Intracellular signalling - Exam Questions Flashcards
When does intercellular signalling occur?
When a cell surface ligand directly binds to its receptor on the target cell.
Cytokines are an example of
a. inter-cellular signalling
b. paracrine signalling
c. endocrine signalling
d. exocrine signalling
e. neuronal signalling
b. Cytokines are an exmaple of paracrine signalling
Paracrine signalling = signal acts on cells very close to the cell that produced it
Acetyl choline, glutamate, dopamine, noradrenaline and GABA are all a. hormones b. amino acids c. inflammatory mediators d. neurotransmitters e. catecholamines
d. Acetyl choline, glutamate, dopamine, noradrenaline and GABA are all neurotransmitters
Match the signal molecule to its chemical type.
a. Insulin
b. Oestradiol
c. Adrenaline
d. Nitric oxide
e. Testosterone
i. Amino acid derivative
ii. Steroid
iii. Gas
iv. Glycosaminoglycan
v. Protein
Insulin=Protein Oestrdiol=Steroid Adrenaline=Amino acid derivative Nitric oxide=Gas Testosterone=Steroid
An example of a cell surface receptor is the receptor for
a. cortisol
b. adenylate cyclase
c. thyroxine
d. glucagon
e. cAMP
d. The receptor for glucagon is a cell surface receptor.
Tyrosine kinase receptors
a. are intracellular receptors
b. are activated by autophosphorylation
c. are G-protein-linked
d. are ion channels
e. bind steroid hormones
b. Tyrosine kinase receptors are activated by autophosphorylation
A signal molecule
a. never enters a cell
b. is a second messenger
c. activates a protein kinase
d. is a primary messenger
e. binds to a second messenger
d. A signal molecule is a primary messenger
The tissue response to a signal molecule
a. is always exactly the same in all tissues
b. varies slightly per tissue, but is always of a similar nature
c. is always the same where the receptor type is the same
d. may be completely different in different tissues
e. varies depending on differences in the signal molecule between
tissues
d. The tissue response to a signal molecule may be completely different in different tissues
Adaptor proteins
a. include Ras
b. associate with the signal molecule
c. are second messengers
d. generate the second messenger
e. associate with the ligand receptor
e. Adaptor proteins associate with the ligand receptor
Second messengers
a. are usually protein kinases
b. activate cAMP
c. are released into the cytosol in response to an extracellular signal
d. are formed in response to activation of a protein kinase
e. include G-proteins
c. second messengers are released into the cytosol in response to an extracellular signal
What does cAMP activate?
Protein kinase A
Protein Kinase A causes phosphorylation of…?
Serine residues
A phosphorylation cascade is when
a. a protein is sequentially phosphorylated and dephosphorylated
b. proteins autophosphorylate in response to a cascade of ligands
binding to them
c. kinases sequentially phosphorylate other kinases
d. proteins are successively phosphorylated by a kinase
e. all proteins in a cell are phosphorylated in response to a signal
A phosphorylation cascade is when kinases sequentially phosphorylate other kinases
Give an advantage of a phosphorylation cascade.
Signal amplification
The action of inositol trisphosphate as a second messenger is to
a. activate diacylglycerol
b. open calcium channels on the endoplasmic reticulum
c. stimulate protein kinase C to translocate to the plasma membrane
d. activate phospholipase C
e. activate protein kinase C
b. The action of inositol triphosphate as a secondary messenger is to open calcium channels on the endoplasmic reticulum.