Proteins Flashcards
What are proteins made up of?
Amino Acids
What are the two classifications of protein?
Dispensable
Indispensable
What does dispensable mean?
Synthesised by the body
Non - essential
Convert one amino acid into another - transamination
What does indispensable mean?
Not synthesised by the body
Are essential
Must be provided by the diet
How many indispensable amino acids are there?
8 for adults
9 for children (Histidine for growth)
Why might other amino acids not be synthesised by the body
During illness or injury some amino acids may not be synthesised and have to be provided by the diet.
What is biological value?
The percentage of protein that is absorbed by the body and used for different functions such as growth
Name 3 things the quality of protein food might be judged by:
Protein content
Amount of indispensable/ essential amino acids present
The degree of which protein is digested and absorbed
What are high biological foods?
Contains all the essential/ indispensable amino acids
Where are HBV proteins found
In animal products ( meat, fish, eggs)
What is the only plant source that is an HBV
Soya products
What are low biological foods?
Contains some but not all the essential/ indispensable amino acids.
Where are LBV proteins found?
In plant sources ( rice, peas, lentils)
What is the only animal source of an LBV?
Gelatine
What is the limiting amino acid?
Lysine
What is homeostasis?
This is maintaining a constant internal environment
How are hormones a function of protein?
Needed for the production of hormones
They regulate metabolic processes, blood glucose levels and digestion.
Vasopressin is a hormone involved in homeostasis
How is acid base balance a function of protein?
Proteins are very sensitive to pH levels
If they are outside a suitable level the protein will become denatured, lose its ability to function and death may occur
Why is fluid base balance an important part of homeostasis?
Prevent loss of body fluids, plasma exerts an osmotic effect to hold fluid within circulation. Oedema can occur
Why is immunity an important part of homeostasis?
low immune system = more susceptible to infection.
Children who suffer protein energy malnutrition are more susceptible to infection
Explain the function transport:
Substances attach themselves to proteins
Are carried around the body
E.g. haemoglobin being transported to muscles
Transportation across a cell membrane
Explain the function blood clotting:
Proteins found in plasma e.g. Fibrinogen increase blood clotting factors and reduce prolonged bleeding
Explain the function body structure:
Protein is needed for growth, repair and maintenance.
Protein requirements increase during times of growth
Protein is synthesised and replaced throughout life
Why must proteins be replaced?
Proteins in tissues must be replaced by amino acids provided by the diet because they are constantly being broken down
Explain the function hair, bones and nails:
They are vital in the formation and structure of all cell membranes
What are novel sources of protein?
Mimic the sensory properties of meat (texture, smell, look)
Mostly suitable for vegetarians
What are the two main novel proteins?
Processed plant foods ( soya products)
Produced from micro-organisms (Quorn)
Some nutritional value of fish, meat and eggs:
HBV proteins Omega 3 in fish Fat soluble vitamins (A and D) Haem Iron Zinc, phosphorus, iodine
Dairy products nutritional value:
Calcium
Phosphorus
Vit A (retinol), D, B12
Plant sources nutritional value:
Non-haem iron low in cholesterol low in saturated fat low in calories Dietary Fibre Antioxidants Isoflavones
Nutritional value of soya:
HBV protein Iron Calcium Antioxidants low GI Selenium and potassium
The nutritional value of Quorn:
HBV proteins Low sodium Low iron Low in vit A, B Soluble and Insoluble fibre Calcium Carbs
Why are isoflavones important?
They are thought to reduce risk of cancer and CVD
What is nitrogen balance?
This is the difference between nitrogen input and nitrogen output. The overall indicator of protein metabolism in the body
