Chapter 1 - biological molecules Flashcards
1
Q
In which three cases does water act as a solvent
A
- In digestion, allowing enzymes to come into contact with nutrients in food
- In excretion, allowing substances such as urea to be transported out of the body in urine
- In transport, allowing many solutes to be transported in blood plasma, including urea, amino acids and glucose
2
Q
What is the test for carbohydrates
A
- Heat with benedicts solution - if positive a brick-red ppt. is formed
- Add iodine solution - if positive solution becomes a blue-black colour
3
Q
What is the test for fats and oils
A
- Emulsion test: dissolve in ethanol then pour into water - positive test is a milky appearence
*
4
Q
What is the test for proteins
A
- Add biuret solution - turns a purple colour
5
Q
What is the test for vitamin C
A
- Add DCPIP - dark blue DCPIP turns colourless
6
Q
What is the definition of an enzyme
A
A protein that functions as a biological catalyst
7
Q
What is the definition of a catalyst
A
A substance that increases the rate of chemical reaction and is not changed by the reaction
8
Q
How do enzymes work
A
- An enzyme has a complimentry shape to the substrate molecules whose reaction it catalyses
- The substrate molecule binds to the enzyme temporarily; this is called an enzyme-substrate complex
- The enzyme changes the substrate to product and then releases it
- The enzyme is unchanged and can now repeat the process with another molecule of its substrate
9
Q
What occurs when an enzyme is denatured
A
- It loses its shape
10
Q
A
