Protein Flashcards
Overview of Protein
- Body is made up of thousands of protein
substances - Contains atoms called nitrogen
- Regulates and maintains body functions– Eg. Enzymes, hormone
Amino Acid composition
R group- R
Amino Group- H-C-NH2
O
|| Acid group- C----- OH
Amino Acid Description
- Building block of proteins
- Most basic unit of proteins
- R group differentiates amino acid
Protein Organization
- Peptide bond = connection between amino acids
- Dipeptide = 2 connected (bonded) amino acids
- Tripeptide = 3 connected (bonded) amino acids
- Polypeptide ≥ 50 amino acids bonded together
Essential AA
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Nonessential AA
Alanine
Arginine
Asparagine
Aspartic Acid
Cysteine
Glutamic acid
Glutamine
Glycine
Proline
Serine
Tyrosine
Types of Dietary Protein
High Quality
- Complete
Low Quality
- Incomplete
All or none principle in protein synthesis
Need all essential AA present or protein cannot be made
Limiting Amino Acid
This refers to the essential AA that is missing but required for protein synthesis
Complementary protein
Two food protein sources that make up for each other’s in
adequate supply of specific essential amino
acids
Conditionally Essential AA
amino acids which
are only essential in times of
stress or injury. Otherwise, they
are nonessential.
Complementary Protein
Grains + Veggies
Nuts/Seeds + Beans
Nuts/Seeds + Veggies
Soy
- Soy protein is similar to animal protein (used in school lunches)
- High in linoleic acid and alpha-linolenic
acid - Calcium source and bone health
- Isoflavones – phytochemicals– Heart disease– Cancer
Protein Turnover
Protein undergo breakdown and synthesis
- Protein balance = protein equilibrium
- Positive protein balance = dietary protein
intake exceeds protein lost - Negative protein balance = dietary protein
intake is less than protein lost - Responds to chang
Denaturation of Proteins
Heat/acid/alkaline/enzymes
Results in alteration of the protein’s three-dimensional structure
Protein Content in Food
Fat, Oils and sweets- Low
Milk, yogurt, cheese- High
Vegetables- Medium
Bread, cereal, rice, pasta- medium
Fruit- Low
Plant Protein
- Provide protein, minerals, and dietary fiber
- Contain no cholesterol
- Limited saturated fats
- Allow a few weeks for the GI tract to adjust
to the higher fiber
Availability of Beano®
Digestion of Protein
- Proteins are denatured by cooking and acid in the stomach
- Gastrin stimulates the release of acid and pepsin
- Pepsin is activated and breaks down proteins to
smaller amino acid chains - Hydrolysis = breaking down of peptide bonds by enzymes
Digestion of Protein in the Small
Intestine
- Pancreas release the protein splitting
enzymes: trypsin, chymotrypsin, and
carboxypeptidase into the duodenum - The enzymes will break peptide bonds
forming smaller peptides and amino acids - Peptides and amino acids are ready for
absorption
Protein Absorption
- Absorbed across the intestinal walls into
blood capillaries - Amino acids are sent to the liver via portal
vein
Functions of Proteins
- Building blocks of body components
- Maintain fluid balance– Edema
- Contribute to acid/base balance – Buffer
Functions of Proteins
- Building blocks for hormones and enzymes
- Immune function
- Gluconeogenesis: glucose synthesis from
lipids or protein - Energy yielding
Is a High-Protein Diet Harmful?
- Low in plant foods (fiber), vitamins,
phytochemicals - High intake of animal protein increases risk for
heart disease (high in saturated fat) - Excessive intake of red meat is linked with colon
cancer - Burden on the kidney
- Increase calcium loss
Individual Amino Acid
Supplement
Supplement may cause imbalances and
toxicities
* Body is designed to handle whole proteins
* Supplement can overwhelm the absorptive
mechanism
* Excess of one AA can hamper absorption of
other AAs
Malnutrition
Protein-Energy Malnutrition
– Consuming insufficient amounts of protein & energy
– Hospitalization
– Diet
– Marasmus, Kwashiorkor:
* Especially persons who already have a disease e.g.
Infection
* Primarily in children
Kwashiorkor
- Moderate energy deficit & severe protein deficit
- “Disease that the first child
gets” - Signs and symptoms:– Apathy, listlessness, failure
to grow, poor weight gain,
change in hair color,
nutrient deficiency, flaky
skin, fatty infiltration in the
liver, massive edema in the
abdomen and legs
Marasmus
- Severe protein and energy
deficit - Starving to death
- “skin and bones” appearance
- Little or no subcutaneous fat
- Reduce brain growth
