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Lecture 7

Lecture 7- Cellular Energetics.docx

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Kathleen Gilmour

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Lecture 7 - Cellular Energetics Pop Quiz: Distinguish between: 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 intracellular 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….. Slide 2 -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 energy -generation of bioluminescence; (i.e. firefly has light generating cells that require energy, jelly fish, toad stools) use energy to generate light. Slide 3 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 Slide 4 -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 Slide 5 -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 *(poorly written) Slide 6 answer:C Slide 7 Glycolisis -(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
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