EasyBiologyHigh School (11–12)Biotechnology › Biotechnology: Principles and ProcessesConceptualAPA-LevelIB
A student must isolate DNA from four materials: a culture of Escherichia coli, a leaf of a tomato…
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A student must isolate DNA from four materials: a culture of Escherichia coli, a leaf of a tomato plant, a mould, and a sample of human blood cells that were separated from the plasma. For each material, say which enzyme opens the cell, if one is needed. After that, name the two enzymes that clean the DNA and the liquid that makes it appear.
Need a reminder? The key ideaShow
The enzyme that opens a cell depends on its wall: lysozyme for bacteria, cellulase for plants, chitinase for fungi. Ribonuclease removes RNA, protease removes proteins, and chilled ethanol makes DNA appear. In a gel, DNA moves to the anode, and smaller fragments move farther. In the model of the lesson, distance .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Four materials.
Plan. First decide whether the cell has a wall. Then choose the enzyme.
Step 1. Escherichia coli is a bacterium: lysozyme.
Step 2. The tomato leaf has plant cells with a cellulose wall: cellulase.
Step 3. A mould is a fungus: chitinase.
Step 4. Human blood cells have no wall, so no enzyme is needed to open the wall. The cells are broken more easily.
Step 5. For all four, ribonuclease removes the RNA, protease removes the proteins, and chilled ethanol makes the DNA come out as fine threads.
Answer: lysozyme; cellulase; chitinase; none; then ribonuclease, protease and chilled ethanol.
Watch out. The enzyme for the wall depends on the cell, but the cleaning steps are the same for all.
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