B4 Flashcards
(39 cards)
Test for reducing suagrs
What is an enzyme?
Biological catalyst involved in metabolic reactions. Breaks down large complex insoluble molecules to small simple soluble molecules.
What does it mean for an enzyme to denature?
Loss of functional shape of enzyme, especially active site. Substrate no longer binds to the active site as it no longer fits which decreases/ stops enzyme activity. Temperature/pH are factors.
What is the active site of an enzyme?
Substrate binds to active site where reaction takes place to form the product.
What are carbohydrates?
Main source of energy.
What is the role of proteins?
Growth and repair of muscles.
Made of amino acids (monomers), e.g. insulin.
What are lipids?
Long term energy store, twice as much energy per unit mass as carbohydrates, also used as an insulator.
Made of fatty acids and glycerol (monomers), e.g. triglycerides.
What factors affect enzyme activity?
Temperature and pH level.
How does temperature affect enzyme activity?
As temperature increases, increase in kinetic energy -> higher chance of successful collisions -> rate of reaction increases. At certain temperatures, enzyme activity will fall, enzymes denature. Optimum temperature is where enzyme activity is highest.
How does pH level affect enzyme activity?
Enzymes have an optimum pH. If the environment is too basic or too acidic, the enzyme hydrogen bonds start to break causing the active site to change shape.
What is the test for glucose?
BENEDICT’s TEST: Add 2cm3 of a solution to be tested, add an equal volume of Benedict’s solution, shake, and bring gently to the boil for 3 mins.
POSITIVE RESULT: Blue turns green → yellowish → orange → finally a brick-red.
What is the test for protein?
BIURET’S TEST: Add 2mL of solution to be tested to a test-tube, add an equal volume of sodium hydroxide solution (Biuret 1) and mix, then add 2-3 drops of copper sulphate solution (Biuret 2) slowly down the side of the test tube and mix.
POSITIVE RESULT: A blue ring (after biuret 2) and a purple colour develops slowly on mixing.
What is the test for starch?
IODINE TEST: Add a few drops of iodine to the solution (or food) to test.
POSITIVE RESULT: The initial yellow/brown colour of the iodine turns blue/black if starch is present.
What is the test for lipids?
EMULSION TEST: Add 2mL of ethanol to a test-tube, dissolve the lipid by shaking vigorously, and add an equal volume of cold water.
POSITIVE RESULT: A cloudy white suspension (this is called an emulsion).
What is the large intestine?
Composed of anus, rectum, and colon; absorbs water and salts from undigested food.
Elements present in carbohydrates
Carbon (C), Hydrogen (H) and Oxygen (O)
Elements present in proteins
Carbon (C), Hydrogen (H), Oxygen (O) and Nitrogen (N)
Elements present in lipids
Carbon (C), Hydrogen (H) and Oxygen (O)
Scurvy
Vitamin C Deficiency—weakness, sore gums, bruising
Rickets
Vitamin D Deficiency—curvy bones (vit D facilitates the use of calcium which helps bone growth)
ingestion
taking substances into the body through the mouth
digestion
breaking down food
absorption
movement of food molecules and ions thought the walls of intestine -> bloodstream
assimilation
movement of digested food molecules into cells where they are needed from the bloodstream
