11 Flashcards
What is nitrogen balance
anything we consume in excess of our needs is broken down and excreted
(because our bodies can’t store protein)
Where does nitrogen come from in our body
amino acids (contain CHON)
- only source from our diets
When are the CHON of aa metabolized
when there is excess protein or not enough carbs
In what form is nitrogen after being broken down as amino acids
Why is it a problem
ammonia (NH3)
has a pKa of 9.3 (but blood pH is 7.35-7.45)
when forming ammonium –> toxic for our bodies (must be removed as urea)
How to take nitrogen off of amino acids
transamination –> transfer nitrogen between aa
deamination –> remove amino group (generates free ammonium)
- generates energy
What is transanimation
transfers nitrogen from one molecule to another
allows tissues to use the leftover carbon skeleton for something eelse (energy metabolism)
allows cells to produce non-essential aa
a-ketoglutarate/glutamate is the most common acceptor of amino group
PLP pyridoxal phosphate = coenzyme required for these reactions and is the active form of vit B
What is deanimation
removes a nitrogen from a molecule but generates nitrogenous waste (NH3/NH4+)
cells can use the leftover carbon skeleton for something else
NH3/NH4+ is toxic and must be removed
- reversible reaction
- too much NH4+ = reaction will reverse, using up all the a-ketoglutarate in the mitochondria
(a-keto depleted – needed for TCA cycle, glutamate builds up, glutamate and glutamine build up in the cell – shift in osmotic balance causing cells to swell)
How is ammonium transported through the body
as urea
as aa (glutamine and alamine) – non toxic polar molecules
Why can alanine travel through the blood
non toxic and polar
- can freely travel in the blood
What does alanine do with ammonium
tissues release excess nitrogen as alanine into the blood
circulates to liver
liver alanine undergoes transanimation – converts it to pyruvate and transfers the nitrogen to glutamate
What happens to the glutamate made aar of transanimation
glutamate can be deanimated to release the nitrogen as NH4+
- can be packaged into urea
How does glutamate transport nitrogen
glutamate (in muscle) undergoes transanimation and transforms into glutamine
glutamine goes to liver and kidneys to be deanimated and secrete ammonium
how is nitrogen excreted
liver packages into urea and it goes to blood where it is excreted
What does high levels of ammonium mean
problem with the liver
(only site of urea pakcaging)
what does high levels of urea mean
problem with the kidneys
(only site of urea excretion)
What is the urea cycle
multistep cycle that takes place inthe livr
enzymatic process where packages and move extra nitrogen into urea
- relies on transanimation and aa metabolism
Describe the urea cycle , what does it start with
mitochondria
CO2 from TCA cycle and water –> forms bicarbonate
joins with amonium to form phospahte
transanimation
forms amino acid
becomes another amino acid
and another amino acid
eventually becomes urea
What are reactive oxygen species
oxygen is biradical (likes ot form two bonds for full valence electrons –> in seperate areas)
therefore oxygen is not very reactive
However, when oxygen gets another electron, it becomes very reactive
*can be a problem in the body as it pulls things away
What are transition states
molecules with extra electrons (radicals) – but trapped in enzymes
When are free radicals dangerous
when not in enzyme
Will steal electrons from other molecules and causes other molecules to be come reactive (chain reaction of damage)
What are sources of reactive oxygen species
Electron transport chain
- transfers electrons between carriers and complexes until it eventually reaches oxygen
Ionizing radiaiton
- water or skin
drug metabolism
- cytochrome P450 enzymes metabolize drugs (including alcohol) and chemical toxins
- oxidize the drugs and other substance sot make them more solubel for excretion
- leaky enyzmes where radicals can escape and become free radicals
Inflammation
- ROS are used to destroy invading pathogesn or clean up dad cells in damaged tissues
- activated neutrophils “respiratory burst” consumes oxygen to create reactive substnaces that will kill phagocytosed bacteria
- release of free radicals in areas of inflmmation can lead to damage in surrounding tissues
What are the species of free radicals
Reactive oxygen species
Nitrogen oxygen species
What are reactive ntirogen-oxygen species
What causes
free radicals and can cause damage
sources:
- nitrates from diets or bacteria produced from intestine
- smoking/pollution/smog
What happens in ROS damage
free radical “pulls” an electron from a molecule, turning that molecule into a radical, which in turns pulls another electron from anoter molecule, turning that into a free radical
