unit 2 - Proteins composed of subunits called amino acids...

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Proteins - composed of subunits called amino acids - there are 20 amino acids in the body, nature, ect - they are made out of carbon, hydrogen, oxygen, and nitrogen (which is unique) - a few amino acids may have sulfur. - Amino acids are joined by peptide bond (chemical bond between amino acids). Peptides are short chains of amino acids ex: insulin. - Proteins are made up of hundreds or thousands of amino acids. - Different proteins have a distinct and exact sequence of amino acids. - The sequence is carried in you DNA. Genes specify proteins (they carry AA sequence). - Attractions and repulsions that cause it to coil and stretch. - Digestion of protein: denaturing by stomach acid. Protease starts breaking those bonds. It is released in the stomach, more is made in the pancreas. - Broken down into single amino acids or very short chains of amino acids. - You can’t absorb a whole protein, only small amino acids. - Functions of protein: can be used as energy, but has a lot more function. Mainly used as structure, like muscle, tendons/ligamints, bone matrix, skin and hair, some cell membranes (but this is mostly lipids). - Constituents of the body made of protein: blood clotting factors, blood transport proteins - Lipo protein - Help maintain fluid balance. Proteins in blood that use osmosis to attract and retain fluid in the blood stream. Generates osmotic pressure moves water into the gut. Blood pressure causes fluid to leave the stream, so osmosis helps balance fluid - Acid base balance: right degree of acidity in fluids. Proteins buffer/stabalize acidity. - Regulation: most proteins are enzymes. They faciliate chemical reactions - Peptide hormones: insulin. Body wide/systemic effect - There are 3 amino acids that are either neurotransmitters or precursors. - Precursor (can be converted in neurotransmitter) - Immune system: depends on protein. - Foreign protein: antigens. Body will recognize it, attack it with antibodies - If you have a protein deficiency, that will reduce your immune response. - Energy: 4 kcal a gram. But is 10-15 percent of your calories/energy. Can be more important if body starts up gluconeogenesis. - Brain is an obligate glucose user. It only burns glucose. Protein (continued) - requirements from protein - RDA of protein: based on age and body weight - It is .8 grams per kg of body weight today. People who are heavier need more protein - Male: 63 grams a day - Female: 44 grams a day
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- Needs meet for typical person. < 1200 k cal - Children: they are growing, need up to 2.2 g/kg - Per kiligram of body weight needs is higher for kids than adults - Pregnancy: higher needs as well - Highly active: athletes will have higher needs: up to 1.5 grams per killigram of body weight - Average intakes in the U.S.: females: 70 grams a day. Males: 90 grams per day - Protein deficiency is rare in countries, if there is, usually a medical issue/disease - People do often try to supplement protein - Excess protein: used for energy. To use it as energy you strip nitrogen, excreted in
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This note was uploaded on 12/13/2011 for the course NUTRI SCI 132 taught by Professor Anderson during the Spring '08 term at University of Wisconsin.

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unit 2 - Proteins composed of subunits called amino acids...

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