Protein Metabolism Flashcards
Where are cellular proteins broken down?
In the cystol and then peptide bonds are broken and the free amino acids are used in new proteins
What are the function of proteins?
Protection (antibodies)
Regulation (enzymes)
Structure (collagen)
Muscle contraction (actin and myosin)
Transportation(hemoglobin)
What are the kinds of amino acids?
Essential and non Essential
What are essential amino acids?
Must be obtained in diet
What are non essential amino acids?
Can be synthesized by the body
What is done with free amino acids?
They can be converted to glucose and fat or directly used as fuel
What are the 3 conversion processes of amino acids?
Deamination (removal of an amino group)
Amination(addition of amino group)
Transaminiation(transfer of amino group from one molecule to the other)
What does protein synthesis involve?
Amination and transamination
How does transamination work?
It is where a keto acid is transformed into a non essential amino acid by replacing its oxygen with an amino group and it transfers the amino group from an amino acid to a keto acid which becomes the new amino acid and allows cells to make non essential amino acids for protein synthesis
What happens when other energy sources are inadequate?
The mitochondria generates atp by breaking down amino acids in tca cycle
What does protein catabolism involve?
Transamination and deamination
How does protein catabolism take place?
Where protease breaks down peptide bonds between amino acids to for peptides or free amino acids
What is the fate of amino acids absorbed by cells?
Used to make proteins
Used as a source of energy
How is the amino group removed?
Oxidative deamination and transamination
What does the removal of the amino group require?
Co enzyme derivative of B6 (pyridoxine)
What does catabolism do?
Produces co enzymes for ETC to provide ATP through Oxidative phoshorylation
What happens when glucose and lipid reserves are inadequate?
The liver cells will break down internal proteins and absorb additional amino acids from blood
What happens when amino acids are deaminated?
Carbon chains broken down to provide ATP
What happens when amino acids are used as fuel?
They must be deaminated and a keto acid remains which may be converted to pyruvic acid,acetyl Co A or none of the acids of the citric acid cycle during a shortage of amino acids citric acid cycle intermediates can be aminated and converted to amino acids
What happens in gluoconeogenesis?
Keto acids are used to synthesize glucose
Where does deamination take place?
In the liver cells and forms the ammonia molecule which is converted to urea and excreted in urine and a keto acid molecule which is oxidized or converted to glucose or fat
How does the urea cycle work?
Two metabolic waste products ammonium ions and Co2 and produces urea which is excreted in urine
What happens after the removal of amino groups?
The carbon skeleton of amino acids is converted to intermediates of TCA or their precursors
What is the fate of keto acid?
Some converted to pyruvic acid transformed to acetyl CoA to enter Krebs cycle
Some converted to acetyl CoA to enter Krebs Cycle
Others directly converted to intermediate molecules in the Krebs Cycle
Some converted to ketone bodies and transported to cells where they can be converted to glucose via gluconeogenesis
TAGs via lipogenesis
What can ketone bodies be tranaminated to?
Non essential amino acids
What are the classification of amino acids ?
Glycogen or Ketogenic
What are glucogenic amino acids?
They produce pyruvate or TCA cycle intermediates such as alpha ketogluterate or oxaloacetate
What are Lysine and Leucine classified as ?
Ketogenic
What are ketogenic amino acids?
Produces only acetyl CoA or acetoacetylCoA
Why is protein catabolism an impractical source of quick energy?
Proteins are more difficult to break apart than carbs and lipids
A by product is ammonium which is toxic to cells
Extensive protein catabolism threatens homeostasis at cellular and system levels
What is the importance of alanine and glutamine?
They serve as substrates for endogenous glucose production in the liver
What is the Alanine cycle?
Where Alanine is generated from pyruvate in exercise muscle and the pyruvate is converted to glucose in the liver
