Chapter Lecture Chapter 6: Proteins: Crucial Components of All Body Tissues © 2017 Pearson Education, Inc What Are Proteins? • Proteins: large, complex molecules found in tissues of all living things • Dictated by genetic material (DNA) • Contain carbon, hydrogen, oxygen, nitrogen • Made from 20 different amino acids © 2017 Pearson Education, Inc Amino Acids • Nine essential amino acids • Cannot be produced in sufficient quantities to meet physiological needs • Must be obtained from food • Nonessential amino acids • Can be synthesized in sufficient quantities © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Amino Acids (cont.) • Transamination • Transfer amine group from an essential amino acid to a different acid group and side chain (R group) • Conditionally essential amino acid • Nonessential amino acid becomes essential • Phenylketonuria (PKU): tyrosine becomes a conditionally essential amino acid that must be provided by the diet © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc How Are Proteins Made? • Proteins are long chains of amino acids • Peptide bonds join amino acids together forming dipeptides, tripeptides, oligopeptides, and polypeptides • Gene expression is the process by which cells use genes to make proteins • Gene: segment of deoxyribonucleic acid (DNA) that serves as a template for the synthesis (expression) of a particular protein © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Too Much Protein Can Be Harmful • Heart disease • High protein diets of mostly animal sources are associated with higher blood cholesterol levels • Consuming proteins low in saturated fat may help © 2017 Pearson Education, Inc Too Much Protein Can Be Harmful (cont.) • Kidney disease • High protein diets can increase risk of kidney diseases in susceptible people • Maximum of g of protein per kilogram body weight each day is safe for healthy people • Important to drink more water with higher protein intake • Increases urea production • Fluid needed to flush excess urea from kidneys © 2017 Pearson Education, Inc ABC News Video: Health Benefits, Downsides to High-Protein Diets © 2017 Pearson Education, Inc Protein Sources • • • • • • • Meats Dairy products Eggs Legumes (including soy) Whole grains Nuts "New foods" (ancient grains, quorn) © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Vegetarian Diets • Vegetarianism: restricting the diet to foods of plant origin • People chose vegetarianism for: • Health benefits • Ecological reasons • Religious reasons • Ethical reasons Concerns over food safety â 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Health Benefits of Vegetarianism • • • • • • Lower fat and total energy intake Lower blood pressure Reduced risk of heart disease Fewer digestive problems Reduced risk of some cancers Reduced risk of kidney disease, kidney stones, and gallstones © 2017 Pearson Education, Inc Challenges of Vegetarian Diets • • • • • Can be low in some nutrients Can be associated with disordered eating Varied and adequate diet planning Soy and complementary proteins Special attention to vitamins B12, D, and riboflavin (B2); minerals iron, calcium, and zinc © 2017 Pearson Education, Inc Protein-Energy Malnutrition • Protein-energy malnutrition: disorder caused by inadequate protein and energy intake • Common forms: Marasmus Kwashiorkor â 2017 Pearson Education, Inc â 2017 Pearson Education, Inc Marasmus Grossly inadequate energy, protein, and nutrient intake • Consequences of marasmus: • Wasting and weakening of muscles (heart) • Stunted brain development and learning • Depressed metabolism and low body temp • Stunted physical growth • Deterioration of the intestinal lining • Anemia (abnormally low levels of hemoglobin) • Severely weakened immune system Fluid and electrolyte imbalances â 2017 Pearson Education, Inc Kwashiorkor • Disease resulting from low protein intake • Kwashiorkor symptoms include: • Some weight loss and muscle wasting • Retarded growth and development • Edema resulting in distention of the belly • Fatty degeneration of the liver • Loss of appetite, sadness, irritability, apathy • Skin problems and hair loss © 2017 Pearson Education, Inc Genetic Disorders • Numerous disorders are caused by defective DNA • Genetic disorders include: • Phenylketonuria • Sickle cell anemia • Cystic fibrosis © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc ... messenger RNA copies the genetic information from DNA in the nucleus • Translation: the genetic information carried by mRNA is translated into the amino acid sequence of a protein at the ribosome ©... Gene expression is the process by which cells use genes to make proteins • Gene: segment of deoxyribonucleic acid (DNA) that serves as a template for the synthesis (expression) of a particular protein... Methods for estimating protein quality • Chemical score: comparison of the amount of the limiting amino acid in a food to the amount in a reference food • Protein digestibility corrected amino