Exam 2, riboflavin

Question 1

coenzyme: riboflavin

Answer 1

FAD (flavin adenine dinucleotide), FMN (flavin mono nucleotide)

Question 2

alexander blythe

Answer 2

isolated pigment from milk, discovered B2

Question 3

why should milk not be packaged in glass bottles? *

Answer 3

riboflavin is sensitive to light. 50% of it can be destroyed in only 2 hours of exposure, which is why milk is now packaged in carton or opaque bottles

Question 4

what is the MAIN function of riboflavin

Answer 4

energy generation through transfer of H ions

Question 5

digestion of riboflavin

Answer 5

-is attached to proteins and freed by denaturation by HCl acid or proteases (stomach/ SI)
-lose phosphates via phosphatases before absorp. in lumen
-phosphorylate later (catalyzed by flavokinase)

Question 6

what source of riboflavin is absorbed best

Answer 6

animal (95%)
*thiamin is the one where plant is absorbed best

Question 7

what is the most common form of riboflavin in liver, tissue and plasma?

Answer 7

liver: FMN -> FAD by FAD synthetase
tissue: most is already in FAD form
plasma: riboflavin form

Question 8

FMN and FAD function as coenzymes for ____ enzyme systems

Answer 8

oxidative (loss of e-) because of their ability to ACCEPT H atoms

Question 9

riboflavin + succinate dehydrogenase

Answer 9

FAD is coenzyme for succinate dehydrogenase, removes e- from succinate to -> fumarate (intermmediate for Krebs) and FADH2 enters TCA cycle

Question 10

FAD in ETC

Answer 10

FADH2 donates electrons to complex II of ETC, gradient ultimately produces ATP

Question 11

fatty acid oxidation

Answer 11

fatty acyl CoA dehydrogenase requires FAD for B-oxidation

Question 12

what is an effective measure of riboflavin *

Answer 12

glutathione REDUCTASE: restores oxidized glutathione to active, reduced form (prevents damage from free radicals)
*requires riboflavin as a coenzyme so no riboflavin, no glutathione reductase

Question 13

other functions (3) of riboflavin

Answer 13

1. antioxidant (glutathione reductase)
2. DNA maintenance
3. synthesis of other B vitamins (niacin from tryptophan, B6 active form)

Question 14

riboflavin deficiency symptoms (by body part)

Answer 14

-mouth: cheilosis
-nose: seborrhea
-skin: dermatitis
-eyes: corneal vascularization (bloodshot)
-tongue: glossitis

Question 15

photograph of riboflavin deficiency, mouth

Answer 15

cheilosis: deep cracks and splits in the corners of the mouth (mouth sores)

Question 16

photograph of greasy nose

Answer 16

seborrhea/ seborrheic dermatitis: riboflavin deficiency

Question 17

bw photograph of child with open mouth and semi-closed eyes

Answer 17

stomatitis: riboflavin deficiency

Question 18

photograph of swollen tongue/ indentation of teeth

Answer 18

glossitis: riboflavin deficiency

Question 19

side to side photograph of inflammed face vs. smooth face

Answer 19

dermatitis: riboflavin deficiency

Question 20

rat with irritated legs/ injured looking

Answer 20

riboflavin deficiency

Question 21

photograph of inflammed eyes/ veins in eye

Answer 21

corneal vascularization: riboflavin deficiency

Question 22

photograph: fusion of two or more fingers/ toes seen in embryo

Answer 22

syndactyly: riboflavin deficiency

Question 23

toxicity of riboflavin

Answer 23

no tolerable upper limit intake levels, water soluble and rapidly excreted

Question 24

RDI riboflavin

Answer 24

M: 1.3 mg, F: 1.1 mg

Question 25

main riboflavin food sources

Answer 25

milk + meat, enriched cereals

Question 26

riboflavin deficiency conditions have underlying reason of

Answer 26

tissue inflammation and breakdown
*riboflavin deficiency = less glutathione, increased oxidative stress/ damage/ inflammation