Digestion and Absorption of Proteins Flashcards
Three things that make up amino acids?
Amine group
Carboxylic acid group
Side chains - R
What is the mnemonic to remember essential amino acids?
PVT TIM HALL
Which essential AA is only essential in children?
Arginine
What are the essential AA?
Phenylalanine
Valine Tryptophan
Threonine
Isoleucine
Methionine
Histidine
Arginine
Lysine
Leucine
What are the acidic AA?
Glutamine
Glutamate
Aspartate
Asparagine
What are the basic AA?
Lys
His
First step in digestion?
Mechanical (chewing)
What is the role of HCl?
Denaturation of proteins
What protease hydrolyzes proteins in the stomach?
Pepsin
What releases proteases?
Pancreas
SI
What do G cells do?
Release gastrin in the stomach
What does gastrin do?
Stimulates the release of HCl from parietal cells
What deactivates pepsin?
Alkaline duodenum
How is pepsinogen activated?
It is partially activated by HCl and then auto-cleaves peptides off to become fully activated
What is the activation process of proteases released from the pancreas?
Enterokinase activates trypsinogen to trypsin
Trypsin activates chymotrypsinogen to chymotrypsin
Trypsin activates procarboxypeptidase to carboxypeptidase
Where do endopeptidases cleave?
At internal amide bonds
Where do ectopeptidases cleave?
At terminal amino acids of peptides
Where are carboxypeptidases cleave?
At C-terminal amino acids of peptides
Where do carboxypeptidases A and B cleave respectively?
A: neutral AA
B: basic AA
How are AA absorbed?
Active transport (mono, di, and tri but di and tri are broken down by enzymes in membrane)
How do AA move out of the villus epithelium?
Facilitated diffusion
What channel transports peptides into the villus?
PEPT1 (peptide transporter 1) along with an H+
What supplies the H+ for peptide absorption?
NHE sodium/hydrogen exchanger
