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Topic 3: exchange of substances with their environment
3.3.1/2/3 exchange systems
protein absorption
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Created by
Millie Higgins
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Cards (5)
peptidases or
proteases
are enzymes which breakdown proteins in a series of
hydrolysis
reactions
Endopeptidases
:
hydrolyse
peptide bonds within a large protein to create
smaller
polypeptide chains
endopeptidases
create more
terminal
ends for exopeptidases to then work on
Exopeptidases:
hydrolyse terminal
peptide
bonds ( between
amino acids
on the ends of a polypeptide chain )
this removes
individual amino acids
and create
smaller polypeptide chains
Dipeptidases:
a type of exopeptidase
located on the membrane of epithelial
cells lining
on the
small intestine
work on
dipeptides
to
hydrolyse
the peptide bond holding them together
this creates
two single
amino acids which can be transported through membrane into
epithelial
cells
In the stomach:
whole
proteins
are
chewed
and swallowed into the stomach
hydrochloric acid
denatures proteins to reveal the
polypeptide
chain
enzymatic digestion by
pepsin
forms shorter
polypeptide
in the small intestine:
4.
trypsin
and other
proteases
continue enzymatic digestion forming tripeptides, dipeptides and amino acids
5. in enterocytes these peptides are broken down further into
amino
acids which are absorbed into the
blood