Metabolism Metabolism is the chemical reactions of life

Metabolism • Metabolism is “the chemical reactions of life; all the various processes by which you obtain energy, grow, heal, think, feel, and dispose of wastes”. • Metabolic reactions are controlled by enzymes. Metabolism

Metabolism Endergonic Exergonic

Enzymes are Proteins Enzymes are just one of the many types of proteins Perfect opportunity for review… Amino acid Structural t. RNA Regulatory Contractile Immunological Transcription DNA Translation m. RNA Protein Transport Enzyme Folded into it’s primary, secondary and tertiary structure.

Metabolic Pathways • A series of ‘steps’ from a starter molecule or To catalyze precursor toward a final end product. means to “speed up” a reaction • Each step is catalyzed by a different enzyme. Enzyme A Precursor chemical When an enzyme is written on a reaction arrow, it means the enzyme catalyzes the reaction shown Enzyme B Intermediate chemical End product

Syllabus Statement 2. 1. U 4 Metabolism is the web of all the enzyme-catalyzed reactions in a cell or organism. Define metabolism and catalysis. State the role of enzymes in metabolism.

CYCLICAL PATHWAY Some metabolic pathways operate in a cyclic way. The scientists who elucidated two of the cycles have had their names attached to the pathways by the scientific community. Remember: each arrowed line in the pathway indicates an enzyme is used to make that step happen. Only the names of the reactants and products are shown. In this case, the names of the enzymes doing the reaction are NOT written.

Metabolism of Phenylalanine • • The metabolism of phenylalanine is an example of a CHAIN metabolic pathway. Failure of the enzymes controlling the metabolic pathway leads to a range of metabolic disorders. Protein in diet Phenylalanine essential amino acid Thyroxine Tyrosine Hydroxyphenylpyruvic acid Homogentisic acid Maleylacetoacetic acid Carbon dioxide and water Melanin

• Write the name of the enzyme required for each step of the pathway on the appropriate line. • The example is just provided as an illustration of how complex and interrelated metabolic pathways can be. You are not expected to know the memorize the details of this pathway. • This is a perfect opportunity for review… keep in mind that each of the ENZYMES you list in this METABOLLIC PATHWAY is a PROTEIN created through TRANSCRIPTION and TRANSLATION of a GENE. The genes usually have two ALLELES, the “normal” version and the “diseased” version of the gene. The diseased allele is caused by a MUTATION in the DNA of the gene. The mutation results in a faulty enzyme because the AMINO ACID sequence (PRIMARY STRUCTURE) of the protein will not be correct. If the primary structure isn’t correct, the SECONDAY, TERIARY and QUARTENARY structures will also be incorrect. So, if the protein folds incorrectly, the functioning of the enzyme will be decreased or lost. See how much you know? ? ? !!! My smarty pants biology students make me proud.

Protein in Diet Phenylalanine Phenylketonuria “PKU” This in turn causes essential amino acid All newborns in the USA are tested for PKU at birth. If present, then the diet is modified so no phenylalanine is ingested. If none is eaten, then there will be no symptoms of the disease. Phenylalanine hydroxylase Faulty enzyme results in buildup of Tyrosine SYMPTOMS Mental retardation, 'mousy’ body odor, light skin color, eczema, excessive muscular tension and activity. Phenylpyruvic acid

Protein in Diet Faulty enzymes cause Phenylalanine essential amino acid Cretinism Thyroxine a series of enzymes Tyrosine Symptoms Dwarfism, mental retardation, low levels of thyroid hormones, retarded sexual development, yellowish skin color.

Protein in Diet Phenylalanine essential amino acid Tyrosine Symptoms Complete lack of the pigment melanin in body tissues, including the skin and hair Tyrosinase Melanin Faulty enzyme causes Albinism

Protein in Diet Phenylalanine essential amino acid Tyrosine Transaminase Hydroxyphenylpyruvic acid

Hydroxyphenylpyruvic acid Faulty enzyme causes Tyrosinosis Hydroxyphenylpyruvic acid oxidase Homogentisic acid Symptoms Death from liver failure or, if surviving, chronic liver and kidney disease. A diseased liver

Symptoms Hydroxyphenylpyruvic acid Dark urine, pigmentation of cartilage and other connective tissues, and, in later years, arthritis. Homogentisic acid oxidase Faulty enzyme causes Maleylacetoacetic acid Carbon dioxide and water Note the blue tint of Alkaptonuria the cartilage in the ear.

Hydroxyphenylpyruvic acid Homogentisic acid , d l ou Maleylacetoacetic acid Carbon dioxide and water h s t i y a f w o e n h ! o t i r t e s s t k e a r g o i w d e n e h a t m 2 y n i z O n s C t e c t ry rodu e jus e v If e inal p ne ar i f n e a l th la y n phe

Syllabus Statement 8. 1. U 4 Metabolic pathways consist of chains and cycles of enzymecatalyzed reactions. Contrast metabolic chain reaction pathways with cyclical reaction pathways.