Lecture 7 Flashcards
Where are hormones released into?
The bloodstream
Fill in the blanks:
Most hormones are _____ in nature
Protein
notable exception: steroid hormones
Why is it harder to design small molecular weight chemicals to mimic the biological activity of the hormones?
Many peptide (protein) hormones make physical contact with their respective receptors through a large surface which makes it much harder to design small molecular weight chemicals to mimic the biological activity of the hormones.
Amine hormones are derivatives of which amino acids?
Tyrosine or tryptophan
What is an example of an amine hormone derived from tyrosine?
Norepinephrine, catecholamines
What is an example of an amine hormone derived from tryptophan?
Melatonin
What is the general modification done to amine hormones?
The carboxyl group is removed while the amine group stays
What are steroid hormones derived from
Cholesterol
Which hormone has the longest half life? amine peptide or steroid
Steroid
How do steroid hormones travel to the target cell?
They are bound to a transport protein
What is the pathway of hormone action for water soluble hormones?
- The hormones bind to membrane receptors on the cell surface
- The binding activates a G protein
- The activated G protein actives adenylyl cyclase
- Adenylyl cyclase catalyses the conversion of ATP to cAMP which is a secondary messenger
- cAMP actives protein kinases
- These protein kinases phosphorylate proteins in the cytoplasm, which activates them, allowing them to alter cell activity.
What is the pathway of hormone action for lipid soluble hormones?
- Lipid soluble hormones diffuse through the plasma membrane
- They bind to the receptor within the cytoplasm forming a receptor-hormone comples
- The receptor hormone complex enters the nucleus and triggers gene transcription
- The transcribed mRNA is translated into proteins that alter the cell activity
What are some second messengers used in a cell signalling pathway?
cAMP, Ca2+ ions
What are the amino acid resides that get phosphorylated in a protein and what allows them to be phosphorylated?
Serine, threonine and tyrosine residues
They all have an -OH group
What is another name for the human growth hormone and what kind of hormone is it
Somatotropin
Peptide hormone
How does the growth hormone work?
- The hypothalamus releases growth hormone releasing hormone
- GHRH stimulates the pituitary gland to release growth hormone
- GH stimulates the liver to release insulin like growth factor 1 which acts on the bone, skeletal muscle and adipose tissue
What is the function of the growth hormone during fasting?
It stimulates the switch from glucose to fatty acids as a source of fuel during fasting
What hormone inhibits the release of growth hormone from the pituitary gland and where is is secreted from?
Somatostatin
Hypothalamus
Which cell is used to produce recombinant growth hormone?
E coli
What kind of dimer is the growth hormone receptor?
Homodimer