3.9 - Cell Fractionation Flashcards
The purpose and process of cell fractionation The steps of cell fractionation (19 cards)
What is cell fractionation?
Laboratory method isolating cell components
What is the purpose of cell fractionation?
To study organelles in detail
What are the four main steps of cell fractionation?
- Sample preparation
- Homogenisation
- Filtration
- Ultracentrifugation
What type of solution is used in sample preparation?
3 Key points
- Ice-cold - This slows down enzyme activity that might otherwise break down organelles.
- Isotonic - It ensures that the water potential inside and outside the organelles is the same, preventing damage through water movement.
- Buffered - Keeping the pH constant is crucial to prevent denaturation of proteins and enzymes.
Why is the solution ice-cold?
To slow down enzyme activity
Why is the solution isotonic?
To prevent damage through water movement
Why is the solution buffered?
To prevent denaturation of proteins and enzymes
What is homogenisation?
Physically breaking open cells
How is homogenisation achieved?
Using a blender to grind cells
What is filtration?
Removing larger pieces of cell debris
What is used for filtration?
The filtration is typically done through a gauze, which allows smaller organelles to pass through while retaining larger debris.
What is ultracentrifugation?
Separating organelles based on density
What is a pellet?
Sediment at the bottom of the tube
What is a supernatant?
Liquid remaining above the pellet
What are the heaviest organelles?
Nuclei
What are the lightest organelles?
Ribosomes
What is the order of organelles from heaviest to lightest?
- Nuclei (heaviest)
- Chloroplasts
- Mitochondria
- Lysosomes
- Endoplasmic reticulum
- Ribosomes (lightest)
How are organelles separated in ultracentrifugation?
By spinning at various speeds
What happens to the supernatant after each spin?
It is transferred to a new tube and centrifuged at a higher speed
