Protein Structure and Function

Protein: Structure and Function

• Amino acids are the building blocks of proteins; there are 20 types.
• Nine essential amino acids must be obtained from the diet.
• Eleven non-essential amino acids can be synthesized by the body.
• Essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
• Non-essential amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.
• Proteins have four levels of structure: primary, secondary, tertiary, and quaternary.
• Primary structure refers to the linear sequence of amino acids.
• Secondary structure involves local folding patterns like alpha-helices and beta-sheets, stabilized by hydrogen bonds.
• Tertiary structure is the overall 3D arrangement of a polypeptide chain, determined by interactions between amino acid side chains.
• Quaternary structure involves the arrangement of multiple polypeptide chains in a protein complex.
• A protein's specific 3D shape is crucial for its function.
• Denaturation alters protein shape and function.
• Protein denaturation involves unfolding and loss of 3D structure, caused by heat, pH changes, or chemicals.
• Protein denaturation is important in cooking, as it makes proteins more digestible, and in digestion, as it breaks down proteins into amino acids.
• Protein synthesis involves transcription (DNA to mRNA) and translation (mRNA to protein).
• Protein functions include serving as enzymes, hormones, structural proteins, transport proteins, and antibodies, and contributing to muscle contraction.
• The RDA for protein is 0.8 grams per kilogram of body weight.
• The AMDR for protein is 10-35% of total daily calories.
• Recommendations can vary based on age, activity level, and health status.
• Positive nitrogen balance indicates protein synthesis is greater than breakdown.
• Negative nitrogen balance indicates protein breakdown is greater than synthesis.
• Complementary proteins combine incomplete proteins to obtain all essential amino acids.
• Examples of complementary proteins include rice and beans, or lentils and corn.

Food Insecurity and Malnutrition

• Food security means access by all people at all times to enough food for an active, healthy life.
• This includes availability, access, utilization, and stability of food supply.
• Hunger is a physiological sensation indicating a need for food.
• Food insecurity means being without reliable access to a sufficient quantity of affordable, nutritious food.
• Groups at risk include those experiencing poverty, unemployment, lack of transportation, and chronic health conditions.
• Children, pregnant women, and the elderly are particularly vulnerable.
• Government programs combat food insecurity.
• The Supplemental Nutrition Assistance Program (SNAP) provides food assistance benefits to low-income individuals and families.
• The National School Lunch Program provides free or reduced-price lunches to eligible students.
• The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) provides food assistance and nutrition education to pregnant women, new mothers, infants, and young children.
• The Commodity Supplemental Food Program (CSFP) provides monthly supplemental food packages to low-income seniors.

Food Safety and Contamination

• Food contamination is the presence of harmful substances in food.
• Types of contamination are: biological, chemical, or physical.
• Biological contamination includes bacteria, viruses, parasites, and fungi.
• Chemical contamination includes pesticides, herbicides, heavy metals, and cleaning agents.
• Physical contamination includes glass, metal, plastic, hair, and insects.
• Causes of contamination include improper food handling, inadequate cooking, cross-contamination, contaminated water, and unsafe food storage.
• Microorganism reproduction requires specific conditions like temperature, moisture, nutrients, time, pH, and oxygen.
• The "danger zone" is between 40°F and 140°F (4°C and 60°C), where bacteria multiply rapidly.
• Food irradiation uses ionizing radiation to kill microorganisms and extend shelf life and does not make food radioactive.
• Consumer-level techniques involves washing hands, surfaces, and utensils thoroughly. Separating raw and cooked foods to prevent cross-contamination. Cooking foods to safe internal temperatures and refrigerating perishable foods promptly.

Alcohol: Production, Metabolism, and Effects

• Alcohol is produced through fermentation, where yeast converts sugars into ethanol and carbon dioxide.
• Alcohol is absorbed rapidly from the stomach and small intestine.
• It is primarily metabolized in the liver by alcohol dehydrogenase.
• Alcohol provides 7 calories per gram.
• Alcohol can contribute significantly to overall energy intake.
• Blood Alcohol Concentration (BAC) is affected by factors such as the amount of alcohol consumed, body weight, and gender.
• Tolerance develops over time with regular alcohol consumption, but does not reduce the harmful effects of alcohol.
• Alcohol abuse can lead to liver disease, heart disease, cancer, neurological disorders, and mental health issues.
• Moderate alcohol consumption has been associated with a reduced risk of cardiovascular disease in some studies.