Bioenergetics Flashcards
define bioenergetics
reaction types which transform energy in metabolism
what is the main reaction type that transforms energy in metabolism
oxidation/reduction
what is oxidation
basis of catabolism where energy is provided, i.e growth/respiration/ATP synthesis
define reduction
forms basis of anabolism where the reaction uses energy. i.e biomolecule synthesis/cell work
what is EMF
“electron motive force”
describes the work done by electron transfers from one chem species to another
what is delta G’0
relates to the number of electrons transferred in a metabolic reaction
what does reducing equivalent and reduction potentials mean
reducing equivalent = single electron equivalent participating in oxidation reduction reactions
reduction potentials = measure of affinity for electrons
are glucose/fats oxidised or reduced in metabolism/catabolism
oxidised
write the half reactions for the following eqn: H2 + F2 —> 2HF
oxidation rxn: H2 —> 2H+ + 2e-
reduction rxn: F2 + 2e- —> 2F-
sum: H2 + F2 –> 2H+ + 2F- = 2HF
what are dehydrogenases
help biological oxidations in catabolism often by removing hydrogen atoms
why is oxygen the terminal electron acceptor
it is the most electronegative
what do hydrogenases do
involve addition of hydrogen atoms in biological reductions in anabolism
what are the main carriers in metabolism
NAD, NADP, FAD, FMN
why are electron carriers important
they are designed to be great electron carrier molecules as they harvest and collect electron energy.
they can carry electrons in cells, and are able to undergo reversible oxi/redu in order to transfer electrons to biomolecules
*usually these are coenzymes
what are NAD and NADP
NAD: nicotinamide adenine dinucleotide (usually in catabolism)
NADP: nicotinamide adenine dinucleotide phosphate (usually in anabolism)
these are soluble e- carriers that can work with enzymes to carry electrons from one chemical species to another
they both derive from vitamine niacin (B3)
what does a niacin deficiency cause
pellagra in humans - results in dermatitis, diarrhea, dementia
how does NAD and NADP work as e- carriers
they have a nicotinamide ring that can accept a hydride ion (2 electrons and a proton)
does NAD+/NADP+ accept or donate hydride ions
accepts them from a reduced substrate
does NADH/NADPH accept or donate hydride ions
donates hydride ion to an oxidised substrate
write a general reaction for a dehydrogenase enzyme
AH2 + NAD+ —–> A + NADH + H+
Write a note on alcohol dehydrogenase
is found in the lining of the stomach/liver
this enzyme allows alcohol consumption. there are different genetic forms of ADH that influence the ability to metabolise alcohol. the enzyme activity varies between men and women and in different populations
write a note on FAD and FMN
FAD- flavin adenine dinucleotide
FMN - flavin mononucleotide
these e- carriers are derived from riboflavin (vit B2)
these are tightly and oftentimes covalently bound to dehydrogenases called flavoproteins
isoalloxazine ring structure of FAD/FMN accepts 1 or 2 electrons
write equations to describe reduction of FAD/FMN
one electron: FAD + 1H+ = FADH
two electrons: FAD + 2H+ = FADH2
