Nutrition - Protein, Lipids - Skildum Flashcards
What converts pepsinogen to pepsin?
H+
What converts trypsinogen to trypsin?
Enteropeptidase
What converts chemotrypsin to chymotrypsin?
Trypsin
What converts proelastase to elastase?
Trypsin
Trypsin converts procarboxylpeptidases to what?
Carboxypeptidases
Trypsin cuts behind what AA?
Arginine and Lysine
In cystic fibrosis, secretion of what is deficient due to blockage of pancreatic duct? What happens to protein and nutrients needed in GI tract?
In patients with cystic fibrosis, secretion of proteases is deficient because of blockage of the pancreatic duct. Malabsorption of protein an other nutrients can result.
Which of these can be transported into gut epithelial cells?
Tripeptides
Dipeptides
Amino acids
All of them.
How are AA transported across intestinal epithelial cells?
Amino acids are transported across intestinal epithelial cells using secondary active transport.
Describe the specificity of AA transporters in GI tract?
Amino acid transporters have overlapping substrate specificity.
Describe the pathophysiology of Hartnup disease. What mutation is involved? What symptoms would you expect?
Inherited mutations in the SLC6A9 transporter (Bo) result in Hartnup disease. This condition results in the symptoms of pellagra because tryptophan is not absorbed or resorbed and can not be used to synthesize niacin.
Pathology: “3 D’s.” Dementia, Dermatitis, and Diarrhea
Describe the pathophysiology of cystinuria. What is the primary presenting symptom?
Inherited mutations in SLC7A9 (B0+) or SLC3A1 (rBAT) cause cystinuria. Patients develop kidney stones.
What is the oxidized form or cysteine?
Cystine
The balance between protein synthesis and degradation is sensitive to what?
The balance between protein synthesis and degradation is sensitive to the metabolic state in the cell.
What is the relationship between mTORC1 and AMPK? Which is upstream in their relationship?
The mTORC1 complex activates protein synthesis and inhibits autophagy.
Activation of AMPK inhibits protein synthesis and promotes autophagy.
AMPK is upstream.
What is the role of PLP and what is seen with deficiency?
transaminations, deaminations, carbon chain transfers
seizures, diarrhea, anemia, EEG abnormalities
What is the role of FH4 and what is seen with deficiency?
One carbon transfers
Magaloblastic anemia
What is the role of BH4 and what is seen with deficiency?
Ring hydroxylations (e.g. Phe –>Tyr)
Seizures, developmental delays
What are two fatty acid derivatives that cause contraction of LES?
Prostaglandins and Thromboxanes
Bile salts do what to fat?
They micellate the fats and increase their surface area.
The hormones secretin and cholecystokinin promote secretion of what?
The hormones secretin and cholecystokinin promote secretion of bile and lipases into the lumen of the gut.
What are the products of pancreatic lipase?
The products of pancreatic lipase are two fatty acids and 2-monoacylglycerol.
What are the products and substrates of cholesterol esterase?
cholesterol ester –> fatty acid + cholesterol
What are the products and substrates of Phospholipase A2?
phospholipid –> fatty acid + lysophospholipid
Fatty acids are re-esterified to 2-monoacylglycerol to make what in intestinal epithelial cells?
Fatty acids are re-esterified to 2-monoacylglycerol to make triacylglycerol in intestinal epithelial cells.
What is the major apoprotein for chylomicrons?
ApoB-48 is the major apoprotein of chylomicrons.
How is ApoB created and what is the unedited form?
RNA editing. The unedited transcript produces full length ApoB-100 in hepatocytes.
What do chylomicrons receive from HDL once they enter the blood?
After chylomicrons enter the blood, they receive ApoCII and ApoE from high density lipoprotein (HDL).
HDL’s function is to maintain cholesterol and apoprotein homeostasis.
What is LPL activated by?
Lipoprotein lipase (LPL) is an extracellular lipase in the capillary beds of muscle and adipose tissue. It is activated by ApoCII.
What is the role of the chylomicron?
Transport DIETARY fat.
What is role of VLDL?
Transport fat generated from CARBOHYDRATES
Fatty acids and cholesterol taken up by the liver from [ ] can be repackaged with [ ] as very low density lipoprotein (VLDL).
What is the similarity between VLDL and chylomicrons?
Fatty acids and cholesterol taken up by the liver from chylomicron remnants can be repackaged with ApoB100 as very low density lipoprotein (VLDL).
VLDL serves a similar function as chylomicrons: To deliver fatty acid fuels to the tissues of the body.
(T/F) Adipose can only store fatty acids as triacylglycerol in the fed state.
True. Adipose can only store fatty acids as triacylglycerol in the fed state, because the glycerol 3-phosphate backbone can only be produced by glycolysis in adipocytes.
Adipose tissue can take up fatty acids from chylomicrons or VLDL particles.
Which has the highest % of cholesterol?
HDL, LDL, ILDL, VLDL, Chylomicron
LDL
