University:
York University
Course:
BIOL 2020 | Biochemistry
Academic year:

2023
Views:

27

Pages:

2
Author:

Nick T.

Hormones Polypeptides Do not carry out chemical reactions alter body biochemistry by: Signaling inhibition or activation of an enzyme altering rate of synthesis of a protein Largest class of hormones Most varied in size & Complexity Include: Insulin, glucagon, endorphins, FSH, TSH Family of Hydrophobic hormones Common Cyclic Structure 3 Major Hormone types Amino acid derivatives Polypeptides Steroids - 4 rings fused together - Steroid Classification of Steroids Mineralocorticoids - regulate electrolyte balance, blood volume, BP Glucocorticoids - regulate glucose metabolism & inflammation Sex Hormones - regulate growth & reproduction Secondary sexual appearance Amino Acid Derivatives Synthesized from Standard amino acids By loss of carboxyl and amine group Monoamines - when further modified Steroid Synthesis Synthesized from Cholesterol Precursor steroid hormone - Progesterone Progesterone Cortisol Testosterone Aldosterone Estradiol Similarities in structure can cause cross-reactivity Hormones Peptide/monoamine hormones are hydrophilic Cannot cross the nonpolar cell membranes but bind to receptors on the surface of the cell Synthesis of second messengers inside the cell Second messengers then activate enzymes Cyclic AMP most common second messenger Phosphodiester synthesized from ATP Anatomy of a Cell Binding of a monoamine or polypeptide messenger to its receptor activates the second messenger Second messenger activates other enzymes Steroid Hormones are hydrophobic Can move across the nonpolar cell membranes into Cytoplasm Bind to specific receptor proteins inside the cell The receptor proteins are carried into the nucleus where they cause a change in gene activity Removal of Message Signaling Second messenger must be destroyed Enzyme destruction molecules break down Reuptake recycling