B Vitamins Quiz

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Questions and Answers

What is the primary function of S-adenosyl-methionine (SAM) in methylation reactions?

It synthesizes dopamine and serotonin

It acts as a methyl donor (correct)

It converts methyleneTHF to THF

It contributes to the formation of choline

Which vitamin deficiency is associated with a methyl folate trap?

Vitamin A deficiency

Vitamin C deficiency

Vitamin B12 deficiency (correct)

Vitamin B6 deficiency

Which condition is NOT commonly linked to folate deficiency?

Dementia

Sickle cell anemia (correct)

Depression

Neural tube defects

What role does tetrahydrobiopterin (THB) play in relation to folate levels?

It aids in the synthesis of dopamine and serotonin. Signup and view all the answers

What is the consequence of reduced activity of the MTHFR gene?

Poor conversion of folate to active forms Signup and view all the answers

What is the primary biochemical role of Vitamin B6 in amino acid metabolism?

Moving amino groups between amino acids and alpha-ketoacids Signup and view all the answers

Which condition can result from a deficiency in Vitamin B6 and is linked to metabolic dysfunction?

Infantile seizures due to glutamate decarboxylase deficiency Signup and view all the answers

What biochemical process is directly influenced by Vitamin B6 that aids in energy production from carbohydrates?

Formation of NAD from glucose-derived substrates Signup and view all the answers

Vitamin B6 functions in the synthesis of which important biochemical substances?

Neurotransmitters, heme, and lipids Signup and view all the answers

In what way does Vitamin B6 deficiency contribute to symptoms observed in microcytic anemia?

It leads to an impaired synthesis of heme, affecting red blood cell production Signup and view all the answers

What biochemical process does biotin primarily catalyze?

Carboxylation reactions Signup and view all the answers

Which of the following biochemical functions is NOT directly associated with biotin (B7)?

Protein synthesis Signup and view all the answers

What happens to xanthurenic acid levels in a vitamin B6 deficiency after a tryptophan load test?

Levels increase Signup and view all the answers

What role does biotin play in blood sugar regulation?

It assists in gluconeogenesis Signup and view all the answers

What is the effect of consuming raw eggs on biotin absorption?

Inhibits biotin absorption due to avidin Signup and view all the answers

In the context of B7, what is a key substrate for fatty acid synthesis?

Acetyl-CoA Signup and view all the answers

What process is directly linked to the absorption of biotin?

Proteolysis of carboxylase enzymes Signup and view all the answers

What is the significance of pyruvate conversion to oxaloacetate in biotin's function?

It is a step in gluconeogenesis Signup and view all the answers

Which coenzyme form of B12 is involved in the methionine synthase reaction?

Methylcobalamin Signup and view all the answers

What process is responsible for releasing B12 from food proteins in the stomach?

Pepsin and hydrochloric acid Signup and view all the answers

Which substance protects B12 from hydrolysis and bacterial utilization in the stomach?

R-proteins Signup and view all the answers

Which form of cobalamin is primarily absorbed in the ileum through receptor-mediated endocytosis?

B12-IF complex Signup and view all the answers

What role does adenosylcobalamin play in metabolism?

Converts propionyl CoA to succinyl CoA Signup and view all the answers

Which of the following conditions results from B12 deficiency due to a methyl folate trap?

Excess homocysteine Signup and view all the answers

How is B12 transported from enterocytes into the bloodstream?

Carrier proteins Signup and view all the answers

What is the primary function of intrinsic factor in B12 absorption?

Assist in the absorption of B12 in the ileum Signup and view all the answers

What method is utilized to test for B12 deficiency?

Methylmalonic acid levels Signup and view all the answers

What form of vitamin B12 is typically found in supplements?

Cyanocobalamin Signup and view all the answers

What is the primary site of storage for vitamin B12 in the body?

Liver Signup and view all the answers

What is a potential consequence of correcting B12 deficiency anemia solely with folate supplementation?

Methyl folate trap Signup and view all the answers

What distinguishes vitamin B12 deficiency symptoms from those of vitamin B9 deficiency?

Neurological deficits Signup and view all the answers

Which of the following symptoms is characteristic of megaloblastic anemia due to B12 deficiency?

Pernicious anemia Signup and view all the answers

Which of the following blood tests is NOT typically used to diagnose B12 deficiency?

Creatinine level Signup and view all the answers

What is the role of THF in cellular metabolism related to B12?

Feeds into purine and pyrimidine synthesis Signup and view all the answers

What might lead to a deficiency in vitamin B12 absorption in elderly patients?

Hypochlorhydria Signup and view all the answers

What is typically expected regarding the duration until symptoms of B12 deficiency appear after cessation of B12 intake?

Years Signup and view all the answers

Study Notes

B-Vitamins Overview

Significant B-vitamins include B6 (Pyridoxine), B7 (Biotin), B9 (Folate), and B12 (Cobalamin).
B-vitamins play crucial roles in metabolic processes and maintaining optimal health.

Vitamin B6 (Pyridoxine)

Absorption, metabolism, and excretion are integral properties of vitamin B6.
Functions in the synthesis of heme, NAD, neurotransmitters, unsaturated fatty acids, and lipids.
Vital for carbohydrate metabolism (energy production) and amino acid metabolism.
Deficiency is linked to infant seizures due to glutamate decarboxylase insufficiency.
Other symptoms of B6 deficiency include microcytic anemia and fatigue.
Testing for deficiency can involve a tryptophan load test assessing xanthurenic acid levels.

Vitamin B7 (Biotin)

Absorption requires the removal of the attached carboxylase enzyme via proteolysis.
Biotin catalyzes carboxylation reactions involved in gluconeogenesis, fatty acid synthesis, and cholesterol synthesis.
High dietary intake of raw egg whites can lead to biotin deficiency due to avidin, which binds biotin and prevents absorption.
Plays a role in blood sugar regulation, especially helpful in diabetes management.

Vitamin B9 (Folate)

Folate is essential for DNA synthesis and crucial in cell division and growth.
Deficiency may contribute to conditions such as megaloblastic anemia and neurological issues.
MTHFR enzyme facilitates conversion to methyl folate, indicating potential implications for depression when deficient.

Vitamin B12 (Cobalamin)

Only found in animal products; essential for energy production and the formation of S-adenosylmethionine (SAM).
Absorption is complex, requiring release from proteins in the stomach by pepsin and HCl, then binding to intrinsic factor for transport to the ileum.
Deficiency can cause megaloblastic anemia (pernicious anemia) and neurological impairments.
Clinical implications: B12 deficiency leads to a methyl folate trap, hindering THF synthesis, necessary for nucleic acid production.

Testing and Diagnostics

Testing for B12 deficiency typically involves blood tests measuring levels of homocysteine and methylmalonic acid, both of which tend to be elevated in deficiency situations.
Symptoms of deficiencies overlap, necessitating careful testing for accurate diagnosis. B9 supplementation can sometimes mask a B12 deficiency, risking neurological damage due to unaddressed B12 needs.

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Description

Test your knowledge on B-vitamins including B6, B7, B9, and B12 with this quiz from Dr. Heisel's BMS200 class. You will explore their biochemical roles and health implications. This quiz challenges your understanding of vitamin absorption and utilization in the body.

B Vitamins Quiz - BMS200