08 Protien Digestion Flashcards
(42 cards)
What are proteins ?
twenty amino acids of which nine are essential and eleven are non-essential.
Four amino acids are considered conditionally essential
What is conditionally essential amino acids ?
Basicly non essintial, but becomes essential under certen conditions
Four amino acids are considered conditionally essential including arginine, tyrosine, glutamine, and cysteine.
………. Are Amino acids that can not be synthesized in the body
Essintial amino acids
An example for conditionally essential AA ?
An example is phenylketonuria (PKU). Individuals with PKU cannot synthesize tyrosine from phenylalanine, so tyrosine becomes essential in the diet of PKU patients
Because whole proteins are not absorbed they must be digested into …………………………….. prior to absorption.
digested into AAs or di- and tri- peptides
Proteins are more diverse than carbohydrates and thus require a broader spectrum of peptidases and transporters than carbohydrates. True or false?
True
Where does protein digestion begins?
In stomach
Where does protein digestion happen?
Digestion begins in the stomach and is accomplished by both gastric and pancreatic proteases, with the vast majority (70%) accomplished by pancreatic proteases.
So this major 70% happens in small intastin intastine
What happens in gastric digestion phase?
gastric phase of digestion begins with the secretion of pepsinogen from chief cells and HCl from parietal cells. HCl works to denature proteins and more importantly converts inactive pepsinogen to active pepsin
What digests protiens in stomach ?
HCL and pepsin
Pepsin targets which type of protein ?
Pepsin cleaves proteins at large aliphatic or large aromatic side chains
When chyme enters the small intestine after coming of out the stomach, how does pepsin get inactivated?
If it is still active it will auto-digestion the intastine
As the chyme enters the intestine, pepsin is inactivated (at pH >4.5)
Clinical Correlation- The requirement for acidic pH to activate pepsinogen has implications for using proton pump inhibitors.
What happens in the intastinal phase ?
The intestinal phase is responsible for the bulk of proteolysis and is mainly due to the actions of the pancreatic proteases.
There are two main forms of pancreatic enzymes
endopeptidase – cleaves internal bonds exopeptidase – cleaves external bonds
What pancreatic enzymes target terminal parts?
Exopeptidase targets external parts / terminal parts examples → aminopeptidase and carboxypeptidase
What pancreatic enzymes target inner parts?
Endopeptidase including trypsin, chymotrypsin and elastase.
Exopeptidases include ……….
Exopeptidases include carboxypeptidase A and B and aminopeptidase. Carboxypeptidase A acts on neutral AA and carboxypeptidase B acts on basic AA
Where are pancreatic enzymes stored ?
Pancreatic enzymes are stored in acinar cells as pro-enzymes (zymogens) and are activated by trypsin, which itself is self-activated (and by enterokinase)
Whaen …………… is activated to Trypsin, it causes activates of all the other enzymes ( Chymotrypsinogen > Chymotrypsin.
Procarboxypeptidase A and B > Carboxypeptidase A and B.
Proelastase > Elastase)
Trypsin
What inhibits trypsin ?
Trypsin inhibitors are small proteins or peptides that are present in plants (Soybeans, peas, beans, wheat), organs (pancreas), and fluids (colostrum). They decrease the activity of trypsin and therefore all proteases. The trypsin inhibitors are inactivated by heat.
How to deactivate/inactivate trypsin inhibitors
The trypsin inhibitors are inactivated by heat.
Additional protein digestion occurs at the brush border, increasing the amount of protein suited for intracellular transport. True or false
True
Brush border peptidases produce …………………..
produce single amino acids and smaller peptides (di and tri-peptides) from tetrapeptides and larger peptides.
What breaks down dipeptides and tripeptides into single amino acids inside the cell?
Intracellular cytoplasmic peptidases
