There are 4 paths from different sources feed substances into lysosomes for digestion:

• Endocytosis

• Phagocytosis

• Macropinocytosis

• Autophagy

TLS Online TPP Program

#Id: 6507

#Unit 7. System Physiology – Animal

Some of the tyrosine is formed from phenylalanine, by Phenylalanine hydroxylase

TLS Online TPP Program

#Id: 6508

#Unit 7. System Physiology – Animal

Tetrahydrobiopterin (BH4) is a cofactor for tyrosine hydroxylase and phenylalanine hydroxylase

TLS Online TPP Program

#Id: 6509

#Unit 7. System Physiology – Animal

Phenylketonuria (PKU) 

Mutation of the gene for phenylalanine hydroxylase

Caused by tetrahydrobiopterin (BH4) deficiency

TLS Online TPP Program

#Id: 6510

#Unit 7. System Physiology – Animal

Tyrosine is transported into catecholamine-secreting neurons via a Na+ - dependent carrier

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#Id: 6511

#Unit 7. System Physiology – Animal

Rate-limiting step in synthesis of catecholamines:  Tyrosine is converted to dihydroxy-phenylalanine (DOPA) by tyrosine hydroxylase

TLS Online TPP Program

#Id: 6512

#Unit 7. System Physiology – Animal

DOPA is converted to dopamine in the cytoplasm of the cells by DOPA decarboxylase (amino acid decarboxylase)