Biotin

Question 1

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Answer 1

*

Question 2

What vitamin is used by carboxylase enzymes?

Answer 2

biotin

biotin is attached at the active site of five mammalian enzymes know as carboxylases (add a CO2 into an organic compound)

includes:
acetyl CoA carboxylase I and II
Pyruvate carboxylase
Methylcrotonyl CoA carboxylase
Propionyl CoA carboxylase

Important! Thiamin as TPP is a coenzyme for enzymes that catalyze DEcarboxylation reactions. These enzymes are called dehydrogenases.

Question 3

What glycoprotein found in raw egg whites may prevent biotin absorption?

Answer 3

avidin

avidin is an antimicrobial protein found in egg white that binds biotin and prevents its absorption

Question 4

Acetyl CoA carboxylase depends on which B vitamin to begin fatty acid synthesis?

Answer 4

biotin

acetyl CoA carboxylase I and II catalyze the binding of bicarbonate to acetyl CoA to form malonyl CoA which is required for the synthesis of fatty acids

biotin is attached at the active site of five mamalian enzymes known as carboxylases

1. acetyl CoA carboxylase I and II
2. Pyruvate carboxylase
3. Methylcrotonyl CoA carboxylase
4. Propionyl CoA carboxylase

Question 5

Which B vitamins use the AI recommendation for adult recommendations because there is insufficient available data to establish EAR and subsequent RDA?

Answer 5

biotin
pantothenic acid

The Food and Nutrition Board of the Institute of Medicine felt the existing evidence was insufficient to calculate an RDA for pantothenic acid and biotin.

Question 6

Quiz ?: The pyruvate dehydrogenase complex depends on all of the following vitamins for its funtion except one?

Answer 6

biotin

Question 7

Name the B vitamins synthesized by intestinal bacteria.

Answer 7

biotin

pantothenic acid

Question 8

Subclinical deficiency of which B-vitamins may develop in a substantial number of pregnant women?

Answer 8

biotin

Question 9

What is the enzymatic function of biotin?

Answer 9

• [ ]A. Coenzyme for carboxylase enzymes
  
  • [ ] 1. Pyruvate carboxylase
    
    • [ ] a) catalyzes carboxylation of pyruvate to form oxaloacetate
    • [ ] b) requires
      
      • [ ] (1) acetyl-CoA
      • [ ] (2) Mg
      • [ ] (3) ATP
  • [ ] 2. Acetyl-CoA carboxylase
    
    • [ ] a) role in the initiation of fatty acid synthesis
    • [ ] b) forms malonyl-CoA
  • [ ] 3. Propionyl-CoA carboxylase
    
    • [ ] a) catabolism of isoleucine, threnonie, and methionine
  • [ ] 4. Beta-methylcrotonyl-CoA carboxylase
    
    • [ ] a) catabolism of leucine

Question 10

What is the nonenzymatic function of biotin?

Answer 10

Gene expression through biotinylation of histones

• [ ] B. Noncoenzyme roles
  
  • [ ] 1. biotinylation of proteins
    
    • [ ] a) biotinylation of histones
      
      • [ ] (1) causes histones to uncoil so transcription factors
        can reach DNA and activate gene promoter sequences
    • [ ] b) over 2000 human genes depend on biotin for expression