Terminology
Diffusion
Passive transport across a membrane from areas of high concentration to low concentration
Why does activate transport require energy?
Because molecules are moving against a concentration gradient (unnatural), and molecules like to be evenly dispersed throughout a medium.
Ligand
Small hormone or chemical that binds to a protein receptor to initiate a signalling pathway
What is the water potential of 0.5M sucrose solution at 21 degrees Celsius in an open system?
-12.22 Bars
Cascade effect
The enhancement of a signal through secondary messenger proteins as one process leads to the next as proteins become activated in a chain like manner. Often can amplify signals.
What are the optimal tonicity conditions for an animal cell vs. a plant cell?
Animal cells- isotonic environment, plant cells- hypotonic environment
Why is cell signalling important?
Maintains homeostasis by responding to environmental change
Using protein pumps, often such as the sodium potassium pump, and utilizing ATP energy, sodium is pumped out of the cell, against a concentration gradient, keeping the sodium molecules outside the cell.
Turgid
The specific pressure created by water filled vacuoles expanding and pressing against the cell walls of plant cells to provide structure for the plant.
How is dynamic equilibrium achieved?
water moves via osmosis to areas of high solute to achieve equal concentrations on both sides. rate of forward is equal to rate of the reverse. VOLUMES are usually not equal
What is quorum sensing?
Bacteria signalling to each other their presence to act as a group in determining if there is enough room or resource to grow the population
Epinephrine is a chemical released during a stressful situation. How can the claim that different components in cell signalling pathways explain the different responses to epinephrine?
Cell signalling is dependent on the ability to detect a signal molecule. Not all cells have receptors for epinephrine, so only the cells with receptors are capable of responding.
Phosphorylation chains
the process of cascade effect being exhibited by the chain like phosphorylation of chemicals (addition of phosphate to activate it) each phosphorlyated chemical phosphorylates the next.
Why is water potential more negative as you get higher?
Water potential is a measure of the are with highest POTENTIAL of water to move or be displaced FROM the area. Negative water potential is moved TO, not FROM.
What sorts of responses are carried out by cell signalling pathways?
gene expression, protein synthesis, apoptosis
Metformin is a drug that treats type two diabetes by decreasing glucose production in the liver. AMPK is a cellular regulator of glucose metabolism. Metformin activates AMPK in liver cells but cannot pass the plasma membrane. By blocking AMPK with an inhibitor, it was discovered that AMPK is needed to be activated in order for metformin to produce an inhibitory effect on glucose production. What describes the component that metformin represents in a signal transduction pathway?
It is a ligand that activates the signal transduction pathway of the activation of AMPK
Receptor mediated endocytosis
energy requiring process that brings in large portions of molecules via vesicles (pinches of plasma membrane) when induced by a signal.
How does the process of exocytosis maintain homeostasis?
Large amounts of waste molecules are removed from the cells environment
How does the alteration of ligand-protein complex initiate transduction?
The protein becomes activated as the form has changed- and form relates to function. Often as they are integral proteins, the innermembrane environment can be altered along with the alteration of the protein.
The insulin receptor is a transmembrane protein that regulates homeostasis. The receptors extracellular domain binds specifically to insulin. the receptors intracellular domain interacts with cellular factors. the binding of insulin to the receptor stimulates a signal transduction pathway that results in the subcellular translocation of GLUT4. (a glucose transport protein that is stored in vesicles inside the cell). What would be the predicted effect of a loss of function of the insulin's receptor's intracellular domain?
The storage of GLUT4 in vesicles inside the cell will increase