Free radical and oxygen toxicity

Question 1

What is oxygen toxicity?

Answer 1

the overall toxic effect of oxidative free radical species at cellular level

Question 2

What is a free radical?

Answer 2

any species capable of independent existence that contains one or more unpaired electrons

Question 3

What are reactive oxidative species?

Answer 3

a collective name for oxygen centered radicals and some non-radical derivatives of oxygen

Question 4

What is oxidative stress?

Answer 4

the overall effect of oxygen species in causing tissue injury due to imbalance of free radicals and antioxidants in the body

Question 5

Mention some cellular sources of free radicals

Answer 5

DNA
peroxisomes
cytoplasm
lysosome 
nucleus
mitochondria
ER(potential source)

Question 6

Some other internal sources of free radicals apart from those in the cell

Answer 6

phagocytes
xanthine oxidase
rxns involving iron and other transition metals
exercise
inflammation

Question 7

Some externally generated sources of free radicals are

Answer 7

smoking
radiation
uv light
ozone
certain drugs

Question 8

What happens when free radicals snare an electron from a neighboring molecule?

Answer 8

it makes that molecule a free radical and sets off a chain reaction that wrecks havoc on cells

Question 9

What is the basis of formation for free radicals?

Answer 9

oxygen

Question 10

What can cause the proliferation of free radicals?

Answer 10

a lack of antioxidants in diet

inability of the body to produce them

Question 11

5 examples of free radicals

Answer 11

trichloromethyl CCl3*
superoxide O3*
hydroxyl OH*
thyil RS*
peroxyl RO2*

Question 12

What does reactivity of a free radical depend on?

Answer 12

type of radical

what the radical is presented with

Question 12

What does reactivity of a free radical depend on?

Answer 12

type of radical

what the radical is presented with

Question 13

What happens when 2 free radicals meet?

Answer 13

they can join and form a covalent bond

Question 14

What happens when a free radical reacts with a non-radical?

Answer 14

a free radical chain reaction results and a new radicals are formed

Question 15

What starts lipid peroxidation atherosclerosis?

Answer 15

attacks of free radicals on membranes or lipoproteins

Question 16

Attack of free radicals on DNA cause

Answer 16

mutation

Question 17

What are some mechanisms of free radical toxicity?

Answer 17

lipid peroxidation
DNA damage
protein oxidation

Question 18

What are the 4 processes of lipid peroxidation?

Answer 18

1. Initiation
2. Propagation
3. Accumulation
4. Cell death

Question 19

What usually initiates peroxidation?

Answer 19

attack of any free radical species capable abstracting hydrogen ion from a polysaturated fatty acid side-chain in a membrane creating a carbon radical

Question 20

What propagates lipid peroxidation?

Answer 20

the carbon radical reacts fast with oxygen resulting in a fatty acid chain peroxyl radical which can attack side chains

Question 21

How is DNA destruction caused?

Answer 21

hydroxyl radicals generated close to DNA attack the purine and pyrimidine bases and cause mutations

Question 22

What is an antioxidant?

Answer 22

a molecule stable enough to donate an electron to a rampaging free radical to neutralize it and reduce its capacity to damage