193256
| Question | Answer |
| Essential Amino Acids | Valine, Lysine, Methionine, Trytophan, Histidine, Threonine, Leucine, Isoleucine,Arginie, Phenylalnine |
| Elemental Composition | Carbon- C Hydrogen- H Oxygen- O Nitrogen- N With traces of iron, sulphur and phosphorus |
| Chemical Composition | Protein composed of amino acids. Amino acids held together by peptide links. each amino acids contains hydrogen, carbon, variable, amino group and a carboxyl group. R donates the variable and changes in every amino acid |
| Basic Structure of amino acid | H=Hydrogen C= Carbon R=Variable NH2= Amino Group COOH= Carboxyl Group |
| Whats an essential amino acids | An amino acid that is not manufactured in the body so has to be taken in by food |
| How many essential amino acids are there? | 10 |
| Whats a non- essential amino acids? | Manufactured in the body and is not obtained from food |
| Peptide Link | Formed when 2 amino acids are joined together |
| How is a peptide link formed? | OH from corboxyl group joins with the H from the amino group. H and OH combine to form water. Called condensation |
| Condensation | When 2 amino acids joined together and h2o molecule lost |
| Hydrolysis | When 2 amino acids are split and h2o molecules are gained |
| Polypeptide Chain | Chain of amino acids joined together |
| Primary Structure | Sequence of amino acids held together by peptide links e.g. insulin |
| Secondary Structure | Occurs when folding of primary structure. Results in definite shape and structure. There are cross links/ bridges present. |
| Disulphide Link | The amino acid cysteine contains sulphur. When 2 cysteine units join together in the same chain or 2 different polypeptide chains are adjacent a disulphide link is formed |
| Hydrogen Bonds | Polypeptide chains can always be linked by 2 hydrogen atoms. The hydrogen in 1 chain joins with the oxygen in the neighbouring chain. e.g. Collagen has hydrogen bonds |
| Tertiary Structure | 3D folding of chain. Structure can be globular or fiborous. Shapes give certain prperties to protein. |
| Globular | Chain rolled like a ball of wool. Structure makes protein soluble. Type of protein found in body cells e.g. myglobin in meat |
| Fiborous | The protein chain is straight, coiled or zig-zaged. makes the protein insoluble and stretchy or tough. e.g. Gluten in wheat has a coiled structure. Collagen in meat has a zig- zag structure |
| Classification of Protein: Simple | Animal - fiborous e.g. collagen (MEAT), Globular e.g. albumin (eggs) |
| Classification of priotein: Simple | Plant- Glutenins- e.g. soluble in acids or alkalis - e.g. gluten (WHEAT) Prolamines- e.g. soluble in alcohol- gliadin (WHEAT) |
| Classification of Protein: Conjugated | Protein+lipid=Lipoproetin e.g. lecithin egg yolk Protein+Phosphate=Phosphoprotein e.g.casein-milk Protein+Nucleic Acid e.g. DNA- deoxyribonuleic Acid Protein+ Carbohydrate=Glycoprotein e.g.ovomucin in egg white Protein+ colour pigment=chromoprotein e.g. hemoglobin in blood |
| Biological Value | Measure of quality of protein. Measured in %. Established by the number of essential amino acids that are present in protein. 2 types HBV and LBV |
| HBV Protein | Contains all essential amino acids.Called complete proteins. Come from animal sources. except: soya beans of plant origin but HBV |
| LBV Protein | Lacks one or more essential amino acid. Called incomplete proteins. LBV come from plant sources. Except: Gelatine animal protein but is LBV |
| Whats is supplementary/complementary value? | When 2 low biological foods combined together give all essential amino acids. e.g. beans on toast. Beans are low in Methionine but high in lysine. Toast is low in lysine and high in Methionine |
| Absorption of Protein | Amino acids pass into blood capillaries of villi in small intestine. Then carried to liver through portal vein. When reach liver used to main and repair liver cells. form new cells and repair tissues. any excess proteins are deaminated in liver |
| Energy Value of Protein | 1g= 4Kcal/17 KJ |
| RDA | 1 gram of protein per 1 kilogram of body weight |
| Deamination | excess protein used for energy, left over amino acids brought to liver. NH2 group broken off changed to ammonia- urea then excreted. Rest of molecule converted to glucose and used for releasing energy. |
| Properties of Protein: Denaturation | Change of a protein. Caused by heat, chemicals and agitation. Irreversible process. |
| Properties of Protein:Heat | Protein sets/ coagulates when heated. e.g. egg white sets when heat added |
| Properties of Protein: Chemicals | Acids, alkali, enzymes and alcohol changes protein structure. e.g. when lemon juice added to milk, the caseinogen curdles |
| Properties of Protein:Agitation | Mechanical action, involves whipping/ whisking. Structure unfolds |
| Properties of Protein: Solubility | Protein insoluble in water except: egg white in cold water and connective tissues- converted to gelatine in hot water |
| Properties of Protein: Maillard Reaction | Known as non- enzymic browning. Occurs when food roasted, grilled and baked. Amino Acid+ carb+ dry heat= brown colour e.g. toast |
| Properties of Protein: Elasticity | Certain proteins have elastic properties e.g. gluten enables bread to rise |
| Properties of Protein: Foam Formation | When egg white whisked, air bubbles formed as protein chains unravel. whisking produces heat, slightly sets egg white. foam will collapse after a while when heat added e.g meringues |
| Properties of Protein: Gel Formation | When heat added collagen forms gelatine. Gelatine forms sol as it absorbs large amounts of water. when cooling, sol becomes solid and gel formed. gels is 3D whereby water becomes trapped e.g. cheesecakes |
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