1 protein and amino acids. 2 the roles of protein building materials enzymes hormones regulators of...
TRANSCRIPT
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Protein And Amino Acids
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The Roles Of Protein
Building materialsEnzymes HormonesRegulators of fluid and electrolyte
balanceAcid-base regulatorsTransportersAntibodies
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As Building Materials
Proteins serve as the building blocks of most body structures.
Bone and teeth contain a protein matrix.
Protein collagen is the material of ligaments and tendons.
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As Enzymes
Enzymes are proteins that facilitate chemical reactions without being changed in the process; Protein catalyst.
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As Hormones
Some hormones are proteins.Growth hormoneInsulin and glucagonThyroxin.Calcitonin and parathyroidAntidiuretic hormone
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As Regulators Of Fluid And Electrolytes Balance
The body’s fluids are contained inside the blood vessels (intravascular), within the cells (intracellular), and between the cells (intercellular).
Fluids flow freely between these compartments. Cells can’t move these fluids, instead they manufacture proteins.
Proteins help regulate the composition of body fluids, as well as their quantity. They maintain equilibrium in the surrounding fluids by moving molecules into and out of cells.
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As Acid-Base Regulators
Acids- compounds that release hydrogen ions.Bases- compounds that accept hydrogen ions.Buffers- compounds that help keep a solution’s acidity
or alkalinity constant.
Normal body processes continually produce acids and bases, which the blood carries to the kidneys and lungs for excretion.
Proteins act as buffers, maintaining the acid-base balance of the blood and body fluids.
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As Transporters
Proteins function as carriers for:
VitaminsMineralsLipidsOxygen
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As Antibodies
Proteins protect the body against disease.
Antibodies are giant protein molecules produced by the immune system designed to combat “foreign invaders”.
They combine with and inactivate the foreign invader thus protecting the body.
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Proteins And Amino Acids
Proteins- compounds composed of carbon, hydrogen, oxygen, and nitrogen atoms, arranged from amino acids linked in chains.
Amino acids- building blocks of proteins: Each contain an amino group (NH2), an acid group (COOH), a hydrogen atom (H), and a distinctive side group all attached to a central carbon atom (C).
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Amino Acids
There are 20 common amino acids which proteins are comprised of. 9 of them are essential, the remaining 11 are not.
* Note: essential means that the human body cannot make them. We must obtain them from our diet.
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Essential Versus Non-Essential
Essential Histidine Lysine Methionine Phenylalanine Threonine Tryptophan Leucine Isoleucine Valine
Non-essential Alanine Arginine Asparagine Aspartic acid Cysteine Glutamic acid Glutamine Glycine Proline Serine Tyrosine
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ProteinsPeptide bonds are the bonds that link amino
acids together to form protein.
Dipeptide- two amino acids bonded together.
Tripeptide- three amino acids bonded together.
Polypeptide- many amino acids bonded together.
Condensation reactions create the bonds between amino acids.
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Digestion Of Proteins
In the stomach-Hydrochloric acid
Denatures the protein structureConverts pepsinogen to pepsin
PepsinCleaves proteins to smaller polypeptides and
free amino acids
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Digestion Of Proteins {continued}
In the small intestines-
EnteropeptidaseConverts pancreatic trypsinogen to
trypsin
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Digestion Of Proteins {continued}
TrypsinCleaves peptide bonds for specific amino acids
Converts pancreatic procarboxypepitases to carboxypeptidases
Converts pancreatic chymotrypsinogen to chymotrypsin
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Digestion Of Proteins {continued}
ChymotrypsinCleaves peptide bonds for specific amino acids
CarboxypeptidasesCleave amino acids from the acid end of
polypeptides
Elastase and collagenaseCleaves polypeptides into smaller polypeptides
into smaller polypeptides and tripeptides
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Digestion Of Proteins {continued}
AminopeptidaseCleaves amino acids from the amino
ends of small polypeptides
TripeptidaseCleaves tripeptides into dipeptides
and amino acids
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Absorption Of Amino Acids
Free amino acids and some di- and tripeptides which escaped digestion enter the bloodstream from the intestinal cells.
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Protein Quality
Can determine how well children grow and how well adults maintain health
Limiting amino acid- the essential amino acid found in the shortest supply relative to the amounts needed for protein synthesis in the body. The four most likely to be limiting: lysine, methionine, threonine, and tryptophan.
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Protein Quality {continued)
Complete protein- a dietary protein that contains all the essential amino acids in relatively the same amounts that human beings require.
Complementary proteins- two or more incomplete proteins whose amino acid assortments complement each other in such a way that the essential amino acids missing from one are supplied by the other.
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Proteins In Foods
Meat, fish, poultry, and dairy products are the richest sources of protein.
Legumes and grain products contain moderate amounts of protein.
Vegetables and fruit provide little protein.
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Recommended Amounts Of Proteins
Protein should account for ~ 15% of total daily energy intake.
The RDA for adults is 0.8 grams per kilogram of body weight.
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Protein-Energy Malnutrition- PEM
PEM is a deficiency of both protein and energy. It is the world’s most widespread malnutrition problem, including kwashiorkor, marasmus, and a combination of both.
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Kwashiorkor
A form of PEM that results either from in-adequate protein intake or infections, however, with adequate calories. Usually acute in nature.
Due to the lack of protein and subsequently, fluid maintenance, faces and limbs become swollen with edema. They develop fatty livers which account for the swollen belly appearance.
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Marasmus
A form of PEM that results from a chronic deficiency of calories, or impaired absorption, of energy, vitamins, and minerals.
This is characterized by extreme loss of muscle and fat, wasted appearance.