Proteins Flashcards
what is protein?
-forms the components of every living cell
-protein come in various sizes and shapes and are composed of different amino acids joined in various proportions and sequences
what are proteins made of?
-large complex molecules composed of individual building blocks called amino acids
-they are made from hydrogen, oxygen, carbon and nitrogen
what is unique to each to each amino acid?
-their nitrogen component
what does the shape of a protein determine?
-how it functions
how is protein stored?
-as muscle, bone, skin, cartilage and lymph
what is the primary function of protein?
-growth, repair and maintenance of body structures and tissues
-body cells are always making proteins to replace those that are broken down from normal wear
proteins are involved in the manufacturing of? what are some examples?
-hormones such as insulin and epinephrine
plasma proteins maintains what?
-plasma proteins such as albumin maintain fluid and electrolyte balance by attracting water and causing changes in osmotic pressure
in what way may proteins may act as enzymes?
-they may bring about certain chemical reactions such as digestion or protein synthesis
what do amino acids contain? what can these do?
-an acid and a base which can neutralize excesses of either acids bases in the body thereby maintaining a normal pH
what do proteins help transport?
-they help transport other substances through the blood e.g. hemoglobin transports oxygen and lipoproteins transports lipids
what is protein function within the immune system?
-they help to create lymphocytes and antibodies that protect the body from infection and disease
how is protein used as a source of energy?
-can be used as a source of energy 1g=4kcal when intake of carbohydrates and fat is inadequate
how is TVP made?
-made from defatted soya bean flour- the product of soya beans which have their oil removed. it needs to be rehydrated before use
what does TVP stand for?
-Textured vegetable protein
what is the process involved in making TVP?
-defatted flour is mixed to a dough with water
-it is forced through a small hole under pressure
-this cooks the dough, opens up its texture and gives it a fibrous meat like texture
what are examples of foods that contain TVP?
-available in plain or white with a savory meat flavor
-comes in dried granules, mince or chunks
-e.g. bachelors bean feast
what is tofu?
-a soya milk curd the texture, appearance and flavor is very different from meat
-not widely used in the UK
what is the nutritional value of quorn?
-nigh protein food containing less protein on weight for weight basis than meat or fish
what is the proteins levels of TVP comparable to?
-cottage cheese
what are the advantages of eating Quorn for vegetarians / vegans
-good value supplement to cereal based diets as it contains amino acids which may be low in some diets
-good fiber content
what is Quorn products made from?
- made from mycoprotein
what are 8 advantages of using quorn based products?
-good nutritional low fat product
-similar shelf life to meat
-not altered by freezing or cooking
-absorbs flavor
-free from fat, gristle and bone
-ideal for vegetarians
-only needs heating through
-texture and color similar to chicken
how many amino acids does the body need and how many can the body make?
-the body needs 20 amino acids
-it can make 10 called dispensable and these are non essential amino acids (AA)
-the body cannot make 10 and these are called indispensable amino acids which are essential in the diet (IAA’s)
what is a HBV protein? what are the sources of HBV protein?
-a high biological value protein is a food that provides all IAA’s
-mostly from animal sources e.g. meat, poultry, eggs and dairy
what are the only two plant based products that are HBV?
-soya beans and soya products e.g. TVP are HBV
what are LBV proteins and what are the sources of these?
-foods that only provide some of the IAA’s
-plant sources e.g. pulses such as peas, beans and lentils and cereals such as pasta, bread and rice
what is the full definition of protein complementation?
-protein complementation is when two LBV foods e.g. a pulse and a cereal are eaten together in one meal e.g. beans on toast, lentil soup and bread, chickpea curry and rice. The IAA’s in the food will compensate for the limiting IAA’s in the other food resulting in a HBV meal. This is particularly useful for vegetarians and vegans
what is nitrogen balance?
-when the amount of protein made is equal to the amount used, as in healthy adults, the body has a neutral
what results in a positive nitrogen balance?
-if protein synthesis exceeds protein breakdown such as during growth or recovery from injury a positive nitrogen balance exists
what results in a negative nitrogen balance?
-a negative nitrogen balance exists when proteins breakdown exceeds protein synthesis such as during starvation
what are the positives and negatives of eating red meat as a protein source?
-haem iron which is easily absorbed
-LDL cholesterol which can increase risk of CVD
–high in calories which can contribute to weight gain
-no fiber
-too much can increase risk of certain types of cancers
-sat fat which raises cholesterol
what are the positives and negatives for eating Quorn as a protein source?
-fiber which helps maintain blood cholesterol levels
-non haem iron which is not as easily absorbed by the body
-low in calories which helps with weight management
-low in sat fat is it originates from vegetables
-Quorn is free from cholesterol
what are the positives and negatives of eating fish as a protein source?
-HBV protein
-provides EFA’s which are essential for normal brain development in unborn babies, and help maintain a healthy heart by lowering blood pressure
-most fish is low in fat
-haem iron which is easier t absorb
-lean source of protein
-fish has no fiber
-oily fish provide fat soluble vitmains A and D
what are the positives and negative of eating pulses as a protein source?
-LBV however if eaten along with grains result in a HBV meal
-do not provide any EFA’s
-low in fat
-higher iron content than fish however this iron is non haem is is harder to absorb that haem
-excellent source of fiber which helps lower LDL cholesterol and the risk of CVD
-are not good sources of fat soluble or water soluble vitamins
what are the positives and negatives of dairy products in terms of versatility as a protein source?
-used in a number of recipes and as snacks throughout the day
-perishable and must be refrigerated and have a short shelf life
-they do not have a long preparation time
-some people have an allergy to intolerance to dairy products
what are the positives and negatives of pulses in terms of versatility as a protein source?
-can be used in recipes and as snack throughout the day
-long shelf life
-most need to be soaked for at least 24 hrs before use to improve digestibility
-not many have an allergy or intolerance to pulses
