Unit 3.docx

Secondary structure shape of the amino acid chain

  • No School
  • AA 1
  • 7

This preview shows page 4 - 6 out of 7 pages.

secondary structure: shape of the amino acid chain either a pleated sheet or alpha helix structure; alpha helix is stabilized by hydrogen bonding be- tween carboxyl and amide groups of the peptide bonds - tertiary structure: three dimensional structure of an amino acid chain; fold- ing of the coiled chain(s); covalent and hydrogen bonds and van der Walls forces may be involved - quaternary structure: protein consisting of more than one amino acid chain - proteins are amphophilic meaning they have polar and non polar side chains in one molecule, forming interfacial films similar to small molecular synthetic emulsifiers - the reaction between proteins and sugars is the most common of these browning (Maillard) reactions that occur in baked products and other goods - selected colour pigments such as chlorophyll are bound in the chloroplasts in a protein-lipid matrix - proteins often contribute texture to foods ex. custards are protein gels in- fluenced by ovalbumin denaturation Lipids - include fats and oils from both plants and animals - cholesterol is a fat found only in animal products - lipids are substances in foods that are soluble in organic solvents - this category includes triglycerides, fatty acids, phospholipids, some pig- ments, some vitamins and cholesterol - in foods, fats provide a source of essential fatty acids, add caloric density, act as carriers for flavours, carry fat-soluble vitamins, contribute to texture and mouthfeel, became precursors of flavour and provide a heat-transfer medium - naturally occurring fatty acids have an even number of carbons - short-chain fatty aids are important in doors - long-chain fatty acids are not volatile and do not contribute much to flavour, although their reaction products are especially important to flavour of foods - fatty acids that are unsaturated contain a double bond - one double bond= monounsaturated - two or more double bond = polyunsaturated - unsaturated fatty acids exist in cis or trans forms - cis double bonds are highly reactive with oxygen - the product of lipid oxidation have undesirable flavours and lead to what is rancidity - some food additives inhibit the oxidation of lipids, known as antioxidants - BHT, BHA, vit c, vit e - triglyceride: three molecules of fatty acids connected to a molecule of glycerol - can be broken apart by enzymes called lipases
Image of page 4

Subscribe to view the full document.

- molecule has one fatty acid removed is called a diglyceride, and then mono- - phospholipids: some fatty acids are connected to a glycerol molecule that contains a molecule of phosphorus - cholesterol is a compound produced by the body that has been strongly linked to heart disease - avg. American consumes 400-800 mg/day and synthesizes 1000-2000 mg/day - cholesterol is used by the body for: bile salts, membrane structure, myelin synthesis, vit D synthesis, steroid hormone synthesis - some ppl have genetic problems with the system that regulates choles- terol and they produce excessive amounts Vitamins - chemical compounds found in food that we need in small amounts that regulate chemical reactions in the body - fat-soluble vitamins: -
Image of page 5
Image of page 6

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern