1. What organs are very important for the absorption of fat-soluble vitamins? 2. What can cause deficiency of fat soluble vitamins?

1. ileum, pancreas 2. malabsorption syndromes, mineral oil intake

Biochemistry (Misc) Flashcards by M V

What is 21-hydroxylase?

**Steroid 21-hydroxylase **is a cytochrome P450 enzyme

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21-hydroxylase is a cytochrome P450 enzyme that is involved with the biosynthesis of ____.

the steroid hormones aldosterone and cortisol.

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Full-term neonate of uneventful delivery becomes mentally retarded and hyperactive and has a musty odor.

Diagnosis is?

PKU

(Phenylketonuria)

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“Stressed executive comes home from work, consumes, 7 to 8 martinis in rapid succession before dinner, and becomes hypoglycemic.”

What is the biochemistry mechanism here?

NADH ↑↑ in the liver,

shunting pyruvate to lactate, and

OAA to malate,

thus preventing gluconeogenesis

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2 y/o girl has ↑ in abdominal girth, failure to thrive, and skin and hair depigmentation.

What is the diagnosis?

Kwashiorkor

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Pellagra is a deficiency of vitamin ___

B₃

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“51 y/o has black spots in his sclera and has noted that his urine turns black upon standing.”

What is diagnosis?

Alkaptonuria

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“A woman complains of intense muscle cramps and darkened urine after exercise.

What is the diagnosis?

McArdle’s disease

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If 2 parents, both with albinism, have a son who is normal, why is the son not affected?

locus heterogeneity

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What organs are very important for the absorption of fat-soluble vitamins?
What can cause deficiency of fat soluble vitamins?

ileum, pancreas
malabsorption syndromes, mineral oil intake

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List the function/role of each of the fat-soluble vitamins:

A - vision
D - bone calcification; calcium homeostasis
E - antioxidant
K - clotting factor

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What molecule/biochemical is thiamine (B1) responsible for?

TPP

thiamine pyrophosphate

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What molecule/biochemical is riboflavin (B2) responsible for?

FAD; FMN

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What molecule/biochemical is niacin (B3) responsible for?

NAD+

NADP+

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What molecule/biochemical is pantothenic acid (B5) responsible for?

CoA

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What molecule/biochemical is pyridoxine (B6) responsible for?

pyridoxal pyrophosphate

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Vitamin B₃ is AKA:

Niacin

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Vitamin B6 is AKA:

pyridoxine

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Vitamin B7 is AKA:

Biotin

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Vitamin B9 is AKA:

folate

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Biotin is Vitamin B ___

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Folate is Vitamin B __.

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What molecule/biochemical is Vitamin B12 responsible for?

homocysteine methyltransferase

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What molecule/biochemical is Vitamin B**9** responsible for?

THF tetrahydrofolate

What happens in B6 deficiency?

convulsions, peripheral neuropathy

**INH** or **oral contraception** can be a problem with vitamin \_\_\_

What medical problems can INH or oral contraceptives induce? (B6 deficiency)

hyperirritability

Which water-soluble vitamins are stored in the liver?

B**12**

What do B-complex deficiencies result in?

dermatitis, glossitis, diarrhea

How should we get our Vitamin A?

leafy vegetables

Vitamin A deficiency results in:

night blindness, dry skin

Too much Vitamin A leads to:

arthralgia, sore throat, alopecia, fatigue

Thiamine is AKA:

Vitamin B1

What happens in Vitamin B1 deficiency?

Beriberi, Wernicke-Korsakoff syndrome, Wernicke encephalopathy

What happens in dry beriberi?

polyneuritis, muscle wasting

What happens in wet beriberi?

high output cardiac failure, edema

What happens as a result of Vitamin B**2** deficiency?

cheilosis, angular stomatitis, corneal vascularization

The liver can synthesize niacin from the amino acid \_\_\_

tryptophan

Vitamin B3 deficiency is AKA:

pellagra

What can cause B3 deficiency?

Hartnup dz; malignant carcinoid syndrome, INH

Why does Hartnup dz lead to B3 deficiency?

Hartnup dz ↓↓ absorption of tryptophan

Why does malignant carcinoid syndrome lead to B3 deficiency ?

malignant carcinoid syndrome ↑↑ tryptophan metabolism

Why can INH lead to B**3** deficiency ?

Because isoniazid can lead to B**6** deficiency

What are the **3 D's** of pellagra?

Dementia, Dermatitis, Diarrhea

What is the function of Vitamin B5?

constituent of CoA, and a component of fatty acid synthase

What can Vitamin B5 deficiency cause?

adrenal insufficiency, alopecia, dermatitis, enteritis

What is the function of Vitamin B6?

it's converted to pyridoxal pyrophosphate (a cofactor in transamination, decarboxylation, heme synthesis)

What is the **cause** of B**12** deficiency?

pernicious anemia (no IF), Crohn's dz (no terminal ileum), malabsorption

What medical problems happen to people with B**12** deficiency?

* macrocytic anemia * megaloblastic anemia * neurological symptoms * glossitis * abnormal myelin

a famous test for B**12** deficiency is \_\_\_\_

the Schilling test

The **Schilling** test is used for patients with a deficiency of vitamin \_\_\_\_.

B**12**

The main syndrome of vitamin ___ deficiency is Biermer's disease (pernicious anemia).

B**12**

The main syndrome of vitamin B**12** deficiency is ___ disease (pernicious anemia).

**Biermer's** disease

Another name for **pernicious anemia** is \_\_\_\_\_.

Biermer's disease, Addison's anemia, or Addison–Biermer anemia

**Biermer's** dz, or **Addison–Biermer** dz, is another name for:

**pernicious** anemia

From where do we get our Vitamin B**12**?

Gut **bacteria** make B12. ## Footnote Animals are Not capable of B12 synthesis.

What are dietary sources of folate?

wide variety of foods, particularly **dark green leafy vegetables**

**Pernicious anemia **is usually the result of insufficient secretion of \_\_\_\_.

**intrinsic factor** within the stomach

In the body, what is the function/role of **folate**?

Folate is needed to carry **one-carbon** groups for **methylation** reactions, and **nucleic acid synthesis** (DNA and RNA)

Vitamin _____ is the only acceptor of methyl-THF, and this reaction produces methylcobalamin. There is also only one acceptor for methylcobalamin, homocysteine, in a reaction catalyzed by homocysteine methyltransferase.

B**12**

Vitamin B12 is the only acceptor of \_\_\_\_, and this reaction produces methyl-B12 (methylcobalamin).

methyl-THF

Vitamin B12 is the only acceptor of methyl-THF, and this reaction produces \_\_\_\_.

methyl-B12 (methylcobalamin)

Vitamin B12 is the only acceptor of methyl-THF, and this reaction produces methyl-B12 (methylcobalamin). There is also only one acceptor for methyl-B12, namely \_\_\_\_, in a reaction that is catalyzed by \_\_\_\_.

1. homocysteine 2. homocysteine methyltransferase.

\_\_\_\_ is an intermediate in the synthesis of folate by bacteria, plants, and fungi. Humans lack the enzymes to convert ____ to folate.

PABA

Humans lack the enzymes to convert PABA to Vitamin \_\_\_\_.

folate

Patients with ____ need to be tested for vitamin B12 deficiency before folate treatment.

megaloblastic anemia

Patients with megaloblastic anemia need to be tested for vitamin ___ deficiency before folate treatment.

B**12**

Patients with megaloblastic anemia need to be tested for vitamin B12 deficiency before giving them ____ treatment, because if the patient has vitamin B12 deficiency, ___ supplementation can remove the anemia, but can also worsen neurologic problems.

folate

In adults, \_\_\_ can be a sign of advanced folate deficiency.

macrocytic or megaloblastic anemia

The most common vitamin deficiency in the US is ___ deficiency.

folate

What is the function of Biotin?

Biotin is a **coenzyme **for carboxylase enzymes, involved in the **synthesis** of **fatty acids**, **isoleucine**, and **valine**, and in **gluconeogenesis**.

List the **carboxylation reactions** that **Biotin** is involved with:

Pyruvate → OAA Acetyl CoA → malonyl CoA Propionyl CoA → methylmalonyl CoA

What causes Biotin deficiency?

raw egg ingestion, abx

What problems can result from Biotin deficiency?

dermatitis, conjunctivitis alopecia

Fcn of Vitamin C is:

1. **hydroxylation** of **proline** and **lysine** in collagen synthesis 2. facilitates **iron absorption** by keeping Fe ²⁺ reduced 3. Cofactor for the **dopamine → NE** reaction

What are the signs/symptoms of scurvy?

swollen gums, bruising, anemia, poor wound healing

What does **G6PD** stand for?

Glucose-6-phosphate dehydrogenase