Thursday, October 22, 2015

LC Biology - DNA Extraction

Photos from Ms Higgins' LC class where they extracted DNA from onion cells. Make sure you know all steps involved and why you do each step.

Chopping onion: 
Breaks cell walls, releasing cytoplasm.
Adding washing-up liquid:
Breaks down cell membranes, releases nuclear material from cell.
Adding salt: 
Minimise attractive forces between DNA and protein, causes DNA to clump together.
Heating mixture to 60 °C for exactly fifteen mins:
Break down of DNAses enzymes. After 15 mins DNA broken down.
Cooling mixture: 
Slowing down any other enzymes before they destroy DNA.
Further destroys cell walls and membranes. Causes release of DNA. Blending > 3s cuts DNA strands.
Adding protease:
Breaks down proteins associated with DNA.
Remove large cellular debris. DNA passes through filter with liquid.
Using cold ethanol:
Forms a layer on top of onion filtrate. Alcohol draws water out of DNA molecule, making it less dense - found between two liquids. DNA insoluble in freezing cold ethanol (soluble in alcohol at room temp)
Testing for DNA:
No method of testing for DNA available for use in school labs 

Wednesday, October 21, 2015

Monday, October 19, 2015

JC Physics - Hooke's Law

LC Chemistry - Flame Tests

Some pics from LC Chemistry

LC Biology - Leaf Yeast Experiment

Some pics for Ms Higgins' Biology class.

Friday, October 9, 2015

Wednesday, October 7, 2015

Thursday, October 1, 2015