1.4 Communication and signalling Flashcards
Compare and contrast hydrophilic and hydrophobic signalling.
Hydrophobic signal molecules diffuse through the hydrophobic phospholipid bilayer, and bind to a steroid receptor, creating a steroid receptor complex. This acts as a transcription factor, which will target the HRE, Hormone Response Element.
Hydrophilic signal molecules will bind to receptors on the surface of the cell. This will cause conformational changes that trigger kinase activity. This creates a phosphorylation cascade, that will eventually elicit a response.
Discuss the role of phosphorylation in signal transduction.
Phosphorylation occurs in the receptor following conformational changes by a ligand. The phosphorylation cascade is when one kinase within a chain activates the next.
Discuss how insulin brings about the recruitment of GLUT4 vesicles to the membrane.
Insulin binds to receptor on the surface of the cell. This creates a phosphorylation cascade, which will trigger the movement of GLUT4 containing vesicles to the cell membrane.
Discuss the molecular differences in Type 1 and Type 2 diabetes.
Type 1 is a failure to produce insulin, where as type 2 is a desensitisation to insulin.
Discuss how hydrophilic signals are transduced in G-proteins.
The binding of a ligand to the receptor triggers the recruitment of a G-protein. This activates the G-protein, which will then activate a response in the target protein, such as enzymes and ion channels.
Describe the structure and function of the Retina.
The retina has photoreceptor cells, which tell the brain what the eye is ‘seeing’. There are two types of photoreceptor cells, rods and cones.
Discuss the functional and structural differences between rods and cones.
While rods see black and white, cones see colour. Multiple rods are connected by a single neuron, where as one cone is connected to one neuron, meaning that amplification allows improved site in the dark. In cone cells, different forms of opsin combine to form red, green, blue or UV wavelengths.
Describe the location of rhodopsin.
Rhodopsin is located in the membrane of the disc area of rod and cone cells.
Describe the structure of rhodopsin.
It has a seven membrane spanning alpha helix with a pit at the centre.
