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SPH-N432 > Exam 1 > Flashcards

Exam 1 Flashcards

1. Function (enzymes, physiological, structural, etc.). 2. Mechanism of absorption (from the mouth, gi tract, to sites of storage and metabolic activity). 3. Factors that affect bioavailability and nutrient absorption (other dietary factors, medications). 4. Various chemical forms (metabolic action, bioavailability, food sources vs. supplement sources). 5. Food sources (rich sources, as well as the most common sources). 6. Recommended intakes throughout the lifecycle. 7. Time of lif

1
Q

Functions and Structure of Thiamin

A

Structure: hex and a pent
Energy Transformation; Coenzyme role
Synthesis of Pentoses and NADPH; coenzyme role
Membrane and nerve conduction; non-coenzyme

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2
Q

Mechanism of absorption Thiamin

A

Thiamin is only absorbed in it’s phosphorylated forms (typically TDP and TPP, but also TMP and TTP) thanks to intestinal phosphatases. The Thiamin is hydrolyzed from the mono, di, and triphosphates leaving the free Thiamin to be absorbed into the intestinal cells.
Absorbed in the Jejunum and Ileum (also the duodenum to a lesser extent)

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3
Q

Factors Affecting Bio-availability Thiamin

A

Thiamin’s methylene bridge is very sensitive to both heat (high temp) and alkaline conditions (pH 8+).
Raw fish have thiaminases (which are rendered inactive by cooking)
Polyhydroxyphenols (found in coffee, nuts, and blueberries) inactivate thiamin by destroying the Thiazole ring

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4
Q

Various Chemical Forms Thiamin

A

Thiamin Mono, Di, and triphosphate

Thiamin Pyrophosphate

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5
Q

Food Sources Thiamin

A

Widely distributed in meats (95% in phosphorylated form) as well as grain products and legumes, but most Thiamin in the American diet comes from enriched sources (much like riboflavin and niacin).

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6
Q

Thiamin’s Role in Energy Transformation

A

Functions as a coenzyme necessary for the ocidative decarboxylation of pyruvate, a-ketoglutarate, and the three branched chain amino acids valine, isoleucine, and leucine. These reactions are all essential in ATP generation

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7
Q

Deficiency symptoms and diseases Thiamin

A

Beriberi, muscle weakness, anorexia, tachycardia, enlarged heart, edema

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8
Q

Assessing Nutritional Status Thiamin

A

Thiamin status can be assessed by measuring thiamin in the blood or urine and by measuring erythrocyte transketolase activity in hemolyzed whole blood.

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9
Q

Function Riboflavin

A

Riboflavin as Flavin mononucleotide (FMN) or Flavin adenine Dinucleotide (FAD) function as coenzymes for a variety of oxidative enzyme systems.

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10
Q

Functional Forms of Niacin

A

Nicotinic Acid and Nicotinamide

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11
Q

Niacin RDA calculations

A

mg of protein over 60

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12
Q

Functions of Pantothenic Acid

A

Functions in the body as a component in the synthesis of 4’-phosphopantetheine and CoA

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13
Q

Assessing Nutritional Status Niacin

A

Urinary metabolite measures as well as serum or red blood cell indicators.

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14
Q

Toxicity Niacin

A

Vasodilatory problems (too much blood flow) as well as gastrointestinal stress.

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15
Q

Deficiency Symptoms Niacin

A

Pellagra, diarrhea, dermatitis, mental confusion, or dementia

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16
Q

Mechanism of Biotin

A

Biotin bonds covalently to each of four carboxlyases. Catalyzed by holocarboxylase synthetase.

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17
Q

Digestion and Absorption of Biotin

A

After having been hydrolyzed by enzymatic digestion, biotin is absorbed nearly completely in the small intestine

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18
Q

Anti Biotin Factors

A

Those who consume large quantities of large eggs or pregnant women are susceptible to biotin deficiency

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19
Q

Functions of Biotin

A

CO2 transfer / Carboxylation reactions
Converts Pyruvate to oxaloacetate
Forms Malonyl CoA from Acetate (ACoA)
Converts Propionyl CoA to Methylmalonyl CoA

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20
Q

Functions of Pantothenic Acid

A

Acyl Transfer reactions

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21
Q

Functional forms of B6

A

Pyridoxine, pyridoxal, pyridoxamine

22
Q

Functions of B6

A

Transamination and decarboxylation reactions

23
Q

Assessment of Nutritional Status of B6

A

Plasma PLP concentrations are typically considered the best indicator. Urinary B6 along with 4-pyridoxic acid over several day have also been used.

24
Q

Deficiency of B6

A

Dermatitis, glossitis, and convulsions

25
Q

Digestion and Absorption of Folate

A

To be absorbed, folate must first be digested to its monoglutamate form (FGCP). It is moved into the cells by the proton-coupled folate transporter (PCFT).

26
Q

Folate’s relationship to b6

A

x

27
Q

Folate’s relationship to b12

A

x

28
Q

SAM and Folate

A

Being deficient in either folate or b12 will reduce the available amounts of SAM

29
Q

Assessment of nutritional status Folate

A

Concentration of folate is often tested in the plasma, serum, or red blood cells.

30
Q

RDA as DFE Folate

A

RDA = 400 ug

31
Q

Consequences of Folate Deficiency

A

Megaloblastic Anemia, diarrhea, fatigue, depression, confusion

32
Q

Functions of B12

A

Responsible for Methylation of homocysteine to methionine;

Conversion of methylmalonyl CoA to succinyl CoA

33
Q

B12 Deficiency disease and cause

A

Megaloblastic Anemia and degeneration of peripheral nerves.

34
Q

DRI

A

Dietary Reference Intake
a system of nutrition recommendations from the Institute of Medicine (IOM) of the U.S. National Academy of Sciences. The DRI system is used by both the United States and Canada and is intended for the general public and health professionals.

35
Q

RDA

A

Recommended Daily Allowance
the daily dietary intake level of a nutrient considered sufficient by the Food and Nutrition Board to meet the requirements of 97.5% of healthy individuals in each life-stage and sex group. It is calculated based on the EAR and is usually approximately 20% higher than the EAR

36
Q

AI

A

Adequate Intake
where no RDA has been established, but the amount established is somewhat less firmly believed to be adequate for everyone in the demographic group.

37
Q

UL

A

Tolerable Upper Limit
to caution against excessive intake of nutrients (like vitamin A) that can be harmful in large amounts. This is the highest level of daily consumption that current data have shown to cause no side effects in humans when used indefinitely without medical supervision.

38
Q

Vitamin Classifications

A

Energy Releasing
Hematopoietic
Other

39
Q

Thiamin’s role in Pentose and NADPH synthesis

A

Part of the Pentose Phosphate Pathway which is key in synthesis of Pentose and NADPH

40
Q

Thiamin as TDP is a coenzyme in…

A

Pyruvate dehydrogenase complex, branched chain a-keto acid dehydrogenase complex, and the a-ketoglutarate dehydrogenase complex. Also needed for the Transketolase used in the Synthesis of NADPH

41
Q

Energy Releasing B Vitamins

A 
B1 Thiamin
B2 Riboflavin
B3 Niacin
B5 Pantothenic Acid
B6 
B7 Biotin
42
Q

Hematopoietic Vitamins

A

B5 Pantothenic Acid
B6
B12
Folate

43
Q

EAR

A

Estimated Average Requirement

expected to satisfy the needs of 50% of the people in that age group based on a review of the scientific literature.

44
Q

Main coenzyme form of riboflavin

A

FAD

45
Q

Main coenzyme form of niacin

A

NAD

46
Q

Thiamin as TDP is important for activity of which enzyme?

A

transketolase

47
Q

What is needed to release biotin from proteins

A

Biotinidase

48
Q

Niacin synthesis precursor

A

Tryptophan

49
Q

Nutritional status of Riboflavin is measured by what enzyme

A

glutathione reductase

50
Q

Essential for the function of B3

A

Biotin

51
Q

Vitamins associated with Pyruvate dehydrogenase complex

A

Niacin, Pantothenic Acid, Riboflavin, Thiamin (TDP)

1, 2, 3, 5

SPH-N432 (8 decks)

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