Topic 3-L2 - Redox reactions Flashcards
Even phototrophic bacteria need a source of
electrons to carry out anabolic reactions in the cell
Electrons are at a lower energy state when they are associated with
more
electronegative atoms
Glucose is a great
source of high energy electrons.
Oxygen is a great
electron sink – leaves electrons at low energy state.
Energy released by electrons moving to lower energy state captured by the cell through
redox reactions
Oxygen is a great electron acceptor because it’s so ____________ - meaning?
electronegative – has a high affinity for electrons…accepts low energy electrons
The reduction potential (E0’ ) of a
redox couple indicates its
propensity to act as an electron donor or recipient
Redox couples with more negative
values (top of table) have a stronger
tendency to act as
electron donors (to be oxidized)
Redox couples with more positive
values (bottom of table) have a strong
tendency to act as
electron acceptors (to be reduced)
Glucose is a great electron _______, O2 is phenomenal electron ________
Donor. acceptor
Why is CO2/glucose a strong electron donor (-ve reduction potential – Eo’)?
Glucose has several C-H bonds – electrons in high energy state. In CO2 electrons have moved close to oxygen – lower energy state
Why is O2/H2O a strong electron acceptor (+ve Eo’) ?
Hydrogen wants to an donate electron, Oxygen is highly electronegative – in O2, electrons equally shared – in H2O, oxygen can “steal” electrons from hydrogen.
Redox reactions between couples that have bigger differences in redox potential
produce more energy
Soluble electron carriers like
(NAD+ / NADH) used to shuttle
electrons around the cell
NAD+ is
oxidizing agent (gets reduced to NADH).
NADH is
reducing agent (Gets oxidized to NAD+)
Electron carriers such as NAD+/NADH are
enzymatic cofactors
Electron carriers allow
electrons donated in one reaction – stored in NADH – and accepted in a different reaction.
Are electron carriers insoluble?
NO they are soluble
Reactant that donates electrons
- E.g. - Glucose 2
- Gets oxidized
- Loss of electrons “electron donor”
- “reducing agent”
- Often loses H atoms and/or gains O atoms
