Lecture 7 - Cellular Energetics
1) A G Protein-coupled receptor, and a G protein.
-G protein coupled receptor is a protein that is embedded in the membrane, and the g-protein is an
2)protein phosphatase and phosphodiesterase
-phosphodiestersae deactivates cyclic amp(catalysizes break down of cAMP)
-protein phosphotase removes phosphate group from a protein
3)protein kinase A and receptor tyrosine kinase
-protein kinase a is intracellular protein
-receptor kinase a is a receptor in the plasma membrane activated by a signal coming from outside the cell
-they are both kinases
-protein kinase a phosphorylates…..
-Energy is the capacity to do work
-with respect to cell it means changing physical or chemical
-i.e. energy is capacity to make physical or chemical changes in the cell
Why cells need energy?
-BioSynthesis requires energy (for example)
-movement throughout the cell requires energy to power that movement (mechanical work)
-moving molecules against a diffusion gradient (use ATP to power movement)
-Electrical work; ion is moved across gradient, to generate electrochemical gradient, and this build up can be
used in the activation of muscles cells
-Generation of heat, used by animals to maintain a high body temperature. Requires the expenditure of
-generation of bioluminescence; (i.e. firefly has light generating cells that require energy, jelly fish, toad
stools) use energy to generate light.
Ultimately energy comes from sunlight. Plants have a pigment (chlorophyll) that allows them to acquire the
light, and convert it to chemical energy (glucose)*high energy levels.
-cells can take these energy containing molecules, and break them down to bring them to cells that require
this energy. They convert it to ATP first.
-the breaking down process is called cellular respiration, its how they extract energy from glucose
-Focus on extracting energy from carbohydrates,lipids, proteins and converting it to ATP which is the form
the cell uses
-ATP is a nucleotide.
-made of three compartments
-Made of a 5 carbon sugar; on the first carbon, nitrogen containing base (adenine)
-on the 5th carbon you have a string of 3 phosphates
-when you have a sugar and base its called Adenosine (nucleoside)
-nucleotide is the whole molecule with at least one phosphate attached to it
-When you take off the end phosphate group of ATP it releases energy
-Inorganic phosphate Pi or HPO4^2- -the negative inorganic phosphate, and the 2 phosphates on ADP both have a negative charge, and so they
tend to repel each other. to bring them together you need to put in energy. and this is why when you
separate them, you get a release of energy.
-also energy is also released, because you have an increase in disorder (you go from having 1 molecule to
2) this increases the entropy* (same as increase disorder)
-phophate on its own is more stable (lower energy) and when they are bound together they are a little less
stable (higher energy) AKA resonance stabilizationgoing from higher energy form, to lower energy form
-ATP is a molecule used to couple the energy yielded by cellular respiration, and disperse it to other cells
-(splitting glucose to pyruvate)
-occurs in cytolplasm in cell
-Converting glucose to 2 molecules of Pyruvate; some ATP is formed
-produces enough energy to reduce NAD+
-when pyruvate enters mitochondrion
-it is first oxidized two a two carbon molecule, Acetyl-CoA,
-this molecule then goes through the Citric Acid cycle
-series of a reactions that generate some ATP, and release enough energy to reduce NAD and FAD
-final step is taking