Nitrogen

Question 1

What is the main supplier of nitrogen?

Answer 1

Glutamine

Question 2

What does Delta-ALA synthesise? Why is this important?

Answer 2

Heme. Heme forms haemoglobin which is important for oxygen transport

Question 3

What forms Delta-ALA?

Answer 3

Glycine and Glutamine

Question 4

What is the condition associated with inefficient Delta-ALA synthesis?

Answer 4

Porphyria

Question 5

What is nitrogen used for in the body?

Answer 5

Synthesis of Delta-ALA
Biosynthesis of Creatine and Phosphocreatine
Glutathione (GSH) production

Question 6

What is phosphocreatine used for?

Answer 6

Replenish ATP levels in the muscle tissue after exercise, it donates a phosphate which allows the conversion of ADP to ATP

Question 7

What is GSH derived from? HINT: Tripeptide

Answer 7

Glutamate, Cysteine, Glycine

Question 8

What are the two forms of GSH?

Answer 8

Reduced: GSH
Oxidised: GSSG

Question 9

What does GSH do?

Answer 9

Protects us from oxidative stress
Keeps biological molecules in their reduced form
- e.g. haemoglobin: remains in Fe2+ from in order to bind to oxygen, Fe3+ form cannot bind

Question 10

What are the repercussions of oxidative stress?

Answer 10

Aging, disease, apoptosis

Question 11

What can the ratio of GSSG: GSH be used as?

Answer 11

A biomarker for oxidative stress

Question 12

How is GSSG formed?

Answer 12

When a disulphide bridge forms between two oxidised cysteine amino acids, that then become known as cystine molecules

Question 13

What causes oxidative damage?

Answer 13

When oxygen is oxidised to superoxide radical, hydrogen peroxide and hydroxyl free radical- these are highly toxic compounds that can damage cell contents and cause oxidative damage

Question 14

Where does oxidative damage occur?

Answer 14

Lipids (rancidity)
Proteins (alters structure which impacts function)
DNA (mutations)

Question 15

How are we protected against oxidative damage? What mediates this process?

Answer 15

Mediated by GSH

Converting GSSG to GSH, by glutathione reductase, protects us from oxidative stress

Question 16

Which amino acid is a precursor for nitric oxide?

Answer 16

Arginine

Question 17

What is nitric oxide?

Answer 17

A vasodilator

Question 18

Where is nitrogen found?

Answer 18

In nucleic acids and amino acids

Question 19

Does nitrogen require a high or low activation energy?

Answer 19

High- due to the triple bond between the two nitrogen molecules, makes it difficult to break

Question 20

What is an example of a nitrogen fixing microorganism?

Answer 20

Archea

Can live in symbiosis with plants or animals

Question 21

What is the nitrogenous complex?

Answer 21

N2 + 3H2 —–> 2NH3

Question 22

What is the nitrogen cycle?

Answer 22

Where nitrogen fixing bacteria and archea convert atmospheric nitrogen to ammonia, which is then used to make amino acids

Question 23

Does nitrogen fixation by the nitrogenous complex have a high or low energy demand?

Answer 23

High- requires 16 ATP and electrons

Question 24

What is the equation for ammonia assimilation into glutamate?
What enzyme catalyses this reaction?

Answer 24

NH4 + alpha-ketoglutarate + NADPH –>/

Question 25

How is glutamine produced?

Answer 25

By adding another ammonia to glutamate

Question 26

What is the most common free amino acid in the blood and what is its role?

Answer 26

Glutamine

Role: to apply nitrogen to reactions around the body, without the need for ammonia

Question 27

What are the 3 types of amino acid?

Answer 27

Non-essential
Conditionally essential
Essential

Question 28

What is the purpose of protein turnover?

Answer 28

To recycle proteins within the body

Question 29

What is the role of nitrogen flow? What enzyme is this reaction catalysed by?

Answer 29

To prevent free ammonia being present in the blood.

Catalysed by glutamate dehydrogenase

Question 30

What is the role of the alanine cycle?

Answer 30

To prevent the formation of lactic acid