Topic:Ultrastructure of eukaryotic cells
Homogenisation and Centrifugation
1st Step - Preparation
Place the tissue in cold, isotonic, buffered solution
- It is cold to reduce enzyme activity
- It being isotonic prevents organelles busting or shrinking as a
result of osmotic gain or loss (must have the same water
potential as the tissue)
- It is buffered to maintain a constant pH
2nd Step - Homogenisation
- The cells are broken up by a homogeniser to release
organelles
- The solution produced is called a homogenate
- The homogenate is then filtered
3rd Step - Centrifugation
- The homogenate is placed in a tube and spun at a high speed
creating a centrifugal force
- 1st spin - The heaviest organelles go to the bottom and form
as a pellet (Nucleus)
- 2nd spin - The fluid left from the first spin also known as the
(supernatant) is removed and spun again, the second heaviest
organelle will form as a pellet
Components of Eukaryotic cells
Nucleus contains Nucleus
DNA - Contains DNA, directs protein synthesis
- Surrounded by a double membrane called the nuclear
envelope protecting DNA containing gaps called nuclear pores
- Largest and most dense organelle
- Usually one per cell
Nucleolus
- Area of the nucleus which produces ribosomes
Mitochondria is Mitochondria
where cellular - Where cellular respiration occurs and releases energy for the
respiration cell
happens - Bound by a double membrane, the inner membrane fold to
form cristae
- Matrix is in the centre
- Has its own strand of DNA
Golgi apparatus Golgi apparatus
is where proteins - Looks like a stack of plates
are stores, - Stores, modifies and packages proteins
modified and Golgi vesicles
Homogenisation and Centrifugation
1st Step - Preparation
Place the tissue in cold, isotonic, buffered solution
- It is cold to reduce enzyme activity
- It being isotonic prevents organelles busting or shrinking as a
result of osmotic gain or loss (must have the same water
potential as the tissue)
- It is buffered to maintain a constant pH
2nd Step - Homogenisation
- The cells are broken up by a homogeniser to release
organelles
- The solution produced is called a homogenate
- The homogenate is then filtered
3rd Step - Centrifugation
- The homogenate is placed in a tube and spun at a high speed
creating a centrifugal force
- 1st spin - The heaviest organelles go to the bottom and form
as a pellet (Nucleus)
- 2nd spin - The fluid left from the first spin also known as the
(supernatant) is removed and spun again, the second heaviest
organelle will form as a pellet
Components of Eukaryotic cells
Nucleus contains Nucleus
DNA - Contains DNA, directs protein synthesis
- Surrounded by a double membrane called the nuclear
envelope protecting DNA containing gaps called nuclear pores
- Largest and most dense organelle
- Usually one per cell
Nucleolus
- Area of the nucleus which produces ribosomes
Mitochondria is Mitochondria
where cellular - Where cellular respiration occurs and releases energy for the
respiration cell
happens - Bound by a double membrane, the inner membrane fold to
form cristae
- Matrix is in the centre
- Has its own strand of DNA
Golgi apparatus Golgi apparatus
is where proteins - Looks like a stack of plates
are stores, - Stores, modifies and packages proteins
modified and Golgi vesicles
