L13 - intro to metabolism Flashcards
define metabolism
totality of all chemical reactions (anabolism / catabolism) in living organisms
general ending for anabolic reactions?
-esis
eg glycogenesis
general ending for catabolic reactions
-lysis
eg glycolysis
why is catabolism usually stepwise instead of all in one go
so energy is released in small useable packages
otherwise large heat loss
allows separate regulation of pathways
what is coupling ?
the ability for molecules to transfer energy released from catabolism to use in anabolic reactions
what is a futile cycle ?
a reaction where an enzyme would speed up forward and backward reaction (due to conc increases etc)
eg A B C
how is a futile cycle avoided
a combination of reversible and irreversible reactions
why is ATP suitable for use in cells
stable at pH 6-9
structural features that can be recognised by proteins
can be hydrolysed by water releasing energy
why is ATP hydrolysis energetically favourable
- relieves repulsion between phos groups
- released phos is resonance stabled
- increases entropy
- high energy bond broken
what ways is ATP used in cells
- directly in cell motility - causes conformational change (eg myosin)
- active transport
- metabolic control (adding Pi) (phosphorylation)
what is the name of the bond between phosphate groups
phosphoanhydride
role of NAD
H atom acceptor
accepts 1 x H and 1 x e
role of NADP
same as NAD but in anabolic reactions so its recognised differently
role of FAD
accepts 2x H
how are metabolic pathways regulated
- changes in amount of enzyme (enzyme synthesis)
- changes in enzyme activity
- allosteric regulation (instant)
- phosphorylation/dephosphorylation (fast)
