Biological Molecules Flashcards
(25 cards)
How do you prepare food samples?
- Break up the food using a pestle and mortar. 2. Transfer to a test tube with distilled water. 3. Mix the food with water by stirring with a glass rod. 4. Filter the mixture using a funnel and filter paper. 5. Collect the solution.
What is the test for lipids?
- Prepare food sample. 2. Add 2 cm³ of ethanol to the food sample. 3. Shake vigorously. 4. Add 2 cm³ of distilled water. 5. A positive result is a cloudy white emulsion forming.
What is the test for glucose?
- Prepare food sample. 2. Add 10 drops of Benedict’s solution to 5 cm³ of food sample. 3. Heat in a water bath of 75°C for 5 minutes. 4. Take the test tube out and observe the color. 5. A positive result shows a color change from blue to brick red.
What are complex carbohydrates like starch and glycogen made up of?
Simple sugars.
What is an amino acid?
An amino acid is a building block of proteins.
What are lipids made up of?
Lipids are made up of glycerol and fatty acids.
What are proteins made up of?
Proteins are made up of amino acids.
What is the enzyme-substrate complex?
The enzyme-substrate complex is formed when a substrate attaches to the active site of an enzyme.
What is a substrate?
A substrate is the reactant of an enzyme-catalyzed reaction.
Describe the effect of pH on the rate of an enzyme-controlled reaction.
The rate of an enzyme-catalyzed reaction is fastest at the optimum pH. If the pH is too high or low, the enzyme will work less efficiently and the active site might be denatured at extremes of pH.
Why does the rate of an enzyme-controlled reaction increase when temperature increases?
As the temperature increases, particles gain more kinetic energy. This increases the chance of collisions between molecules being successful and leading to a reaction.
Describe the effect of temperature on the rate of an enzyme-controlled reaction.
As the temperature increases, so does the rate of reaction. Once the temperature exceeds the optimum, the enzymes denature and the rate of reaction decreases.
What is the active site?
The active site is the region of an enzyme where a specific substrate attaches for the reaction to be catalyzed.
What is denatured?
When an enzyme is denatured, its active site changes shape and can no longer bind to a specific substrate. This results in a loss of enzyme function.
What happens to enzymes at low temperatures?
Enzymes work slowly due to a lack of kinetic energy and collisions between the substrate and the active sites.
What are enzymes?
Enzymes are proteins that act as biological catalysts to speed up the rate of chemical reactions.
What is the effect of heating an enzyme beyond the optimum temperature?
The bonds that hold the enzyme together break, causing it to lose shape and become denatured.
What are four factors that affect enzyme function?
Temperature, pH, substrate concentration, enzyme concentration.
What chemical elements are present in proteins?
Carbon, hydrogen, oxygen, nitrogen, sulfur (CHONS).
What chemical elements are present in carbohydrates?
Carbon, hydrogen, oxygen (CHO).
What chemical elements are present in lipids?
Carbon, hydrogen, oxygen (CHO).
What is the test for proteins?
- Prepare food sample. 2. Add 2 cm³ of Biuret solution to 2 cm³ of food sample. 3. Give gentle shake. 4. Positive result is a color change from blue to violet/purple.
What is the test for starch?
- Prepare food sample. 2. Add a few drops of iodine solution to food sample. 3. Give gentle shake. 4. Positive result is a color change from orange-brown to blue-black.
