0312 Cell Biology 3 Flashcards
How are cells constructed? How do cells function? How do they attach to each other? How do they “talk” to each other? How do they “react” to each other?
What is the predominant adhesion molecule responsible for cell adhesion to macromolecules in the extracellular matrix? What is it’s function
Integrins. Integrins are receptors that connect the extracellular matrix to the cytoskeleton (specifically microfilaments) inside the cell. Among the ligands of integrins are collagen, elastic fibres and GAGs
What are some components of the extracellular matrix that adhesion proteins can bind to
Simple components: basal lamina, elatic fibres, collagen, GAGs
Complex components: tendons, connective tissue sheaths
List some examples of proteins involved in close cell-cell interactions (adjacent cell adhesion)
IgCAMs and cadherins (bind to complementary molecules close cells). Selectins (bind to glycoproteins on other cells)
What are the 3 types of cell-cell junctions and what are their defining characteristics
Tight junctions (Semipermeable, cell adhesion and barrier). Gap junctions (pores, direct chemical communication). Adherens junctions (structural, connecting cytoskeletons)
What is a receptor
Most receptors are cellular detectors of environmental stimuli. They are mostly transmembrane proteins with a binding site on cell surface. They function to transfer signals across a lipid bi-layer
Describe two main methods a receptor may use to generate a signal?
- Conformational change of receptor 2. Dimerisation due to ligand binding
What is an agonist? What is an antagonist
An agonist binds to a receptor and there is a +ve outcome (i.e. expected and classical response). An antagonist opposes that affect (inhibition is at receptor not pathway)
What is attenuation/adaption/ desensitisation, etc
Reduction of signal response due to sustained stimulation/exposure of ligand
Describe the signal/receptor system in regards to photoreceptors
Photon + rhodopsin (receptor) results in conformational change. This change activates a series of enzymes that has a net result of decrease [cGMP]. cGMP keeps glutamate channels open and inhibiting these channels reduces [glutamate] in cell. Glutamate is a neurone inhibitor (= neuron is less inhibited)
Name a tissue in which large numbers of gap junctions are foundt
Cardiac muscle. The signal to contract passes efficiently through gap junctions, allowing for simultaneous contraction
What is the name of the chromophore in the light receptor?
Rhodopsin
In what part of the cell are steroid receptors located
They are found in the nucleus, cytoplasm (migrate to nucleus), or sometimes in the plasma membrane
