Lecture 7 - Oxidative stress

Question 1

oxidative stress is the imbalance between which two things in the cell? what does the imbalance lead to the accumulation of?

Answer 1

pro and antioxidants, accumulation of oxidative damage

Question 2

define a free radical

Answer 2

any molecular species with one or more unpaired valance electrons which do not contribute to bonding

Question 3

ROS are free radicals with which element at their centre?

Answer 3

oxygen

Question 4

which ROS has a magnesium centre instead of an oxygen centre? it relieves the ECM of superoxide by translating it to what?

Answer 4

SOD, H2O2

Question 5

learn diagram for generation and turnover of ROS and RNS

Answer 5

ON A4

Question 6

out of the 3 ROS, order from highest to lowest reactivity: superoxide, H2O2, hydroxyl radical

Answer 6

highest: hydroxyl radical
high: superoxide
low: H2O2

Question 7

out of the 3 ROS, order from longest to shortest half life: superoxide, H2O2, hydroxyl radical

Answer 7

longest: H2O2 sec-min
middle: superoxide (conc dependent) msec-h
shortest: hydroxyl radical micro sec

Question 8

which ROS out of these 3 is both soluble in water and lipids?: superoxide, H2O2, hydroxyl radical

Answer 8

H2O2

Question 9

name the 3 types of antioxidants which are the cell’s primary defence against ROS

Answer 9

enzymatic, non enzymatic scavengers, metal chelators

Question 10

give 4 examples of enzymatic antioxidants

Answer 10

superoxide dismutases (SODs)
catalase
GPXs
TRXs

Question 11

give 3 examples of lipid soluble non - enzymatic antioxidants

Answer 11

vitamin E, carotenoids, Q10

Question 12

give 3 examples of water soluble non - enzymatic antioxidants

Answer 12

vitamin C, GSH, uric acid

Question 13

name the 4 cellular secondary defences of DNA repair

Answer 13

base excision repair (BER)
nucleotide excision repair (NER)
mismatch repair
DSB repair

Question 14

name 2 cellular secondary defences associated with protein turnover

Answer 14

ubiquitin proteasome system
autophagy in lysosome

Question 15

autophagy of damaged……. occurs in the …… of lysosomes

Answer 15

damaged mitochondria in vesicles

Question 16

true or false, cumulative oxidative stress shortens telomeres?

Answer 16

true

Question 17

in which 3 model organisms is long life associated with high ROS

Answer 17

c elegans, mice, naked mole rats

Question 18

the formation of which types of bonds/crosslinks in ROS is associated with damage?

Answer 18

disulphide

Question 19

hormesis is rejuvenation via a ……phasic response to exposure to …… amounts of a substance

Answer 19

biphasic, increasing

Question 20

true or false, ROS production can be both damaging and signalling?

Answer 20

true

Question 21

is oxidative stress a direct cause of ageing?

Answer 21

no it is part of the complex network of changes which cause ageing