BIOC Lecture 6: Nitrogen I Flashcards
Can we store nitrogen in our bodies?
No, if there is excess it has to be removed
What is the main compound our body uses to get rid of nitrogen?
Urea
Where are AA’s obtained from?
Dietary protein, body protein degradation or newly synthesised
What are AA’s used for?
to synthesise proteins and other Nitrogen containing compounds or generate energy
What happens to excess AA’s?
Rapidly degraded
What happens to excess Nitrogen?
Needs to be excreted
What are some ways AA’s are used?
- Synthesised into glucose, used to make fatty acids and therefore ketone bodies.
- Made into body proteins or non-protein N containing compounds
How do AA’s turn into urea?
Enzymes remove the ammonia group and this ammonia will end up as urea
What are examples of non-protein nitrogen-containing compounds?
- Pyrimidines
- Purines (uric acid)
- Creatine (creatinine)
- Haem (bilirubin)
What is an important enzyme in protein digestion?
Pepsin
Protein digestion summary
Stomach: HCl and Pepsin
SI: Pancreatic enzymes
What are the non-essential AA’s?
- Alanine
- Aspartic acid
- Asparagine
- Arginine
- Glutamic Acid
- Glutamine
- Proline
- Serine
- Glycine
- Cysteine
- Tyrosine
What are the essential AA’s?
- Phenylalanine
- Valine
- Threonine
- Tryptophan
- Isoleucine
- Methionine
- Histidine
- Arginine
- Leucine
- Lysine
What AA is on both sides?
Arginine
Why is Arginine both essential and non-essential?
Under certain physical conditions arginine is required in high amounts and the body can not synthesize enough arginine to keep up with the bodies needs (E.g. when you are young and growing at a high rate)
AA’s are precursors of what?
Important regulators of metabolism
What is tyrosine a precursor for?
- Dopamine
- Adrenaline and noradrenaline
- Thyroid hormones
What is tryptophan a precursor for?
- Serotonin
- Melatonin
What is histamine a precursor for?
Arginine -> Nitric Oxide (allergic reactions)
Where does creatine come from?
Derived in skeletal muscles by spontaneous cyclisation of creatine and creatine phosphate
What are urine creatinine levels proportional to?
Muscle mass - high = higher muscle mass
What are blood creatinine levels a measure of?
Kidney function - High = bad function
Where is creatine in its phosphorylated form made?
Muscle
Creatine acts as a fast supplier of what?
Phosphate to make ATP
Creatine phosphate in the muscle is involved in what?
Energy metabolism
What is creatine phosphate made from?
Creatine kinase
What is creatine kinase?
The enzyme that creates creatine phosphate
What does creatine kinase in the blood indicate?
Muscle damage
What are aminotransferases?
a group of enzymes that play a crucial role in the metabolism of amino acids
What can carbon skeletons be?
Glucogenic or ketogenic
What decides carbon skeletons class?
Whether they can be utilized to make glucose or ketone bodies
What is a glucogenic amino acid?
Any amino acid that can be broken down into pyruvate or can be used in the TCA cycle (be made into a carbon backbone)
What is a ketogenic amino acid?
If your amino acid can be directly broken down into acetyl-coA
What are the nitrogen containing products excreted in urine?
- Urea
- Ammonia
- Uric acid
- Creatinine
How many forms does ammonia come in?
2
What form is ammonia largely found in?
Protonated form - Ammonium Ion (NH4+)
What is the other form of ammonia?
Ammonia NH3
What do elevated blood uric levels indicate?
Gout
What is nitrogen balance?
A measure of N input versus N output
What is an individuals nitrogen balance dependent on?
- Dietary nitrogen intake
- Physiological state
Where does nitrogen intake come from?
Dietary amino acids (nucleotides etc)
Where does nitrogen excretion come from?
- Urine, faeces, hair, skin loss and perspiration
- Obligatory loss
What are possible causes of positive nitrogen balance?
- Childhood and adolescent growth
- Pregnancy
- Body building
What are possible causes of negative nitrogen balance?
- Injury
- Surgery
- Infection
- Starvation
