Proteins: Crucial Components of All Body Tissues

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Proteins: Crucial Components of All Body Tissues

Proteins Are Required in Our Diet

Proteins are essential macronutrients that play a wide variety of roles in the human body. It is recommended that protein intake make up 10–35% of total daily energy intake. Proteins are required for numerous physiological and structural functions.

Recommended Intake: 10–35% of total daily energy intake should come from protein.
Key Functions: Proteins are involved in growth, repair, immunity, and as a last-resort energy source.

Reasons We Need Protein

Reasons We Need Protein	Examples/Details
Proteins Form Many Biological Compounds	Enzymes: Speed up chemical reactions (e.g., digestive enzymes). Hormones: Chemical messengers (e.g., insulin, glucagon). Transport Proteins: Move nutrients in blood (e.g., hemoglobin transports oxygen). Neurotransmitters: Transmit signals between neurons. Blood Clotting Factors: Prevents excessive bleeding after injury.
Proteins Provide Immunity	Antibodies: Specialized proteins that bind and neutralize harmful substances (e.g., bacteria, viruses).
Proteins Provide Structure and Mechanical Support	Collagen: Structural protein in skin, bones, and connective tissue. Keratin: Structural protein in hair and nails.
Proteins Maintain Fluid and Electrolyte Balance	Blood Plasma Proteins: Help maintain fluid balance in the bloodstream and tissues (e.g., albumin).
Proteins Are a Backup, "Last-Resort" Energy Source	When carbohydrates and fats are insufficient, proteins can be broken down for energy. Some amino acids can be used for energy if needed, especially during prolonged fasting or starvation.

Examples of Protein Functions

Enzymes: Digestive enzymes like amylase and protease help break down food in the digestive tract.
Hormones: Insulin regulates blood glucose levels.
Antibodies: Immunoglobulins protect against infections.
Transport Proteins: Hemoglobin carries oxygen in the blood.
Structural Proteins: Collagen provides strength to skin and bones.

Protein and Acid-Base Balance

Proteins help maintain the body's pH as they can act as buffers. Before amino acids are used for energy (e.g., during gluconeogenesis), they must undergo deamination.

Buffer: A substance that resists changes in pH by neutralizing added acids or bases.
Deamination: The removal of an amino group from an amino acid, producing ammonia and a carbon skeleton that can be used for energy.

Key Terms

Buffer: A compound that helps maintain stable pH in a solution.
Deamination: The process of removing an amino group from an amino acid.

Practice Questions and Key Concepts

Enzymes are crucial biological molecules that are considered proteins.
A diet high in carbohydrates, fat, and low in protein may cause:
- Lack of energy
- Impaired immune function and increased susceptibility to disease
- Complications with GI tract and skin health
Symptoms of not having enough protein include:
- Swelling and fluid retention (edema)
- Impaired immune response
- Delayed wound healing
- Muscle wasting
Deamination is the removal of an amino group from a protein, which is then converted to urea and excreted in urine.

Summary Table: Protein Functions and Examples

Function	Example
Enzyme	Amylase, protease
Hormone	Insulin, glucagon
Transport	Hemoglobin
Immunity	Antibodies (immunoglobulins)
Structure	Collagen, keratin
Energy (last resort)	Deamination of amino acids for gluconeogenesis

Key Equations

Deamination Reaction:

Recommended Protein Intake:

Additional info: The standard protein intake for healthy adults is approximately 0.8 g per kg of body weight per day, but this may increase for athletes, pregnant women, or individuals recovering from illness.