Cell Communication Flashcards
Give an example of contact dependent Signalling
Antibody to Antigen
Give an example of Paracrine signalling
Interferons, Hedgehog expression in Drosophila stimulates Dpp expression which interacts with the ECM and surrounding cells.
Give an example of endocrine signalling
Adrenaline, pheromones
Give an example of a pheromone
Stigmolon - Myxococcus
What is the French Flag Model, give an example.
Where there is a quantitative response to different to signal strength; multiple signal thresholds which can result in a morphogen gradient. Female Drosophila deposit bicoid (Bcd) mRNA into the egg, protein gradient of Bcd in their embryos, establishes the anterior part of the embryo
Tell me about Myeloproliferative neoplasms
Associated with >95% of Polycythemia vera cases. V617F mutation in the JAK2 tyrosine kinase. Mutation in the negative regulatory pseudokinase domain results in it’s constitutive activation and proliferation of red and white blood cells and platelets. (Hypertension)
Tell me about chronic myeloid leukaemia
Philadelphia chromosome; Pieces of chromosome 9 and 22 break of and swap places. Results in fusion of BCR promoter region to ABL protein (BCR-ABL1 fusion). ABL, a tyrosine kinase is constitutively active resulting in white blood cell proliferation.
How do cells respond to signalling?
Very fast: change the structure of existing proteins (Ion channels opening)
Quite fast: change post-translational modification of proteins
Slow: Change levels of protein expression via gene expression
Where do cells regulate signalling pathways
Primary Transduction: specificity and expression of receptors. Intracellular transduction: amplification of signal, signal relay. Effector proteins: can feedback onto the signalling pathway.
What are the differences between positive and negative feedback
Positive feedback responses are fast and the system quickly maxes out and is sustained beyond stimulus, requires fast effector turnover, often using post-translational modifications such as phosphorylation or GTPases. Negative feedback responses can max out the system if stimulus is maintained. Response decays after the stimuli ends.
