Lecture 23 Flashcards
standard reduction potential
- a measure of electron affinity (Eº)
- hydrogen electrode is used as a standard
- electrons can flow towards or away from reference cell
Postive Eº
- electrons flow from reference cell to wards the test cell
Negative Eº
- electrons flow from test cell towards the reference cell
the more negative a redox potential is the …
- lower electron affinity it has (it is more likely to transfer electrons to something else)
- NADH is a good electron donor and O2 is a good electron acceptor
when electrons are passed down the ETC
the reduction potential increases with each transfarr
how to calculate E
G = -nFE
- n= number of electrons transferred
- F = faradays constant (96.5)
how do you know if a reaction is spontaneous
- G is negative and E is positive
What role do metals play
- metals are often found bound to a protein and function as an electron carrier
- Example: NADH dehydrogenase (complex 1) contains iron sulfur centres
Example: cytochromes have iron containing heme group
photosynthesis
- light driven reaction that creates organic molecules from atmospheric carbon dioxide.
- requires water and releases O2
- O2 produced made aerobic respiration widespread
- carried out in chloroplast
chloroplasts
- specialized intracellular organelles where photosynthesis takes place
thylakoid membrane
- folds to form flattened sacs known as thylakoid which contain internal space known as the thylakoid space
- thylakoids can be stacked into grand
describe stage 1 and stage 2 of photosynthesis
stage 1 (light energy): protons are pumps into the thylakoid space driving the synthesis of atp
- NADP+ is reduced to NADHP
- light energy is required
stage 2 (dark reactions): ATP and NADPH are consumed to drive the manufacture of sugars from CO2
chlorophyll
- light capturing pigments
- absorbs green light poorly because light is absorbed by electrons by porphyrin ring in blue
- contains a hydrophobic tail which holds the chlorophyll in the thylakoid membrane
phtosystem
- is a multi protein complex containing chlorophyl that captures light energy and converts it into chemical energy
- contains a set of antenna complexes and a reaction centre