which cofactor is required to decarboxylate L-dopa to L-dopamine? Which enzyme catalyzes this reaction?	Vit B6Dopa Decarboxylase
Which cofactor is required to synthesize -aminolevulinic acid, an intermediate in heme biosynthesis?	Vit B6 -ALA synthetase (enzyme)
Which vitamin contains a cobalt ion as the center ion?	Cyanocobalamin B12
Deficiency of intrinsic factor can cause malabsorption of which vitamin?	Vit B12
What are the metabolically active forms of vitamin B12?	Methylcobalamin and Deoxyadenosylcobalamin
Describe the two reactions in which vitamin B12 participates?	Deoxycobalamin and Methylcobalamin
Deoxycobalamin	the coenzyme for the conversion of methylmalonyl-CoA to succinyl CoA
Methylcobalamin is the conenzyme in	The conversion of homocysteine to methionine, and The conversion of methyl tetrahydrofolate to tetrahydrofolate
Which vitamin is required to convert homocysteine to methionine?	Vit B12
Which active form of the vitamin B12 is required to convert homocysteine to methionine?	Methylcobalamin
Which functional group is transferred to homocysteine to form methionine?	Methyl group
What cofactor contributes this functional group to produce methionine? Methyl group	Methionine synthase
Which vitamin is required to produce succinyl-CoA from methylmalonyl-CoA?	Vitamin B-12
Which active form of vitamin B12 is required to convert methylmalonyl-CoA to succinyl-CoA?	Deoxyadenosylcobalamin
Which enzyme catalyzes the conversion of methylmalonyl-CoA to succinyl-CoA?	Methylmalonyl Co-A Mutase
Which intestinal mucosal protein supports transportation of vitamin B12 in to blood circulation?	Transcobalamin II
What is the function of transcobalamin II?	To bind to B-12 and transport to blood
What is the storage form of vitamin B12 within a tissue?	Hydroxycobalamin
Which protein maintains the storage from of vitamin B12 within a tissue?	Transcobalamin I
What is the function of transcobalamin I?	Maintain storage of B-12
At which cellular location methylcobalamin is produced?	Cytosol
At which cellular location deoxyadenosylcobalamin is produced?	Mitochondria
Deficiency of which vitamin can cause homocystinuria?	Vitamin B12
Which of the following is the active form of the vitamin folic acid?	Tetrahydrofolate
Which enzyme catalyzes the formation of the active for of folic acid or folate?	Gamma-Glutamylhydrolase
Which vitamin is required to convert serine to glycine?	Folate
Which two vitamins are required in the biochemical conversion of homocysteine to methionine?	Folate and B-12
Which vitamin is required for the conversion of dTMP from dUMP?	Folate
Folate deficiency can cause	a defect in DNA metabolism
Folate deficiency can cause	uracil misincorporation during DNA biosynthesis
Folate deficiency can cause	defective methylation of DNAs stopping gene transcription
Deficiency of which vitamin can interrupt with the carboxylation reaction?	Biotin
Which vitamin is used as the cofactor for carboxylation reaction	Biotin
Biotin is the cofactor of which enzyme?	Carboxylase
Pyruvate carboxylase catalyzes the conversion of pyruvate to oxaloacetate. What is the cofactor in this reaction?	Biotin
What is the cofactor for the acetyl-CoA carboxylase.	Biotin
What is the cofactor used in the reaction catalyzed by propionyl-CoA carboxylase?	Biotin
What cofactor is used in the reaction that is catalyzed by -methylcrotonyl-CoA carboxylase?	Biotin
Which of the following can prevent absorption of biotin from the intestinal mucosal cells and cause biotin deficiency?	Avidin
Which enzyme required for the biosynthesis of vitamin C is not present in humans?	Gulonolactone
What is the active form of vitamin C?	Ascorbic acid
What are the general dietary sources of vitamin C?	Citrus, fruits, berries, melons, tomatoes, green peppers, raw cabbage,
Briefly describe the structural stability of vitamin C.	least stable of all water-soluble vitamins-highly heat labile-stable freezing
Approximately how many months human tissue can store vitamin C?	3-4 months
Briefly describe the enzymatic functions of vitamin C.	-electron donor for at least 8 enzymes in humans-enzyme that require vitamin c or ascorbate are either monooxygenase/dioxygena
non-enzymatic functions of vitamin C	Intracellular-electron donor (reducing agent or antioxidant)
non-enzymatic functions of vitamin C(extracellular)	scavenger of free radicals protects against oxidants and oxidant-mediated damageincrease absorption of iron in small intestinevitamin c reduces o2, no3-, cytochrome a fe3+, cytochrome fe3+,methemoglobin
Briefly describe the signs and symptoms of vitamin C deficiency.	areas of bleeding under skinBleeding gumsHyperkeratosisJoint painFluid in joints Fatigue
Which dose of vitamin C could be toxic?	More than 1000mg/day
What is the RDA value for vitamin C in normal adult individual?	65-75 mg/day
Why fat soluble vitamins sometime can produce toxicity?	They can build up because fat soluble compounds are more difficult to excrete out of the body. Whereas water soluble vitamins are easily broken down due to the high amount of water content in the human body.
Deficiency of which vitamins can cause night blindness and xerophthalmia?	Vitamin A
What are the biologically active forms of vitamin A?	Retinoids. i.e. retinol, retinal, retinoic acid
What are the major dietary sources of vitamin A?	animal foods (liver, fish oils, fortifies milk, eggs, and margarine) and plant foods (dark green and orange fruits and vegetables, ex. Carrots, spinach, sweet potatoes, broccoli.)
What is the storage form of vitamin A?	retinol
What is the major storage form of vitamin A in animal tissues?	In liver, it is stored as retinyl ester. In lipocytes, as lipoglycoprotein complex
What are the major functions of retinol?	Reproduction: binds to nuclear protein receptors; controls certain gene expressionImmune: activation and proliferation of lymphocytes
What are the major functions of retinal?	Responsible for ability to see color and gives you vision when exposed to poorly lit areas
Which isoform of vitamin A supports reproduction?	Retinol
Briefly describe the mechanism by which retinal participates in vision.	All-trans-retinal --> 11-cis retinal Enzyme=retinal isomerase. This binds to opsin and forms rhodopsin. When rhodopsin is exposed to light, it dissociates as it is bleached and forms all-trans-retinal and opsin.
Which is the visual pigment?	Rhodopsin
Which eye cells are responsible for weak light perception and for black and white vision?	rod cells
Which eye cells are responsible for bright light perception and for color vision?	Cone Cells
Which isomer of retinal produces rhodopsin?	11-cis-retinal
Which isomer of retinal is the substrate for retinal isomerase?	All-trans-retinal
What are the major functions of retinoic acid?	Cellular differentiation and protein synthesis, differentiation and maintenance of epithelial cells, lubricants, and prevention of skin, lung, bladder, and breast cancer.
Deficiency of which form of vitamin A can interrupt transport of oligosaccharides across the lipid bilayer?	Retinoyl phosphate
Which dose of vitamin A is highly toxic leading to cellular disruption and even death?	15,000 mg/day or greater
Can you use carotenoids as an antioxidant, the action of which is effective at low oxygenconcentration? If your answer is briefly explain how carotenoids function as an antioxidant.	Yes. They trap free O2 atoms and peroxides
What is the RDA value for vitamin A?	1000 RE for men, 800 RE for women
What is retinal equivalent?	Units for RDA
Biosynthesis of which vitamin needs exposure of sunlight upon the skin?	Vit. D
What are the key functions of vitamin D?	Calcium and phosphate metablosim
What are the major sources of dietary vitamin D?	Meat, Fish, Milk
What is the effect of heating and general food processing on the activity of vitamin D?	none
What is the provitamin form of vitamin D obtained from plant sources?	Ergosterol
What is the precursor for vitamin D obtained from animal sources?	7-dehydrocholesterol
Briefly discuss how vitamin D is biosynthesized in humans from its precursors.	7-dehydrocholesterol is present in skin, UV light on skin opens up ring to form Vit. D, cholecalciferol
Which enzyme is the rate-regulatory enzyme in vitamin D biosynthesis?	1-a-hydroxylase
What is the biologically active form of vitamin D in humans?	Calcitriol
Which tissues are involved in the biosynthesis of vitamin D?	liver and kidneys
Which hormone activates the rate-limiting enzyme for vitamin D biosynthesis?	Parathyroid hormone
What is the effect of decreased plasma calcium levels on vitamin D biosynthesis?	Hypocalcemia
What is the effect of decreased plasma phosphate levels on vitamin D biosynthesis?	Hypophosphatemia
How higher amounts of skin pigmentation caused by melanin impact vitamin D biosynthesis?	Requires 10-fold longer exposure to stimulated sunlight to make same amount of vit. D3 then someone with lower pigmentation.
What is the effect of calcitonin on calcitriol biosynthesis?	It inactivates calcitriol production by kidney
What is hypocalcemia?	Low levels of calcium
Defective bone mineralization is caused by	a. Malabsorption of calcium and phosphate b. Decreased intestinal absorption of calcium c. Decreased secretion of parathyroid hormone
Deficiency of calcium can lead to	Rickets Osteomalacia
What is the RDA value for vitamin D?	5-15 micrograms
Which dose of vitamin D can produce toxicity?	100 mg/day
Vitamin E is also known as	Tocopherol
What are dietary sources of vitamin E?	plant oils, animal oils, some fruits, vegetables
How defects in fat metabolism may have impact on vitamin E absorption?	Active fat absorption promotes absorption of Vit. E, so defective fat metabolism will cause a deficiency of Vit. E.
What are the general biologic functions of vitamin E?	Antioxidant, selenium metabolism, maintains membrane permeability and stability
Can you use vitamin E as an antioxidant when tissues are damaged following high oxygen concentration exposure? Briefly discuss the mechanism.	Prevents tissues from free radical damages, particularly effective at high oxygen concentrations
Which mineral is essential to elicit full vitamin E activity?	Selenium
How long vitamin E can be stored in tissues?	5-6 months
What is the RDA value for vitamin E?	10mg/d- men, 8mg/d- women
What are the precursors of vitamin K?	Phylloquinones and menaquinones
Which precursor form of vitamin K is found in plant?	Phylloquinones
Which precursor form of vitamin K is found in animal tissues?	Menaquinones
How a defective fat metabolism can adversely impact the absorption, transportation and action of vitamin K and why?	need normal fat absorption and therefore fat metabolism to absorb Vit. K
Describe the general function of vitamin K.	Required for synthesis of blood clotting factors, enhance Ca 2+ binding potential
Vitamin K is used as cofactor of which enzyme? What is the function of this enzyme?	γ-Carboxylase –converts glutamate to γ –carboxyglutamate
Which vitamin has a major role in blood clotting?	Vit. K
What is the active form of vitamin K?	Fibrin
Which vitamin is required to maintain normal levels of the blood clotting factors II, VII, IX and X?	Vit. K
What is the RDA value for vitamin K?	60 – 80 micrograms in adults

Created by: DixieDoll

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