Studying Cells Flashcards
Define Homogenisation
Homogenisation
Breaking of cells
What happens after Homogenisation of cells in ‘ Cell Fractionation ‘
Placed in cold , isotonic , buffered solution
Why are samples of cells placed in a cold solution ?
To stop/ prevent enzyme activity
Why are samples of cells placed in a buffered solution ?
To prevent denaturing of enzymes / proteins
Define the term ‘ Isotonic ‘
Water potential inside cell is equal to the water potential outside the cell
Why are samples of cells placed in an isotonic solution ?
Prevent osmotic damage to organelles
What might happen to cells as a result of not being placed in an isotonic solution ?
Hypertonic solution - Water moves out of cell, shrivelling cell
Hypotonic Solution - Cell swells, Bursts (Animal cells) or becomes Turgid ( Plant Cells )
Where must you blend / homogenise the cells ?
In the cold, isotonic , buffered solution
Why is the solution of homogenised cells filtered before ultracentrifugation ?
Separate large debris that hadn’t been separated in homogenisation
What happens in the first step of ultracentrifugation ?
Centrifuge is spun at a slower speed
Most dense organelles gather as a ‘ pellet ‘ at the bottom
What is the solution inside the centrifuge known as ?
The supernatant
Why are optical microscopes unable to view sub-cellular structures ?
Resolution is too low
Due to longer wavelength of light
Describe how to test for a non-reducing sugar ?
Boil with acid
Neutralise
Heat with benedicts solution
Form brick red colour in high quantities of sugar
