BSI Lecture 39-40 Free Radicals and Antioxidants

Question 1

What is another name for free radicals?

Answer 1

Reactive Oxygen Species (ROS) or Reactive Nitrogen Species (RNS)

Question 2

What is a free radical?

Answer 2

An atom or molecule with an unpaired electron.

Question 3

T or F? Free radicals are very reactive with other molecules.

Answer 3

True

Question 4

What is the name of O2 (superscript dot)?

Answer 4

Superoxide

Question 5

What is the name of HO (superscript dot)?

Answer 5

Hydroxyl radical

Question 6

What is the name of NO (superscript dot)?

Answer 6

Nitric Oxide

Question 7

What are the ROS/RNS that are technically not free radical?

Answer 7

Hydrogen peroxide (H2O2) and Peroxynitrite (ONOO-)

Question 8

What do ROS/RNS do?

Answer 8

1. Act as signaling molecules

2. Damage other molecules (i.e proteins, lipids, nucleic acids)

Question 9

How do ROS/RNS react with other molecules?

Answer 9

1. Attach itself to another molecule
2. Act as an oxidizing agent
3. Act as reducing agents

Question 10

Where in the cells are ROS/RNS produced?

Answer 10

Mitochondria

Question 11

T or F? ROS/RNS are produced only in certain cells.

Answer 11

False, they are produced in all cells of the body during aerobic respiration

Question 12

Single electrons “leak” from complexes ___ and ____ of the ETC and attach to O2 to form superoxide.

Answer 12

1; 3

Question 13

What converts superoxide to H2O2?

Answer 13

Superoxide dismutase

Question 14

Hydrogen peroxide is converted into H2O by what enzyme?

Answer 14

Catalase or Glutathione peroxidase (GPX)

Question 15

Increase production of peroxide and/or an increased amount of reduced iron can cause peroxide to be converted into a _____

Answer 15

Hydroxyl radical

Question 16

Nitric oxide and peroxy nitrite are produced in the ____________

Answer 16

Mitochondria

Question 17

What enzyme produces Nitric oxide?

Answer 17

Nitric Oxide Synthase

Question 18

In conditions where there is increased production of superoxide and/or nitric oxide, superoxide and nitric oxide can react to form _________

Answer 18

peroxynitrite

Question 19

What is the ideal pathway for superoxide?

Answer 19

To be converted to H2O2 and then immediately to H2O

Question 20

T or F? White blood cells produce bleach?

Answer 20

True

Question 21

What type of cell produces superoxide, hydrogen peroxide, hydroxyl radical and hypochlorous acid?

Answer 21

White Blood Cells

Question 22

In WBC, what is the function of ROS?

Answer 22

To kill bacteria and viruses

Question 23

T or F? ROS can leak out of WBC and damage surrounding healthy tissue.

Answer 23

True

Question 24

What are the environmental/external sources which can contain or stimulate ROS/RNS production in cells?

Answer 24

1. UV light
2. Ionizing radiation
3. Smoking
4. Air pollution
5. Medications (such as acetaminophen and doxorubicin)

Question 25

How do cells protect against ROS/RNS?

Answer 25

1. Antioxidant 2. Enzymatic antioxidants 3. Non-enzymatic antioxidants

Question 26

_____ converts a reactive species into a less reactive species.

Answer 26

Antioxidant

Question 27

What are the 3 enzymatic antioxidants?

Answer 27

1. Superoxide dismutase 2. Catalase 3. Glutathione peroxidase (GPX)

Question 28

List 7 non-enzymatic antioxidants

Answer 28

1. Glutathione (GSH) 2. Coenzyme Q 3. Alpha-lipoic acid 4. Vitamin C 5. Vitamin E 6. N-acetylcystein (NAC) 7. Flavonoids

Question 29

______ is tripeptide consisting of cysteine, glutamate, and glycine, are synthesized in all cells of the body.

Answer 29

Glutathione (GSH)

Question 30

What are the 2 mechanisms of how GSH can neutralize ROS/RNS/Xenobiotics?

Answer 30

1. Hydrogen peroxide (H2O2) via GPx and 2(GSH) reacting to form glutathione disulfide (GSSG) and 2 H2O 2. GSH can also be conjugated to chemicals to neutralize them.

Question 31

T or F? When H2O2 is neutralized, GSH is being conjugated to it.

Answer 31

False, not conjugation, GSH is donating it's H's.

Question 32

What enzyme creates a conjugation between GSH and a xenobiotic or chemical to create a Glutathione-S-Conjugate?

Answer 32

Glutathione-S-transferase (GST)

Question 33

T or F? Conjugation can also occur without an enzyme catalyzing the reaction.

Answer 33

True

Question 34

What happens to the Glutathione-S-Conjugate after it is formed?

Answer 34

It is filtered out of the body

Question 35

What is used to determine the oxidative stress level in a cell?

Answer 35

The ratio between GSH and GSSH

Question 36

High levels of GSH and low Levels of GSSG indicates that the cell is in _____ level of oxidative stress.

Answer 36

Low

Question 37

What non-enzymatic antioxidants are produced by the body?

Answer 37

Glutathione, Coenzyme Q and Alpha-lipoic acid

Question 38

What are the 3 details of Alpha-lipoic acid?

Answer 38

1. Water and lipid soluble 2. Can protect against free radicals in all parts of cell 3. It can also enhance function of vitamin C and E

Question 39

Which antioxidants are not synthesized by the body?

Answer 39

Vitamin C -Water Soluble Vitamin E - Lipid Soluble (protects agains ROS/RNS damage in membranes) N-Acetylcysteine (NAC) Flavonoids

Question 40

What does N-acetylcysteine (NAC) do?

Answer 40

Acts as a donor of cysteine for GSH biosynthesis | Available as a drug (mucomyst) used to treat acetaminophen overdose

Question 41

The term used to describe an imbalance between ROS/RNS production and antioxidant status.

Answer 41

Oxidative stress

Question 42

T or F? Oxidative stress causes damage to macromolecules?

Answer 42

True

Question 43

DNA damage by ROS/RNS can lead to what?

Answer 43

Increase mutation and deletions in nuclear DNA and mtDNA (mitochondria DNA)

Question 44

Damaged proteins by oxidation or nitration can lead to what?

Answer 44

Altered activity and /or function of the protein

Question 45

Damage lipids by lipid peroxidation can lead to what?

Answer 45

Loss of membrane fluidity or altered cell signaling.

Question 46

What is the ultimate outcome of damage caused by ROS/RNS?

Answer 46

Dysfunctional cells or cell death

Question 47

What are a few diseases that are caused by oxidative stress or plays a role in the progression of the disease?

Answer 47

1. Cancer 2. Cardiovascular disease 3. Alzheimer's disease 4. Parkinson's disease 5. Diabetes 6. Many more