Biotin

Question 1

biotin foods

Answer 1

ALL FOODS
liver, beef

Question 2

food form of biotin

Answer 2

free or covalently bound to proteins like biocytin

Question 3

small amount of biotin is produced by __ in __

Answer 3

small amount of biotin is produced by bacteria in colon

Question 4

SMVT aka

Answer 4

shared multivitamin transporter

Question 5

biotin transporter

Answer 5

SMVT

Question 6

SMVT is inhibited by

Answer 6

excess biotin

Question 7

SMVT is a

Answer 7

Na-depdent symporter

Question 8

biotin enters cell from

Answer 8

intestinal lumen (mainly jejunum)

Question 9

biotin is found mostly __ in __ with small amounts bound to __, __, and __

Answer 9

biotin is found mostly free in plasma with small amounts bound to albumin, globulins, and biotinidase

Question 10

biotin uptake in __ and other cells is likely mediated by __ carrier and __

Answer 10

biotin uptake in liver and other cells is likely mediated by SMVT carrier and monocarboxylate transporter (MCT)

Question 11

biotin is present in small amounts in

Answer 11

brain
liver
muscle

Question 12

biotin has __ and __ functions

Answer 12

biotin has coenzyme and non coenzyme functions

Question 13

4 coenzyme functions of biotin

Answer 13

1. pyruvate carboxylase
2. acetyl CoA carboxylase
3. propionyl CoA carboxylase
4. beta-methylcrotonyl CoA carboxylase

Question 14

1 nonenzyme function of biotin

Answer 14

regulation of gene expression

Question 15

the enzyme __ covalently attaches __ groups to target proteins (__ and __)

Answer 15

the enzyme holocarboxylase synthetase (HCS) covalently attaches biotin groups to target proteins (enzymes and histones)

Question 16

HCS deficiency

Answer 16

within hours to weeks of birth
emesis, hypotonia, lethargy, metabolic ketolactic acidosis

Question 17

similar diagnosis to HCS (they are often confused)

Answer 17

biotinidase deficiency (appears after 3 months)

Question 18

2 non-coenzyme roles of biotin

Answer 18

1. biotinylation of proteins and gene regulation
2. cell cycle

Question 19

biotinylation of proteins and gene regulation (3)

Answer 19

1. histones: biotinylation opens up DNA-histones
2. over 2,000 genes depend on biotin expression
3. non-histone proteins are also targets for biotinylation

Question 20

biotinidase function

Answer 20

recycles biotin to be used by the body

Question 21

biotin is an essential coenzyme for 5 __

Answer 21

biotin is an essential coenzyme for 5 carboxylases

Question 22

what vitamin is involved in carboxylase activity?

Answer 22

biotin

Question 23

biotin in cell cycle

Answer 23

required for progression
biotin deficiency causes cell arrest in G1 phase

Question 24

the biotin cycle

Answer 24

1. biotin enters from diet
2. HCS helps biotin find and bind targets (holocarboxylases)
3. once active, holocarboxylases participate in protein, lipid, and carb metabolism
4. once used, holocarboxylases are degraded
5. biocytin remains after degradation
6. biotinidase releases biotin for next round of activation

Question 25

biotin is essential in __, __, and __ metabolism

Answer 25

biotin is essential in **protein**, **lipid**, and **carb** metabolism

Question 26

excretion metabolites produces from __ of __ via __

Answer 26

excretion metabolites produced from **oxidation** of **valeric acid** via **urine, some in feces**

Question 27

assessment of biotin status (2)

Answer 27

1. plasma and urinary biotin 2. urinary excretion of 3-hydroxy-isovaleric acid

Question 28

is biotin deficiency common?

Answer 28

no, very rare but lethal if untreated

Question 29

groups at risk for deficiency

Answer 29

alcohol addiction diets high in raw eggs genetic mutations (biotinidase)

Question 30

groups at risk for deficiency

Answer 30

alcohol addiction diets high in raw eggs genetic mutations (biotinidase)

Question 31

biotin deficiency symptoms

Answer 31

neurologic: lethargy, depression, hallucinations skin abnormalities: dermatitis around eyes, mouth, and eyes

Question 32

how to treat biotin deficiency

Answer 32

free biotin daily

Question 33

all biotin are attached to a

Answer 33

lysine

Question 34

biotinidase is present

Answer 34

everywhere!

Question 35

SMVT requires what to transport biotin into cell

Answer 35

Na

Question 36

biotin cycle: HCS binds to __ and biotinylates them making other enzymes biologically active

Answer 36

biotin cycle: HCS binds to **histones** and biotinylates them making other enzymes biologically active

Question 37

biotin is mainly secreted as an __ product

Answer 37

biotin is mainly secreted as an **oxidized** product