An Phys Chem Lect 2

Front 1

Free Radical

Back 1

chemical compound with odd number of electrons

Front 2

Characteristics of free radical

Back 2

1. Extremely unstable and reactive
2. Consequence tendency
3. Free radicals have low chemical specificity
4. Results in chain reactions

Front 3

Reactive oxygen species (ROS or ROI)

Back 3

- Non-ion, non-radical (H2O2)
- Ions (OCl-)
-Ion-radicals (O2-, ROO-, OH-)

Front 4

Enzymatice Formation of Free Radicals

Back 4

-byproduct of cellular respiration and metabolism
-phagocytic enzyme
- prostaglandin synthesis
- Cytochrome P450 (Liver)
- Cells of the thyroid gland generate hydrogen peroxide

Front 5

Cytochrome P450 system

Back 5

-in liver for drug and toxin removal

NADPH + H+ + O2 + RH  NADP+ + H2O + R-OH

Front 6

Externally generated free radicals

Back 6

- Exposure to abnormal environments such as hypoxia or hyperoxia
- Drugs, pesticides, anesthetics and industrial solvents
- Interaction of ionizing radiation
- Cigarette smoke, environmental pollutants, ultraviolet light & ozone

Front 7

Physiological Functions of ROS and RNS

Back 7

- T4 Synthesis
- Bactericidal enzymes
- Blood O2 levels
- ventilation
- erythropoietin production
- Signal transduction
- NO ion-> vasorelaxant
- cellular maturation

Front 8

Oxidative Stress

Back 8

- Highly toxic to cells
- Cell membrane damage
- LIPID PERIOXIDATION
- Direct attack of membrane proteins

Front 9

LIPID PERIOXIDATION

Back 9

- ROS attacks unsaturated fatty acids in membrane phospholipids.
-Results in increase in membrane rigidity

Front 10

ROS attack of membrane proteins

Back 10

- induces lipid-lipid, lipid-protein and protein-protein cross-linking, causing:
a.Decreased activity of membrane-bound enzymes (e.g. sodium pumps)
b. Altered activity of membrane receptors
c. Altered permeability

Front 11

Diseases associtated with Oxidative Stress

Back 11

- Diabetes mellitus
- Chronic inflammation
- Cancer
- Arthrosclerosis
-Cardiovascular accidents

Front 12

diabetes mellitus

Back 12

- Mitochondrial oxidative stress
- affects insulin R’-> insulin resistance

Front 13

Highly significant correlation between consumption of _____and ____ and death rate from certain cancers

Back 13

fats & oils

Front 14

Atherosclerosis

Back 14

- condition in which an artery wall thickens as the result of a build-up of fatty materials such as cholesterol
- Diet-derived lipids in the arterial wall and serum produce peroxides and other substances ->cell injury and produce changes in the arterial walls

Front 15

Enzymatic antioxidants

Back 15

- Superoxide dismutase (SOD)
- H2O2 catalase
- Glutathione reductase and peroxidase
- Uric acid, bilirubin and ubiquinol

Front 16

Dismutation

Back 16

A reaction or reactions involving two identical molecules in which one gains what the other loses
- Ie: an oxidation/reduction
- speeds up a spontaneous reaction to reduce radical transition time

Front 17

Inducible enzymes

Back 17

- An enzyme that is normally present in minute quantities within a cell, but whose concentration increases dramatically when a substrate compound is added.
- exposure to higher concentrations of O2 results in rapid increases in the SOD concentration

Front 18

H2O2 catalase

Back 18

- Catalase is found in peroxisomes in eucaryotic cells.
- It degrades H2O2 to water and O2, and hence finishes the detoxification reaction started by SOD

Front 19

Glutathione
[peroxidase & reductase]

Back 19

- Oxidized and reduced form of glutathione
- a Tripeptide
- most important intracellular defense against damage by reactive oxygen species
- degrades hydrogen peroxide

Front 20

Glutathione reductase is oxidized to peroxidase by radicals. In a follow-up redox reaction, the reductase is regenerated. What molecule is the electron acceptor in the second reaction?

Back 20

- NADPH

Front 21

Antioxidant

Back 21

- a reducing agent
– a molecule stable enough to donate an electron to neutralize free radical, thus reducing its capacity to damage

Front 22

Non-enzymatic antioxidants that protect cells from oxidant stress

Back 22

- Vit. E + Selenium
- Vit. C
- Vit A

Front 23

Vitamin E (alpha-tocopherol)

Back 23

- major lipid-soluble antioxidant
- Breaks the links that ROS have formed between fatty acid side chains in membrane lipids, thus protects membranes from oxidation
-traps peroxy radicals in cellular membranes

Front 24

What 2 molecules act synergistically as an antioxidant

Back 24

Vitamin E and selenium

Front 25

Vitamin C

Back 25

- most abundant water-soluble antioxidant in the body.
- Acts primarily in cellular fluid
- Combats free-radical formation caused by pollution and cigarette smoke
- Helps return vitamin E to its active form

Front 26

Phagocytosis

Back 26

- engulfment of microorganisms, foreign particles, and cellular debris by WBC such as neutrophils and monocytes (macrophages)
- an important body defense mechanism

Front 27

Chemotaxis

Back 27

need answer

Front 28

Diapedisis

Back 28

the outward passage of blood cells through intact vessel walls

Front 29

O2 independent system

Back 29

method of bacteriocide using pH changes inside the phagocytes and lysosomal enzymes

Front 30

O2 dependent system

Back 30

method of bacteriocide using the generation of free radicals

Front 31

Respiratory Burst

Back 31

– rapid consumption of O2 that accompanies the formation of O2.-.
- Catalyzed by NADPH oxidase (located in the WBC cell membrane.)

Front 32

Deficiency in NADPH oxidase leads to what problem.

Back 32

- recurrent infections
- chronic granulomatous disease