biochem 2.7.pdf

Proteins: Amino Acids  Protein Functions in body Building materials for growth (collagen-tissues, bones and teeth) Enzymes Hormones Fluid balance (albumin) Transporters (Hemoglobin and other carrier proteins) Antibodies (Immunoglobulins) Energy source (gluconeoge...

Proteins: Amino Acids  Protein Functions in body Building materials for growth (collagen-tissues, bones and teeth) Enzymes Hormones Fluid balance (albumin) Transporters (Hemoglobin and other carrier proteins) Antibodies (Immunoglobulins) Energy source (gluconeogenesis) Amino Acids Side groups  Amino Acids Nonessential amino acids Body can synthesize from nitrogen and fragments of CHO and lipids Essential amino acids Body cannot make in sufficient amounts Conditionally essential amino acids Nonessential amino acid becomes essential under special circumstances (Tyrosine from PKU)  Dipeptide Condensation reaction  Proteins Polypeptide  Proteins Amino acid sequences Determines the shape of the polypeptide chain Shape impacts function Variety of sequences  Protein shape and function  Proteins Protein denaturation Change in a protein’s shape Change in shape leads to function Causes of denaturation Heat Agitation Acid Base Alcohol Heavy metals (mercury and silver)- milk is the antidote  Protein Digestion Mouth Stomach Hydrochloric acid denatures proteins Pepsinogen to pepsin Small intestine Hydrolysis reactions Peptidase enzymes Protein Digestion Amino Acid Transport  Absorption of AAs Systems: Secondary active transport driven by Na+ gradient Facilitated diffusion  Protein Synthesis DNA template to make mRNA Transcription mRNA carries code to ribosome Ribosomes are protein factories mRNA specifies sequence of amino acids Translation tRNA Sequencing errors Disorders/Inborn errors of Protein Metabolism Protein Synthesis  Roles of Proteins Growth and maintenance Building blocks for most body structures Collagen Replacement of dead or damaged cells Enzymes Break down, build up, and transform substances Catalysts Roles of Proteins  Roles of Proteins Hormones Messenger molecules Transported in blood to target tissues Regulators of fluid balance Edema Acid-base regulators Attract hydrogen ions Transporters – specificity Roles of Proteins  Roles of Proteins Antibodies Defend body against disease Specificity Immunity – memory Energy and glucose Starvation and insufficient carbohydrate intake Other roles  Preview of Protein Metabolism Protein turnover & amino acid pool Continual production and destruction Amino acid pool pattern is fairly constant Used for protein production Used for energy – if stripped of nitrogen Nitrogen balance Zero nitrogen balance Positive and negative nitrogen balance  Preview of Protein Metabolism Excreting urea Liver releases urea into blood Kidneys filter urea out of blood Liver disease Kidney disease Protein intake and urea production Water consumption Preview of Protein Metabolism  Protein Regulations for Food Labels Quantity of protein in grams Percent Daily Value Not mandatory Protein claims Consumption by children under 4 years old Quality of protein  Protein Quality Reference protein Preschool-age children High-quality proteins Animal proteins Plant proteins Complementary proteins Low-quality proteins combined to provide adequate levels of essential amino acids  Protein Quality Two factors Digestibility Other foods consumed Animal vs. plant proteins Amino acid composition Essential amino acid consumption Nitrogen-containing amino groups Limiting amino acid  Preview of Protein Metabolism Making fat Energy and protein exceed needs Carbohydrate intake is adequate Can contribute to weight gain Deaminating amino acids Stripped of nitrogen-containing amino group Ammonia Keto acid  Preview of Protein Metabolism Making other compounds Neurotransmitters Melanin Thyroxin Niacin Energy and glucose Wasting of lean body tissue Adequate intake of carbohydrates and fats  Protein Quality Reference protein Complementary proteins Combining different amino acids to provide all essential amino acids  Protein-Energy Malnutrition (PEM) Insufficient intake of protein, energy, or both Prevalent form of malnutrition worldwide Impact on children Poor growth Most common sign of malnutrition Impact on adults Conditions leading to PEM END OF SECTION 5_CHON