Lab 5 Flashcards
(25 cards)
major source or nitrogen for most higher plants
nitrate
nitrate is the most important nutrient that – plant growth
limits
influx of nitrate occurs – an electrochemical potential gradient
against
reduction of nitrate to nitrite is catalyzed in leaf by –
nitrate reductase (NR)
NR transfers – from NADH to nitrate via three redox centers
2 electrons
three redox centers
FAD, heme and cofactor with molybdate and pterin
reduction of nitrite to ammonium is performed by a – enzyme nitrite reductase (NiR)
chloroplast
majority of enzyme activity is induced by –
nitrate
rise in NR is due –
de novo
– is also required for synthesis of nitrate-induced NR and the constitutive NR
light
in – leaf segments are incubated in a solution containing nitrate, 2-propanol, and phosphate buffer
colorimetric in vivo assay for NR
nitrite is converted to an – by reaction with SA and NEED
azodye
how to measure nitrite
inhibit nitrite’s reduction to ammonia
under – conditions, reduction of nitrite is inhibited
anaerobic
add – to make tissue anaerobic
2-propanol
2-propanol also increase – thus facilitating the energy of nitrate and release of nitrite
cell permeability
due to the rxn’s sensitivity to molecular oxygen, all operations should be conducted in – to reduce photosynthesis
dim room light
handle hot test tubes with –
tongs
surface sterilize seeds by soaking them in a 10% solution of – for 10 min
commercial bleach
water with mineral solution minus –
nitrate
growth chamber
14 h light and 10 h dark
water in tube #1
5ml
experiment 1
NR induction time
experiment 2
light requirement for constitutive and induced NR
