Proteins and Amino Acids - Biology - Lecture Slides, Slides of Biology

Download Proteins and Amino Acids - Biology - Lecture Slides and more Slides Biology in PDF only on Docsity! Chapter 6: The Proteins and Amino Acids Docsity.com Introduction • What do you think of when you hear the word “protein”? • Proteins have many roles in the body, but their basic structure is the same Hair, skin, eyesight, and the health of the whole body depend on protein from food Docsity.com Inherited Amino Acid Sequences • Determined by heredity • Incorrect amino acid sequence can be harmful – e.g. Sickle-cell disease • Genes determine the sequence DNA  RNA  protein Docsity.com Nutrients and Gene Expression • Every cell nucleus contains the DNA for making every human protein • Some genes are “expressed” and others are not • Nutrients influence gene expression Docsity.com Denaturation of Proteins • Proteins can be denatured – Heat, radiation, alcohol, pH, heavy salts – During digestion – During cooking Docsity.com The Roles of Proteins in the Body • Proteins are versatile, unique, and play important roles in the body • The body makes enzymes, hormones, and chemical messengers • Antibodies defend against foreign proteins • Proteins help regulate the body’s electrolytes and fluids • Proteins buffer the blood against excess acidity • Proteins clot the blood to prevent death from uncontrolled bleeding Docsity.com Providing Energy and Glucose • Used for energy when CHO/fat scarce • Deamination - removal of nitrogen part • No storage form of amino acids Docsity.com The Fate of An Amino Acid • Amino acids can be: – Used to build protein – Converted to another compound – Dismantled • Can be used for energy: – Amine group removed – Amine group excreted in the urine • Can be stored in a different form: – Amine group excreted – Converted to glucose or fat Docsity.com Which Kinds of Protein-Rich Foods Are Easiest To Digest? • Digestibility of protein varies • Cooking with moist heat can improve digestibility (dry: impairs digestibility!) • Amino acids from animal proteins are most easily digested and absorbed (over 90%) • Amino acids from legumes are next (80 to 90%) • Amino acids from plant foods vary (70 to 90%) Docsity.com Amino Acid Composition • High-quality proteins • Low-quality proteins – If a non-essential amino acid is unavailable from food, the cell synthesizes it Docsity.com Complementary Proteins: Mutual supplementation John A. Rizzo/Photodisc/ © Michael Newman/PhotoEdit Getty Images © Polara Studios, Inc. 34 Coatmeal= 5g i 1/2 c pasta Protein total 5g 1c beans 1c vegetables Protein total 20g 2 tos Parmesan cheese Protein total lle Lys Met Trp Legumes J Grains JS Together J wi Protein Deficiency And Excess • Protein deficiencies and energy deficiencies are the world’s leading form of malnutrition • Both protein deficiencies and excess are of concern Docsity.com What Happens When People Consume Too Little Protein? • Protein energy malnutrition (PEM) takes two different forms: – Marasmus – Kwashiorkor Docsity.com Marasmus • Extreme food energy deficiency Kwashiorkor Ghanaian: “the evil spirit that infects the 1st child when the 2nd is born” The edema and enlarged liver characteristic of kwashiorkor are apparent in this child’s swollen belly. The extreme loss of muscle and fat characteristic of marasmus is apparent in this child’s matchstick arms Docsity.com The Advantage of Legumes • The protein quality of legumes is almost comparable to that of meat. • Soy protein can be considered equivalent to that of meat. Legumes: Protein rich and exceptionally nutritious Docsity.com Controversy: Vegetarian And Meat-Containing Diets: What Are The Benefits And Pitfalls? Can a diet without meat supply the needed nutrients? Docsity.com TABLE Cot Some of the terms below are in common usage, but others are useful only to researchers. fruitarian includes only raw or dried fruits, seeds, and nuts in the diet. lacto-ovo vegetarian includes dairy products, eggs, vegetables, grains, legumes, fruits, and nuts; excludes flesh and seafood. lacto-vegetarian includes dairy products, vegetables, grains, legumes, fruits, and nuts; excludes flesh, seafood, and eggs. macrobiotic diet a vegan diet composed mostly of whole grains, beans, and certain vegetables; taken to extremes, macrobiotic diets can compromise nutrient status. ovo-vegetarian includes eggs, vegetables, grains, legumes, fruits, and nuts; excludes flesh, seafood, and milk products. partial vegetarian a term sometimes used to mean an eating style that includes seafood, poultry, eggs, dairy products, vegetables, grains, legumes, fruits, and nuts; excludes or strictly limits certain meats, such as red meats. pesco-vegetarian same as partial vegetarian, but eliminates poultry. vegan includes only food from plant sources: vegetables, grains, legumes, fruits, seeds, and nuts; also called strict vegetarian. vegetarian includes plant-based foods and eliminates some or all animal-derived foods.