PROTEIN Flashcards
Originated from a Greek word “proteios” meaning “to hold first place” or “is of prime importance”
- large complex organic compounds composed of amino acids as the building units linked together in peptide bonds
PROTEIN
1 g of Nitrogen
6.25 g protein
Proteins perform three (3) general
functions:
- Build and repair cells and tissues
(structural role) - Supply energy (fuel nutrient)
- 1 gram yields 4 kcal
- Regulate body processes (regulator
of physiologic processes)
building blocks of protein molecule and they serve as the “currency of protein nutrition and malnutrition.”
Amino Acids
“amino” comes from the basic
amino radical group “acid” comes the or carboxylic group and a distinctive side group (or side chain) are attached
-NH2
–COOH
one that the body cannot be
synthesized,
therefore; they must be supplied
in the diet.
ESSENTIAL AMINO ACID (EAA) OR
INDISPENSABLE AMINO ACID
ESSENTIAL AMINO ACID (EAA) OR
INDISPENSABLE AMINO ACID
P - Phenylalanine
V - Valine
T - Threonine
T - Tryptophan
I - Isoleucine
M - Methionine
H- Histidine
A - Arginine
L - Leucine
L - Lysine
arginine is an essential amino acid for optimal growth and development, and must
therefore be provided in the diet.
For young organisms
arginine is a conditionally essential amino acid, especially in such conditions as trauma, burn injury, small-bowel resection, and renal failure.
For adults
normally not essential but
become essential under certain
clinical conditions
must be supplied by the diet when
the need for these AAs exceeds
the body’s ability to produce them
SEMI-ESSENTIAL AMINO
ACID OR SEMI-INDISPENSABLE AMINO ACID
SEMI-ESSENTIAL AMINO
ACID OR SEMI-INDISPENSABLE AMINO ACID
Proline
Serine
Arginine
Tyrosine
Glycine
Cysteine
Taurine
not a dietary essential
can be synthesized by the body
from essential AA or from an
available source of nitrogen to
form the amino group and a
carbon skeleton composed of
fragments from CHO or fat to form
the rest of the structure of the
available if they are not available
in the diet
NON-ESSENTIAL AMINO ACID (NEAA) OR
DISPENSABLE AMINO ACID
NON-ESSENTIAL AMINO ACID (NEAA) OR
DISPENSABLE AMINO ACID
Alanine
Aspartate
Glutamine
Glutamate
yields only AA upon complete hydrolysis
ex: albumins, globulins, glutenins, gliadin
Simple Proteins
simple proteins combined with non-protein groups
ex:
nucleoprotein,
phosphoprotein, etc.
lipoprotein,
Compound Proteins
According to Chemical Structure
ex:
peptones, proteoses and peptides
formed in various stages of protein
digestion
Derived Proteins
According to Shape/Physical Form
ex: collagen of connective tissues,
keratin of hair and nails, myosin,
elastin, and febrin
Fibrous Proteins
ex: casein in milk, egg albumin, serum
albumin, globulins of blood
Globular Proteins
containing all the essential AA in
amount sufficient for growth and
maintenance of life
Complete Protein
maintain life but do not support growth.
Partially Complete Protein
cannot support life and growth
Incomplete Protein
The first step in digesting a food (or any other solid food)
chewing
secrete saliva to
aid swallowing and the passage of the partially mashed food through the esophagus.
salivary glands
The stomach releases gastric juices
containing
and the enzyme, which initiate the chemical digestion of protein
hydrochloric acid
enzyme
Muscular contractions,
called
peristalsis
called peristalsis, also aid in digestion. The powerful stomach contractions churn the partially digested protein into a more uniform mixture, which is called chyme.
- Muscular Contractions
Because of the hydrochloric acid in the stomach, it has a very low pH of
1.5-3.5.
an enzyme that is secreted by the cells that line the stomach and is activated by hydrochloric acid. Begins breaking peptide bond, creating shorter polypeptides.
pepsin
secretes digestive juices
into the small intestine, and these
contain more enzymes to further breakdown polypeptides.
pancreas
The two major pancreatic enzymes
that digest proteins in the small
intestine are
chymotrypsin and trypsin.
Trypsin activates other protein-
digesting enzymes called
proteases
If there is not enough glucose or energy available, amino acids can also be used in one of these ways
Rearranged into glucose for fuel for the brain and red blood cells
Metabolized as fuel, for an immediate source of ATP
pancreatic enzyme that
digests protein
Chymotrypsin
process of breaking proteins
into smaller peptides
Proteolysis
hormone released in the small
intestine to aid in digestion
Secretin
pancreatic enzyme that activates
chymotrypsin and digests protein
Trypsin
total calorie requirement or intake should come from protein (CHON) for adults above 19 years old (PDRI)
10-15%
additional grams of protein added for pregnant and lactating women
27 grams
Animal-based protein sources
include
meat, fish, dairy products,
eggs and insects
A standard serving
size of lean meat or poultry contains about
25 g of protein.
Plant-based protein sources include
nuts, seeds, tubers, legumes, lentils,
grains.
