Nitrogen fixation lecture Flashcards
Why do we need nitrogen?
It is a building block for AA’s, which are then used to synthesise proteins
Can we obtain nitrogen from the air?
No. Atmospheric nitrogen cannot be broken down by the body. Needs to be fixed into form we can use. Usually done by bacteria in soil or roots of plants. Fixed to ammonia
What is required to fix nitrogen?
Enzyme complex. 8 electrons. 16 ATP. This fixes/break downs 1 nitrogen, get 2 ammonia.
Is hydrogen used to break down nitrogen?
Yes
What do most dinitrogenases use to reduce nitrogen?
8 electrons
Do transamination reactions require pyridoxal-5’-phosphate and an amino transferase?
Yes. Both
Are transamination reactions reversible?
yes
What is a keto-acid converted to in transamination?
an AA
What are essential AA’s?
Cannot be formed by mammals, need to obtain from diet.
Can excess dietary AA’s be converted to other metabolites?
yes
Which 2 AA’s are responsible for transport of nitrogen from muscle to liver?
Alanine and glutamate
What does the urea cycle do?
Converts ammonia into a less toxic substance (urea)
What is arginine hydrolysed to in the urea cycle?
Urea and ornithine
During catabolism of carbon skeletons of AA’s, What are ketogenic AA’s converted to?
acetyl-CoA
During catabolism of carbon skeletons of AA’s, what can glucogenic AA’s be converted to during starvation?
Glucose
