study notes for lecture three: classifications of hormones

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8 Mar 2011
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LECTURE THREE: CLASSIFICATION OF HORMONES
((peptide/protein = 3+ AAs, steroid = cholesterol, amine hormones = single AA)
Ætheir properties are based largely on their composition
HORMONE CLASSIFICATIONS
Hormone
Synthesis, Packaging, Release
Processing
Other Considerations
peptide
hormone
synthesized like proteins
- preprohormone mRNA sequence is
transcribed with an ER signal sequence
- ribosomes translate the prohormone and in
the ER it undergoes modifications
- after ER prohormone goes into the golgi
where it undergoes more modifications and
packaging into a vesicle {part of the golgi}
- vesicle will be released from golgi into
extracellular space when needed
- made in advance
- stored in vesicles in the tissues/cells where
LW¶VPDGH
- released into the bloodstream via exocytosis
only when needed
- release is caused by an external stimulus
insulin
pre-pro-insulin in the ER, released
into golgi
released from the golgi as pro-
insulin after modification
cleaved to form active insulin and
non-active C-peptide
during exocytosis both insulin and
C-peptide are released into the
bloodstream in a 1:1 fashion
o most hormones, most common
o water soluble, dissolved in plasma =
GRHVQ¶WQHHGDFDUULHUWRFLUFXODWHWKHERG\
o short half life, easily degraded when
exposed to surroundings
o bind to plasma membrane receptors (they
proteins cannot enter the cell)
o C-peptide is not active like insulin
o because insulin has such a short half life
and is metabolized quickly, can measure
insulin levels by measuring levels of C-
peptide
steroid
hormone
- synthesized only from cholesterol
- made on demand
- released via simple diffusion into the cell
cholesterol is modified by enzymes
to make steroid hormones
adrenal cortex = aldosterone,
cortisol
ovary = estrogen
o water insoluble ± bound to carriers in the
blood
o long half life (compared to peptide
hormones)
o has cytoplasm/nucleus receptors because it
can move among cells
o because receptors are at nucleus, can
regulate gene expression
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Document Summary

Lecture three: classification of hormones ((peptide/protein = 3+ aas, steroid = cholesterol, amine hormones = single aa) their properties are based largely on their composition. S pre-pro-insulin in the er, released: most hormones, most common, water soluble, dissolved in plasma = into golgi. S released from the golgi as pro- insulin after modification. S cleaved to form active insulin and non-active c-peptide. C-peptide are released into the bloodstream in a 1:1 fashion. S cholesterol is modified by enzymes: water insoluble bound to carriers in the to make steroid hormones. S adrenal cortex = aldosterone, blood long half life (compared to peptide hormones: has cytoplasm/nucleus receptors because it can move among cells, because receptors are at nucleus, can regulate gene expression. Hormone peptide hormone steroid hormone synthesized like proteins. Preprohormone mrna sequence is transcribed with an er signal sequence. Ribosomes translate the prohormone and in the er it undergoes modifications.

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