Proteins

Notes: Proteins Protein is made of amino acids Amino acids are the building blocks of protein- they are organic acids Contain nitrogen Each amino acid has side chains that gives it its identity

Notes: Amino acids have a carboxyl group –COOH and and amine group –NH2, and a variable side group. (Figure 17-1 p. 258) Glycine is the simplest amino acid (figure 17-2) Amino acids join together by peptide bonds to make a protein molecule. (FIG. 17-3) Peptide bonds connect the nitrogen of the amine group of one amino acid to a carbon of a second amino acid (at the carboxyl group carbon). (p. 258-259) when amino acids link/chain together they form what are called polypeptides.

Each amino acid is a distinctive chemical- 20

The 20 amino acids are like letters and form different sequences The number is greater than the number of English words. A single human cell may contain 10,000 different proteins

Notes: The body is able to make 50 % of amino acids Essential amino acids must be ingested through food The shapes of the proteins enable them to perform different tasks in the body.( Figure 17-4, 17-5) Shapes determine a protein’s function: Shapes (examples) -globular structure-hemoglobin -fibrous (rope-like spirals)-collagen and elastin

Notes: Denaturation The change (unfolding) of a protein’s shape it can be brought on by the following and a few other methods (text p. 260-261) -Heat (most common method) -Acids or bases -Alcohol -Beating --It breaks the peptide bonds.

Notes: Coagulation Denaturation is the first step in the process of coagulation. (Figure 17-6) Coagulation changes a liquid into a soft semi-solid clot or solid mass. After peptide bonds break new bonds produce the coagulated state Example: Making scrambled eggs

Each protein is designated for a special purpose in a particular tissue of a specific kind of animal or plant Protein breaks down to amino acids and rearranges them into specific human body proteins.

Notes: Protein in Food Sources: All meats and animal products- eggs, cheese Fish Legumes 1 cup = 30% RDA Beans- Soybeans [tofu] , lentils, lima Peanut butter

Protein in Eggs- shell , yolk, white

Meat proteins

Fish- proteins

fish Protein structure in fish has less connective tissue and its type liquefies easily. More tender and cooks quickly Cooked when flakes

Nuts and legumes Black beans Peas Garbanzo beans Kidney beans Lentils Navy beans Pinto beans Chick peas soybeans

Notes: Cooking with proteins (How are they used?) 1. Emulsifiers- proteins stabilize oil and water mixtures ex. Egg yolk in Salad dressings 2. Foams- air bubbles trapped in protein film when whipped ex. meringues or creams See text p. 264-267

Notes: 3. Gelatin- sets desserts and thickens meat sauces collagen from bones and hides Heat and water needed

Notes: 4. Gluten- an elastic substance formed by mixing water with protein found in wheat. [ fibrous and globular proteins] gives baked products their structure and shape] Kneading- denatures the protein and produces a smooth elastic dough.

Notes: Role of proteins in the body 1. Support growth of new tissue 2. Helps replace worn out cells- each red blood cell lives 3-4 months

Notes: 3. Fluid and electrolyte balance- in and out of cells

Notes: 4. Provides some energy If not enough CHO or fat

Notes: 5. Hormones Chemical messengers secreted by some of the organs in response to conditions that require regulation. Each hormone affects a specific organ or tissue and has a specific purpose.

Notes: 6. Antibodies Large proteins in the blood Produced by the immune system to react to an invasion in the body by foreign substances eg bacteria, viruses

Notes: Proteins -During Digestion Proteins are denatured by acid Starts in mouth Continues in stomach by acids Worked on in intestines until broken into single amino acids where they are then absorbed and circulated through blood

Notes: Some proteins are more easily digested than others Animal proteins and soybeans are generally complete proteins that is they contain all the essential amino acids. Figure 17-8 Other plant sources are generally incomplete proteins and lacking one or more essential amino acids.

Requirements .8 grams per KG body weight per day 60 kg needs = 48 gms protein

Deficiency 33,000 children die a day Marasmus- calorie deficiency disease Kwashiorkor- protein deficiency disease

Kwashiorkor

Marasmus

Vegetarian Why? 1. Ethical - abuse of animals - killing animals 2. health 3. Environmental manure pollution uses 10X amount of land as crops less water [ 1 lb beef = 390 gal ]

Ovo- lacto vegetarian Includes eggs and milk products

Partial vegetarian Does not eat red meat May include chicken or fish

Vegan---Only plant food sources No animals or animal products Vegetables, fruits, grains

Good and bad of vegetarian diets pros Eat more fruits and veggies More fiber-fewer digestive disorders More health conscious Less alcohol and smoking Less obesity Less heart disease Less type II diabetes Cons Harder to get protein Risky when pregnant or ill and children More care in getting all nutrients Increase in deficiency diseases