2.3 Cell fractication

Question 1

Cell fractication

Answer 1

• Cell fractionation takes cells apart and
separates the major organelles from one
another
• Centrifuges fractionate cells into their
component parts
• Cell fractionation enables scientists to
determine the functions of organelles

Question 2

Technique

Answer 2

Tissue cells -> homogenization (make a mixture of two mutually non-soluble liquids the same throughout) -> homogenate -> centrifugation

Centrifuged at 1000 g which is 1000 times the force of gravity -> 10 minutes
=> pellet rich in nuclei + cellular debris

supernatant poured into next tube

20 000 g -> 20 minutes
=> pellet rich in mitochondria (+ chloroplasts if plant cells)

80 000 g -> 60 minutes
=> pellet rich in microsomes

150 000 g -> 3 hours
=> pellet rich in ribosomes

Question 3

sucrose gradient fractionation

Answer 3

• velocity centrifugation

- particles of different sizes sediment as discrete bands