2. Enzymes of course are proteins. What effect do pepsin and a very low pH in ou

Question

2. Enzymes of course are proteins. What effect do pepsin and a very low pH in our stomach have on proteins? (2 pts) a. b. What is the effect of intestinal and pancreatic peptidases and proteases on proteins and peptides? (2 pts) In what form and by what mechanism are proteins absorbed in adults? (See Sillvethorn Figure 21-17) (2 pts) c. What is the likelihood of an adult absorbing a whole enzyme through their small intestine? (1 pt) d. How do you think your immune system would react to a whole foreign protein in your blood? (2 pts) e. Do you think that gene regulatory proteins from a tomato would recognize g in human DNA? Why or why not? (2 pts) f.

Explanation / Answer

a) Chewing alone doesn't break food enough to get digest it. The release of stomach acid in response to the presence of food initiates churning and intestinal contraction that brak down food into semi liquid form called Chyme.

The stomach acid commonly called HCl has low pH i.e. around 1.8 which not only kills the harmful bacteria present in the food but also activates proenzyme pepsinogen into active enzyme pepsin. Pepsin further converts proteins into proteases and peptones(peptides).

b) Pancreatic juice contains inactive enzymes such as trypsinogen, chymotrypsinogen, amylases etc. Trypsinogen activated by an enzyme enterokinase, secreted by intestinal mucosa, into active trypsin, which in turn activates other pancreatic enzymes. This trypsin converts proteins, peptones, proteoses into Dipeptides.

The intestinal mucosal epithelium has goblet cells, the secretion of goblet cells constitute succus entericus, which contains a variety of enzymes such as dipeptidases, lipases, maltases, etc. Dipeptidases further break down dipeptides into suitable amino acids.

c) Proteins are absorbed in Amino acids form. two mechanisms are involved in amino acid absorption.

i) Carrier protein transport system-It is the main syatem for amino acids absorption which is a active process that requies ATP.

ii) Glutathione transport system- This process is used to transport amino acids from intestinal lumen to cytosol of intetinal mucosal cells.

d) The small intestine is the site of digestion and absorption. The process carried out in various ways and the two important part of intestine jejnum and ileum plays a crucial role in digestion and absorption.

e) As far as food is concern some food do cause immune response, as we all heard about llergic reactions due to sea foods, nuts etc.Besides this this also true that during digestion our digestive system break down the food into simpler and smaller molecules of proteins , lipids, carbohydrates, etc., which are quite similar to our body components. So, when these are pass through intestine, then these are not recognized as foreign particale by immune system.

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