More than _____ of proteins are found in skeletal muscle **** 40%
proteins are nutritionally essential because of their constituent ____________ ****
amino acids
proteins make up ____________ of the solid content of cells **** over half
__________ combine with other substances to provide a means of carrying those
substances in the blood, or into cells, or out of cells **** transporters
buffers **** a compound that ameliorates a change in pH that would otherwise
occur in response to the addition of alkali or acid to a solution
fluid balancers **** proteins attract water to blood
proteins are built from _________ by __________ **** amino acids; peptide
bonds
primary structure is the ___________ arrangement of ____________ in a protein
and the location of ____________ between amino acids **** linear; amino acids;
covalent bonds
secondary structure is the areas of ____________ or __________ within a protein
achieved through weaker bonding such as ___________ bonding **** folding;
coiling; hydrogen
tertiary structure is the final _____________ structure of a protein, which results
from a large number of ___________________ bonds between _____________
**** three-dimensional; non-covalent; amino acids
quaternary structure occurs when ______________ bonds bind multiple
_____________ into a single, larger protein **** non-covalent; polypeptides
hemoglobin is an example of __________ structure **** quaternary
, exogenous proteins are sources of the ________________ amino acids and are the
primary source of additional nitrogen needed to synthesize ___________ amino
acids **** essential; non-essential
endogenous proteins **** desquamated mucosal cells
digestive enzymes and glycoproteins
___________ protein digestion begins in the ______________ **** exogenous;
stomach
HCl serves two main functions: **** 1. denatures the quaternary, tertiary, and
secondary structures
2. activates pepsinogen to pepsin
____________ hydrolyzes peptide bonds. **** pepsin
The end products of pepsin include __________, along with some ___________
and ___________ and are emptied into the _____________ **** polypeptides;
oligopeptides; free amino acids; duodenum
pepsinogen is a ____ enzyme, meaning that it has ____ enzymatic activity ****
pro; no
In the duodenum, the end products stimulate the release of regulatory hormones
and peptides, such as ____________ and ____________ **** secretin;
cholecystokinin (CCK)
_________ and __________ stimulate the pancreas to release pancreatic juice
containing ____________ **** secretin; cholecystokinin (CCK); zymogens
zymogens are **** digestive proenzymes, precursor of active enzymes
in the small intestine, in response to secretin and CCK, membrane-bound
______________ is secreted by the _____________ of duodenum to activate
________________ converting it to trypsin **** enteropeptidase; brush border;
trypsinogen
____________ initiates the activation cascade of other enzymes (including itself)
for ______________ digestion **** trypsin; protein