New version page

U-M BIOLOGY 172 - Lecture 8

Documents in this Course
Load more

This preview shows page 1 out of 4 pages.

View Full Document
View Full Document

End of preview. Want to read all 4 pages?

Upload your study docs or become a GradeBuddy member to access this document.

View Full Document
Unformatted text preview:

Lecture 8UTR = untranslated region. The portion of the mRNA outside of the coding sequence.Intron: portion of primary transcript removed from the mature mRNA (processed transcript ).(introns do NOT contain coding sequences – except in case of alternative splicing)Exon: portion of primary transcript that is retained in mature mRNA.(exons contain both coding sequences and UTR sequences)I. Post-translational Modifications of PolypeptidesA. transport to appropriate cellular destinationB. Proper foldingC. Addition of phosphate, lipid, or carbohydrate groupsD. denaturation-loss of protein conformation1. promoted by heat, pH change, chemicals2. inhibited by chaperoneE. renaturation1. possible for some preteinsII. Determinants of Protein ConfromationA. folding aids1. chaperon proteins. Which assit in folding other proteins2. created a sheltered envrioment to allow protein to adopt specific configuration3. helps with one of the biggest problems from partially unfoled or unfolded proteins-premature or inapprpiate association of hydrophobic regionsIII. Energy- the capacity to do workA. Potential energyi. energy stored in an objectB. Kinetic Energyi. energy of motion includes motion at the molecular scaleC. Free Energy- energy that can be used to do worki. Higher free energy1. less stable2. More concentrated3. More ordered4 greater work capacityii. Lower Free energy1. More stable2. Less concentrated3. less ordered4. less work capcityiii. objects tend to move from free energy to lower free energyiv. Gravitational Motion1. objects move spontaniesly from a higher altitude to a lower onev. Diffusion1. Molecules in a drop of due diffuse until they are randomly dispersedv. Chemical Reactions1. in a cell a sugar molcules is broken down into sipler molecules D. Change in free energy determines reaction characteristicsi. Exergonic1. energy relaseaing reactions2. reactions have more energy than products, spontaneous energy is released, change in G< 03. reaction rate depends on kinetic energy and activation energy required for reactant to reach the transition state4. even if the the change in G is negative, a reaction will occur very slowly if the activation energy is high ii. Exothremic1. heat relaeasing reactioniii. Spontaneous1. overall energy is releasediv. Endergonic1. energy consuming reaction 2. reactants have less energy than products, non spontaneous, energy is required, consumed, change in G>0v. endothermic1. heat absorbing reactionsvi. Non Spontaneous1. Reaction requires sustained input of energy ∆G = Gibbs free energy change:∆G = Gfinal state - Gstarting state∆G = ∆H - T∆S∆H = Difference in potential energy between the products and the reactants∆S = change in entropy = measure of disorder; increases in universe as a wholeIV. Protein SynthesisA.. a protein is more ordered, less stable, than its amino acid subunitsB. This reaction should be endergonic, and non-spontaneous.C. Endergonic reactions are coupled to exergonic reactions which allowsendergonic reactions to take place. We’ll come back to this conceptwhen we look at enzymes. V. Effect of a catalyst on a reactionA. a acatlyst lowers the activation energy of a reaction stabilizing the tranisition stateB. Catalyst do not change the change in G or Keq and are not consumber in the reactionC. they lower activation and thus speed up the rate of reactionVI. Enzymes-protein catalysts and typically catalyze a single reactionA. Most biological chemical reactions occur at meanginful rates only in the presence of an enzymeB. enzymes bring substrate together in specific postions that facilitate reaction and are very specific as to which reactions they catalyzeC. Cleft or groove on the enxyme where the substrate binds is called the active siteD. Induced fiti. allows tighted binding betwenn enzyme and substrateE. enzumes can only catalyze reactions that are ulltimatley down hiil where change in g is negativei. sometime reactions need to be coupled so that the overall delta G is negative* ATP provide the energy for Many rreaction in the Cell… the bonds linking thses phoasphate groups have high potential energyF. coupled reaction overall delta G is negative and together reaction are spontanouesG. Characteristcs of Enzyme Actioni. enzymes are substrate specificii. region that binds substrate is active siteiii. binding involves interaction between enzymes R- groups and substratesiv. binding destabilizes bond in substratesH. Functioni. active site binds substrate substrate specificity ii. binding involes unteraction between enzymes R groups and substrateiii. Binding destabilizes chemical bonds in substrate  lowers the activation energy  reaction goes faster1. An enzyme holds reactants (substrates) close together in the right orientation for the reaction, which reduces the reliance on random collisions.2. An enzyme may put a “strain” on existing bonds, making them easier to break.3. An enzyme provides a “microenvironment” that is more chemically suited to the reaction.4. Sometimes the active site of the enzyme itself is directly involved in the reaction during the transition states.I. Enzyme KineticsA. basic enzymatic reastionsB. Reaction Rate= amount of product formed(or substrate used) /timeC. Factors affecting the rate of a Reactioni. substarte concentrationii. enzyme concentrationiii. temperatureiv. pH(and the concentration of other


View Full Document
Loading Unlocking...
Login

Join to view Lecture 8 and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Lecture 8 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?