Lecture 41

Question 1

Phenylketonuria (PKU) is caused by a deficiency in _____ _____. Symptoms
include ____pigmentation, intellectual disability, microcephaly, and seizures. Remember that tyrosine is derived from ______, and one of the molecules derived from tyrosine is _____ (pigment).

Answer 1

Phenylalanine hydroxylase

Hypopigmentation

Phenylalanine

Melanin

Question 2

Hyperphenylalaninemia can also be caused by deficiencies in any of the enzymes required to synthesize _________ (BH4), which is necessary for hydroxylase catalyzed reactions. This would lead to a more severe phenotype than PKU bc catecholamine and seratonin synthesis would also be impaired.

Answer 2

Tetrahydrobipterin (BH4)

Question 3

Maple syrup urine disease (MSUD) is caused by a deficiency in oxidative decarboxylation of ____ ____ AAs, which can interfere with brain function.

Answer 3

Branched Chain

Question 4

_____ results from defective copper-requiring tyrosinase.

Answer 4

Albinism

Question 5

Homocystinuria can be caused by Cystathionine beta-synthase and/or _____ __6, 12, and folate deficiency. It is characterized by high levels of homocysteine (which is linked to cardiovascular disease) and methionine in the blood.

Answer 5

Vitamin B6, 12, and Folate

Question 6

Alkaptonuria results from a deficiency in _____ degradation. The urine from these patients becomes very dark when left in open air due to oxidation of homogentisic acid.

Answer 6

Tyrosine

Question 7

Conversion of L-arginine to L-citrulline results in the formation of _____ _____ via the enzyme ____ ____ synthase. In ______ cells, this molecule causes relaxation and thus vasodilation. Treatment for Erectile Dysfunction inhibit degradation of ______ in this pathway, thereby keeping it “turned on” longer.

Answer 7

Nitric Oxide

Nitric Oxide

Endothelial

cGMP