Lecture 30 Electron Transport.docx

5 Pages
Unlock Document

University of Toronto St. George
Michael Baker

BCH210H © Lisa | Page 12 Lecture 30: Electron Transport  use of energized electrons from the reduction rxns and the reduced coenzymes NADH, FADH QH 2 2 to produce ATP  krebs cycle, PDH complex in matrix  SDH is attached to inner membrane  ETC takes place in the inner membrane and matrix -  inner membrane is the location for e flow coming from the donors  electrons come down a series of carriers found in the inner membrane  e start at FADH and NADH 2 - - +  NADH can only accommodate 1e in its reduced structure, so the 2 e are balanced by 1 H + o NADH + H  FADH ha2 the 2 protons built in -  transit of e down carriers down an NRG hill (NRG slope)—from donors to acceptors (each carrier can exist as a reduced or oxidized form, as an reducing agent or oxidizing agent)—steps - (gradual release) instead of sudden release of e conserves NRG and produce ATP  where NRG is defined by reduction potential - o the NRG of reduction associated w these e is establishing the nature of this NRG hill  as NRG is going down NRG hill, the NRG is released  series of redox rxs  last receptor is O 2  it will pick up e and form H O 2 - o H 2 doesn’t give up its e easily, and thus is the last product  e from NADH to H O 2  outer membrane has pores  inner membrane is tight (location of e transport carriers) - -  as reduction potential of e decreases as e are passing through carriers, NRG is released and ATP is made 0 -  standard reduction potential (E ’)—the ability of a reducing agent to lose e  under standard conditions  NADH: E ’ = -0.32 volts -  good e donor  gives up e easily  good reducing agent  H O: E ’ = +0.82 volts 2  poor reducing agent  doesn’t give e up  goes from a good reducing agent through a series of gradually lower reducing potentials - 0  e fl-w from more negative to more positive E ’ -  e carriers are arranged in complexes in the inner membrane (focal areas of e transport)  related ones that transport to each other are located in groups (complexes)  e transport from complex to complex Complex 1  NADH entering  very NRGetic e - -  NADH-DH creates an e flow BCH210H © Lisa | Page 22 -  e enter and proceed through carriers  NADH donates its e and 2 protons for reduction of next carrier FMN  FMN has higher ΔG° than FAD but has similar structure, more NRGetic  FMN is reduced by e and 2 protons are added resulting in FMNH 2  NADH is the reducing agent  loses its e- -  FMN picks up e which becomes than reduced  FMNH uses its e to reduce CoenzymeQ 2 -  FMNH tr2nsfers e and 2 protons to reduce CoQ to produce CoQH 2  NRG drop from -0.32 V to +0.04 V allows production of ATP Complex 2  SDH is also a member of the Krebs Cycle(is the one attached to the inner membrane)  has a FADH 2  (for SDH to work, need to convert FADH quickly2to FAD)  FAD and FADH are2tightly attached to SDH  need to take e and protons away to get cycle 0  FADH a2d COQH are si2ilar in E ’, thus similar in NRG, not a huge drop, and no ATP  more of a side mvmt (sideward motion)  quick generation of CoQH /QH 2 2  (formation of QH al2ows FADH to par2icipate again in the Krebs cycle) Complex 3  CoQ = ubiquinone = Q  CoQH c2n either come from complex I or II  complex I goes down to form it  complex II goes across to form it - -  in complex III, CoQH pa2s its e to elements called cytochromes (bigger e acceptors, they are proteins w heme groups)  in inner membrane  cytochromes carry e w the heme groups (hemoglobin and myoglobin carry O ) 2  exist in 2 oxidation states  red in colour  have Fe in centre of heme  can exist as ferrous (+2) OR ferric (+3) o this is prevented in Hb and Mb bc it ruins the fx, but is encouraged in cytochromes in order - to transport e as electron donors or acceptors  protons are released bc cytochromes can’t carry them -
More Less

Related notes for BCH210H1

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.