Lecture 7 - Oxidative stress Flashcards
oxidative stress is the imbalance between which two things in the cell? what does the imbalance lead to the accumulation of?
pro and antioxidants, accumulation of oxidative damage
define a free radical
any molecular species with one or more unpaired valance electrons which do not contribute to bonding
ROS are free radicals with which element at their centre?
oxygen
which ROS has a magnesium centre instead of an oxygen centre? it relieves the ECM of superoxide by translating it to what?
SOD, H2O2
learn diagram for generation and turnover of ROS and RNS
ON A4
out of the 3 ROS, order from highest to lowest reactivity: superoxide, H2O2, hydroxyl radical
highest: hydroxyl radical
high: superoxide
low: H2O2
out of the 3 ROS, order from longest to shortest half life: superoxide, H2O2, hydroxyl radical
longest: H2O2 sec-min
middle: superoxide (conc dependent) msec-h
shortest: hydroxyl radical micro sec
which ROS out of these 3 is both soluble in water and lipids?: superoxide, H2O2, hydroxyl radical
H2O2
name the 3 types of antioxidants which are the cell’s primary defence against ROS
enzymatic, non enzymatic scavengers, metal chelators
give 4 examples of enzymatic antioxidants
superoxide dismutases (SODs)
catalase
GPXs
TRXs
give 3 examples of lipid soluble non - enzymatic antioxidants
vitamin E, carotenoids, Q10
give 3 examples of water soluble non - enzymatic antioxidants
vitamin C, GSH, uric acid
name the 4 cellular secondary defences of DNA repair
base excision repair (BER)
nucleotide excision repair (NER)
mismatch repair
DSB repair
name 2 cellular secondary defences associated with protein turnover
ubiquitin proteasome system
autophagy in lysosome
autophagy of damaged……. occurs in the …… of lysosomes
damaged mitochondria in vesicles
true or false, cumulative oxidative stress shortens telomeres?
true
in which 3 model organisms is long life associated with high ROS
c elegans, mice, naked mole rats
the formation of which types of bonds/crosslinks in ROS is associated with damage?
disulphide
hormesis is rejuvenation via a ……phasic response to exposure to …… amounts of a substance
biphasic, increasing
true or false, ROS production can be both damaging and signalling?
true
is oxidative stress a direct cause of ageing?
no it is part of the complex network of changes which cause ageing
