Steroid Hormones Flashcards
What type of signalling molecule cannot enter the cell without a receptor or other means
Hydrophilic/lipophobic
Are steroids hydrophilic or hydrophobic
hydrophobic
What is cholesterol
metabolic precursor to steroid hormones and bile acids
What is progesterone
sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species
Define a steroid
cholesterol-derived ligands for intracellular receptor proteins which mediate hormone signals by altering the expression of specific genes
What processes do steroids play a key role in
cell development
reproductive biology
organismal physiology
what are the categories of steroid hormones and what does each play a role in
glucocorticoids - glucose metabolism
mineralocorticoids - salt and water balances
androgens - development and maintenance of male characteristics in vertebrates
estrogens - development and maintenance of female reproductive systems
how are steroid hormones transported via endocrine signalling
they diffuse across membranes and bind (transport proteins (albumin) that keep them soluble
Explain a steroid mode of action
Passively diffuse into target cells
bind to hormone receptors in the cytoplasm which then move to the nucleus
hormone-bound receptor triggers changes in gene expression
what are the cell-specific parameters that govern physiological responses to steroid hormones
cell-specific expression of nuclear receptors
availability of ligands
accessibility of target gene DNA sequences in chromatin
Where on DNA do activated nuclear receptors bind
hormone regulatory elements (HREs)
Why do steroid receptors flip when they dimerize
to increase the specificity of the sequences they can bind
What do palindromic hormone response elements decrease the chance of
The sequence being found elsewhere in the genome by chance alone
What stabilizes the dimer interface in glucocorticoid
zinc ion (zinc finger domain)
How does glucocorticoid receptor interact with DNA
amino acid side chains in the zinc finger domain make sequence-specific contacts with bases of the major groove of DNA
