Cell Structure: Cell Fractionation

Question 1

What is cell fractionation?

Answer 1

= organelles of cells are seperated so that they can studied

Question 2

What is done to the tissue?

Answer 2

= Take sample of the tissue
= homogenise the tissue
=use a blender or homogeniser

Question 3

What does homogenise mean?

Answer 3

= break it up
= break open all of the cells

Question 4

What is a homoginiser?

Answer 4

= Glass tube containing a plunger

Question 5

How does the homoginiser work?

Answer 5

= place tissue sample in glass tube
= cover with a buffer solution to keep ph constant
= water potential of the buffer is the same as the cell- prevents osmosis and bursting cell

Question 6

When then happens to the homoginiser?

Answer 6

= Placed in ice
= enzymes work more slowly and prevents them from destroying cells
= push the plunger up and down to distrupt the tissue and break open the cells

Question 7

What does the cell homogonate contain?

Answer 7

= All the organelles found in cells
= to find what these do they need to be seperated

Question 8

What is the smallest to largest order of organelles?

Answer 8

= ribosomes
= lysosomes
= mitochondria
= nucleus
= ER is very large but gets broken up

Question 9

What is the process of fractionation?

Answer 9

= place the sample with the cell homogonate into centriguge
= centrifuge spins the sample and organelles are flung to the bottom

Question 10

What happens to the larger organelles in the cell homogonate?

Answer 10

= experience greater force
= move towards the bottom of the tube faster than smaller organelles

Question 11

What happens first?

Answer 11

= centrifuge starts with a slow spin
= nuclei form a pellet at the bottom
= remaining organelles remain suspended in the liquid- supernatant.

Question 12

What happens secondly?

Answer 12

= Supernatant is transferred into a new test tube and spun at a higher speed
= pellet contains mitochondria

Question 13

What happens thirdly?

Answer 13

= supernatant is transferred into a new test tube and spun at a higher speed
= pellet contains lysosomes

Question 14

What happens finally?

Answer 14

= supernatant is transferred into a new test tube and spun at a higher speed
= pellet contains ribosomes

Question 15

What are some key points?

Answer 15

= keep the pellets in ice until used- slow down enzymes which may damage the organelles
= difficult to seperate organelles fully
= other organelles such as ER or golgi may be present in fractions