Ch. 6 Proteins

Question 1

Describe the function of proteins.

Answer 1

Collagen
Enzymes
Fluid & electrolyte balance
Acid base balance
Transport
Antibodies
Energy
Hormones

Question 2

Beginning with amino acids (AA), describe the building of a protein. What is a protein, AA, dipeptide, tripeptide, polypeptide?

Answer 2

Building proteins: Two amino acids bonded together form a dipeptide. A third amino acid can be added to the chain to form a tripeptide. As additional amino acids join the chain, a polypeptide is formed. The primary structure of a protein is determined by the sequence of amino acids.

AA: building blocks of proteins.

Protein: compounds composed of carbon, hydrogen, oxygen, and nitrogen atoms, arranged into amino acids linked in a chain.

Dipeptide: two amino acids bonded together

Tripeptide: three amino acids bonded together

Polypeptide: many (10 or more) amino acids bonded together

Question 3

Differentiate between essential AA, nonessential AA, & conditionally essential AA.

Answer 3

Essentail AA: body can’t make at all/can’t make in sufficient amounts.

Nonessential AA: body can make, can also get from diet.

Conditionally Essential AA: nonessential AA becomes essential
–ex: tyrosine in PKU disease

Question 4

Explain what is meant by “consider quality and quantity” of protein.

Answer 4

PRO Quantity:
–Amounts

PRO Quality:

• -Complete vs Incomplete PRO
• -High quality PRO
• -Digestibility of PRO

Question 5

Discuss issues of protein quality.

Answer 5

Complete: contains all essential AA in relative same amount humans require

Incomplete: lacking/low in one or more essential AA

Limiting AA

High-quality proteins: generally found in meat, fish, poultry, cheese, eggs, yogurt, milk

Digestibility

• -most animal protein: 90-99% digestibility
• -plant proteins: 70-90% digestibility
• -soy protein and legumes: 90% digestibility

Question 6

What is the dietary relevance of “protein sparing?”

Answer 6

Dietary PRO, no matter what the quality, will not be used sufficiently if CHO and FAT are lacking in your diet.

Question 7

What is PEM?

Answer 7

Protein-energy malnutrition.

It’s a protein deficiency.

Question 8

Describe PKU. What’s the relevance to our discussion about proteins?

Answer 8

PKU: can’t convert phenylalanine to tyrosine.

Relevance: main treatment for PKU is diet. Omitting phenylalanine containing protein foods:

• -high protein foods
• -other

People with PKU must also avoid food/beverages made with aspartame (diet soda)

Question 9

What are concerns with excessive protein intake?

Answer 9

Impact on kidneys, increase calcium excretion, stored as fat

Question 10

State the recommendation for protein intake.

Answer 10

AMDR: 10-35% energy intake

RDA: 0.8 g/kg/d

• -people are healthy
• -protein is mixed
• -the body will use protein efficiently

Question 11

Define the following: vegan, lacto-ovo-vegetarian, lactovegetarian. What are nutrients that may be lacking in a vegetarian diet?

Answer 11

Vegan: people who exclude all animal-derived foods (including meat, poultry, fish, eggs, and dairy products).

Lacto-ovo-vegetarian: people who include milk, milk products, and eggs, but exclude meat, poultry, and seafood from their diets.

Lactovegetarian: people who include milk and milk products, but exclude meat, poultry, seafood, and eggs from their diets.

Nutrients lacking: protein, iron, zinc, calcium, vitamin B12, vitamin D, and omega-3 fatty acids.