Proteins Flashcards
Dietary Protein Intake in the U.S.
- Approximately ___of total calories in the average U.S. diet are supplied by protein.
- Recommended protein levels are in the range of ____. (calories coming from protein)
- Research indicates that the current level of protein in the U.S. is ___ ___and may actually be ____
- Approximately 17% of total calories in the average U.S. diet are supplied by protein.
- Recommended protein levels are in the range of 10-15%. (calories coming from protein)
- Research indicates that the current level of protein in the U.S. is not beneficial and may actually be harmful.
What Happens to Excess Protein?
- Excess protein consumed cannot be ___ in ____
- It is converted to ___ or ___ and then either ____(as fat)or ____________
- Excess protein consumed cannot be stored in the tissues.
- It is converted to glucose or fat and then either stored(as fat)or metabolized for energy production.
Essential vs. Non-Essential Amino Acids
Essential amino acids: Amino acids that ___________________. They are sometimes referred to as “______ amino acids.”
Non-essential amino acids: Amino acids that ____________________. Also referred to as “______ amino acids.”
Conditionally essential amino acids: An amino acid that is normally ______ but must be supplied by the diet in ___ ___ when the ___ for it exceeds the _______
Example: ___
Essential amino acids: Amino acids that cannot be synthesized in adequate amounts by humans and therefore must be obtained from the diet. They are sometimes referred to as “indispensable amino acids.”
Non-essential amino acids: Amino acids that can be readily produced by humans from other components of the diet (carbohydrates, fats, and nitrogen). Also referred to as “dispensable amino acids.”
Conditionally essential amino acids: An amino acid that is normally non-essential, but must be supplied by the diet in special circumstances when the need for it exceeds the body’s ability to produce it.
Example: Tyrosine
Table 1
Role of Specific Amino Acids
Proteins
v The term protein is derived from the Greek word “_____” meaning “____” or ____
v
v Proteins are virtually involved in ___ ___ ____ in the human body.
v The term protein is derived from the Greek word “proteos” meaning “first” or important.
v
v Proteins are virtually involved in every biological process in the human body.
Role of Proteins
v Growth and maintenance of body tissue.
v Participation in chemical reactions.
v Regulation of fluid and electrolyte balance.
v Maintenance of acid-base balance.
v Transportation of other nutrients.
v Maintenance of immunity.
v Regulation of body processes.
v Production of energy (if needed).
v
Digestion of Protein
Partial protein digestion by ___ ___ and the enzyme___
Further protein digestion in ___ ___ by enzymes relesased by the____
Final conversion of protein to aa takes place____ ____ ____
aa absorbed into the ___ ___ and transported to the ___. From here they enter the ____ ____
____ dietary protein is present in the feces
Partial protein digestion by stomach acid and the enzyme pepsin
Further protein digestion in small intestine by enzymes relesased by the pancreas
Final conversion of protein to aa takes place inside intestinal cells.
aa absorbed into the portal vien and transported to the liver. From here they enter the general circulation
Litle dietary protein is present in the feces
Protein Turnover
Input to aa pool in cell:
- aa from
- aa from
Output:
- ______ ___ containing compounds such as____
- Synthesis of___ ___ for ___ ___ and other needed components of the body, such as ____ ,____, and ____ ____ ____
- ___ made from ___ ____ (_________________)
- _____ production from___ ______ for body cells; yield on avg______
- ______production from _____ ( )
Last three go into _______–> ________–> _____
Input to aa pool in cell:
- aa from cell breakdown
- aa from diet
Output:
- Nonprotein N containing compounds such as serotonin
- Synthesis of body proteins for cell structure and other needed components of the body, such as enzymes, hormones, and muscle contractile proteins
- Fat made from C skeletons (liver cells only and generally not much)
- E production form C skeletons for body cells; yield on avg 4kcal/g
- Glucose production from C skeletons (liver and kidney cells only)
Last three go into free amonia (NH3)–> Urea synthesis in liver–> Urinary excretion
Quality of Protein: Complete Proteins
Proteins that contain ________________amino acids in____ ____ to support ___ and ____ ____
Examples include ___ ____ ____ and ___ These proteins are also referred to as “___ ____” proteins.
Proteins that contain all of the essential amino acids in amounts needed to support growth and tissue maintenance.
Examples include meat, milk, eggs, and soy. These proteins are also referred to as “high-quality” proteins.
Quality of Protein: Incomplete Proteins
Proteins that are ______________________ essential amino acids.
Examples include __ ___ ___
Proteins that are deficient in one or more essential amino acids.
Examples include wheat, rice and corn.
Protein Quality: Complementary Proteins
__________ proteins whose amino acid composition _____ each other in such a way that the
For example; ___ and___, ___ and ___, ___ and ____
Two or more proteins whose amino acid composition complements each other in such a way that the essential amino acids deficient in one are supplied by the other.
For example; black beans and rice, peanut butter on wheat bread, cereal and milk.
Concept of Limiting Amino Acid
q The ____ ___ ___in ____ concentration in a ___ or ___ relative to the _____ ___
q The essential amino acid in lowest concentration in a food or diet relative to the body needs.
- Beans:
- _
- ___ ___ and ____
- ___ and ___
- Grains:
- __
- ___
- ___ and ____, ____, ___ and ___
- Nuts and seeds:
- _
- ____
- ___ and ____; ___, ___ and ____ ; and ____
- Veggies:
- _
- ___ ___ and ___
- ____ and ____
- Corn:
- __
- ___
- ____ and ____
Beans: M: Grains nuts and seeds: red beans and rice
Grains: KT: Legumes: Rice and red beans, lentils, curry and rice
Nuts and seeds: K: Legumes: soybeans and ground seseme seeds; peanuts, rice and black eyed and green peas; and sunflower seeds
Veggies: M: Grains nuts seeds: Green beans and almonds
Corn: WK: Legumes: Corn Torillas and Beans
Complementary Proteins
Two food protein sources that make up for each other’s ___ ___ of specific essential amino acids.
Together they yield _____________
Examples: rice and beans, cereal and milk, etc.,
vTwo food protein sources that make up for each other’s inadequate supply of specific essential amino acids.vTogether they yield a sufficient amount of all essential amino acids.vExamples: rice and beans, cereal and milk, etc.,
Assessment of Protein Quality
____ ___ ____
_____
v Amino Acid Composition
v Digestibility
Reference Protein
For example, egg protein is regarded as ___ and ____
A standard against which other proteins can be compared.
For example, egg protein is regarded as complete and digestible.
Measures of Protein Quality
§Amino Acid Scoring
§
§Biological Value (BV)
§
§Net Protein Utilization (NPU)
§
§Protein Efficiency Ratio (PER)
§
§PDCAAS
Biological Value (BV)
Biological Value (BV) is expressed as a _______of the ___ ____that is ____.
A protein with a BV of ____ or greater can support human ___ as long as ___ ____ is adequate.
Biological Value (BV) is expressed as a percentage of the absorbed nitrogen that is retained. A protein with a BV of 70 or greater can support human growth as long as energy intake is adequate.
Table 2
Biological Values (BV) of Selected Foods
Egg
Milk
Beef
Fish
Corn
Egg 100
Milk 93
Beef 75
Fish 75
Corn 72
Net Protein Utilization (NPU)
Like Biological Value, NPU measures ____ _____. Instead of measuring retention of absorbed nitrogen, NPU measures retention of ____ ____
Like Biological Value, NPU measures nitrogen retention. Instead of measuring retention of absorbed nitrogen, NPU measures retention of food nitrogen.
Protein Efficiency Ratio (PER)
The protein efficiency ratio measures the ____ ____ of a growing animal and compares it to the animal’s ___ ____ (used to establish the protein quality for ___ ____ and ___ ___).
The protein efficiency ratio measures the weight gain of a growing animal and compares it to the animal’s protein intake (used to establish the protein quality for infant formulas and baby foods).
The ____________________ (PDCAAS)
The PDCAAS method compares the ____ ____ ____ of a protein with human amino acid _____ and corrects for ____ (recommended by the____/___ and used to establish protein quality of foods for ____ ____ ____ on ___ ___).
The PDCAAS method compares the amino acid content of a protein with human amino acid requirements and corrects for digestibility (recommended by the FAO/WHO and used to establish protein quality of foods for Daily Value percentages on food labels).
PDCAAS Values of Selected
Casein
Egg White
Soybean
Beef
Pea Flour
Kidney Beans
Chick Peas
Pinto Beans
Rolled Oats
Lentils
Peanut Meal
Whole wheat
PDCAAS Values of Selected
Casein
1.00
Egg White
1.00
Soybean (isolate)
.99
Beef
.92
Pea flour
.69
Kidney beans (canned)
.68
Chick peas (canned)
.66
Pinto beans (canned)
.63
Rolled oats
.57
Lentils (canned)
.52
Peanut meal
.52
Whole wheat
.40
