lecture 10 Flashcards
(39 cards)
what is oxidation
gain in oxygen, loss of hydrogen, loss of electrons
what is reduction
loss of oxygen, gain of hydrogen, gain of electrons
what is an oxidant
oxidizes another chemical by taking electrons, hydrogen, or by adding oxygen
what is a reductant
reduces another chemical by supplying electrons, hydrogen, or by removing oxygen
what are free radicals
free radicals attack and snatch energy from other cells to satisfy themselves
what are the most important pro-oxidants
ROS and RNS
what are some examples of free radicals
they have one or more unpaired electrons, so carbon center, nitrogen centered, oxygen centered, and sulfur centered
how are non radicals characterized?
has strong oxidizing potential or help to form strong oxidants
how long can some pro oxidants live for?
- hydrogen peroxide can live for minutes
- nitric oxide can live for seconds
- singlet oxygen can live for microseconds
- hydroxyl radical can live for nanoseconds
what are some endogenous sources of ROS
- endoplasmic reticulum
- cytoplasm
- mitochondria
- lysosomes
- peroxisomes
- plasma membrane
what does 90% of ROS from a cell come from?
the mitochondria, ETC contains several redox centers that may leak e- to oxygen
what is the result of oxidative damage to lipids from mitochondrial oxidative stress?
membrane peroxidation and decreased membrane fluidity
what is the result of oxidative damage to DNA from mitochondrial oxidative stress?
mutations and deletions
what is the result of oxidative damage to proteins as result of mitochondrial oxidative stress
oxidation of sulfhydryl groups, reactions with aldehydes and protein aggregation
where is NADPH oxidase mainly present in?
mainly in neutrophils but still present in many other cell types
why does NADPH oxidase make ROS on purpose?
because absence of ROS will result in chronic granulomatous disease
how does lysosomes generate ROS and RNS
through myeloperoxidase
how does peroxysomes generate ROS and RNS
through enzymes
what does lipid peroxidation lead to?
- structural changes in membranes
- adducts/crosslinkes with non lipids
- direct toxicity of lipid peroxidation products
- dna damage and mutagenesis
what are the structural changes in membranes that come from lipid peroxidation
- alter fluidity and channels
- alter membrane bound signaling proteins
- increases ion permeability
- disruptions in membrane dependent signaling
what are the consequences of protein oxidation?
- oxidation of catalytic sites on enzymes
- formation of mixed sulfide bonds
- increased susceptibility to proteolysis
what are the consequences of DNA oxidation?
- dna adducts/AP sites/strand breaks results in mutations or initiations of cancer
- overstimulation of dna repair
what does oxidation of catalytic sites on enzymes result in?
causes loss of function/abnormal function
what exactly happens in overstimulation of dna repair?
- can deplete energy reserves of cell (PARP)
- induction of error prone polymerases
- activation of checkpoint related signaling pathways
