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Carbohydrates ( digest starch into maltose then into glucose)
Digestion occurs two places- mouth and small intestine
starch salivary amylase maltose maltase** glucose
mouth small intestine
starch pancreatic amylase* maltose maltase** glucose small intestine small intestine
2. Proteins (digest proteins into peptides then into amino acids)
Digestion occurs in two places- stomach and small intestine
protein pepsin peptides peptidases** amino acids
stomach small intestine
protein trypsin* peptides peptidases** amino acids
small intestine small intestine
3. Lipids (emulisfy fats then digest fats into fatty acids into glycerol)
Digestion occurs small intestine
big fat drops bile from liver little fat drops lipases* fatty acids and glycerol emulisfy small intestine
* From pancreas to small intestine at duodenum - pancreatic amylase, trypsin and lipases
**Intestinal glands into small intestine - peptidases and maltase
From salivary glands into mouth - saliva
From gastric glands into small intestine - pepsin and HCl
Question - Our stomach has an enzyme called pepsin, which digests
proteins into polypeptides and our small intestine also has an enzyme
called trypsin which digests protein into
polypeptides too. Since our stomach has an enzyme which can digest protein,
why does protein digestion still take place in small intestine?
------------
The enzymes you a referring to are generally called
'proteases', proteins that degrade other proteins.
They do not do this randomly, but use a specific
amino acid sequence to cleave. And that iwhy we
produce different proteases in our digestive tract: to
chop up as much as protein, in as small fragments as
possible. After all, not every protein contains
sufficient target sequences for trypsin or pepsin to
generate small enough fragments.
Trudy Wassenaar
=========================================================
Nelly - Pepsin only begins the digestion of proteins as it breaks specific
bonds, adjacent to precise amino acids; it leaves many other bonds intact.
The enzymes in the small intestine finish the job, breaking the rest of the
bonds that link amino acids together to make proteins.
Is that what you need?
Ellen Mayo
=========================================================
Because proteins are very long complicated molecules. Proteins have 3 levels
of complexity. The most complex level is the 3 dimensional level. Pepsin
helps to "unwind" the proteins and breaks the bonds between the amino acids
in certain places. The food passes to the small intestine and other enzymes
break the bonds between different amino acids than pepsin. Because proteins
are such complicated molecules it takes a long time and more than one enzyme
to completely break them down into amino acids.
vanhoeck
=========================================================
All polypeptides are composed of amino acids which have various side chains
that distinguish the 20 different amino acids from each other. Some of these
side chains carry a positive charge; some, a negative charge; and some, no
charge at all. To break down a peptide to usable components the digestive
system must be designed to attack all the different charges. In the acidic
environment of the stomach, the negative side chains are addressed by pepsin.
In the more alkaline environment of the intestine, the positive side chains
are digested by trypsin. Each of these enzymes are similar to each other but
through evolution have been selected for stomach and intestine because pepsin
works better in an acidic environment and trypsin works better in alkaline
environments.
Digestion occurs two places- mouth and small intestine
starch salivary amylase maltose maltase** glucose
mouth small intestine
starch pancreatic amylase* maltose maltase** glucose small intestine small intestine
2. Proteins (digest proteins into peptides then into amino acids)
Digestion occurs in two places- stomach and small intestine
protein pepsin peptides peptidases** amino acids
stomach small intestine
protein trypsin* peptides peptidases** amino acids
small intestine small intestine
3. Lipids (emulisfy fats then digest fats into fatty acids into glycerol)
Digestion occurs small intestine
big fat drops bile from liver little fat drops lipases* fatty acids and glycerol emulisfy small intestine
* From pancreas to small intestine at duodenum - pancreatic amylase, trypsin and lipases
**Intestinal glands into small intestine - peptidases and maltase
From salivary glands into mouth - saliva
From gastric glands into small intestine - pepsin and HCl
Question - Our stomach has an enzyme called pepsin, which digests
proteins into polypeptides and our small intestine also has an enzyme
called trypsin which digests protein into
polypeptides too. Since our stomach has an enzyme which can digest protein,
why does protein digestion still take place in small intestine?
------------
The enzymes you a referring to are generally called
'proteases', proteins that degrade other proteins.
They do not do this randomly, but use a specific
amino acid sequence to cleave. And that iwhy we
produce different proteases in our digestive tract: to
chop up as much as protein, in as small fragments as
possible. After all, not every protein contains
sufficient target sequences for trypsin or pepsin to
generate small enough fragments.
Trudy Wassenaar
=========================================================
Nelly - Pepsin only begins the digestion of proteins as it breaks specific
bonds, adjacent to precise amino acids; it leaves many other bonds intact.
The enzymes in the small intestine finish the job, breaking the rest of the
bonds that link amino acids together to make proteins.
Is that what you need?
Ellen Mayo
=========================================================
Because proteins are very long complicated molecules. Proteins have 3 levels
of complexity. The most complex level is the 3 dimensional level. Pepsin
helps to "unwind" the proteins and breaks the bonds between the amino acids
in certain places. The food passes to the small intestine and other enzymes
break the bonds between different amino acids than pepsin. Because proteins
are such complicated molecules it takes a long time and more than one enzyme
to completely break them down into amino acids.
vanhoeck
=========================================================
All polypeptides are composed of amino acids which have various side chains
that distinguish the 20 different amino acids from each other. Some of these
side chains carry a positive charge; some, a negative charge; and some, no
charge at all. To break down a peptide to usable components the digestive
system must be designed to attack all the different charges. In the acidic
environment of the stomach, the negative side chains are addressed by pepsin.
In the more alkaline environment of the intestine, the positive side chains
are digested by trypsin. Each of these enzymes are similar to each other but
through evolution have been selected for stomach and intestine because pepsin
works better in an acidic environment and trypsin works better in alkaline
environments.
