Session 5 (2) - Byproducts of metabolism Flashcards Preview

Semester 1 - Metabolism > Session 5 (2) - Byproducts of metabolism > Flashcards

Flashcards in Session 5 (2) - Byproducts of metabolism Deck (22):
1

How are ROS's formed?

Some electrons leaked from electron transport chain (1+3), prematurely reducing oxygen to super oxide radicals (O(x2)-. Oxygen molecule with unpaired electron.

2

What do ROS cause damage to?

DNA, protein and membranes

3

What enzyme catalyses formation of hydrogen peroxide and oxygen from ROS?

Superoxide Dismutase (SOD)

4

What is the issue with hydrogen peroxide production?

It is in itself a Reactive Oxygen Species

5

What enzyme is used to remove H2O2

Enzyme catalase therefore rapidly breaks it down into molecular oxygen and water.

6

What do you add to H2O2 to form hydroxyl radicals? Give equation.

H2O2 + Fe2+ --> OH- (hydroxyl radicals)

7

What is the issue with hydroxl radicals?

Highly reactive, damage cell membranes but cannot be elimated by enzymatic reaction.

8

How are hydroxyl radicals removed?

NADPH provides H+ and converts to water.

9

How are ROS useful in the body? What enzyme is used in reaction? What happens to cell and surrounding bacterial cells? What system is this used in?

Neutrophils and monocytes can rapidly produce a release of ROS, known as an oxidative burst. NADPH Oxidase is used.
Electrons from NAPH transfer across membrane.
Cell and surround bacterial cells destroyed.
Immune system.

10

How can oxidizing agents be produced in the body via artificial means?

Primaquine (anti-malarial) and Paraquat (banned herbicide)
Ionising radiation

11

What is produced from Arginine in the body? What enzyme is used, and what is it involved in?

NO, produced from arginine via Nitric Oxide synthase.
NO combines with O2 to produce peroxynitrite, which is involved cell damage.

12

Name five cell defences against ROS other than SOD and catalase

NADPH, glutathione, anti-oxidant vitamins, flavenoids and minerals

13

What is NADPH, and where is it produced?

reducing agent that is mostly produced by the pentose phosphate pathway.

14

What is glutathione?

a tripeptide that is usually abundant in cells and acts as an important antioxidant. The thiol (-SH) group in cysteine can donate its H and therefore act as a reducing agent.

15

How is oxidised glutathione converted bact to reduced form?
What enzmes catalyse the reactions?

NADPH
glutathione peroxidise and glutathione reductase

16

Name three anti-oxidant vitamins

Vitamin C, Vitamin E, Vitamin A

17

How is diabetes mellitus related to ROS?

(Type 1) B cell destruction by ROS

18

How is alzheimers disease caused by ROS

Protein damage and misfolding by ROS

19

How are the negative effects of cardiovascular disease compounded by ROS?

Reperfusion causes huge amounts of ROS to be produced. ROS switched on by cells when dying, encouraged by reoxygenation.

20

Outline cellular defences against following
O2-
H2O2
OH-
NO-
ONOO-

SOD
Catalase
NADPH
Glutathione
Other antioxidants

21

What is oxidative stress?

When ROS levels are excessive, or not enough anti-oxidants.

22

What clinical condition is NADPH oxidase complicit in?

Atherosclerosis