Exam 3 – Dr. Sullivant Protein Metabolism Flashcards
What methods of protein metabolism occur in the liver?
Breakdown of amino acids
Formation of urea for removal of ammonia from body fluids
Formation of virtually all plasma proteins
Manipulation of amino acids and synthesis of other stuff from amino acids
What is the breakdown of amino acids in the liver for?
Energy
Conversion to CHO and fats
What is ammonia formed by in the liver?
Deamination
Gut bacteria
What is protein used for?
Energy Gluconeogenesis/ketogenesis Enzymes Transport proteins Structural support Muscles
What is one of the major transport proteins?
Albumin
What are amino acids?
Building block of proteins
What do all amino acids have?
An acidic group and a nitrogen atom attached
How many AA are in the body?
Approximately 20
How are AA arranged?
Into chains via peptide linkages to form proteins
What is the average protein size?
400 AA
How long does protein digestion in the GI tract take?
About 2-3 hours
What is the final breakdown product of protein digestion?
Amino acids
Once in the blood stream, how quickly are amino acids absorbed by cells?
5-10 minutes
What does a quick absorption of amino acids do?
Prevents any build-up of circulating AA
What do amino acids require to diffuse through a cell wall?
Facilitated diffusion or active transport
What happens to amino acids that make it to the kidneys?
They are mostly resorbed by the proximal convoluted tubule
What is the fate of amino acids in the cell?
Turnover is rapid
They are quickly used up to make proteins
What can happen to most intracellular proteins?
They can be degraded rapidly to yield AA
What does the body prefer as its main energy sources?
CHO and fats
What is used as energy sources after a couple of weeks of starvation?
Amino acids
Where is growth hormone from?
Pituitary gland
Where is insulin from?
Pancreas
What do growth hormone and insulin do?
Increase formation of tissue protein
What do glucocorticoids from adrenal gland do?
Increase plasma concentration of AA
Increase protein production in the liver
How do glucocorticoids increase plasma concentration of AA?
By breaking down extrahepatic proteins to provide AA for energy
What does testosterone do?
Increases protein deposition in tissues
What does thyroxine do?
Increase the rate of protein synthesis or increase the rate of protein degradation for energy
What are the protein functions?
Plasma proteins
Essential and non-essential amino acids
Source of energy
What are the different plasma proteins?
Albumin
Globulins
Fibrinogen
What does albumin do?
Provides oncotic pressure
Transporter
Involved in healing
What do globulins do?
Immunity and enzyme functions
What does fibrinogen do?
Polymerizes into fibrin to form blood clots
What are essential amino acids?
Cannot be synthesized and therefore must be in the diet
What are non-essential amino acids?
Synthesized by the body from keto-acids, which are precursors to the AA
What is the process of amino acids being synthesized from kets-acids called?
Transamination
What are aminotransferase enzymers derived from?
Vitamin B6, pyridoxine
What are the essential amino acids for both dogs and cats?
Arginine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine
What is the essential amino acid that only cats need?
Taurine
What does the degradation of protein occur in the liver by?
Deamination
What happens to an amino group when proteins are used for energy?
It is transferred to another molecule or released in form of ammonia
What are deaminated protein end-products used to do?
Synthesize glucose and fats
What can protein breakdown products be used for?
Gluconeogenesis or ketogenesis
Where does the urea cycle occur?
Liver
What does the urea cycle do?
Controls ammonia levels in the body
Prevent hepatic encephalopathy
What is the process of the urea cycle?
Ammonia from deamination becomes urea and then it goes through renal excretion
